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1.
Indian J Pharmacol ; 48(Suppl 1): S41-S46, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28031607

RESUMO

OBJECTIVES: Flipped classroom (FC) is a pedagogical model to engage students in learning process by replacing the didactic lectures. Using technology, lectures are moved out of the classroom and delivered online as means to provide interaction and collaboration. Poll Everywhere is an audience response system (ARS) which can be used in an FC to make the activities more interesting, engaging, and interactive. This study aims to study the perception of undergraduate pharmacy students on FC activity using Poll Everywhere ARS and to study the effectiveness of FC activity as a teaching-learning tool for delivering complementary medicine module in the undergraduate pharmacy program. MATERIALS AND METHODS: In this nonrandomized trial on interrupted time series study, flipped class was conducted on group of 112 students of bachelor of pharmacy semester V. The topic selected was popular herbal remedies of the complementary medicine module. Flipped class was conducted with audio and video presentation in the form of a quiz using ten one-best-answer type of multiple-choice questions covering the learning objectives. Audience response was captured using web-based interaction with Poll Everywhere. Feedback was obtained from participants at the end of FC activity and debriefing was done. RESULTS: Randomly selected 112 complete responses were included in the final analysis. There were 47 (42%) male and 65 (58%) female respondents. The overall Cronbach's alpha of feedback questionnaire was 0.912. The central tendencies and dispersions of items in the questionnaire indicated the effectiveness of FC. The low or middle achievers of quiz session (pretest) during the FC activity were three times (95% confidence interval [CI] = 1.1-8.9) at the risk of providing neutral or negative feedback than high achievers (P = 0.040). Those who gave neutral or negative feedback on FC activity were 3.9 times (95% CI = 1.3-11.8) at the risk of becoming low or middle achievers during the end of semester examination (P = 0.013). The multivariate analysis of "Agree" or "Disagree" and "Agree" or "Strongly Agree" was statistically significant. CONCLUSION: This study provides insight on how the pharmacy students learn and develop their cognitive functions. The results revealed that the FC activity with Poll Everywhere is an effective teaching-learning method.


Assuntos
Educação em Farmácia/métodos , Software , Inquéritos e Questionários , Cognição , Avaliação Educacional , Feminino , Medicina Herbária/educação , Humanos , Masculino , Percepção , Estudantes de Farmácia , Ensino
2.
J Basic Clin Pharm ; 7(4): 105-109, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27999469

RESUMO

INTRODUCTION: Reports on medication adherence and its associated factors in patients with epilepsy in South East Asian countries are lacking. The primary purpose of this study was to assess the degree of medication adherence and its relationship with patient's satisfaction, psychosocial factors, quality of life and mental health in a sample of Malaysian epilepsy patients. METHODOLOGY: It is a cross-sectional study and was carried out in the outpatient Neurology Department of Hospital Kuala Lumpur, Malaysia (n=272). Data was collected by administering the structured questionnaire. RESULTS AND DISCUSSION: Results showed that 49.3% of the epilepsy patients were non-adherent to their prescribed regimen. Univariate analysis showed significant associations between medication adherence and the following factors: race, seizure frequency, overall patient satisfaction, medication taste and smell, medication cost and physical appearance, medication effectiveness, complexity of medication regimen, patient barrier, patient understanding, patient role functioning, patient positivity, vitality and general interest. Multiple regression analysis indicated that factors that are influencing medication adherence are seizure frequency (P = 0.048), overall patient satisfaction (P = 0.043) and patient understanding about their illness (P = 0.001). The model chosen for testing the relationship between medication adherence and its associated factors give an R2 value of 25.2% with an adjusted R2 of 21.4%. The F value was also significant (P = 0.000). Based on the research findings, the researchers recommends that clinicians need to play a vital role in educating the patients on their disease conditions. By educating the patients on nature of epilepsy, different modalities of treatment and benefits of adherence to treatment will help in the better adherence and management.

