HISTOLOGIC EVALUATION OF END-TO-SIDE NEURORRHAPHY. EXPERIMENTAL STUDY IN RATS

Objective: The aim of this study was to histologically compare the axonal sprouting after end-to-side neurorrhaphy with or without epineurotomy. Methods: twenty male Wistar rats were used, divided into two groups of 10 rats each. A 1.0cm segment of the tibial nerve E was dried and sutured on the opposite side, where it was sutured into the sciatic nerve D. In Group I, the suture was made directly in the epineurium and in Group II, epineurotomy was performed. After 4 weeks, histological evaluation was carried out of the transposed segment and the sciatic nerve distal to the suture. Results: the results showed a small number of remyelinated fibers, varying from 7 to 51 fibers in Group I and from 10 to 91 fibers in Group II. The Mann-Whitney U test was used, with p=0.311, showing there is no statistically significant difference between the two groups. There was no positive relation between the number of remyelinated fibers in the graft and in the suture site distal to the sciatic lesion. Conclusion: lateral-ending neurorrhaphy, with or without epineural window, does not promote efficient remyelinization. Level of Evidence: Level II, prospective comparative study.

Myeloperoxidase as Inflammatory Marker of Periodontal Disease: Experimental Study in Rats

Rationale: Previous studies have used myeloperoxidase (MPO) as an inflammatory marker to estimate the accumulation of neutrophils in inflamed regions. Objective: The aim of this experimental study was to quantify the levels of MPO related to experimental periodontal disease in rats. Methods: Periodontal disease was induced in a group of rats using placement of a ligature around molar teeth. A group of rats without ligature placement served as a control. Measurements were made on the 3rd, 7th, 15th and 30th day from baseline. Gingival tissues were taken for quantification of MPO levels by ELISA. Results: The rats with induced periodontal disease showed statistically higher MPO levels (p 0.05) when compared to control rats. A significant increase in the levels of MPO released on days 7 and 30 was observed, with higher levels in the group with induced periodontitis. Conclusion: The levels of MPO were found to be higher in rats with induced periodontal disease, confirming the hypothesis that MPO may serve as an inflammatory marker for periodontitis.

Azo-group dihedral angle torsion dependence on temperature: A theorerical-experimental study

Quantum chemical calculations were carried out to explain the observed shifts in the absorption spectrum of different azo-aromatic compounds due to changes in the dihedral angle of the azo-group. Our results reveal that the pi-pi* transition presents a hypsochromic shift and an oscillator strength drop upon increase of the dihedral angle. Nevertheless, the pi-pi* transition exhibits the opposite behavior. This effect is attributed to the reduction in the pi-electron conjugation length of the molecule. Experimentally, we performed temperature dependence measurements of the linear absorption spectrum. Both the theoretical and experimental results demonstrate that small energy changes are mirrored in the electronic transitions of conjugated linear molecules. (C) 2010 Elsevier B.V. All rights reserved.

Photocatalytic degradation of methylene blue by TiO(2)-Cu thin films: Theoretical and experimental study

In this work the effect of doping concentration and depth profile of Cu atoms on the photocatalytic and surface properties of TiO(2) films were studied. TiO(2) films of about 200 nn thickness were deposited on glass substrates on which a thin Cu layer (5 nm) was deposited. The films were annealed during 1 s to 100 degrees C and 400 degrees C, followed by chemical etching of the Cu film. The grazing incidence X-ray fluorescence measurements showed a thermal induced migration of Cu atoms to depths between 7 and 31 nm. The X-ray photoelectron spectroscopy analysis detected the presence of TiO(2), Cu(2)O and Cu(0) phases and an increasing Cu content with the annealing temperature. The change of the surface properties was monitored by the increasing red-shift and absorption of the ultraviolet-visible spectra. Contact angle measurements revealed the formation of a highly hydrophilic surface for the film having a medium Cu concentration. For this sample photocatalytic assays, performed by methylene blue discoloration, show the highest activity. The proposed mechanism of the catalytic effect, taking place on Ti/Cu sites, is supported by results obtained by theoretical calculations. (C) 2010 Elsevier B.V. All rights reserved.

