Denervação acetabular cranial e dorsal no tratamento da displasia coxofemoral em cães: 360 dias de evolução de 97 casos

Realizou-se a pesquisa com o intuito de avaliar os resultados clínicos da denervação acetabular cranial e dorsal por curetagem em cães com displasia coxofemoral. Foram estudados, para tanto, 97 cães, sem predileção racial ou sexual, de 1-7 anos de idade, com diagnóstico clínico e radiográfico de displasia coxofemoral. Para avaliação dos resultados da técnica cirúrgica, de curetagem das fibras nervosas do periósteo acetabular cranial e dorsal, exames clínicos foram realizados no momento pré-operatório (exame inicial), e pós-operatório, nos dias dois, sete, 14, 21, 30, 60, 180 e 360. Todos os animais foram avaliados quanto à claudicação, dor à movimentação e toque, grau de atrofia muscular, sensibilidade dolorosa ao teste de Ortolani, e qualidade de vida. A denervação reduziu a claudicação, e dor à movimentação e toque à partir de dois dias de pós-operatório, reduziu atrofia muscular aos 60 dias pós-operatórios, e melhorou a qualidade de vida dos pacientes tratados, sob a ótica dos proprietários e veterinários aos 360 dias de pós-operatório. A dener-vação acetabular dorsal é técnica factível no tratamento da dor conseqüente à displasia coxofemoral em cães, com decréscimo significativo desta após dois dias da intervenção cirúrgica, aumenta qualidade de vida e proporciona maior atividade aos pacientes com proprietários satisfeitos quanto aos resultados do procedimento. A técnica cirúrgica deve incluir a curetagem das fibras nervosas do periósteo acetabular tanto da região cranial quanto dorsal.

Nerve endings of filliform, fungiform and vallate papillae of dorsal tongue mucosa of White-lipped peccary (Tayassu pecari): Neurohistological observations

The neurohistologic observations were performed using the specimens prepared by Winkelmann and Schmitt silver impregnation method. The tissues were fixed in 10% formalin solution and sections of 40µm thickness were obtained by Leica Cryostat at -30ºC. The sections of dorsal mucosa of White-lipped peccary tongue showed numerous filliform and fungiform papillae, and two vallate papillae on the caudal part. The epithelial layer revealed queratinized epithelial cells and the connective tissue papillae of different sizes and shapes. Thick nerve fiber bundles are noted into the subepithelial connective tissue of the papillae. The connective tissue of fungiform and vallate papillae contained numerous sensitive nerves fibers bundles forming a complex nerve plexus.

A musculatura epaxial e a fibrose epidural na compressão medular em cães submetidos à laminectomia dorsal modificada

O objetivo deste experimento foi isolar a musculatura epaxial da medula espinhal de cães submetidos à laminectomia dorsal modificada (LDM) e averiguar se os músculos influenciaram na formação da fibrose epidural, na compressão medular e no aparecimento dos sinais neurológicos. Para isso, dez cães hígidos foram submetidos à LDM entre as vértebras T13 e L1 e distribuídos aleatoriamente em dois grupos denominados controle (I) onde a medula espinhal permaneceu exposta sem a presença de implante, e tratado (II)onde foi colocado um im-plante a base de alumínio entre a musculatura epaxial adjacente e a medula espinhal exposta pela LDM. As avaliações constaram de exames neurológicos diários até 180 dias de pós-operatório (PO); mielografia, decorridos 15, 30 e 60 dias de PO; e avaliação macroscópica mediante a reintervenção cirúrgica. Não houve diferença durante as avaliações neurológicas. Aos 15 dias de PO, foi verificado na mielografia, que o grau de compressão da linha de contraste foi maior no grupo tratado (P<0,05) quando comparado ao grupo controle, não havendo diferença dos demais tempos estudados. Na avaliação macroscópica, pode-se observar que no Grupo II, a musculatura epaxial adjacente à medula espinhal não estava em contato com a fibrose epidural, diferentemente do grupo controle. O implante pôde ser removido facilmente e apresentava discreto grau de deformidade crânio-dorsal. Pode-se concluir que a musculatura epaxial adjacente é isolada da medula espinhal pelo implante à base de alumínio em cães submetidos à LDM, e esta não influencia na formação da fibrose epidural, compressão medular e no aparecimento dos sinais neurológicos.