3.
Food Chem Toxicol ; 66: 295-306, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24518542

RESUMO

The current study aimed to ascertain the antidiabetic potential of Pseuduvaria monticola bark methanolic extract (PMm) using in vitro mechanistic study models. In particular, the study determined the effect of PMm on cellular viability, 2-NBDG glucose uptake, insulin secretion, and NF-κB translocation in mouse pancreatic insulinoma cells (NIT-1). Furthermore, in vivo acute toxicity and antidiabetic studies were performed using streptozotocin (STZ)-induced type 1 and STZ-nicotinamide-induced type 2 diabetic rat models to evaluate various biochemical parameters and markers of oxidative stress and pro-inflammatory cytokines. Five isoquinoline alkaloids and three phenolic compounds were tentatively identified in the PMm by LC/MS Triple TOF. The study results showed that PMm is non-toxic to NIT-1 cells and significantly increased the glucose uptake and insulin secretion without affecting the translocation of NF-κB. Moreover, the non-toxic effects of PMm were confirmed through an in vivo acute toxicity study, which revealed that the serum insulin and C-peptide levels were significantly upregulated in type 2 diabetic rats and that no significant changes were observed in type 1 diabetic rats. Similarly, PMm was found to downregulate the levels of oxidative stress and pro-inflammatory cytokines in type 2 diabetic rats by alleviating hyperglycemia. Therefore, we conclude that PMm may be developed as an antidiabetic agent for the treatment of type 2 diabetes-associated conditions.


Assuntos
Annonaceae/química , Citocinas/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Insulina/metabolismo , Estresse Oxidativo , Animais , Regulação para Baixo , Mediadores da Inflamação/metabolismo , Secreção de Insulina , Niacinamida , Casca de Planta/química , Extratos Vegetais/farmacologia , Ratos , Estreptozocina , Regulação para Cima
4.
Ultrasonics ; 53(6): 1150-62, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23541960

RESUMO

Experimental and theoretical studies on degradation of composite-epoxy adhesive joints were carried out on samples having different interfacial and cohesive properties. Oblique incidence ultrasonic inspection of bonded joints revealed that degradation in the adhesive can be measured by significant variation in reflection amplitude as also by a shift in the minima of reflection spectrum. It was observed that severe degradation of the adhesive leads to failure dominated by interfacial mode. Through this investigation it is demonstrated that a correlation exists between the bond strength and a frequency shift in reflection minimum. The experimental data was validated using analytical models. Though both bulk adhesive degradation and interfacial degradation influences the shift in spectrum minimum, the contribution of the latter was found to be significant. An inversion algorithm was used to determine the interfacial transverse stiffness using the experimental oblique reflection spectrum. The spectrum shift was found to depend on the value of interfacial transverse stiffness using which a qualitative assessment can be made on the integrity of the joint.

5.
J Acoust Soc Am ; 126(5): 2324-30, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19894815

RESUMO

Conventional analytical/numerical methods employing triangulation technique are suitable for locating acoustic emission (AE) source in a planar structure without structural discontinuities. But these methods cannot be extended to structures with complicated geometry, and, also, the problem gets compounded if the material of the structure is anisotropic warranting complex analytical velocity models. A geodesic approach using Voronoi construction is proposed in this work to locate the AE source in a composite structure. The approach is based on the fact that the wave takes minimum energy path to travel from the source to any other point in the connected domain. The geodesics are computed on the meshed surface of the structure using graph theory based on Dijkstra's algorithm. By propagating the waves in reverse virtually from these sensors along the geodesic path and by locating the first intersection point of these waves, one can get the AE source location. In this work, the geodesic approach is shown more suitable for a practicable source location solution in a composite structure with arbitrary surface containing finite discontinuities. Experiments have been conducted on composite plate specimens of simple and complex geometry to validate this method.


Assuntos
Acústica , Algoritmos , Teste de Materiais/métodos , Modelos Teóricos , Localização de Som , Carbono , Compostos de Epóxi , Vidro
6.
Ultrasonics ; 49(8): 696-705, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19539965

RESUMO

Time reversal active sensing using Lamb waves is investigated for health monitoring of a metallic structure. Experiments were conducted on an aluminum plate to study the time reversal behavior of A(0) and S(0) Lamb wave modes under narrow band and broad band pulse excitation. Damage in the form of a notch was introduced in the plate to study the changes in the characteristics of the time reversed Lamb wave modes experimentally. Time-frequency analysis of the time reversed signal was carried out to extract the damage information. A measure of damage based on wavelet transform was derived to quantify the hidden damage information in the time reversed signal. It has been shown that time reversal can be used to achieve temporal recompression of Lamb waves under broadband signal excitation. Further, the broad band excitation can also improve the resolution of the technique in detecting closely located defects. This is demonstrated by picking up the reflection of waves from the edge of the plate, from a defect close to the edge of the plate and from defects located near to each other. This study shows the effectiveness of Lamb wave time reversal for temporal recompression of dispersive Lamb waves for damage detection in health monitoring applications.


