Norma Hernández

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Dipyrone microinjection into the periaqueductal gray matter (PAG) elicits antinociception in rats by activating endogenous opioidergic circuits in PAG and the rostral ventromedial medulla. We have now found that endogenous opioids in the spinal cord are also involved. Responses of dorsal spinal neurons to noxious stimulation of a hindpaw were diminished (to(More)
BACKGROUND Because bacterial pathogens are the primary cause of travelers' diarrhea (TD), antibiotic prophylaxis is effective in TD prevention. This study assessed the efficacy and safety of the nonsystemic antibiotic rifaximin in preventing TD in US travelers to Mexico. METHODS Healthy adult students traveling to Mexico received rifaximin 600 mg/d or(More)
BACKGROUND Enteropathogens cannot be identified in 40% to 50% of subjects with travelers' diarrhea (TD). METHODS We used polymerase chain reaction (PCR) methods to look for the presence of two bacterial causes of diarrhea in a large group of international travelers after failing to detect a pathogen by conventional tests. DNA was isolated from the(More)
Microinjection of dipyrone (metamizol) into the periaqueductal gray matter (PAG) in rats causes antinociception. This is mediated by endogenous opioidergic circuits located in the PAG itself, in the nucleus raphe magnus and adjacent structures, and in the spinal cord. The clinical relevance of these findings, however, is unclear. Therefore, in the present(More)
The nucleus isthmi (NI) is a target of tectofugal fibers in non-mammalian vertebrates, and its likely homologue in mammals, the nucleus parabigeminalis, is also a target of efferents from the superior colliculus. In turn, the nucleus isthmi and the nucleus parabigeminalis project to the optic tectum and the superior colliculus, respectively. The present(More)
Reflex responses and neuronal excitation elicited by noxious stimuli applied to a given body site can be inhibited by application of noxious stimulation to another, even distant body region. Such heterotopic noxious stimulation (HNS) has been proposed to act via 'diffuse noxious inhibitory controls' (DNIC) which involve supraspinal components. The so-called(More)
gamma-Aminobutyric acid (GABA) is thought to be a neurotransmitter in the vetebrate retina. We studied the voltage and Ca2+ dependency of the process of release of [3H]GABA from the retina of the teleost Eugerres plumieri, using a microsuperfusion technique. Two depolarizing agents, veratridine and high potassium, produced a concentration-dependent release(More)
Neurons in the nucleus raphe magnus and adjacent structures of the rostral ventromedial medulla (RVM) are involved in the control of nociceptive transmission. In the RVM the so-called on-cells are excited, and the so-called off-cells are inhibited, by noxious stimuli applied almost anywhere on the body surface, thus showing that they receive information(More)
On- and off-cells of the rostral ventromedial medulla project to the spinal cord, where off-cells are postulated ot inhibit, and on-cells to facilitate, nociceptive transmission. In the present experiments, unitary recordings were made from ventrobasal (VB) thalamic neurons and, simultaneously, on- or off-cells in lightly anesthetized rats. When the tail(More)