Renal cortex copper concentration in acute copper poisoning in calves

The aim of this study was to estimate the diagnostic value of renal cortex copper (Cu) concentration in clinical cases of acute copper poisoning (ACP). A total of 97 calves that died due to subcutaneous copper administration were compiled in eleven farms. At least, one necropsy was conducted on each farm and samples for complementary analysis were taken. The degree of autolysis in each necropsy was evaluated. The cases appeared on extensive grazing calf breeding and intensive feedlot farms, in calves of 60 to 200 kg body weight. Mortality varied from 0.86 to 6.96 %, on the farms studied. The first succumbed calf was found on the farms between 6 and 72 hours after the susbcutaneous Cu administration. As discrepancies regarding the reference value arose, the local value (19.9 parts per million) was used, confirming the diagnosis of acute copper poisoning in 93% of the analyzed kidney samples. These results confirm the value of analysis of the cortical kidney Cu concentration for the diagnosis of acute copper poisoning.

The neural processes generating visual phenomenal consciousness: ERP and neuronavigated brain stimulation studies

One of the greatest conundrums to the contemporary science is the relation between consciousness and brain activity, and one of the specifi c questions is how neural activity can generate vivid subjective experiences. Studies focusing on visual consciousness have become essential in solving the empirical questions of consciousness. Th e main aim of this thesis is to clarify the relation between visual consciousness and the neural and electrophysiological processes of the brain. By applying electroencephalography and functional magnetic resonance image-guided transcranial magnetic stimulation (TMS), we investigated the links between conscious perception and attention, the temporal evolution of visual consciousness during stimulus processing, the causal roles of primary visual cortex (V1), visual area 2 (V2) and lateral occipital cortex (LO) in the generation of visual consciousness and also the methodological issues concerning the accuracy of targeting TMS to V1. Th e results showed that the fi rst eff ects of visual consciousness on electrophysiological responses (about 140 ms aft er the stimulus-onset) appeared earlier than the eff ects of selective attention, and also in the unattended condition, suggesting that visual consciousness and selective attention are two independent phenomena which have distinct underlying neural mechanisms. In addition, while it is well known that V1 is necessary for visual awareness, the results of the present thesis suggest that also the abutting visual area V2 is a prerequisite for conscious perception. In our studies, the activation in V2 was necessary for the conscious perception of change in contrast for a shorter period of time than in the case of more detailed conscious perception. We also found that TMS in LO suppressed the conscious perception of object shape when TMS was delivered in two distinct time windows, the latter corresponding with the timing of the ERPs related to the conscious perception of coherent object shape. Th e result supports the view that LO is crucial in conscious perception of object coherency and is likely to be directly involved in the generation of visual consciousness. Furthermore, we found that visual sensations, or phosphenes, elicited by the TMS of V1 were brighter than identically induced phosphenes arising from V2. Th ese fi ndings demonstrate that V1 contributes more to the generation of the sensation of brightness than does V2. Th e results also suggest that top-down activation from V2 to V1 is probably associated with phosphene generation. The results of the methodological study imply that when a commonly used landmark (2 cm above the inion) is used in targeting TMS to V1, the TMS-induced electric fi eld is likely to be highest in dorsal V2. When V1 was targeted according to the individual retinotopic data, the electric fi eld was highest in V1 only in half of the participants. Th is result suggests that if the objective is to study the role of V1 with TMS methodology, at least functional maps of V1 and V2 should be applied with computational model of the TMS-induced electric fi eld in V1 and V2. Finally, the results of this thesis imply that diff erent features of attention contribute diff erently to visual consciousness, and thus, the theoretical model which is built up of the relationship between visual consciousness and attention should acknowledge these diff erences. Future studies should also explore the possibility that visual consciousness consists of several processing stages, each of which have their distinct underlying neural mechanisms.