Assuntos
Algoritmos , Ondas de Choque de Alta Energia , Teste de Materiais/métodos , Metais/análise , Metais/química , Modelos Químicos , Ultrassonografia/métodos , Simulação por Computador , Espalhamento de Radiação
7.
J Neurosci Res ; 66(5): 981-91, 2001 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-11746427

RESUMO

Ammonia is a toxin that has been strongly implicated in the pathogenesis of hepatic encephalopathy (HE), and the astrocyte appears to be the principal target of ammonia toxicity. The specific neurochemical mechanisms underlying HE, however, remain elusive. One of the suggested mechanisms for ammonia toxicity is impaired cellular bioenergetics. Because there is evidence that the mitochondrial permeability transition (MPT) is associated with mitochondrial dysfunction, we determined whether the MPT might be involved in the bioenergetic alterations related to ammonia toxicity. Accordingly, we examined the mitochondrial membrane potential (Deltapsi(m)) in cultured astrocytes and neurons using laser-scanning confocal microscopy after loading the cells with the voltage-sensitive dye JC-1. We found that ammonia induced a dissipation of the Deltapsi(m) in a time- and concentration-dependent manner. These findings were supported by flow cytometry using the voltage-sensitive dye tetramethylrhodamine ethyl ester (TMRE). Cyclosporin A, a specific inhibitor of the MPT, completely blocked the ammonia-induced dissipation of the Deltapsi(m). We also found an increase in the mitochondrial permeability to 2-deoxyglucose in astrocytes that had been exposed to 5 mM NH(4)Cl, further supporting the concept that ammonia induces the MPT in these cells. Pretreatment with methionine sulfoximine, an inhibitor of glutamine synthetase, blocked the ammonia-induced collapse of Deltapsi(m), suggesting a role of glutamine in this process. Over a 24-hr period, ammonia had no effect on the Deltapsi(m) in cultured neurons. Collectively, our data indicate that ammonia induces the MPT in cultured astrocytes, which may be a factor in the mitochondrial dysfunction associated with HE and other hyperammonemic states.


Assuntos
Amônia/metabolismo , Astrócitos/metabolismo , Encéfalo/metabolismo , Metabolismo Energético/fisiologia , Encefalopatia Hepática/metabolismo , Membranas Intracelulares/metabolismo , Mitocôndrias/metabolismo , Amônia/farmacocinética , Amônia/toxicidade , Cloreto de Amônio/farmacologia , Animais , Animais Recém-Nascidos , Astrócitos/efeitos dos fármacos , Benzimidazóis , Encéfalo/fisiopatologia , Calcineurina/metabolismo , Inibidores de Calcineurina , Cálcio/metabolismo , Carbocianinas , Células Cultivadas , Desoxiglucose/farmacocinética , Metabolismo Energético/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Citometria de Fluxo , Corantes Fluorescentes , Glutamato-Amônia Ligase/antagonistas & inibidores , Glutamato-Amônia Ligase/metabolismo , Encefalopatia Hepática/fisiopatologia , Membranas Intracelulares/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Microscopia Confocal , Mitocôndrias/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Permeabilidade/efeitos dos fármacos , Ratos
8.
J Neurosci Res ; 66(2): 282-8, 2001 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-11592125

