Leucoencefalomalácia em equídeos da região Leste de Mato Grosso

Background: Fumonisins produced by Fusarium verticillioides are among the most important medical mycotoxins known. The intake of concentrate based on corn and corn by-products contaminated with fumonisins can cause severe poisoning in horses. The injuries are observed mainly in the white matter of the brain, and the disease is known as Equine Leukoencephalomalacia (ELEM). This study aims to describe and discuss the epidemiological, clinical and diagnostic aspects of an outbreak of ELEM occurred in three farms in the municipalities of Canarana and Agua Boa, in the eastern region of Mato Grosso, Brazil.Materials, Methods & Results: The outbreak occurred between May and August 2010. The disease affected six horses and four mules of different ages and sex. Clinical examination was only possible in animals with chronic evolution of the disease. All the affected animals showed neurological clinical signs such as ataxia and recumbency, which progressed to death or sudden death. Histopathological analysis showed foci of necrosis that predominantly affected the white matter, and the presence of gitter cells. Degenerative lesions were observed in the liver of the animals. Mortality rate ranged from 12.5 to 71%, and lethality reached 100%. The cases were preceded by sudden drops in the weather temperature. Fumonisins levels of 6.6 ppm were detected in the feed of the animals.Discussion: The presumptive diagnosis of leukoencephalomalacia was consistent and based on clinical and epidemiological studies. However, the definitive diagnosis was based upon the histological features of the brain including the presence of extensive areas of malacia. Moreover, the animals were being fed with corn or corn by-products contaminated with fumonisins levels considered to be toxic to equids. The mortality and lethality rates are in agreement with outbreaks described in previous studies. The animals showed neurological signs as the predominant clinical manifestation, with gait ataxia followed by recumbency, prostration and death between 24 h and 29 days. Similarly to other reports, the disease was more frequent in adult animals, which succumbed in 24-48 h. Conversely, the evolution of the disease in young animals was of 10 to 29 days. Sudden death was more prevalent in the mules. Previous studies have shown a predominance of cerebral and brainstem lesions in horses, whereas in mules the clinical signs are related to brainstem lesions. Corn and corn by-products are commonly used as energy supplementation to horses in the southern of Mato Grosso state, but outbreaks of the disease are uncommon. This may be influenced by the prevalence of hot climate conditions, which does not favor the production of toxin by the fungus. The atypical low weather temperatures (9-11 degrees C) observed prior to the outbreak could have contributed to the mycotoxin production by F. verticillioides, which requires temperatures between 8-12 degrees C to produce toxins. However, the disease in the region may be underestimated, considering that the practice of necropsies is not common among field technicians, mainly in the occurrence of sporadic deaths among horses intended for work. Preventive measures include avoiding the use of corn and corn by-products for horses after periods of sudden drops in temperature in the region. Furthermore, clinical and epidemiological surveys and post-mortem and histopathological analyses are undoubtedly important for appropriate differential diagnosis, especially in equids with neurological signs.

Phox2b-expressing retrotrapezoid neurons and the integration of central and peripheral chemosensory control of breathing in conscious rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

ATP in the locus coeruleus as a modulator of cardiorespiratory control in unanaesthetized male rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relação entre toxicidade urêmica, anemia e perda auditiva neurossensorial em indivíduos com doença renal crônica: um estudo prospectivo

Pós-graduação em Bases Gerais da Cirurgia - FMB

Avaliação audiológica comportamental e eletrofisiológica no transtorno do espectro do autismo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Exposição neonatal a drogas ototóxicas e possíveis alterações auditivas

Introduction: Scientific evidence indicates that neonatal exposure to ototoxic drugs cause hearing loss in newborns. Objective: To characterize the use of ototoxic antibiotics in newborns (NB), treated in the Neonatal Intensive Care Unit (NICU) and evaluate possible hearing modifications. Methods: A descriptive cross-sectional quantitative approach, using data from medical records of infants who were at some time in the NICU and used antibiotics, including ototoxic, from January to June 2004 as much as 2010, and the data were compared and analyzed. Parents/guardians of infants born in 2004 were contacted and applied a questionnaire containing questions about the children’s hearing. These children were submitted to audiological evaluation. Results: There was significant reduction in the time of use, the amount of antibiotics prescribed to newborns and Vancomycin prescription in 2010 compared to 2004. The hearing tests of 13 born in 2004 showed: sensorineural hearing loss in only 2 (one with moderate hearing loss and descending configuration in pure tone audiometry and the other with bilateral cochlear impairment); audiometric thresholds within the normal range in 11 patients, and the presence of otoacoustic emissions in 9. In Evoked Auditory Brainstem Response (ABR) no changes were observed. Conclusion: The reduction in the time of use, the amount and types of antibiotics observed may be related to the adoption of a Protocol in 2008, by the service. In contrast, auditory alterations may be related to a neonatal exposure to antibiotics in 2004.