Behavioral effects of "vehicle" microinjected into the dorsal periaqueductal grey of rats tested in the elevated plus maze

To investigate the behavioral effects of different vehicles microinjected into the dorsal periaqueductal grey (DPAG) of male Wistar rats, weighing 200-250 g, tested in the elevated plus maze, animals were implanted with cannulas aimed at this structure. One week after surgery the animals received microinjections into the DPAG of 0.9% (w/v) saline, 10% (v/v) dimethyl sulfoxide (DMSO), 2% (v/v) Tween-80, 10% (v/v) propylene glycol, or synthetic cerebrospinal fluid (CSF). Ten min after the injection (0.5 &micro;l) the animals (N = 8-13/group) were submitted to the elevated plus maze test. DMSO significantly increased the number of entries into both the open and enclosed arms when compared to 0.9% saline (2.7 &plusmn; 0.8 and 8.7 &plusmn; 1.3 vs 0.8 &plusmn; 0.3 and 5.1 &plusmn; 0.9, respectively, Duncan test, P<0.05), and tended to increase enclosed arm entries as compared to 2% Tween-80 (8.7 &plusmn; 1.3 vs 5.7 &plusmn; 0.9, Duncan test, P<0.10). In a second experiment no difference in plus maze exploration was found between 0.9% saline- or sham-injected animals (N = 11-13/group). These results indicate that intra-DPAG injection of some commonly used vehicles such as DMSO, saline or Tween-80 affects the exploratory activity of rats exposed to the elevated plus maze in statistically different manners

Localization of NMDA receptors in the cerebral cortex: a schematic overview

The fundamental role of N-methyl-D-aspartate (NMDA) receptors in many cortical functions has been firmly defined, as has its involvement in a number of neurological and psychiatric diseases. However, until recently very little was known about the anatomical localization of NMDA receptors in the cerebral cortex of mammals. The recent application of molecular biological techniques to the study of NMDA receptors has provided specific tools which have greatly expanded our understanding of the localization of NMDA receptors in the cerebral cortex. In particular, immunocytochemical studies on the distribution of cortical NMDA receptors have shown that NMDA receptors are preferentially localized on dendritic spines, have disclosed an unknown fraction of presynaptic NMDA receptors on both excitatory and inhibitory axon terminals, and demonstrated that cortical astrocytes do express NMDA receptors. These studies suggest that the effects induced by the activation of NMDA receptors are not due solely to the opening of NMDA channels on neuronal postsynaptic membranes, as previously assumed, but that the activation of presynaptic and glial NMDA receptors may mediate part of these effects

Rapid eye movement (REM) sleep deprivation reduces rat frontal cortex acetylcholinesterase (EC 3.1.1.7) activity

Rapid eye movement (REM) sleep deprivation induces several behavioral changes. Among these, a decrease in yawning behavior produced by low doses of cholinergic agonists is observed which indicates a change in brain cholinergic neurotransmission after REM sleep deprivation. Acetylcholinesterase (Achase) controls acetylcholine (Ach) availability in the synaptic cleft. Therefore, altered Achase activity may lead to a change in Ach availability at the receptor level which, in turn, may result in modification of cholinergic neurotransmission. To determine if REM sleep deprivation would change the activity of Achase, male Wistar rats, 3 months old, weighing 250-300 g, were deprived of REM sleep for 96 h by the flower-pot technique (N = 12). Two additional groups, a home-cage control (N = 6) and a large platform control (N = 6), were also used. Achase was measured in the frontal cortex using two different methods to obtain the enzyme activity. One method consisted of the obtention of total (900 g supernatant), membrane-bound (100,000 g pellet) and soluble (100,000 g supernatant) Achase, and the other method consisted of the obtention of a fraction (40,000 g pellet) enriched in synaptic membrane-bound enzyme. In both preparations, REM sleep deprivation induced a significant decrease in rat frontal cortex Achase activity when compared to both home-cage and large platform controls. REM sleep deprivation induced a significant decrease of 16% in the membrane-bound Achase activity (nmol thiocholine formed min-1 mg protein-1) in the 100,000 g pellet enzyme preparation (home-cage group 152.1 ± 5.7, large platform group 152.7 ± 24.9 and REM sleep-deprived group 127.9 ± 13.8). There was no difference in the soluble enzyme activity. REM sleep deprivation also induced a significant decrease of 20% in the enriched synaptic membrane-bound Achase activity (home-cage group 126.4 ± 21.5, large platform group 127.8 ± 20.4, REM sleep-deprived group 102.8 ± 14.2). Our results suggest that REM sleep deprivation changes Ach availability at the level of its receptors through a decrease in Achase activity