RESUMO

Elevated levels of ammonia in blood and brain result in derangement of cerebral function. Recently, lipid peroxidation and oxidative stress have been implicated in ammonia neurotoxicity. Because ammonia is primarily detoxified in astrocytes, we postulated that pathophysiological concentrations of ammonia might induce free radical formation in these cells. To test this hypothesis, we examined the extent of free radical production in primary cultures of astrocytes that had been preloaded with the fluorescent dye 5- (and 6-)carboxy-2',7'-dichlorodihydrofluorescein diacetate (DCFDA). DCFDA fluorescence was found to be increased in a dose-dependent manner when astrocytes were exposed to 1, 5, and 10 mM NH(4)Cl. This phenomenon was transitory; it peaked at 2.5 min after exposure and declined subsequently. By 2 hr after treatment, DCFDA fluorescence was below control level. Addition of catalase or superoxide dismutase to 5 mM NH(4)Cl-treated astrocytes reduced free radical formation. Pretreatment with 3 mM methionine sulfoximine, an inhibitor of glutamine synthetase, also suppressed free radical formation by 5 mM NH(4)Cl. The results of this study suggest that elevated concentrations of ammonia induce the formation of free radicals in astrocytes and that this process is associated with the synthesis of glutamine. We propose that astrocyte-derived free radicals may be responsible for some of the pathophysiological changes associated with hyperammonemic conditions.


Assuntos
Cloreto de Amônio/farmacologia , Astrócitos/efeitos dos fármacos , Radicais Livres , Animais , Astrócitos/metabolismo , Catalase/farmacologia , Células Cultivadas/efeitos dos fármacos , Células Cultivadas/metabolismo , Inibidores Enzimáticos/farmacologia , Fluoresceínas/análise , Corantes Fluorescentes/análise , Fluorometria , Glutamato-Amônia Ligase/antagonistas & inibidores , Glutamina/biossíntese , Hiperamonemia/metabolismo , Hiperamonemia/fisiopatologia , Peroxidação de Lipídeos , Metionina Sulfoximina/farmacologia , Proteínas do Tecido Nervoso/antagonistas & inibidores , Ratos , Superóxido Dismutase/farmacologia
9.
Neurochem Int ; 37(2-3): 255-68, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10812211

RESUMO

It is well established that ammonia is detoxified in the brain to form glutamine and that astrocytes play a major role in this process. The synthesis of glutamine requires glutamate and ATP. Since glutamate and ATP are also required for the synthesis of glutathione (GSH), we examined the effect of pathophysiological concentrations of ammonia on levels of GSH in primary cultures of astrocytes. GSH content in the medium increased in a dose- and time-dependent manner in the presence of ammonia. After an initial decrease, cellular GSH content increased in a similar manner. The levels of glutathione disulfide (GSSG) were also increased. A linear relationship was observed between ammonia concentration and the increase in GSH levels. An increase in the efflux of GSH from cells into medium was also observed under these conditions. Buthionine sulfoximine and acivicin, but not methionine sulfoximine, blocked the ammonia induced increase in GSH levels. No, or minor, changes in the activities of enzymes (gamma-glutamyl transpeptidase, GSH reductase and GSH-peroxidase) that might influence GSH levels were identified and thus could not account for the ammonia induced increase in GSH levels in astrocytes. These findings indicate that pathophysiological concentrations of ammonium ions result in increased astroglial levels of GSH which may affect the metabolism and function of astrocytes.


Assuntos
Amônia/farmacologia , Astrócitos/metabolismo , Glutationa/metabolismo , Cloreto de Amônio/farmacologia , Animais , Animais Recém-Nascidos , Astrócitos/efeitos dos fármacos , Astrócitos/enzimologia , Butionina Sulfoximina/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Inibidores Enzimáticos/farmacologia , Glucosefosfato Desidrogenase/antagonistas & inibidores , Glucosefosfato Desidrogenase/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Isoxazóis/farmacologia , L-Lactato Desidrogenase/metabolismo , Metionina Sulfoximina/farmacologia , Oxirredução , Ratos , gama-Glutamiltransferase/metabolismo
10.
Biochem Pharmacol ; 56(2): 237-41, 1998 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-9698078