Photocatalytic decomposition of methylene blue via Fenton mechanisms by silicon wafer doped with Au and Cu: a theoretical and experimental study

In this work, we studied the photocatalytic and the structural aspects of silicon wafers doped with Au and Cu submitted to thermal treatment. The materials were obtained by deposition of metals on Si using the sputtering method followed by fast heating method. The photocatalyst materials were characterized by synchrotron-grazing incidence X-ray fluorescence, ultraviolet-visible spectroscopy, X-ray diffraction, and assays of H(2)O(2) degradation. The doping process decreases the optical band gap of materials and the doping with Au causes structural changes. The best photocatalytic activity was found for thermally treated material doped with Au. Theoretical calculations at density functional theory level are in agreement with the experimental data.

Nervo alógeno conservado em glicerol: estudo experimental em ratos

A utilização de aloenxerto de nervo conservado em glicerol é uma alternativa a auto-enxertia em casos de lesões de nervos periféricos com perda de substância que diminui a morbidade cirúrgica e provem material suficiente para a reparação neural. O objetivo deste trabalho foi comparar o grau de reparação nervosa, utilizando análises histológica e funcional, através da interposição de enxerto autógeno (grupo A), de tubo de veia conservada em glicerol (grupo B) e de interposição de nervo alógeno conservado em glicerol (grupo C) em defeitos de 5 mm no nervo fibular de ratos Wistar. A análise histológica foi feita após o sacrifício dos animais( 6 semanas) , usando o corante azul de toluidina a 1%. No grupo A (auto-enxerto) verificou-se reação tecidual perineural e escape de fibras axonais mielinizadas para fora dos limites do epineuro que foi maior se comparada ao verificado no Grupo B (Veia autógena + glicerol) e Grupo C (aloenxerto de nervo).A avaliação funcional foi feita através da análise dos padrões das pegadas das patas posteriores dos ratos ("Walking Track Analysis"), nos períodos: pré-operatório, pós-operatório imediato, na terceira e sexta semanas. Na recuperação funcional, não houve diferença estatisticamente significativa entre os três grupos em nenhum dos períodos avaliados.

Avaliação histológica da neurorrafia término-lateral: estudo experimental em ratos

OBJETIVO: Realizar estudo histológico comparando o crescimento axonal após neurorrafia término-lateral com e sem epineurectomia. MÉTODOS: foram utilizados vinte ratos Wistar, machos, divididos em dois grupos de 10 ratos cada. Um segmento de 1,0cm do nervo tibial e, foi transposto para o lado contralateral, sendo suturado no nervo ciático D. No grupo I, a sutura foi realizada diretamente no epineuro, enquanto que no grupo II foi realizado epineurectomia. Após 4 semanas foi realizado avaliação histológica do segmento transposto e no nervo ciático D, no sitio distal à lesão. RESULTADOS: demonstrou-se baixa quantidade de fibras remielinizadas, variando de 7 a 51 fibras no Grupo I e de 10 a 91 fibras no Grupo II. Utilizou-se o teste U de Mann-Whitney, com p=0,31, demonstrando que não há diferença estatisticamente significante entre os dois grupos. Não há relação positiva entre o número de fibras remielinizadas no enxerto e no sitio distal à lesão do ciático. CONCLUSÃO: A neurorrafia término-lateral, com e sem janela epineural, não promove remielinização eficiente. Nivel de evidência: Nível II: Estudo prospectivo comparativo

Estudo experimental do movimento de partículas carregadas em campos elétricos e magnéticos: seletor de velocidades

Neste trabalho é apresentado um experimento incluído no contexto de experimentos longos adotado nas disciplinas experimentais de eletricidade, magnetismo e óptica, e consiste na caracterização de um seletor de velocidades que funciona com campos elétricos e magnéticos cruzados. Utiliza-se um tubo de raios catódicos para gerar um feixe de elétrons. As placas de deflexão vertical do tubo geram o campo elétrico e um par de bobinas, com os eixos perpendiculares ao eixo do tubo, gera o campo magnético. São realizados estudos de trajetória dos elétrons com auxílio de um programa de simulação de elétrons.

