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Public health concerns exist surrounding the epidemic of the Zika virus (ZIKV) and the rapid growth of transplantation in developing countries, including endemic zones of active arbovirus transmission, as well as travel to such regions by potential organ donors and recipients. Few data exist regarding the clinical characteristics of ZIKV infection in immunocompromised hosts. Laboratory screening protocols for transplantation to differentiate ZIKV infections from other endemic viral diseases and for the detection of possible donor-derived infection have not been stated. The diagnosis of ZIKV infection remains a challenge, fueled by the lack of standardized commercially available diagnostic tests and validated reference diagnostic laboratories, as well as the limited duration of ZIKV viremia. In this small series, ZIKV infection in renal and liver recipients presented without rash, conjunctivitis, or neurological symptoms, and with abnormal graft function, thrombocytopenia, and bacterial superinfection. We report the first case series of ZIKV infection in solid organ recipients, with a description of clinical and laboratory features and therapeutic management.
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Rejeição de Enxerto/etiologia , Transplante de Órgãos/efeitos adversos , Viremia/etiologia , Infecção por Zika virus/complicações , Zika virus/patogenicidade , Rejeição de Enxerto/diagnóstico , Sobrevivência de Enxerto , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , RNA Viral/genética , Fatores de Risco , Viremia/diagnóstico , Zika virus/genética , Infecção por Zika virus/virologiaRESUMO
A common mutation in the BRAF gene, comprising the T1799A nucleotide transversion, which leads to the V600E amino acid substitution in the BRAF protein, has been observed in about 50% of papillary thyroid carcinomas (PTCs). However, BRAF protein expression has been rarely examined in such tumors. Clinical studies have shown important associations between BRAF mutation and clinical parameters in PTC, such as progression, invasion, and recurrence. The aim of this study was to evaluate the association between BRAF protein overexpression and the BRAF V600E mutation in a group of PTC patients. The study group included 116 patients with PTC from Araújo Jorge Hospital, Goiânia, Goiás, Brazil. Immunohistochemistry was utilized to analyze BRAF protein expression. Presence of the BRAF V600E mutation was determined by polymerase chain reaction amplification and restriction fragment length polymorphism, and confirmed by direct sequencing. The chi-square test with Yates correction and the Fisher exact test were used for statistical analysis. BRAF overexpression was detected in 55 patients with PTC (47.4%) and the BRAF V600E mutation was observed in 74 patients (63.8%). In the studied group, significant associations were observed between the BRAF V600E mutation and BRAF protein overexpression (P = 0.0115), and also between BRAF overexpression and extra-thyroid extension of the tumor (P = 0.0111). This study demonstrated a significant association between BRAF overexpression and the BRAF V600E mutation in PTC, highlighting the importance of these molecular events in the process of PTC carcinogenesis.
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Substituição de Aminoácidos , Carcinoma/genética , Mutação Puntual , Proteínas Proto-Oncogênicas B-raf/genética , Neoplasias da Glândula Tireoide/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Sequência de Bases , Carcinoma/patologia , Carcinoma/cirurgia , Carcinoma Papilar , Análise Mutacional de DNA , Feminino , Expressão Gênica , Humanos , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Estudos Retrospectivos , Câncer Papilífero da Tireoide , Neoplasias da Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/cirurgiaRESUMO
Tributyltin (TBT) is a biocide used in the formulation of antifouling paints and it is highly harmful. Despite the ban, the compound persists in the environment, contaminating marine foodstuffs and household products. Therefore, considering the route of exposure to the contaminant, the gastrointestinal tract (GIT) acts as an important barrier against harmful substances and is a potential biomarker for understanding the consequences of these agents. This work aimed to evaluate histological and neuronal alterations in the duodenum of male Wistar rats that received 20 ng/g TBT and 600 ng/g via gavage for 30 consecutive days. After the experimental period, the animals were euthanized, and the duodenum was intended for neuronal histochemistry (total and metabolically active populations) and histological routine (morphometry and histopathology). The results showed more severe changes in neuronal density and intestinal morphometry in rats exposed to 20 ng/g, such as total neuronal density decrease and reduction of intestinal layers. In rats exposed to 600 ng/g of TBT, it was possible to observe only an increase in intraepithelial lymphocytes. We conclude that TBT can be more harmful to intestinal homeostasis when consumed in lower concentrations.