RESUMO

Multiple neurotransmitter systems have been implicated in the etiology of cerebral dysfunction in acute and chronic hyperammonemic states. Involvement of the neurotransmitter systems of glutamate and gamma-aminobutyric acid has been reported, whereas not much information is available on the role of the cholinergic system in the etiology of hyperammonemic states. In the present investigation, muscarinic acetylcholine receptors (mAChR) were studied, using tritium-labelled quinuclidinyl benzilate ([3H]QNB), in rats administered ammonium acetate (AA), and the changes in the treated rats were compared with measurements in normal rats. The presence of two affinity (high and low) systems for [3H]QNB binding was observed in the cerebral cortex (CC), while a single affinity system was seen in the cerebellum (CE) and pons-medulla (PM). A decrease in the Bmax of both the high and low affinity systems for [3H]QNB binding was observed in the CC with no significant change in the Kd values in rats administered an acute dose of AA (25 mmol/kg of body weight). The Bmax values were unaltered in CE and PM, but a significant increase in the Kd value was observed in the CE. Studies of [3H]QNB binding in the presence of pirenzepine (a specific antagonist of M1 receptors) indicated the predominance of non-M1-type (M2, M3, M4, and M5) receptors (85-90% of the total specific binding) in the CE and PM, whereas in the CC, 60% was represented by non-M1 and 40% by M1 receptors. Reduction in [3H]QNB binding to M1 receptors was observed in the CC and PM of rats administered an acute dose of AA. Administration of lower doses of AA (2.5 mmol/kg of body weight) had no effect on CC and CE mAChRs, while an increase in non-M1 and a decrease in M1 receptors was observed in the PM. As the neurotransmitter receptors play a key role in signal transduction, the observed changes in receptor functions may be responsible for some of the behavioral changes reported in hyperammonemic states.


Assuntos
Amônia/sangue , Encéfalo/metabolismo , Receptores Muscarínicos/metabolismo , Amônia/metabolismo , Animais , Modelos Animais de Doenças , Cinética , Quinuclidinil Benzilato/metabolismo , Ratos , Ratos Wistar , Trítio
11.
J Neurochem ; 70(4): 1644-51, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9523582

RESUMO

In the present investigation, in vitro phosphorylation of CNS proteins of the silkworm Bombyx mori during the postembryonic development have been studied. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of phosphorylated proteins revealed the presence of major phosphoproteins of 59/60 kDa. Based on molecular mass, calcium/calmodulin-dependent autophosphorylation, substrate specificity, KN-62 inhibition, apparent Km for ATP and syntide-2, these proteins were identified as calcium/calmodulin-dependent protein kinase II (CaM kinase II). Anti-rat CaM kinase II monoclonal antibody showed immunoreactivity with Bombyx CaM kinase II isoforms. This kinase showed a high degree of autophosphorylation in neural tissue. During postembryonic development of Bombyx, two distinct peaks of enzyme activity could be noticed, one at the late-larval and another at the late-pupal stage, which were associated with an increase in amount of the enzyme. These results suggested that the expression of CaM kinase II in the CNS of Bombyx was developmentally regulated.


Assuntos
Envelhecimento/metabolismo , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Sistema Nervoso Central/enzimologia , Animais , Bombyx/crescimento & desenvolvimento , Catálise , Sistema Nervoso Central/crescimento & desenvolvimento , Imuno-Histoquímica , Isoenzimas/metabolismo , Larva/crescimento & desenvolvimento , Metamorfose Biológica/fisiologia , Ácido Okadáico/farmacologia , Fosforilação , Distribuição Tecidual
12.
Neurosci Lett ; 184(2): 137-40, 1995 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-7724048

RESUMO

Uptake of branched chain amino acids (BCAA, leucine and isoleucine) was studied in synaptosomes prepared from the cerebral cortex of rats of 1, 3 and 24 months of age. In addition to the conventional low affinity sodium independent transport system, a high affinity sodium dependent stereospecific transport system for the transport of BCAA was identified in synaptosomes prepared from the cerebral cortex of the above three age groups. There was an overall decrease in Km and Vmax of both high and low affinity transport systems for leucine and isoleucine in the cortical synaptosomes of 24-month-old rats when compared with younger age groups. This study indicates that the non-neurotransmitter essential amino acids are transported by high and low affinity transport systems and these systems undergo age-dependent alterations. These changes might be due to the altered synthesis of these transporter proteins and/or synthesis of transporters with altered conformation and/or changes in the physical properties (fluidity) of the membrane. The decrease in the transport of BCAA is on a par with the decrease in the overall metabolism of BCAA in brain. As food consumption decreases in the older age groups of animals, the availability of essential amino acids to the tissues might also be lowered. Under such conditions, it is suggested that the observed increase in the affinity (decreased Km) of the carrier might be helpful in the supply of essential amino acids.