Effects of entorhinal cortex lesions on memory in different tasks

Lesions of the entorhinal cortex produce retrograde memory impairment in both animals and humans. Here we report the effects of bilateral entorhinal cortex lesions caused by the stereotaxic infusion of N-methyl-D-aspartate (NMDA) in rats at two different moments, before or after the training session, on memory of different tasks: two-way shuttle avoidance, inhibitory avoidance and habituation to an open field. Pre- or post-training entorhinal cortex lesions caused an impairment of performance in the shuttle avoidance task, which agrees with the previously described role of this area in the processing of memories acquired in successive sessions. In the inhibitory avoidance task, only the post-training lesions had an effect (amnesia). No effect was observed on the open field task. The findings suggest that the role of the entorhinal cortex in memory processing is task-dependent, perhaps related to the complexity of each task

NADPH-diaphorase activity in area 17 of the squirrel monkey visual cortex: neuropil pattern, cell morphology and laminar distribution

We studied the distribution of NADPH-diaphorase activity in the visual cortex of normal adult New World monkeys (Saimiri sciureus) using the malic enzyme "indirect" method. NADPH-diaphorase neuropil activity had a heterogeneous distribution. In coronal sections, it had a clear laminar pattern that was coincident with Nissl-stained layers. In tangential sections, we observed blobs in supragranular layers of V1 and stripes throughout the entire V2. We quantified and compared the tangential distribution of NADPH-diaphorase and cytochrome oxidase blobs in adjacent sections of the supragranular layers of V1. Although their spatial distributions were rather similar, the two enzymes did not always overlap. The histochemical reaction also revealed two different types of stained cells: a slightly stained subpopulation and a subgroup of deeply stained neurons resembling a Golgi impregnation. These neurons were sparsely spined non-pyramidal cells. Their dendritic arbors were very well stained but their axons were not always evident. In the gray matter, heavily stained neurons showed different dendritic arbor morphologies. However, most of the strongly reactive cells lay in the subjacent white matter, where they presented a more homogenous morphology. Our results demonstrate that the pattern of NADPH-diaphorase activity is similar to that previously described in Old World monkeys

Methylmercury intoxication and histochemical demonstration of NADPH-diaphorase activity in the striate cortex of adult cats

The effects of methylmercury (MeHg) on histochemical demonstration of the NADPH-diaphorase (NADPH-d) activity in the striate cortex were studied in 4 adult cats. Two animals were used as control. The contaminated animals received 50 ml milk containing 0.42 µg MeHg and 100 g fish containing 0.03 µg MeHg daily for 2 months. The level of MeHg in area 17 of intoxicated animals was 3.2 µg/g wet weight brain tissue. Two cats were perfused 24 h after the last dose (group 1) and the other animals were perfused 6 months later (group 2). After microtomy, sections were processed for NADPHd histochemistry procedures using the malic enzyme method. Dendritic branch counts were performed from camera lucida drawings for control and intoxicated animals (N = 80). Average, standard deviation and Student t-test were calculated for each data group. The concentrations of mercury (Hg) in milk, fish and brain tissue were measured by acid digestion of samples, followed by reduction of total Hg in the digested sample to metallic Hg using stannous chloride followed by atomic fluorescence analysis. Only group 2 revealed a reduction of the neuropil enzyme activity and morphometric analysis showed a reduction in dendritic field area and in the number of distal dendrite branches of the NADPHd neurons in the white matter (P<0.05). These results suggest that NADPHd neurons in the white matter are more vulnerable to the long-term effects of MeHg than NADPHd neurons in the gray matter.