Experimental evaluation on the oil influence in capillary tubes

This work presents the results of an experimental study on pure refrigerant R-134a and refrigerant-oil mixtures flowing through capillary tubes in order to analyse the oil influence in component performance. Tests were carried out for capillary tubes internal diameters of 0.69 mm and 0.82 mm, condensing temperatures ranging from 40 degrees C to 50 degrees C, and subcooling degrees between 3 degrees C and 12 degrees C. Pure refrigerant flow measurements were compared to those for refrigerant-oil mixtures with oil concentrations of 1.0% and 3.0%. (C) 2009 Elsevier Ltd. All rights reserved.

IS SPLENECTOMY A DYSLIPIDEMIC INTERVENTION? EXPERIMENTAL RESPONSE OF SERUM LIPIDS TO DIFFERENT DIETS AND OPERATIONS

Spleen removal may be recommended during organ transplantation in ABO-incompatible recipients as well as for hypoperfusion of the grafted liver, besides conventional surgical indications, but elevation of serum lipids has been observed in certain contexts. Aiming to analyze the influence of two dietary regimens on lipid profile, an experimental study was conducted. Methods: Male Wistar rats (n = 86, 333.0 +/- 32.2 g) were divided in four groups: group 1: controls; group 2: sham operation; group 3: total splenectomy; group 4: subtotal splenectomy with upper pole preservation; subgroups A (cholesterol reducing chow) and B (cholesterol-rich mixture) were established, and diet was given during 90 days. Total cholesterol (Tchol), high-density lipoprotein (HDL), low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL), and triglycerides were documented. Results: After total splenectomy, hyperlipidemia ensued with cholesterol-reducing chow. Tchol, LDL, VLDL, triglycerides, and HDL changed from 56.4 +/- 9.2, 24.6 +/- 4.7, 9.7 +/- 2.2, 48.6 +/- 11.1, and 22.4 +/- 4.3 mg/dL to 66.9 +/- 11.4, 29.9 +/- 5.9, 10.9 +/- 2.3, 54.3 +/- 11.4, and 26.1 +/- 5.1 mg/dL, respectively. Upper pole preservation inhibited abnormalities of Tchol, HDL, VLDL, and triglycerides, and LDL decreased (23.6 +/- 4.9 vs. 22.1 +/- 5.1, P = 0.002). Higher concentrations were triggered by splenectomy and cholesterol-enriched diet (Tchol 59.4 +/- 10.1 vs. 83.9 +/- 14.3 mg/dL, P = 0.000), and upper-pole preservation diminished without abolishing hyperlipidemia (Tchol 55.9 +/- 10.0 vs. 62.3 +/- 7.8, P = 0.002). Conclusions: After splenectomy, hyperlipidemia occurred with both diets. Preservation of the upper pole tended to correct dyslipidemia in modality A and to attenuate it in subgroup B. (c) 2008 Wiley-Liss, Inc. Microsurgery 29:154-160, 2009.

Pulmonary lesion induced by low and high positive end-expiratory pressure levels during protective ventilation in experimental acute lung injury

Objective: To investigate the effects of low and high levels of positive end-expiratory pressure (PEEP), without recruitment maneuvers, during lung protective ventilation in an experimental model of acute lung injury (ALI). Design: Prospective, randomized, and controlled experimental study. Setting: University research laboratory. Subjects: Wistar rats were randomly assigned to control (C) [saline (0.1 ml), intraperitoneally] and ALI [paraquat (15 mg/kg), intra peritoneally] groups. Measurements and Main Results: After 24 hours, each group was further randomized into four groups (six rats each) at different PEEP levels = 1.5, 3, 4.5, or 6 cm H(2)O and ventilated with a constant tidal volume (6 mL/kg) and open thorax. Lung mechanics [static elastance (Est, L) and viscoelastic pressure (Delta P2, L)] and arterial blood gases were measured before (Pre) and at the end of 1-hour mechanical ventilation (Post). Pulmonary histology (light and electron microscopy) and type III procollagen (PCIII) messenger RNA (mRNA) expression were measured after 1 hour of mechanical ventilation. In ALI group, low and high PEEP levels induced a greater percentage of increase in Est, L (44% and 50%) and Delta P2, L (56% and 36%) in Post values related to Pre. Low PEEP yielded alveolar collapse whereas high PEEP caused overdistension and atelectasis, with both levels worsening oxygenation and increasing PCIII mRNA expression. Conclusions: In the present nonrecruited ALI model, protective mechanical ventilation with lower and higher PEEP levels than required for better oxygenation increased Est, L and Delta P2, L, the amount of atelectasis, and PCIII mRNA expression. PEEP selection titrated for a minimum elastance and maximum oxygenation may prevent lung injury while deviation from these settings may be harmful. (Crit Care Med 2009; 37:1011-1017)