Assuntos
Envelhecimento/metabolismo , Aminoácidos de Cadeia Ramificada/metabolismo , Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/metabolismo , Sinaptossomos/metabolismo , Animais , Transporte Biológico , Cinética , Masculino , Ratos , Ratos Wistar
13.
Neurosci Lett ; 175(1-2): 103-6, 1994 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-7970187

RESUMO

High affinity uptake systems have been identified for the transport of leucine, isoleucine and methionine in synaptosomes but not in the mitochondria of rat cerebral cortex. These systems were found to be different from the conventional low affinity uptake systems in terms of their affinity, sodium dependency and the rate of transport. As these amino acids have no neurotransmitter function, it is suggested that high affinity uptake systems might be involved in the transport of essential amino acids and maintain a minimal level in brain when the concentrations of these amino acids are low in blood (as in starvation, malnutrition). As some of these amino acids serve as precursors for neurotransmitters, such as glutamate (leucine, isoleucine), taurine (methionine), it is also suggested that high affinity uptake systems for the essential amino acids might also replenish the precursor pools of neurotransmitter amino acids.


Assuntos
Aminoácidos Essenciais/metabolismo , Córtex Cerebral/metabolismo , Sinaptossomos/metabolismo , Animais , Transporte Biológico , Isoleucina/metabolismo , Cinética , Leucina/metabolismo , Metionina/metabolismo , Mitocôndrias/metabolismo , Ratos , Ratos Wistar , Radioisótopos de Enxofre
14.
Neurochem Res ; 19(3): 353-8, 1994 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8177376

RESUMO

The functional significance of ammonia production in brain under physiological or pathological conditions is not clearly known. NH4+ stimulates Na+, K+ activated ATPase causing stabilization of neuronal membranes of which gangliosides are major structural components. Moreover ammonia is known to inhibit lysosomal enzymes which include enzymes degrading gangliosides. Gangliosides have been shown to stimulate neuritogenesis in neuronal cultures and prevent the damage of the neurons from glutamate toxicity particularly in areas of brain ischemia. Hyperammonemia without any behavioural changes was induced in experimental rats by intraperitoneal administration of either a single dose (0.8 mmol/100 g wt.) or by six 'hourly' doses (0.6 mmol/100 g wt.) of ammonium acetate. An increase in the content of gangliosides along with a rise in the content of GD1A and GD1B without any change in beta-galactosidase and N-acetylhexosaminidase was observed in cerebral cortex, cerebellum, and brain stem, following the administration of single dose of ammonium acetate. Gangliosides, after extraction from the different brain regions, were estimated by the thiobarbituric acid method and expressed in terms of sialic acid. Individual gangliosides were separated and estimated by thin layer chromatography using resorcinol as the staining agent. These results suggest that ammonia production in the neuronal pathways in brain either as a result of repeated stimulation under physiological conditions or as a result of focal ischemia or injury, may likewise cause an increase in the content of gangliosides which may help in neuritic growth (physiological conditions facilitating synaptic plasticity) and may exert a protective effect on the neurons in the ischemic area against glutamate toxicity.


Assuntos
Acetatos/farmacologia , Amônia/farmacologia , Encéfalo/metabolismo , Gangliosídeos/metabolismo , Acetilglucosaminidase/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Tronco Encefálico/metabolismo , Cerebelo/metabolismo , Córtex Cerebral/metabolismo , Feminino , Gangliosídeo G(M1)/metabolismo , Gangliosídeos/isolamento & purificação , Masculino , Especificidade de Órgãos , Ratos , beta-Galactosidase/metabolismo
15.
Neurosci Lett ; 161(1): 37-40, 1993 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-8255543

RESUMO

Activity levels of enzymes of glycolytic pathway viz., hexokinase (EC.2.7.1.1), phosphofructokinase (EC.2.7.1.11), aldolase (EC.4.1.2.13), glyceraldehyde-3-phosphate dehydrogenase (EC.1.2.1.12), enolase (EC.4.2.1.11), pyruvate kinase (EC.2.7.1.40) and lactate dehydrogenase (EC.1.1.1.27) were estimated in cerebral cortex, cerebellum and brainstem of the rats treated with subacute and acute doses of ammonium acetate and compared with those of control animals. In general, the activities of all the enzymes except for hexokinase and lactate dehydrogenase, were elevated in all the three regions of the brain. The results suggests an enhanced rate of glycolysis in brain in hyperammonemic states and strengthens the role of ammonium ion in stimulating certain enzymes of the glycolytic pathway.