Electro-oscillographic correlation between dorsal raphe nucleus, neocortex and hippocampus during wakefulness before and after serotoninergic inactivation

Theta rhythm in many brain structures characterizes wakefulness and desynchronized sleep in most subprimate mammalian brains. In close relation to behaviors, theta frequency and voltage undergo a fine modulation which may involve mobilization of dorsal raphe nucleus efferent pathways. In the present study we analyzed frequency modulation (through instantaneous frequency variation) of theta waves occurring in three cortical areas, in hippocampal CA1 and in the dorsal raphe nucleus of Wistar rats during normal wakefulness and after injection of the 5-HT1a receptor agonist 8-OH-DPAT into the dorsal raphe. We demonstrated that in attentive states the variation of theta frequency among the above structures is highly congruent, whereas after 8-OH-DPAT injection, although regular signals are present, the variation is much more complex and shows no relation to behaviors. Such functional uncoupling after blockade demonstrates the influence of dorsal raphe nucleus efferent serotoninergic fibers on the organization of alertness, as evaluated by electro-oscillographic analysis.

Axotomy increases NADPH-diaphorase activity in the dorsal root ganglia and lumbar spinal cord of the turtle Trachemys dorbigni

Seven days after transection of the sciatic nerve NADPH-diaphorase activity increased in the small and medium neurons of the dorsal root ganglia of the turtle. However, this increase was observed only in medium neurons for up to 90 days. At this time a bilateral increase of NADPH-diaphorase staining was observed in all areas and neuronal types of the dorsal horn, and in positive motoneurons in the lumbar spinal cord, ipsilateral to the lesion. A similar increase was also demonstrable in spinal glial and endothelial cells. These findings are discussed in relation to the role of nitric oxide in hyperalgesia and neuronal regeneration or degeneration.

Probable effect of photoperiod on seasonal variation in the nuclear volume of the adrenal cortex of viscacha (Lagostomus maximus maximus)

The neuroendocrine system regulates several organic functions such as reproduction, metabolism and adaptation to the environment. This system shows seasonal changes linked to the environment. The experimental model used in the present study was Lagostomus maximus maximus (viscacha). The reproduction of males of this species is photoperiod dependent. Twenty-four adult male viscachas were captured in their habitat at different times during one year. The adrenal glands were processed for light microscopy. Serial cuts were stained with hematoxylin-eosin for the morphometric study, and 100 nuclei of each zone of the adrenal cortex were counted per animal. Data were analyzed statistically by ANOVA and the Tukey test. The cells of the glomerulosa zone are arranged in a tube-shaped structure. The fasciculata zone has large cells with central nuclei and clearly visible nucleoli and with a vacuolar cytoplasm. In the reticularis zone there are two of types of cells, one with a nucleus of fine chromatin and a clearly visible nucleolus and the other with nuclear pycnosis. Morphometric analysis showed maximum nuclear volumes during the February-March period with values of 133 ± 7.3 µm3 for the glomerulosa, 286.4 ± 14.72 µm3 for the fasciculata, and 126.3 ± 9.49 µm3 for the reticularis. Minimum nuclear volumes were observed in August with values of 88.24 ± 9.9 µm3 for the glomerulosa, 163.7 ± 7.78 µm3 for the fasciculata and 64.58 ± 4.53 µm3 for the reticularis. The short winter photoperiod to which viscacha is subjected could inhibit the adrenal cortex through a melatonin increase which reduces the nuclear volume as well as the cellular activity.

Anxiolytic effect of methylene blue microinjected into the dorsal periaqueductal gray matter

The dorsal periaqueductal gray (DPAG) has been implicated in the behavioral and autonomic expression of defensive reactions. Several results suggest that, along with GABA, glutamate and serotonin, nitric oxide (NO) may play a role in defense reactions mediated by this region. To further investigate this possibility we microinjected methylene blue (MB; 10, 30 or 100 nmol/0.5 µl) into the DPAG of rats submitted to the elevated plus-maze test, an animal model of anxiety. MB has been used as an inhibitor of soluble guanylate cyclase (sGC) to demonstrate cGMP-mediated processes, and there is evidence that NO may exert its biological effects by binding to the heme part of guanylate cyclase, causing an increase in cGMP levels. The results showed that MB (30 nmol) significantly increased the percent of time spent in the open arms (saline = 11.57 ± 1.54, MB = 18.5 ± 2.45, P<0.05) and tended to do the same with the percentage of open arm entries (saline = 25.8 ± 1.97, MB = 33.77 ± 3.07, P<0.10), but did not change the number of enclosed arm entries. The dose-response curve, however, had an inverted U shape. These results indicate that MB, within a limited dose range, has anxiolytic properties when microinjected into the DPAG.