Respiratory manifestations of panic disorder in animals and humans: A unique opportunity to understand how supramedullary structures regulate breathing

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cardiovascular alterations at different stages of hypertension development during ethanol consumption: Time-course of vascular and autonomic changes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Subluxação atlantoaxial canina

The atlantoaxial subluxation or luxation is an instability of this articulation that produces excessive flexion of this joint causing the cranial aspect of the axis to rotate dorsally into the vertebral channel with subsequent spinal cord compression. This disorder is most commonly found in young small breed dogs. The diagnosis of this disease is done by survey radiographs, where there is a larger distance between the atlas dorsal arch and the axis spinal process characterize the atlantoaxial subluxation. Surgical stabilization is the treatment of choice and multiple implants show the best results to stabilize the atlantoaxial joint. The main complications are sudden death or implant failure. The sudden death happens because of cardiorespiratory arrest and it is most likely caused by brainstem iatrogenic trauma. However, a larger study comparing different surgical stabilization techniques should be performed to evaluate relative success rates in dogs that have the same initial neurologic status

Potencial evocado auditivo de tronco encefálico em equinos

Pós-graduação em Medicina Veterinária - FMVZ

Estudo hodológico e neuroquímico das aferências da região noradrenérgica A5 aos neurônios da raiz coclear

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The nucleus of the solitary tract and the coordination of respiratory and sympathetic activities

It is well known that breathing introduces rhythmical oscillations in the heart rate and arterial pressure levels. Sympathetic oscillations coupled to the respiratory activity have been suggested as an important homeostatic mechanism optimizing tissue perfusion and blood gas uptake/delivery. This respiratory-sympathetic coupling is strengthened in conditions of blood gas challenges (hypoxia and hypercapnia) as a result of the synchronized activation of brainstem respiratory and sympathetic neurons, culminating with the emergence of entrained cardiovascular and respiratory reflex responses. Studies have proposed that the ventrolateral region of the medulla oblongata is a major site of synaptic interaction between respiratory and sympathetic neurons. However, other brainstem regions also play a relevant role in the patterning of respiratory and sympathetic motor outputs. Recent findings suggest that the neurons of the nucleus of the solitary tract (NTS), in the dorsal medulla, are essential for the processing and coordination of respiratory and sympathetic responses to hypoxia. The NTS is the first synaptic station of the cardiorespiratory afferent inputs, including peripheral chemoreceptors, baroreceptors and pulmonary stretch receptors. The synaptic profile of the NTS neurons receiving the excitatory drive from afferent inputs is complex and involves distinct neurotransmitters, including glutamate, ATP and acetylcholine. In the present review we discuss the role of the NTS circuitry in coordinating sympathetic and respiratory reflex responses. We also analyze the neuroplasticity of NTS neurons and their contribution for the development of cardiorespiratory dysfunctions, as observed in neurogenic hypertension, obstructive sleep apnea and metabolic disorders.

Contribution of retrotrapezoid/parafacial respiratory region to the expiratory-sympathetic coupling in response to peripheral chemoreflex in rats

Central mechanisms of coupling between respiratory and sympathetic systems are essential for the entrainment between the enhanced respiratory drive and sympathoexcitation in response to hypoxia. However, the brainstem nuclei and neuronal network involved in these respiratory-sympathetic interactions remain unclear. Here, we evaluated whether the increase in expiratory activity and expiratory-modulated sympathoexcitation produced by the peripheral chemoreflex activation involves the retrotrapezoid nucleus/parafacial respiratory region (RTN/pFRG). Using decerebrated arterially perfused in situ rat preparations (60–80 g), we recorded the activities of thoracic sympathetic (tSN), phrenic (PN), and abdominal nerves (AbN) as well as the extracellular activity of RTN/pFRG expiratory neurons, and reflex responses to chemoreflex activation were evaluated before and after inactivation of the RTN/pFRG region with muscimol (1 mM). In the RTN/pFRG, we identified late-expiratory (late-E) neurons (n = 5) that were silent at resting but fired coincidently with the emergence of late-E bursts in AbN after peripheral chemoreceptor activation. Bilateral muscimol microinjections into the RTN/pFRG region (n = 6) significantly reduced basal PN frequency, mean AbN activity, and the amplitude of respiratory modulation of tSN (P < 0.05). With respect to peripheral chemoreflex responses, muscimol microinjections in the RTN/pFRG enhanced the PN inspiratory response, abolished the evoked late-E activity of AbN, but did not alter either the magnitude or pattern of the tSN reflex response. These findings indicate that the RTN/pFRG region is critically involved in the processing of the active expiratory response but not of the expiratory-modulated sympathetic response to peripheral chemoreflex activation of rat in situ preparations.

Effect of lithium on behavioral disinhibition induced by electrolytic lesion of the median raphe nucleus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Coupling of respiratory and sympathetic activities in rats submitted to chronic intermittent hypoxia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)