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Duodeno , Plasticidade Neuronal , Ratos Wistar , Compostos de Trialquitina , Animais , Compostos de Trialquitina/toxicidade , Masculino , Plasticidade Neuronal/efeitos dos fármacos , Plasticidade Neuronal/fisiologia , Duodeno/efeitos dos fármacos , Duodeno/patologia , Neurônios/efeitos dos fármacos , Neurônios/patologia , Ratos , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/patologia , Sistema Nervoso Entérico/efeitos dos fármacos , Sistema Nervoso Entérico/patologiaRESUMO
The expansion of economic activities in coastal areas has significantly increased chemical contamination, leading to major environmental challenges. Contaminants enter the human body through the food chain, particularly via seafood and water consumption, triggering biomagnification and bioaccumulation processes. The gastrointestinal tract (GIT) acts as a selective barrier, protecting against chemical pollutants and maintaining homeostasis through a complex network of cells and immune responses. This study assessed impact of tributyltin (TBT), a highly toxic organometallic compound used in antifouling coatings for ships, on the GIT and myenteric neural plasticity in young rats. TBT exposure leads to histopathological changes, including epithelial detachment and inflammatory foci, especially at lower environmental doses. The study found that TBT causes significant reductions in villi height, increases in goblet cells and intraepithelial lymphocytes, and disrupts the myenteric plexus, with higher densities of extraganglionic neurons in exposed animals.
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The treatment of gastroesophageal reflux disease may be clinical or surgical. The clinical consists basically of the use of drugs; however, there are new techniques to complement this treatment, osteopathic intervention in the diaphragmatic muscle is one these. The objective of the study is to compare pressure values in the examination of esophageal manometry of the lower esophageal sphincter (LES) before and immediately after osteopathic intervention in the diaphragm muscle. Thirty-eight patients with gastroesophageal reflux disease - 16 submitted to sham technique and 22 submitted osteopathic technique - were randomly selected. The average respiratory pressure (ARP) and the maximum expiratory pressure (MEP) of the LES were measured by manometry before and after osteopathic technique at the point of highest pressure. Statistical analysis was performed using the Student's t-test and Mann-Whitney, and magnitude of the technique proposed was measured using the Cohen's index. Statistically significant difference in the osteopathic technique was found in three out of four in relation to the group of patients who performed the sham technique for the following measures of LES pressure: ARP with P= 0.027. The MEP had no statistical difference (P= 0.146). The values of Cohen d for the same measures were: ARP with d= 0.80 and MEP d= 0.52. Osteopathic manipulative technique produces a positive increment in the LES region soon after its performance.
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Diafragma , Esfíncter Esofágico Inferior/fisiopatologia , Refluxo Gastroesofágico/fisiopatologia , Refluxo Gastroesofágico/terapia , Osteopatia , Adulto , Idoso , Feminino , Humanos , Masculino , Manometria , Pessoa de Meia-Idade , Pressão , RespiraçãoRESUMO
Given the important role of leptin in metabolism, we looked for a possible association of leptin and leptin receptor polymorphisms with carcass and growth traits in Nellore cattle. We examined associations of leptin and leptin receptor SNPs with ultrasound carcass (longissimus dorsi muscle area (ribeye area), backfat thickness and rump fat thickness and growth traits (weaning weight adjusted to 210 days of age, yearling weight adjusted to 550 days of age, weight gain of weaning to yearling and scrotal circumference adjusted to 550 days of age) of 2162 Bos primigenius indicus (Nellore) animals. Allele and genotypic frequencies were calculated for each marker. Allele substitution, additive and dominance effects of the polymorphisms were also evaluated. Some alleles of the molecular markers had low frequencies, lower than 1%, in the sample analyzed, although the same polymorphisms described for B. p. taurus cattle were found. Due to very low allelic frequencies, the E2JW, A59V and UASMS2 markers were not included in the analysis, because they were almost fixed. E2FB was found to be significantly associated with weight gain, ribeye area and backfat thickness. The promoter region markers, C963T and UASMS1, were also found to be significantly associated with ribeye area. T945M was significantly associated with weight gain. We conclude that the leptin and receptor gene markers would be useful for marker-assisted selection.
