Production and properties of xylanases from Aspergillus terricola Marchal and Aspergillus ochraceus and their use in cellulose pulp bleaching.

Aspergillus terricola and Aspergillus ochraceus, isolated from Brazilian soil, were cultivated in Vogel and Adams media supplemented with 20 different carbon sources, at 30 degrees C, under static conditions, for 120 and 144 h, respectively. High levels of cellulase-free xylanase were produced in birchwood or oat spelt xylan-media. Wheat bran was the most favorable agricultural residue for xylanase production. Maximum activity was obtained at 60 degrees C and pH 6.5 for A. terricola, and 65 degrees C and pH 5.0 for A. ochraceus. A. terricola xylanase was stable for 1 h at 60 degrees C and retained 50% activity after 80 min, while A. ochraceus xylanase presented a t(50) of 10 min. The xylanases were stable in an alkali pH range. Biobleaching of 10 U/g dry cellulose pulp resulted in 14.3% delignification (A. terricola) and 36.4% (A. ochraceus). The brightness was 2.4-3.4% ISO higher than the control. Analysis in SEM showed defibrillation of the microfibrils. Arabinase traces and beta-xylosidase were detected which might act synergistically with xylanase.

Xylanases from Aspergillus niger, Aspergillus niveus and Aspergillus ochraceus produced under solid-state fermentation and their application in cellulose pulp bleaching.

This study describes the production of xylanases from Aspergillus niveus, A. niger, and A. ochraceus under solid-state fermentation using agro-industrial residues as substrates. Enzyme production was improved using a mixture of wheat bran and yeast extract or peptone. When a mixture of corncob and wheat bran was used, xylanase production from A. niger and A. ochraceus increased by 18%. All cultures were incubated at 30 degrees C at 70-80% relative humidity for 96 h. For biobleaching assays, 10 or 35 U of xylanase/g dry cellulose pulp were incubated at pH 5.5 for 1 or 2 h, at 55 degrees C. The delignification efficiency was 20%, the brightness (percentage of ISO) increased two to three points and the viscosity was maintained confirming the absence of cellulolytic activity. These results indicated that the use of xylanases could help to reduce the amount of chlorine compounds used in cellulose pulp treatment.

[Electrical stimulation and swimming in the acute phase of axonotmesis: their influence on nerve regeneration and functional recovery]. / Estimulación eléctrica y natación en la fase aguda de la axonotmesis: influencia sobre la regeneración nerviosa y la recuperación funcional.

INTRODUCTION: Little attention has been given to the influence of low-frequency phasic electrical stimulation (LFPES) and physical exercise on the quality of peripheral nerve regeneration and functional recovery. AIM. To evaluate the influence of LFPES, swimming and the association between the two in terms of the morphology of the regenerated sciatic nerve following axonotmesis. MATERIALS AND METHODS: Thirty Wistar mice (222.05 +/- 42.2 g) were distributed into groups: control (C), denervated (D), denervated + swimming (DS), denervated + electrostimulation (DE) and denervated + swimming + electrostimulation (DSE). After 24 hours of axonotmesis, the soleus muscle of the DE and DSE groups was stimulated electrically. The DS and DSE groups swam over a period of 22 days. The number of axons, morphometric data on the nerve and the functional index of the sciatic nerve (FIS) were evaluated. RESULTS: The number of axons in the denervated groups was higher than in the control group, and in the DE group the figure was higher than in the D group. The axonal diameter was smaller in the denervated groups, yet in the DS group it was higher than in the D group. The other morphometric parameters were quite similar to those of the C group. The FIS between days 7 and 14 of the post-operative period was different to the pre-operative index and that measured on day 21 of the post-operative period; the DSE group, however, differed from the pre-operative values. CONCLUSIONS: Swimming and LFPES, applied on an individual basis, do not affect the maturation of the regenerated fibres or functional recovery. LFPES favoured axonal regeneration and combining the treatments delayed functional recovery without having any influence on nerve regeneration.

Estimulación eléctrica y natación en la fase aguda de la axonotmesis: influencia sobre la regeneración nerviosa y la recuperación funcional / Electrical stimulation and swimming in the acute phase of axonotmesis: Their influence on nerve regeneration and functional recovery

Introducción. Poco se ha discutido sobre la influencia de la estimulación eléctrica fásica de baja frecuencia (EEFBF) y del ejercicio físico sobre la calidad de la regeneración nerviosa periférica y la recuperación funcional. Objetivo. Evaluar la influencia de la EEFBF, de la natación y de la asociación entre ambas con respecto a la morfología del nervio isquiático regeneradotras la axonotmesis. Materiales y métodos. Treinta ratones Wistar (222,05 ± 42,2 g) se distribuyeron en grupos: control (C), denervado (D), denervado + natación (DN), denervado + electroestimulación (DE) y denervado + natación + electroestimulación (DNE). Después de 24 horas de la axonotmesis, se electroestimuló el músculo sóleo de los grupos DE y DNE. Los grupos DN y DNE nadaron durante 22 días. Se evaluó el número de axones, los datos morfométricos del nervio y el índice funcional del nervio ciático (IFC). Resultados. El número de axones en los grupos denervados fue mayor que en el grupo control, y en el grupo DE fue mayor que en el D. El diámetro axonal fue menor en los grupos denervados; sin embargo, en el grupo DN fue mayor que en el D. Los demás parámetros morfométricos no fueron muy diferentes a los del grupo C. El IFC entre los días 7 y 14 del postoperatorio difirió del índice preoperatorio y el día 21 postoperatorio; sin embargo, el grupo DNE difirió del preoperatorio. Conclusiones. La natación y la EEFBF aplicadas individualmente no interfieren en la maduración delas fibras regeneradas o en la recuperación funcional. La EEFBF favoreció la regeneración axonal, y la asociación de los tratamientos retrasó la recuperación funcional, sin influir en la regeneración nerviosa