Assuntos
Amônia/farmacologia , Encéfalo/enzimologia , Glicólise , Amônia/sangue , Animais , Encéfalo/efeitos dos fármacos , Cerebelo/enzimologia , Córtex Cerebral/enzimologia , Frutose-Bifosfato Aldolase/metabolismo , Gliceraldeído-3-Fosfato Desidrogenases/metabolismo , Hexoquinase/metabolismo , L-Lactato Desidrogenase/metabolismo , Fosfofrutoquinase-1/metabolismo , Fosfopiruvato Hidratase/metabolismo , Piruvato Quinase/metabolismo , Ratos , Ratos Wistar
16.
Neurosci Lett ; 159(1-2): 131-4, 1993 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-8264955

RESUMO

Effects of in vivo and in vitro pathophysiological concentrations of ammonium acetate were studied on the activities of acetyl and pseudocholinesterases in the synaptosomes isolated from cerebral cortex, cerebellum and brain stem of rat brain. Administration of subacute and acute doses of ammonium acetate elevated the activities of both the cholinesterases in synaptosomes of all the above three regions. A linear relationship (r = 0.98) was observed between brain-ammonia levels and magnitude of elevation in the activities of cerebral cholinesterases. Kinetic analysis revealed that this elevation was due to a change in the Vm but not in the Km of the enzymes. Incubation of synaptosomes isolated from normal animals with 1, 5 and 10 mM ammonium acetate marginally elevated the activities of these enzymes and had no effects on purified enzyme. It is suggested that the changes in the activities might be due to altered architecture of the membranes which exposes more number of catalytic sites.


Assuntos
Amônia/farmacologia , Encéfalo/enzimologia , Colinesterases/metabolismo , Sinaptossomos/enzimologia , Acetilcolinesterase/sangue , Acetilcolinesterase/metabolismo , Amônia/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Química Encefálica/efeitos dos fármacos , Butirilcolinesterase/sangue , Butirilcolinesterase/metabolismo , Membrana Celular/efeitos dos fármacos , Membrana Celular/enzimologia , Colinesterases/sangue , Injeções Intraperitoneais , Cinética , Ratos , Ratos Wistar , Sinaptossomos/efeitos dos fármacos
17.
Mol Chem Neuropathol ; 19(3): 297-312, 1993 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8104403

RESUMO

Pathophysiological concentrations of ammonia, both in vivo and in vitro, suppressed the oxidation of glutamate by rat cerebellar mitochondria. The transport of glutamate into mitochondria was either unaltered or enhanced during hyperammonemic states. Activities of mitochondrial enzymes, aspartate aminotransferase, alanine aminotransferase, glutamate dehydrogenase, glutaminase, and GABA-transaminase were suppressed during hyperammonemic states. Suppression of 14CO2 production with (aminooxy)acetic acid but not with glutamic acid diethyl ester indicated that transamination but not oxidative deamination of glutamate plays a major role in glutamate oxidation during normal and hyperammonemic states.


Assuntos
Amônia/toxicidade , Cerebelo/efeitos dos fármacos , Glutamatos/metabolismo , Mitocôndrias/efeitos dos fármacos , Amônia/sangue , Animais , Transporte Biológico/efeitos dos fármacos , Dióxido de Carbono/metabolismo , Radioisótopos de Carbono , Cerebelo/metabolismo , Cerebelo/ultraestrutura , Ácido Glutâmico , Técnicas In Vitro , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , Ratos , Ratos Wistar
18.
Biochem Mol Biol Int ; 30(5): 861-6, 1993 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8106070

RESUMO

[3H]glutamate binding has been studied using the synaptic membrane preparations of rat cerebellum. The binding was observed to be specific, saturable and reversible. Curvileniarity of the Scatchard plots revealed the presence of two distinct populations of binding sites (one with a high affinity and the other with a low affinity to glutamate). [3H]glutamate bound to cerebellar synaptic membranes was displaced by kainate, N-methyl-D-aspartate and quisqualate indicating the presence of these three subtypes of glutamate receptors in cerebellum.