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Bovinos/crescimento & desenvolvimento , Bovinos/genética , Leptina/genética , Carne , Polimorfismo de Nucleotídeo Único/genética , Característica Quantitativa Herdável , Receptores para Leptina/genética , Alelos , Animais , Frequência do Gene/genética , Estudos de Associação Genética , Marcadores Genéticos , Genótipo , UltrassomRESUMO
A new concept of oxide-metal-oxide structures that combine photothermoelectric effect with high reflectance (~ 80%) at wavelengths in the infrared (> 1100 nm) and high transmittance in the visible range is reported here. This was observed in optimized ITO/Ag/ITO structure, 20 nm of Silver (Ag) and 40 nm of Indium Tin Oxide (ITO), deposited on Aluminum doped Zinc Oxide (AZO) thin film. These layers show high energy saving efficiency by keeping the temperature constant inside a glazed compartment under solar radiation, but additionally they also show a photothermoelectric effect. Under uniform heating of the sample a thermoelectric effect is observed (S = 40 mV/K), but when irradiated, a potential proportional to the intensity of the radiation is also observed. Therefore, in addition to thermal control in windows, these low emission coatings can be applied as transparent photothermoelectric devices.
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Genital mycoplasmas are natural inhabitants of the male urethra and are potentially pathogenic species playing an aetiological role in both genital infections and male infertility. This study aims to determine the presence of Mycoplasma genitalium DNA in urine samples of HIV-1-infected men in São Paulo city. Realtime polymerase chain reaction (PCR) was performed using the primers My-ins and Mgso-2 and the Taqman probe Mgen-P1 as described previously. A total of 223 HIV-1-infected men were tested with a mean age of 44 years. Thirteen (5.8%) presented M. genitalium in urine and the co-infection was more common among homosexual men (76.9% versus 51.9%, P < 0.26). In conclusion, realtime PCR was a useful and rapid method for detecting M. genitalium DNA in urine samples. Further studies should be conducted to assess the clinical significance of these results on HIV transmission and its impact on HIV viral load.
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Infecções por HIV/epidemiologia , HIV-1 , Doenças Urogenitais Masculinas/epidemiologia , Infecções por Mycoplasma/epidemiologia , Mycoplasma genitalium/isolamento & purificação , Adulto , Brasil/epidemiologia , Comorbidade , DNA Bacteriano/urina , Homossexualidade Masculina , Humanos , Masculino , Doenças Urogenitais Masculinas/diagnóstico , Infecções por Mycoplasma/diagnóstico , Mycoplasma genitalium/genética , Reação em Cadeia da Polimerase , Prevalência , Fatores de RiscoRESUMO
The magnetic properties of Ar- and N-implanted single crystalline TiO(2) rutile were studied and correlated with the induced disorder in order to clarify the influence of defects in the magnetic behaviour. Nominal fluences of 1 × 10(17) and 2 × 10(17) cm(-2) and an implantation energy of 100 keV were used. The as-implanted single crystals exhibited ferromagnetic behaviour up to 380 K. Annealing at 1073 K induced recovery of the lattice structure and the decrease of the ferromagnetic moment in the case of Ar-implanted samples, but the magnetic moment did not change significantly for the samples implanted with nitrogen. No impurities, other than the implanted species were detected and consequently the ferromagnetic behaviour is attributed to defects created during implantation, which in the case of nitrogen remained in the lattice even after partial recovery of the structure.
