Papers by Rita Sinigaglia-Coimbra
Proceedings of the 2nd International Congress on Vascular Dementia, 2002
Choline – now recognized as an essential nutrient – is the most common polar group found in the o... more Choline – now recognized as an essential nutrient – is the most common polar group found in the outer leaflet
of the plasma membrane bilayer. Brain ischemia-reperfusion causes lipid peroxidation triggering multiple cell
death pathways involving necrosis and apoptosis. Membrane breakdown is, therefore, a major
pathophysiologic event in brain ischemia. The ability to achieve membrane repair is a critical step for
survival of ischemic neurons following reperfusion injury. The availability of choline is a rate-limiting factor
in phospholipid synthesis and, therefore, may be important for timely membrane repair and cell survival.
This work aimed at verifying the effects of 7-day oral administration with different doses of choline on
survival of CA1 hippocampal neurons following transient global forebrain ischemia in rats. The
administration of 400 mg/kg/day divided into two daily doses for 7 consecutive days significantly
improved CA1 pyramidal cell survival, indicating that the local availability of this essential nutrient may
limit postischemic neuronal survival.
Journal of the neurological …, Jan 1, 2002
Systemic administration of cyclosporine A (CsA) in single daily doses provides a powerful protect... more Systemic administration of cyclosporine A (CsA) in single daily doses provides a powerful protection to the ischemic rat brain only to sites where the blood -brain barrier (BBB) is disrupted. This study was aimed at evaluating the effectiveness of prolonged treatment and multiple daily doses of systemic CsA following transient global ischemia in rats without BBB breakdown. Multiple daily doses selectively enhanced cell survival at 7-day recovery in regions displaying delayed neuronal death (DND). The effect was dose dependent, enhanced by prolonging the treatment or further fractionating daily doses, and not accompanied by drug-induced hypothermia. These results suggest that CsAsusceptible immune mediators of DND may be active during the first days following transient global ischemia. Conversely, postischemic hyperthermia may enhance and/or perpetuate similar mechanisms and trigger Alzheimer-like neurodegeneration, as recently reported. D
Brazilian Journal of …, Jan 1, 2008
Chronic neurodegenerative processes have been identified in the rat forebrain after prolonged sur... more Chronic neurodegenerative processes have been identified in the rat forebrain after prolonged survival following hyperthermia (HT) initiated a few hours after transient global ischemia. Since transient global ischemia and ischemic penumbra share pathophysiological similarities, this study addressed the effects of HT induced after recirculation of focal brain ischemia on infarct size during long survival times. Adult male Wistar rats underwent intra-luminal occlusion of the left middle cerebral artery for 60 min followed by HT (39.0-39.5°C) or normothermia. Control procedures included none and sham surgery with and without HT, and middle cerebral artery occlusion alone. Part I: 6-h HT induced at recirculation. Part II: 2-h HT induced at 2-, 6-, or 24h recirculation. Part III: 2-h HT initiated at recirculation or 6-h HT initiated at 2-, 6-or 24-h recirculation. Survival periods were 7 days, 2 or 6 months. The effects of post-ischemic HT on cortex and striatum were evaluated histopathologically by measuring the area of remaining tissue in the infarcted hemisphere at -0.30 mm from bregma. Six-hour HT initiated from 6-h recirculation caused a significant decrease in the remaining cortical tissue between 7-day (N = 8) and 2-month (N = 8) survivals (98.46 ± 1.14 to 73.62 ± 8.99%, respectively). When induced from 24-h recirculation, 6-h HT caused a significant reduction of the remaining cortical tissue between 2-(N = 8) and 6-month (N = 9) survivals (94.97 ± 5.02 vs 63.26 ± 11.97%, respectively). These data indicate that post-ischemic HT triggers chronic neurodegenerative processes in ischemic penumbra, suggesting that similar fever-triggered effects may annul the benefit of early recirculation in stroke patients over the long-term.
Acta neuropathologica, Jan 1, 2002
This study addresses the effects of induced hyperthermia on post-ischemic rat brain evaluated his... more This study addresses the effects of induced hyperthermia on post-ischemic rat brain evaluated histologically and/or immunohistochemically after 7-day, 2-month or 6-month survival. Hyperthermia (38.5°–40°C) maintained (by heating the cage environment to 34–35°C) for two consecutive periods of 5 and 9 h timed, respectively, from 4- and 21-h recirculation following 10-min global ischemia (two-vessel occlusion + hypotension) induced chronic neuronal death that became apparent in the rat forebrain from 7-day to 2-month survival. Associated immunohistochemical findings after 2 or 6 months of recovery included: (1) complement activation (membrane attack complex formation); (2) generalized overexpression of ubiquitin in surviving forebrain neurons; (3) persistent activation of macrophages; (4) presence of gemistocytic astrocytes in the hippocampus; (5) maturation of amyloid plaques (identified by immunohistochemistry using anti-human β-A4 primary antibody) in cerebral cortex; and (6) intracellular deposits identified by anti-human hyperphosphorylated tau protein antibodies. This novel non-transgenic, self-sustained model of neurodegeneration triggered by the association of two prevalent insults to the aging human brain (ischemia and hyperthermia) presents morphological features similar to those of Alzheimer's disease. This finding raises the possibility that febrile complications of acute brain injuries may similarly impair human cognitive function in the long run.
