Reversal by methylene blue of tetanic fade induced in cats by nitric oxide

Previous data from our laboratory have indicated that nitric oxide (NO) acting at the presynaptic level increases the amplitude of muscular contraction (AMC) of the phrenic-diaphragm preparations isolated from indirectly stimulated rats, but, by acting at the postsynaptic level, it reduces the AMC when the preparations are directly stimulated. In the present study we investigated the effects induced by NO when tetanic frequencies of stimulation were applied to in vivo preparations (sciatic nerve-anterior tibial muscle of the cat). Intra-arterial injection of NO (0.75-1.5 mg/kg) induced a dose-dependent increase in the Wedensky inhibition produced by high frequencies of stimulation applied to the motor nerve. Intra-arterial administration of 7.2 µg/kg methylene blue did not produce any change in AMC at low frequencies of nerve stimulation (0.2 Hz), but antagonized the NO-induced Wedensky inhibition. The experimental data suggest that NO-induced Wedensky inhibition may be mediated by the guanylate cyclase-cGMP pathway

Use of magnitude-squared coherence to identify the maximum driving response band of the somatosensory evoked potential

The present study proposes to apply magnitude-squared coherence (MSC) to the somatosensory evoked potential for identifying the maximum driving response band. EEG signals, leads [Fpz'-Cz'] and [C3'-C4'], were collected from two groups of normal volunteers, stimulated at the rate of 4.91 (G1: 26 volunteers) and 5.13 Hz (G2: 18 volunteers). About 1400 stimuli were applied to the right tibial nerve at the motor threshold level. After applying the anti-aliasing filter, the signals were digitized and then further low-pass filtered (200 Hz, 6th order Butterworth and zero-phase). Based on the rejection of the null hypothesis of response absence (MSC(f) > 0.0060 with 500 epochs and the level of significance set at a = 0.05), the beta and gamma bands, 15-66 Hz, were identified as the maximum driving response band. Taking both leads together ("logical-OR detector", with a false-alarm rate of a = 0.05, and hence a = 0.0253 for each derivation), the detection exceeded 70% for all multiples of the stimulation frequency within this range. Similar performance was achieved for MSC of both leads but at 15, 25, 35, and 40 Hz. Moreover, the response was detected in [C3'-C4'] at 35.9 Hz and in [Fpz'-Cz'] at 46.2 Hz for all members of G2. Using the "logical-OR detector" procedure, the response was detected at the 7th multiple of the stimulation frequency for the series as a whole (considering both groups). Based on these findings, the MSC technique may be used for monitoring purposes.

Opioidergic orofacial antinociception induced by electroacupuncture at acupoint St36

The participation of opioids in the antinociceptive effect of electroacupuncture was evaluated in terms of nociception produced by thermal stimuli applied to the face of male Wistar rats, weighing 180-230 g. Electrical stimulation (bipolar and asymmetric square wave with 0.5 mA intensity for 20 min) of acupoint St36, located in the anterior tibial muscle 10 mm distal to the knee joint, induced antinociception in the present model, which was maintained for 150 min. Acupoint LI4, located in the junction of the first and second metacarpal bones, did not achieve antinociception at any frequency studied (5 Hz: 1.7 ± 0.1; 30 Hz: 1.8 ± 0.1; 100 Hz: 1.7 ± 0.1 vs 1.4 ± 0.2). The antinociception obtained by stimulation of acupoint St36 was only achieved when high frequency 100 Hz (3.0 ± 0.2 vs 1.0 ± 0.1) was used, and not with 5 or 30 Hz (1.2 ± 0.2 and 0.7 ± 0.1 vs 1.0 ± 0.1). The antinociceptive effect of acupuncture occurred by opioid pathway activation, since naloxone (1 and 2 mg/kg, subcutaneously) antagonized it (1.8 ± 0.2 and 1.7 ± 0.2 vs 3.0 ± 0.1).

Diabetes mellitus affects the biomechanical function of the callus and the expression of TGF-beta1 and BMP2 in an early stage of fracture healing

Transforming growth factor beta 1 (TGF-β1) and bone morphogenetic protein-2 (BMP-2) are important regulators of bone repair and regeneration. In this study, we examined whether TGF-β1 and BMP-2 expressions were delayed during bone healing in type 1 diabetes mellitus. Tibial fractures were created in 95 diabetic and 95 control adult male Wistar rats of 10 weeks of age. At 1, 2, 3, 4, and 5 weeks after fracture induction, five rats were sacrificed from each group. The expressions of TGF-β1 and BMP2 in the fractured tibias were measured by immunohistochemistry and quantitative reverse-transcription polymerase chain reaction, weekly for the first 5 weeks post-fracture. Mechanical parameters (bending rigidity, torsional rigidity, destruction torque) of the healing bones were also assessed at 3, 4, and 5 weeks post-fracture, after the rats were sacrificed. The bending rigidity, torsional rigidity and destruction torque of the two groups increased continuously during the healing process. The diabetes group had lower mean values for bending rigidity, torsional rigidity and destruction torque compared with the control group (P<0.05). TGF-β1 and BMP-2 expression were significantly lower (P<0.05) in the control group than in the diabetes group at postoperative weeks 1, 2, and 3. Peak levels of TGF-β1 and BMP-2 expression were delayed by 1 week in the diabetes group compared with the control group. Our results demonstrate that there was a delayed recovery in the biomechanical function of the fractured bones in diabetic rats. This delay may be associated with a delayed expression of the growth factors TGF-β1 and BMP-2.