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Aluminium doped zinc oxide (AZO) films were grown by Atomic Layer Deposition (ALD) on yellow Kapton and transparent Kapton (type CS) substrates for large area flexible transparent thermoelectric applications, which performance relies on the thermoelectric properties of the transparent AZO films. Therefore, their adhesion to Kapton, environmental and bending stability were accessed. Plasma treatment on Kapton substrates improved films adhesion, reduced cracks formation, and enhanced electrical resistance stability over time, of importance for long term thermoelectric applications in external environment. While exposure to UV light intensity caused the films electrical resistance to vary, and therefore their maximum power density outputs (0.3-0.4 mW/cm3) for a constant temperature difference (â¼10 °C), humidity exposure and consecutive bending up to a curvature radius above the critical one (â¼18 mm) not. Testing whether the films can benefit from encapsulation revealed that this can provide extra bending stability and prevent contacts deterioration in the long term.
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In this work, eco-friendly magnesium-silicide (Mg2Si) semiconducting (n-type) thermoelectric pastes for building components concerning energy-harvesting devices through 3D printing, spray and electrospinning were synthetized and tested for the first time. The Mg2Si fine powders were obtained through the combination of ball milling and thermal annealing under Ar atmosphere. While the latter process was crucial for obtaining the desired Mg2Si phase, the ball milling was indispensable for homogenizing and reducing the grain size of the powders. The synthetized Mg2Si powders exhibited a large Seebeck coefficient of ~ 487 µV/K and were blended with a polymeric solution in different mass ratios to adjust the paste viscosity to the different requirements of 3D printing, electrospinning and low-pressure spray. The materials produced in every single stage of the paste synthesis were characterized by a variety of techniques that unequivocally prove their viability for producing thermoelectric parts and components. These can certainly trigger further research and development in green thermoelectric generators (TEGs) capable of adopting any form or shape with enhanced thermoelectric properties. These green TEGs are meant to compete with common toxic materials such as Bi2Te3, PbTe and CoSb that have Seebeck coefficients in the range of ~ 290-700 µV/K, similar to that of the produced Mg2Si powders and lower than that of 3D printed bulk Mg2Si pieces, measured to be ~ 4866 µV/K. Also, their measured thermal conductivities proved to be significantly lower (~ 0.2 W/mK) than that reported for Mg2Si (≥ 4 W/mK). However, it is herein demonstrated that such thermoelectric properties are not stable over time. Pressureless sintering proved to be indispensable, but difficultly achievable by long thermal annealing (even above 32 h) in inert atmosphere at 400 °C, at least for bulk Mg2Si pieces constituted by a mean grain size of 2-3 µm. Hence, for overcoming this sintering challenge and become the silicide's extrusion viable in the production of bulk thermoelectric parts, alternative pressureless sintering methods will have to be further explored.
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Hepatopulmonary Syndrome (HPS) is a triad of liver disease, intrapulmonary vascular dilatation (IPVD), and arterial deoxygenation. Orthotopic liver transplantation (OLT) constitutes the only effective treatment; however, adverse outcomes have been reported. The aim of this study was to evaluate the early morbidity and short- and long-term survival after OLT for patients with and without HPS. We studied 59 transplant recipients divided into 2 groups: with HPS (HPS group n = 25) and without HPS (control group, n = 34) before the OLT. IPVD was diagnosed using transthoracic contrast-enhanced echocardiography. Arterial deoxygenation was defined as PA-a,O(2) >or= 15 mm Hg. The HPS and control groups were homogeneous regarding age (P = .36; 43.8 +/- 12.2 vs 46.9 +/- 13.5), gender (P = .47), male/female ratio (68%:32% and 78%:22%, respectively), and severity of liver disease. The PaO(2) was significantly lower (74.9 +/- 12.1 vs 93 +/- 6.4 mm Hg; P < .001) and the PA-a,O(2) was significantly higher in the HPS group (30.3 +/- 10.6 vs 11.0 +/- 7.0; P < .001). The percentage of severe (n = 3) and very severe (n = 1) hypoxemia was 16%. There were no significant differences between HPS and control groups regarding short- (68% vs 77%; P = .27) and long-term survival (60% vs 64%; P = .67) as well as among patients with mild, moderate, severe, or very severe HPS and the control group (P = .53). Also, intensive care unit (ICU) stay (7.0 vs 5.5; P = .41), duration of mechanical ventilation (38.0 vs 27.5; P = .43), reintubation rate (32.0% vs 23.5%; P = .45), and early postoperative complications (P = .72) were not different. In conclusion, there were no significant differences regarding the outcomes of OLT for patients with versus without HPS related to early morbidity or short- and long-term survival.