Atypical enteropathogenic Escherichia coli (aEPEC) inject various effectors into intestinal cells... more Atypical enteropathogenic Escherichia coli (aEPEC) inject various effectors into intestinal cells through a type three secretion system (T3SS), causing attaching and effacing (A/E) lesions. We investigated the role of T3SS in the ability of the aEPEC 1711-4 strain to interact with enterocytes in vitro (Caco-2 cells) and in vivo (rabbit ileal loops) and to translocate the rat intestinal mucosa in vivo. A T3SS isogenic mutant strain was constructed, which showed marked reduction in the ability to associate and invade but not to persist inside Caco-2 cells. After rabbit infection, only aEPEC 1711-4 was detected inside enterocytes at 8 and 24 hours pointing to a T3SS-dependent invasive potential in vivo. In contrast to aEPEC 1711-4, the T3SS-deficient strain no longer produced A/E lesions or induced macrophage infiltration. We also demonstrated that the ability of aEPEC 1711-4 to translocate through mesenteric lymph nodes to spleen and liver in a rat model depends on a functional T3SS, since a decreased number of T3SS mutant bacteria were recovered from extraintestinal sites. These findings indicate that the full virulence potential of aEPEC 1711-4 depends on a functional T3SS, which contributes to efficient adhesion/invasion in vitro and in vivo and to bacterial translocation to extraintestinal sites.
PloS one, Jan 1, 2012
This study evaluated the effects of bone marrow-derived mesenchymal stem cells (BMSCs) or their c... more This study evaluated the effects of bone marrow-derived mesenchymal stem cells (BMSCs) or their conditioned medium (CM) on the repair and prevention of Acute Kidney Injury (AKI) induced by gentamicin (G). Animals received daily injections of G up to 20 days. On the 10 th day, injections of BMSCs, CM, CM+trypsin, CM+RNase or exosome-like microvesicles extracted from the CM were administered. In the prevention groups, the animals received the BMSCs 24 h before or on the 5 th day of G treatment. Creatinine (Cr), urea (U), FENa and cytokines were quantified. The kidneys were evaluated using hematoxylin/eosin staining and immunohystochemistry. The levels of Cr, U and FENa increased during all the periods of G treatment. The BMSC transplantation, its CM or exosome injections inhibited the increase in Cr, U, FENa, necrosis, apoptosis and also increased cell proliferation. The pro-inflammatory cytokines decreased while the anti-inflammatory cytokines increased compared to G. When the CM or its exosomes were incubated with RNase (but not trypsin), these effects were blunted. The Y chromosome was not observed in the 24-h prevention group, but it persisted in the kidney for all of the periods analyzed, suggesting that the injury is necessary for the docking and maintenance of BMSCs in the kidney. In conclusion, the BMSCs and CM minimized the G-induced renal damage through paracrine effects, most likely through the RNA carried by the exosome-like microvesicles. The use of the CM from BMSCs can be a potential therapeutic tool for this type of nephrotoxicity, allowing for the avoidance of cell transplantations.
Eukaryotic …, Jan 1, 2011
Here, we describe extracellular vesicles carrying highly immunogenic ␣-linked galactopyranosyl (␣... more Here, we describe extracellular vesicles carrying highly immunogenic ␣-linked galactopyranosyl (␣-Gal) epitopes in Paracoccidioides brasiliensis. P. brasiliensis is a dimorphic fungus that causes human paracoccidioidomycosis (PCM). For vesicle preparations, cell-free supernatant fluids from yeast cells cultivated in Ham's defined medium-glucose were concentrated in an Amicon ultrafiltration system and ultracentrifuged at 100,000 ؋ g. P. brasiliensis antigens were present in preparations from phylogenetically distinct isolates Pb18 and Pb3, as observed in immunoblots revealed with sera from PCM patients. In an enzyme-linked immunosorbent assay (ELISA), vesicle components containing ␣-Gal epitopes reacted strongly with anti-␣-Gal antibodies isolated from both Chagas' disease and PCM patients, with Marasmius oreades agglutinin (MOA) (a lectin that recognizes terminal ␣-Gal), but only faintly with natural anti-␣-Gal. Reactivity was inhibited after treatment with ␣-galactosidase. Vesicle preparations analyzed by electron microscopy showed vesicular structures of 20 to 200 nm that were labeled both on the surface and in the lumen with MOA. In P. brasiliensis cells, components carrying ␣-Gal epitopes were found distributed on the cell wall, following a punctuated confocal pattern, and inside large intracellular vacuoles. Lipid-free vesicle fractions reacted with anti-␣-Gal in ELISA only when not digested with ␣-galactosidase, while reactivity with glycoproteins was reduced after -elimination, which is indicative of partial O-linked chain localization. Our findings open new areas to explore in terms of host-parasite relationships in PCM and the role played in vivo by vesicle components and ␣-galactosyl epitopes.