Introduction. Little attention has been given to the influence of low-frequency phasic electrical stimulation (LFPES) and physical exercise on the quality of peripheral nerve regeneration and functional recovery. Aim. To evaluate the influence of LFPES, swimming and the association between the two in terms of the morphology of the regenerated sciatic nervefollowing axonotmesis. Materials and methods. Thirty Wistar mice (222.05 ± 42.2 g) were distributed into groups: control (C),denervated (D), denervated + swimming (DS), denervated + electrostimulation (DE) and denervated + swimming + electrostimulation (DSE). After 24 hours of axonotmesis, the soleus muscle of the DE and DSE groups was stimulated electrically. The DS and DSE groups swam over a period of 22 days. The number of axons, morphometric data on the nerve and the functional index of the sciatic nerve (FIS) were evaluated. Results. The number of axons in the denervated groups was higher than in the control group, and in the DE group the figure was higher than in the D group. The axonal diameter was smaller in the denervated groups, yet in the DS group it was higher than in the D group. The other morphometric parameters were quitesimilar to those of the C group. The FIS between days 7 and 14 of the post-operative period was different to the pre-operative index and that measured on day 21 of the post-operative period; the DSE group, however, differed from the pre-operative values. Conclusions. Swimming and LFPES, applied on an individual basis, do not affect the maturation of the regenerated fibres or functional recovery. LFPES favoured axonal regeneration and combining the treatments delayed functional recoverywithout having any influence on nerve regeneration

O efeito do intervalo da estimulação elétrica no músculo desnervado de rato / The effect of time interval between electrical stimulation on the denervated rat muscle

OBJETIVO: Comparar o efeito da estimulação elétrica (EE) aplicada diariamente e em dias alternados na densidade de área do tecido conjuntivo (TC) e na área de secção transversa (AST) das fibras do músculo desnervado. MATERIAIS E MÉTODOS: Trinta e cinco ratos foram divididos em grupos controle (C), desnervado (D), desnervado + eletroestimulado diariamente (EED) e desnervado + eletroestimulado em dias alternados (EEA). A aplicação da EE no músculo gastrocnêmio teve início 24 horas após lesão nervosa do tipo axoniotmese, sendo a mesma aplicada durante 20 e 30 dias. Cortes transversais foram corados com HE para mensurações da AST e densidade de área de TC. Análise estatística: teste Shapiro Wilk, seguido pela análise de variância (ANOVA) F (one-way) e teste de Tukey (5 por cento). RESULTADOS: Na análise da densidade de área do TC, observou-se que somente o Grupo EED apresentou valores similares ao Grupo C nos dois períodos analisados. No Grupo 20 dias, não houve diferença na AST quando comparados os grupos submetidos à EE com o Grupo D (p> 0,05), e após 30 dias todos os grupos experimentais alcançaram valores similares ao Grupo C. CONCLUSÕES: A EE não foi eficiente para minimizar a atrofia das fibras musculares. Entretanto, o TC foi responsivo à EE, sendo a aplicação diária mais benéfica ao músculo do que a aplicação em dias alternados, sugerindo que o intervalo de aplicação da EE em músculo desnervado é variável importante para as adaptações do TC.

OBJECTIVE: To compare the effect of electrical stimulation (ES) applied daily and on alternate days, on the area density of the connective tissue (CT) and on the cross-sectional area (CSA) of the denervated muscle fibers. METHODS: Thirty-five rats were divided into the following groups: control (C), denervated (D), denervated + daily electrical stimulation (D+DES) and denervated + alternate-day electrical stimulation (D+ES). The application of ES on the gastrocnemius was started 24 hours after nerve damage of axonotmesis type and was applied for 20 and 30 days. Cross-sections were stained with hematoxylin-eosin to measure the CSA and area density of CT. The statistical analysis consisted of the Shapiro Wilk test followed by analysis of variance (ANOVA) F (one-way) and the Tukey test (p< 0.05). RESULTS: Analysis of the area density of CT showed that only the D+DES Group presented values similar to those of the C Group, for the two analysis periods. There was no difference in CSA in the 20-day Group between the ES Groups and the D Group (p> 0.05). After 30 days, all the experimental groups reached CSA values similar to the C Group. CONCLUSIONS: The ES was inefficient for minimizing the muscle fiber atrophy. However, the CT was responsive to ES, and daily applications were more beneficial for the muscle than were alternate-day applications, thus suggesting that the interval for applying ES to denervated muscle is an important variable for CT adaptation.