Recruitment maneuver in pulmonary and extrapulmonary experimental acute lung injury

Objective. The aim of this study is to test the hypothesis that recruitment maneuvers (RMs) might act differently in models of pulmonary (p) and extrapulmonary (exp) acute lung injury (ALI) with similar transpulmonary pressure changes. Design: Prospective, randomized, controlled experimental study. Setting. University research laboratory. Subjects: Wistar rats were randomly divided into four groups. In control groups, sterile saline solution was intratracheally (0.1 mL, Cp) or intraperitoneally (1 mL, Cexp) injected, whereas ALI animals received Escherichia coli lipopolysaccharide intratracheally (100 jig, ALIp) or intraperitoneally (1 mg, ALIexp). After 24 hrs, animals were mechanically ventilated (tidal volume, 6 mL/kg; positive end-expiratory pressure, 5 cm H2O) and three RMs (pressure inflations to 40 cm H2O for 40 secs, 1 min apart) applied. Measurements and Main Results. Pao(2), lung resistive and viscoelastic pressures, static elastance, lung histology (light and electron microscopy), and type III procollagen messenger RNA expression in pulmonary tissue were measured before RMs and at the end of 1 hr of mechanical ventilation. Mechanical variables, gas exchange, and the fraction of area of alveolar collapse were similar in both ALI groups. After RMs, lung resistive and viscoelastic pressures and static elastance decreased more in ALIexp (255%,180%, and 118%, respectively) than in ALIp (103%, 59%, and 89%, respectively). The amount of atelectasis decreased more in ALIexp than in ALIp (from 58% to 19% and from 59% to 33%, respectively). RMs augmented type III procollagen messenger RNA expression only in the ALIp group (19%), associated with worsening in alveolar epithelium injury but no capillary endothelium lesion, whereas the ALIexp group showed a minor detachment of the alveolar capillary membrane. Conclusions. Given the same transpulmonary pressures, RMs are more effective at opening collapsed alveoli in ALIexp than in ALIp, thus improving lung mechanics and oxygenation with limited damage to alveolar epithelium.

Impact of pressure profile and duration of recruitment maneuvers on morphofunctional and biochemical variables in experimental lung injury

Objective: To investigate the effects of the rate of airway pressure increase and duration of recruitment maneuvers on lung function and activation of inflammation, fibrogenesis, and apoptosis in experimental acute lung injury. Design: Prospective, randomized, controlled experimental study. Setting: University research laboratory. Subjects: Thirty-five Wistar rats submitted to acute lung injury induced by cecal ligation and puncture. Interventions: After 48 hrs, animals were randomly distributed into five groups (seven animals each): 1) nonrecruited (NR); 2) recruitment maneuvers (RMs) with continuous positive airway pressure (CPAP) for 15 secs (CPAP15); 3) RMs with CPAP for 30 secs (CPAP30); 4) RMs with stepwise increase in airway pressure (STEP) to targeted maximum within 15 secs (STEP15); and 5) RMs with STEP within 30 secs (STEP30). To perform STEP RMs, the ventilator was switched to a CPAP mode and positive end-expiratory pressure level was increased stepwise. At each step, airway pressure was held constant. RMs were targeted to 30 cm H(2)O. Animals were then ventilated for 1 hr with tidal volume of 6 mL/kg and positive end-expiratory pressure of 5 cm H(2)O. Measurements and Main Results: Blood gases, lung mechanics, histology (light and electronic microscopy), interleukin-6, caspase 3, and type 3 procollagen mRNA expressions in lung tissue. All RMs improved oxygenation and lung static elastance and reduced alveolar collapse compared to NR. STEP30 resulted in optimal performance, with: 1) improved lung static elastance vs. NR, CPAP15, and STEP15; 2) reduced alveolar-capillary membrane detachment and type 2 epithelial and endothelial cell injury scores vs. CPAP15 (p < .05); and 3) reduced gene expression of interleukin-6, type 3 procollagen, and caspase 3 in lung tissue vs. other RMs. Conclusions: Longer-duration RMs with slower airway pressure increase efficiently improved lung function, while minimizing the biological impact on lungs. (Crit Care Med 2011; 39:1074-1081)