Age-related macular degeneration (AMD) is the leading cause of visual loss in patients older than... more Age-related macular degeneration (AMD) is the leading cause of visual loss in patients older than 65 years in developed countries, 1,2 with risk factors including age and most likely genetics, smoking, and an associated inflammatory process. The AMD subtype with neovascular membrane development is seen in 10% to 20% of eyes but is the main cause of visual loss in AMD. 1,5
Retina, Jan 1, 2012
Purpose: To evaluate the retinal penetration and toxicity of two doses of intravitreal infliximab... more Purpose: To evaluate the retinal penetration and toxicity of two doses of intravitreal infliximab in primates.
• Ethanol-induced behavioral sensitization activated orexin neurons in the LH.
Aging leads to progressive deterioration of physiological function and diminished responses to en... more Aging leads to progressive deterioration of physiological function and diminished responses to environmental stress. Organic and functional alterations are frequently observed in elderly subjects. Although chronic sleep loss is observed during senescence, little is known about the impact of insufficient sleep on cellular function in aging neurons. Disruption of neuronal calcium (Ca 2 + ) signaling is related to impaired neuronal function and cell death. It has been hypothesized that sleep deprivation may compromise neuronal stability and induce cell death in young neurons; however, it is necessary to evaluate the impact of aging on this process. Therefore, the aim of this study was to evaluate the effects of chronic sleep restriction (CSR) on Ca 2 + signaling and cell death in the hippocampus of young and aged animals. We found that glutamate and carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP) induced a greater elevation in cytosolic Ca 2 + ([Ca 2 + ] c ) in hippocampal slices from aged rats subjected to CSR compared to age-matched controls. Interestingly, aged-matched controls showed a reduced Ca 2 + response to glutamate and FCCP, relative to both CSR and control young animals. Apoptotic nuclei were observed in aged rats from both treatment groups; however, the profile of apoptotic nuclei in aged CSR rats was highly variable. Bax and Bcl-2 protein expression did not change with aging in the CSR groups. Our study indicates that aging promotes changes in Ca 2 + signaling, which may also be affected by CSR. These age-dependent changes in Ca 2 + signaling may increase cellular vulnerability during CSR and contribute to Ca 2 + signaling dysregulation, which may ultimately induce cell death.
Neurobiology of Disease, 2011
It is well known that the uncoupling between local cerebral glucose utilization (LCGU) and local ... more It is well known that the uncoupling between local cerebral glucose utilization (LCGU) and local cerebral blood flow (LCBF), i.e. decrease in LCBF rates with high LCGU, is frequently associated with seizure-induced neuronal damage. This study was performed to assess if the neuroprotective effect of the adenosinergic A 1 receptor agonist R-N-phenylisopropyladenosine (R-Pia) injected prior to pilocarpine is able to reduce the uncoupling between LCGU and LCBF during status epilepticus (SE). Four groups of rats were studied: Saline, Pilo, R-Pia + Saline and R-Pia + Pilo. For LCGU and LCBF studies, rats were subjected to autoradiography using [ 14 C]-2-deoxyglucose and [ 14 C]-iodoantypirine, respectively. Radioligands were injected 4 h after SE onset. Neuronal loss was evaluated by Fluorojade-B (FJB) at two time points after SE onset (24 h and 7 days). The results showed a significant increase in LCGU in almost all brain regions studied in the Pilo and R-Pia + Pilo groups compared to controls. However, in R-Pia pretreated rats, the uncoupling between LCGU and LCBF was moderated in a limited number of structures as substantia nigra pars reticulata and hippocampal formation rather in favor of hyperperfusion. Significant increases in LCBF were observed in the entorhinal cortex, thalamic nuclei, mammillary body, red nucleus, zona incerta, pontine nucleus and visual cortex. The neuroprotective effect of R-Pia assessed by FJB showed a lower density of degenerating cells in the hippocampal formation, piriform cortex and basolateral amygdala. In conclusion our data shows that the neuroprotective effect of R-Pia was accompanied by a compensatory metabolic input in brain areas involved with seizures generation.