Assuntos
Síndrome Hepatopulmonar/cirurgia , Transplante de Fígado/estatística & dados numéricos , Gasometria , Ecocardiografia Transesofagiana , Síndrome Hepatopulmonar/diagnóstico por imagem , Humanos , Transplante de Fígado/mortalidade , Oxigênio/sangue , Estudos Retrospectivos , Análise de Sobrevida , Sobreviventes/estatística & dados numéricosRESUMO
This article reports the case of a patient who underwent transjugular intrahepatic portosystemic shunt, which migrated to the right atrium. During liver transplantation, the extracardiac portion was sectioned and the portion adherent inside the atrium was managed expectantly.
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Átrios do Coração/cirurgia , Complicações Intraoperatórias/fisiopatologia , Transplante de Fígado/efeitos adversos , Derivação Portossistêmica Transjugular Intra-Hepática/efeitos adversos , Transfusão de Sangue , Transfusão de Eritrócitos , Feminino , Humanos , Período Intraoperatório , Transfusão de Plaquetas , Veia Porta/cirurgiaRESUMO
INTRODUCTION: Hepatic artery stenosis (HAS) after liver transplantation can lead to altered hepatic function and/or thrombosis, there by increasing morbidity and mortality. The prevalence of HAS in the literatures varies from 4% to 11%. OBJECTIVE: We sought to describe the prevalence and treatment of hepatic artery stenosis. METHODS: We performed a descriptive retrospective analysis of 253 liver transplantations from March 1998 to May 2007, including patients with suspected HAS owing to increased hepatic enzymes, altered Doppler ultrasound (us) and hepatic biopsy. The confirmation of HAS was achieved through areriography. RESULTS: Nine patients were identified to have HAS, a 3.5% prevalence. Among the HAS patients, seven were male and two female. Their average age was 35.5 years (range, 65 to 53). The average time between the diagnosis and transplantation was 14.2 months (range, 9 to 68). The increase in hepatic enzymes among this group averaged: aspartate aminotransferase 131 U/L (range, 26 to 412) and alanine aminotransferase 192 U/L (range, 35 to 511). Doppler US showed alteration in the resistance level index. All patients underwent areriography; only one could not be treated owing to severe hepatic artery spasm, which also occurred during another attempt weeks after the first one. Among the eight patients, six were treated with stents and two with angioplastis. All treated patients displayed improvements in parameters. Four patients treated with stents required retreatment: two underwent angioplasty and two, a thrombolytic. One graft rethrombosed but evolved in compensated fashion with recanalization by collaterals. There has been no graft loss or mortality in this population. The average time of posttreatment follow-up was 31.28 (range, 9 to 68) months. CONCLUSION: The prevalence of HAS in our unit was within that reported in the literature. Treatment with a stent or angioplasty proved to be efficient to control this complication, considering that hepatic function recovered and that there was neither graft nor patient loss.