Assuntos
Cerebelo/metabolismo , Glutamatos/metabolismo , Receptores de Glutamato/metabolismo , Membranas Sinápticas/metabolismo , Animais , Sítios de Ligação , Ligação Competitiva , Ácido Glutâmico , Ácido Caínico/metabolismo , Masculino , N-Metilaspartato/metabolismo , Ácido Quisquálico/metabolismo , Ratos , Ratos Wistar , Especificidade da Espécie
19.
Neurochem Res ; 18(6): 647-54, 1993 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8099717

RESUMO

Astrocytes, neuronal perikarya and synaptosomes were prepared from rat cerebellum. Kinetics of high and low affinity uptake systems of glutamate and aspartate, nominal rates of 14CO2 production from [U-14C]glutamate, [U-14C]aspartate and [1-14C]glutamate and activities of enzymes of glutamate metabolism were studied in these preparations. The rate of uptake and the nomial rate of production of 14CO2 from these amino acids was higher in the astroglia than neuronal perikarya and synaptosomes. Activities of glutamine synthetase and glutamate dehydrogenase were higher in astrocytes than in neuronal perikarya and synaptosomes. Activities of glutaminase and glutamic acid decarboxylase were observed to be highest in neuronal perikarya and synaptosomes respectively. These results are in agreement with the postulates of theory of metabolic compartmentation of glutamate while others (presence of glutaminase in astrocytes and glutamine synthetase in synaptosomes) are not. Results of this study also indicated that (i) at high extracellular concentrations, glutamate/aspartate uptake may be predominantly into astrocytes while at low extracellular concentrations, it would be into neurons (ii) production of alpha-ketoglutarate from glutamate is chiefly by way of transamination but not by oxidative deamination in these three preparations and (iii) there are topographical differences glutamate metabolism within the neurons.


Assuntos
Ácido Aspártico/metabolismo , Cerebelo/metabolismo , Glutamatos/metabolismo , Animais , Astrócitos/metabolismo , Dióxido de Carbono/metabolismo , Córtex Cerebelar/metabolismo , Cerebelo/citologia , Glutamato Desidrogenase/metabolismo , Glutamato-Amônia Ligase/metabolismo , Ácido Glutâmico , Neurônios/metabolismo , Ratos , Ratos Wistar , Sinaptossomos
20.
Biochem Mol Biol Int ; 29(4): 711-7, 1993 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8098241

RESUMO

Kinetics of uptake and release, rates of oxidation of glutamate and aspartate, activities of the enzymes of glutamate metabolism were studied in the mitochondrial, synaptosomal and cytosolic preparations of rat cerebellum. Transport of these amino acids into mitochondria was by a single low affinity carrier, whereas in synaptosomes both high and low affinity uptake systems were observed. The depolarization induced release of these amino acids from nerve terminals was observed to be calcium dependent. Mitochondria oxidized both these two amino acids at a higher rate than synaptosomes and the oxidation in cytosol was very minimal. Transamination appears to be the major reaction for the metabolism of glutamate and aspartate. Activities of GDH, GLNSE and GABA-T were highest in mitochondria, whereas activities of GS and GAD were highest in cytosol and synaptosomes respectively.


Assuntos
Ácido Aspártico/metabolismo , Cerebelo/metabolismo , Glutamatos/metabolismo , Mitocôndrias/metabolismo , 4-Aminobutirato Transaminase/metabolismo , Análise de Variância , Animais , Cerebelo/enzimologia , Citosol/enzimologia , Citosol/metabolismo , Glutamato Descarboxilase/metabolismo , Glutamato Desidrogenase/metabolismo , Glutamato-Amônia Ligase/metabolismo , Ácido Glutâmico , Glutaminase/metabolismo , Cinética , Masculino , Mitocôndrias/enzimologia , Oxirredução , Ratos , Ratos Wistar , Frações Subcelulares/metabolismo , Sinaptossomos/enzimologia , Sinaptossomos/metabolismo
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