OBJECTIVE: The aim of this study was to characterize the neuroprotection of the RPia in rats subj... more OBJECTIVE: The aim of this study was to characterize the neuroprotection of the RPia in rats subjected to status epilepticus (SE) induced by pilocarpine (Pilo). METHODS: We evaluated the mismatch between local cerebral glucose utilisation (LCGU) and local cerebral blood flow (LCBF) 4 hours after SE induction. Neuronal loss was evaluated by Fluoro Jade-B (FJB) 24 hours and 90 days after SE. Four groups were studied: Saline, Pilo, RPia+ Saline and RPia+ Pilo.
…, Jan 1, 2005
Purpose: Animal models are useful for the study of status epilepticus (SE)-induced epileptogenesi... more Purpose: Animal models are useful for the study of status epilepticus (SE)-induced epileptogenesis and neurological sequelae, especially during early brain development. Here, we show several permanent abnormalities in animals subjected to multiple SE during early development.
Brain research, Jan 1, 2012
Systemic injection of pilocarpine in rodents induces status epilepticus (SE) and reproduces the m... more Systemic injection of pilocarpine in rodents induces status epilepticus (SE) and reproduces the main characteristics of temporal lobe epilepsy (TLE). Different mechanisms are activated by SE contributing to cell death and immune system activation. We used BALB/c nude mice, a mutant that is severely immunocompromised, to characterize seizure pattern, neurochemical changes, cell death and c-Fos activation secondarily to pilocarpine-induced SE. The behavioral seizures were less severe in BALB/c nude than in BALB/c wild type mice.
Behavioural Brain …, Jan 1, 2012
We investigated pCREB expression in the amygdala and fear memory after sleep deprivation. Sleep d... more We investigated pCREB expression in the amygdala and fear memory after sleep deprivation. Sleep deprivation reduced pCREB expression in the central amygdaloid nucleus. Sleep deprivation impaired fear memory retention. Twenty-four hours of sleep recovery restored pCREB expression. Twenty-four hours of sleep recovery prevented memory deficit.
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Papers by Rita Sinigaglia-Coimbra
of the plasma membrane bilayer. Brain ischemia-reperfusion causes lipid peroxidation triggering multiple cell
death pathways involving necrosis and apoptosis. Membrane breakdown is, therefore, a major
pathophysiologic event in brain ischemia. The ability to achieve membrane repair is a critical step for
survival of ischemic neurons following reperfusion injury. The availability of choline is a rate-limiting factor
in phospholipid synthesis and, therefore, may be important for timely membrane repair and cell survival.
This work aimed at verifying the effects of 7-day oral administration with different doses of choline on
survival of CA1 hippocampal neurons following transient global forebrain ischemia in rats. The
administration of 400 mg/kg/day divided into two daily doses for 7 consecutive days significantly
improved CA1 pyramidal cell survival, indicating that the local availability of this essential nutrient may
limit postischemic neuronal survival.
of the plasma membrane bilayer. Brain ischemia-reperfusion causes lipid peroxidation triggering multiple cell
death pathways involving necrosis and apoptosis. Membrane breakdown is, therefore, a major
pathophysiologic event in brain ischemia. The ability to achieve membrane repair is a critical step for
survival of ischemic neurons following reperfusion injury. The availability of choline is a rate-limiting factor
in phospholipid synthesis and, therefore, may be important for timely membrane repair and cell survival.
This work aimed at verifying the effects of 7-day oral administration with different doses of choline on
survival of CA1 hippocampal neurons following transient global forebrain ischemia in rats. The
administration of 400 mg/kg/day divided into two daily doses for 7 consecutive days significantly
improved CA1 pyramidal cell survival, indicating that the local availability of this essential nutrient may
limit postischemic neuronal survival.
Deve ser mencionado que o sistema nervoso e o sistema endócrino trabalham em harmonia, de tal forma que informações sobre os meios externo e interno são analisadas e ajustes são feitos a todo instante para manter a homeostase do organismo.
Cada sistema (nervoso e endócrino) utiliza seus sinalizadores químicos para coordenar as funções e a integração entre ambos é mediada pelo hipotálamo. O mecanismo da ação dos hormônios nas suas células-alvo pode ser basicamente de três tipos:
• hormônios peptídicos ou protéicos que se ligam a receptores da membrana da célula-alvo e não atravessam a membrana plasmática, desencadeando a ativação de um sistema de segundos mensageiros;
• hormônios esteróides (lipossolúveis) atravessam a membrana e ativam diretamente os receptores nucleares e;
• os hormônios análogos ou derivados de aminoácidos que alteram a diferença de potencial elétrico de células musculares e nervosas.