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Arteriopatias Oclusivas/epidemiologia , Artéria Hepática , Transplante de Fígado/efeitos adversos , Complicações Pós-Operatórias/epidemiologia , Adulto , Idoso , Alanina Transaminase/sangue , Arteriopatias Oclusivas/terapia , Aspartato Aminotransferases/sangue , Humanos , Pessoa de Meia-Idade , Complicações Pós-Operatórias/terapia , PrevalênciaRESUMO
Intestinal failure is the patient's inability to maintain hydroelectric and nutritional support by the digestive route, arising from massive enterectomy or diseases in which the bowel is incapable of adequately absorbing fluids and nutrients. Patients with intestinal failure associated with short bowel syndrome (SBS) and with other functional diseases with malabsorption or with total parenteral nutrition-related complications (recurrent sepsis and thrombosis of one or more deep venous accesses) are candidates for small bowel transplantation (SBT), which can be an isolated small bowel, a combined liver and small bowel, or a multivisceral graft. At our institution, three isolated SBTs were performed as our initial experience with this transplant.
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Intestino Delgado/transplante , Adulto , Idoso , Brasil , Evolução Fatal , Feminino , Hospitais de Ensino/estatística & dados numéricos , Humanos , Enteropatias/cirurgia , Masculino , Síndrome do Intestino Curto/cirurgia , Resultado do TratamentoRESUMO
INTRODUCTION: Adherence to treatment is essential for a successful liver transplantation (LT) because LT requires information, abilities, and competencies of patients and family members. OBJECTIVES: This study sought to identify whether the information received about the LT process was enough for either patients or family members who attended a liver transplant center in a school hospital. METHODS: This was a transversal study using questionnaires to verify received information on LT. It included 50 patients on the waiting list for LT, 50 transplanted patients, and 50 family members. RESULTS: There was a prevalence of men (82%) among patients, age range from 19 to 67 years (average: 46.87 ± 10.99), and of women (74%) among family members, age range from 18 to 80 years (average: 43.5 ± 11.77). The majority of subjects (88%) had a low education level. The most frequent etiology of hepatic cirrhosis was viral hepatitis associated with alcohol. A significant number of the listed and transplanted patients as well as all family members reported insufficient information about the process of the transplantation. The kind of insufficient information varied according to the period of treatment. The best way to obtain information, as reported by patients and family members, was a combination of oral and written information. CONCLUSIONS: Our data show the need for improvement in the means of delivering information to patients and family members, and an explanatory manual was created from this study.
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Família , Cirrose Hepática/cirurgia , Transplante de Fígado , Educação de Pacientes como Assunto , Transplantados , Acesso à Informação , Adulto , Idoso , Idoso de 80 Anos ou mais , Escolaridade , Feminino , Hepatite Viral Humana/complicações , Humanos , Cirrose Hepática/etiologia , Cirrose Hepática Alcoólica/cirurgia , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Listas de Espera , Adulto JovemRESUMO
Experiments using localized infusions into selected brain structures of agonists and antagonists of various synaptic receptors, given before or after behavioral training, have led to the following conclusions: (1) Memory is processed shortly after training in the amygdala, medial septum and hippocampus by glutamatergic NMDA and AMPA receptors activated in that sequence. Cholinergic muscarinic receptors are activated concurrently with the former. GABAA receptors modulated by brain benzodiazepines and by beta-noradrenergic receptors inhibit the process. (2) The sequential involvement of NMDA and AMPA receptors suggests that long-term potentiation (LTP) of the synapses activated by the learning experiences in the hippocampus and/or amygdala and medial septum is the crucial event. Expression of this LTP at the time of testing is necessary for retrieval: AMPA receptor blockade in the hippocampus and amygdala at the time of testing hinders retrieval. This suggests that the LTP underlies the memory process itself. (3) The amygdala, medial septum and hippocampus mediate different types of memory and/or different components of memories. The entorhinal cortex, through mechanisms that require intact NMDA receptors and are inhibited by GABAA receptors, intervenes in post-training memory processing 90-180 min after the other limbic regions. The entorhinal cortex integrates consecutively acquired memories; this role could be maintained by the LTP that is generated after training in the amygdala, hippocampus and medial septum. Post-training intervention of the entorhinal cortex does not occur if this region is inhibited at the time of training.