Recruitment maneuver in experimental acute lung injury: The role of alveolar collapse and edema

Objective: In acute lung injury, recruitment maneuvers have been used to open collapsed lungs and set positive end-expiratory pressure, but their effectiveness may depend on the degree of lung injury. This study uses a single experimental model with different degrees of lung injury and tests the hypothesis that recruitment maneuvers may have beneficial or deleterious effects depending on the severity of acute lung injury. We speculated that recruitment maneuvers may worsen lung mechanical stress in the presence of alveolar edema. Design: Prospective, randomized, controlled experimental study. Setting: University research laboratory. Subjects: Thirty-six Wistar rats randomly divided into three groups (n = 12 per group). Interventions: In the control group, saline was intraperitoneally injected, whereas moderate and severe acute lung injury animals received paraquat intraperitoneally (20 mg/kg [moderate acute lung injury] and 25 mg/kg [severe acute lung injury]). After 24 hrs, animals were further randomized into subgroups (n = 6/each) to be recruited (recruitment maneuvers: 40 cm H(2)O continuous positive airway pressure for 40 secs) or not, followed by 1 hr of protective mechanical ventilation (tidal volume, 6 mL/kg; positive end-expiratory pressure, 5 cm H(2)O). Measurements and Main Results: Only severe acute lung injury caused alveolar edema. The amounts of alveolar collapse were similar in the acute lung injury groups. Static lung elastance, viscoelastic pressure, hyperinflation, lung, liver, and kidney cell apoptosis, and type 3 procollagen and interleukin-6 mRNA expressions in lung tissue were more elevated in severe acute lung injury than in moderate acute lung injury. After recruitment maneuvers, static lung elastance, viscoelastic pressure, and alveolar collapse were lower in moderate acute lung injury than in severe acute lung injury. Recruitment maneuvers reduced interleukin-6 expression with a minor detachment of the alveolar capillary membrane in moderate acute lung injury. In severe acute lung injury, recruitment maneuvers were associated with hyperinflation, increased apoptosis of lung and kidney, expression of type 3 procollagen, and worsened alveolar capillary injury. Conclusions: In the presence of alveolar edema, regional mechanical heterogeneities, and hyperinflation, recruitment maneuvers promoted a modest but consistent increase in inflammatory and fibrogenic response, which may have worsened lung function and potentiated alveolar and renal epithelial injury. (Crit Care Med 2010; 38: 2207-2214)

Indirect study of (p, alpha) and (n, alpha) reactions induced on boron isotopes

Several experiments were performed to investigate both (p, alpha) and (n, alpha) reactions induced on boron isotopes, by means of Quasi-Free (QF) reactions induced on deuteron target. The experimental study of the astrophysically relevant, (11)B(p, alpha(0))(8)Be reaction was performed by selecting the QF-contribution on the (2)H((11)B, alpha(8)(0)Be)n reaction. Moreover, due to the large interest of a better understanding of (n, alpha) reactions both for nuclear and astrophysical developments, a preliminary study of the (10)B(n, alpha)(7)Li through the QF (2)H((10)B, alpha(7)Li)p reaction was also performed. The results concerning the two experiments will be shown and discussed.