Analysis of fracture healing in osteopenic bone caused by disuse: experimental study

Osteoporosis has become a serious global public health issue. Hence, osteoporotic fracture healing has been investigated in several previous studies because there is still controversy over the effect osteoporosis has on the healing process. The current study aimed to analyze two different periods of bone healing in normal and osteopenic rats. Sixty, 7-week-old female Wistar rats were randomly divided into four groups: unrestricted and immobilized for 2 weeks after osteotomy (OU2), suspended and immobilized for 2 weeks after osteotomy (OS2), unrestricted and immobilized for 6 weeks after osteotomy (OU6), and suspended and immobilized for 6 weeks after osteotomy (OS6). Osteotomy was performed in the middle third of the right tibia 21 days after tail suspension, when the osteopenic condition was already set. The fractured limb was then immobilized by orthosis. Tibias were collected 2 and 6 weeks after osteotomy, and were analyzed by bone densitometry, mechanical testing, and histomorphometry. Bone mineral density values from bony calluses were significantly lower in the 2-week post-osteotomy groups compared with the 6-week post-osteotomy groups (multivariate general linear model analysis, P<0.000). Similarly, the mechanical properties showed that animals had stronger bones 6 weeks after osteotomy compared with 2 weeks after osteotomy (multivariate general linear model analysis, P<0.000). Histomorphometry indicated gradual bone healing. Results showed that osteopenia did not influence the bone healing process, and that time was an independent determinant factor regardless of whether the fracture was osteopenic. This suggests that the body is able to compensate for the negative effects of suspension.

Vida e teatro em Guimarães Rosa: Grande sertão: veredas e pirlimpsiquice

Este artigo inicia-se com uma exposição sucinta da metáfora do teatro, tal como aparece em Platão. Em seguida, após levantamento dos momentos capitais da literatura, investiga-se a metáfora em Guimarães Rosa, no Grande sertão: veredas e no conto Pirlimpsiquice. No Grande sertão, a atuação no palco é tomada como equivalente ao desempenho na vida. Teatro e vida são, portanto, domínios que se identificam. Para isto, concorrem a religião cristã e o pensamento de Plotino. Em Pirlimpsiquice, o Autor investiga por menorizadamente os limites e aproximações entre teatro e vida, sendo que o grau mínimo da metáfora é conferido pelas práticas histórica e cultural. Por fim, retomando a polêmica de Hegel com o platonismo, conclui-se que a representação e a vida estão amalgamadas, numa constante dialetização entre história e cultura.

A lição de Heráclito

Heráclito é conhecido na história do pensamento filosófico como o propositor da doutrina do mobilismo universal O "tudo flui, nada permanece", asserção pela qual é comumente sintetizada, integra o cerne da Metafísica: suscita em Platão a não menos conhecida Teoria das Formas, que acabará por tomar-se o pensamento diretor da filosofia do Ocidente. Para melhor compreender essas ressonâncias, desenvolveremos algumas considerações sobre a essência do devir heraclítico.

Teatro e pensamento

Platão tem uma visão negativa da arte e da tragédia. A "irracionalidade" da prática artística está na base dessa negação. Sua visão é contrária ao perspectivismo humanista de Eurípedes e dos sofistas. Na filosofia renascentista, o sujeito observador (temporal e racional) pressupõe o múltiplo e o infinito. O perspectivismo está na base dessa orientação e Shakespeare é a melhor expressão artística desse pressuposto defendido na filosofia por Giordano Bruno.

A demarcação platônica de novas fronteiras epistêmicas para o discurso filosófico: um estudo sobre o sofista

No Sofista, mediante os circuitos do procedimento ontológico-binário das divisões dialéticas, Platão busca não somente chegar à verdade das coisas em si, mas, também, a sua correta expressão. A superação das aporias relativas à natureza da linguagem por um tratamento metódico rigoroso, que minimiza suas limitações e inadvertências e a instala numa dimensão transcendente, entre os gêneros do Ser, assegura-lhe o estatuto de discurso filosófico, capaz de dizer aquilo que é como ele é.

A visão sensível como imagem da visão dos inteligíveis

O artigo pretende explicitar em que consiste a visão (ópsis) na República de Platão, usada pelo filósofo como imagem que ajudaria a fazer compreender o que ele entende por conhecimento de Ideias.

Kant and zeno of elea: historical precedents of the "sceptical method"

For Kant's interpretation of Zeno in KrV A502-507/B530-535, scholars have usually referred to Plato's Phaedrus (261d); in reality the sources Kant uses are, on one hand, Brucker (who depends in turn on the pseudo-Aristotelian De Melisso, Xenophane, et Gorgia, 977 b 2-21), and, on the other, Plato's Parmenides (135e6-136b1) and Proclus' commentary on it, as quoted by Gassendi in a popular textbook he wrote on the history of logic.

Rousseau Misantropo

RESUMO:O objetivo de nossa exposição é mostrar que, em sua Carta a d’Alembert, Rousseau retoma o debate clássico sobre a relação entre o teatro e a moral nas mesmas bases estabelecidas por Platão. Sendo assim, a disputa sobre o teatro tem, da parte de Rousseau, uma objetividade que não encontramos no artigo de d’Alembert. Portanto, não se trata de uma diferença de opinião entre Rousseau e d’Alembert, mas da capacidade filosófica de bem compreender o que é próprio ao teatro e à moralidade.