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Sistema Límbico/fisiologia , Memória/fisiologia , Neurotransmissores/fisiologia , Animais , Humanos , Sistema Límbico/efeitos dos fármacos , Memória/efeitos dos fármacos , Receptores de Neurotransmissores/efeitos dos fármacos , Receptores de Neurotransmissores/fisiologiaRESUMO
Zinc protoporhyrin-9 (ZnPP) is an inhibitor of heme oxygenase, the enzyme involved in the biosynthesis of carbon monoxide (CO). CO regulates the activity of glutamatergic synapses and has been proposed to play a role in the early phases of long-term potentiation. The present paper reports on the effect of ZnPP on memory of inhibitory avoidance and of habituation to a novel environment. The bilateral infusion of ZnPP (2 micrograms/side) into the dorsal hippocampus caused amnesia for the inhibitory avoidance task when given before training or 0 or 30 min, but not 60 or 100 min, after training. The immediate post-training intrahippocampal infusion of ZnPP also caused amnesia for the habituation task. The immediate post-training intra-amygdala infusion of ZnPP had no effect on retention of the avoidance task. The data are consistent with the hypotheses that memory involves long-term potentiation initiated at the time of training in the hippocampus, and that hippocampal but not amygdala long-term potentiation may be regulated by CO.
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Amnésia Retrógrada/induzido quimicamente , Tonsila do Cerebelo/fisiologia , Heme Oxigenase (Desciclizante)/antagonistas & inibidores , Hipocampo/fisiologia , Protoporfirinas/farmacologia , Amnésia Retrógrada/psicologia , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Habituação Psicofisiológica/efeitos dos fármacos , Injeções , Potenciação de Longa Duração/efeitos dos fármacos , Masculino , Protoporfirinas/administração & dosagem , Ratos , Ratos WistarRESUMO
This experiment investigated the effect on memory, in rats, of the bilateral intrahippocampal post-training infusion of the glutamate metabotropic receptor (mGLUR) agonist, ACPD (1S, 2R-aminocyclopentane dicarboxylate) and of the mGLUR antagonist, MCPG ([RS]-alpha-methyl-4-carboxyphenyl glycine). Male Wistar rats were implanted bilaterally with cannulae in the CA1 region of the dorsal hippocampus. After recovery from surgery they were trained in a step-down inhibitory avoidance task and tested for retention 24h later. Immediately or 180min after training they received a bilateral intrahippocampal infusion of saline (0.5µl), ACPD (1.0 or 2.5µg/side), MCPG (2.5µg/side) or ACPD plus MCPG, in 0.5µl saline. Upon immediate post-training infusion, ACPD caused a dose-dependent enhancement of memory and MCPG was amnestic. The effect of MCPG was antagonized by the simultaneous administration of ACPD. When given 180min after training, the drugs had no effect on memory. The results indicate that the early phase of memory is regulated by mGLURs in the hippocampus, and support the suggestion that memory involves long-term potentiation initiated at the time of training in the hippocampus.
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The bilateral infusion into the entorhinal cortex of the NMDA receptor antagonist, AP5 (5.0µg) or of the GABA(A) agonist, muscimol (0.03µg) 90min after training but not 30min before training, 0min after training or 10min before testing, hindered retention test performance 24h after inhibitory avoidance in rats. Glutamate (5.0µg) or picrotoxin (0.08µg) infused 90min after training had no effect. In animals trained with a low level footshock a second training session, 120min after the first, was needed in order to obtain a good retention test performance. This was taken to reflect summation of the consecutive memory traces left by the two training sessions. In these animals, the infusion of AP5 or muscimol into the entorhinal cortex between the two training sessions impeded their summation. The present results suggest that the entorhinal cortex plays a late role in memory processing, that this role does not need a hyperactivation of the entorhinal cortex, and that it is important for the interaction between consecutive memory traces.