RESUMO
La elemental tarea de delimitación del concepto de biocombustible, encierra en sí misma aspectos problemáticos. Podemos referirlo como noción genérica incluyendo toda substancia orgánica utilizada por el hombre como fuente energética (ej., leña) y/o aludir al fenómeno tal como se desenvuelve en las actuales circunstancias, haciendo alusión al resultante de complejos sistemas de transformación de biomasa (ej., bioetanol, biodiesel). El debate sobre los biocombustibles ha ocupado, desde hace tiempo, un considerable espacio en los medios de divulgación (diarios, revistas, TV), pero la información es exhibida en forma desordenada, como expresión de bandos en pugna. Por un lado están aquellos que sólo parecen manifestar las bondades del modelo, aludiendo a países como Argentina (por sus características) como ejecutores privilegiados de esta nueva iniciativa. Representa una tarea ineludible encarar una visión que trascienda los planteos superficiales, aspirando a brindar evidencias claras de la etapa actual. La sola sospecha de competencia por territorio entre cultivos que tengan como destino la producción energética y aquella que persigue la obtención de alimentos, merece un riguroso examen. El presente trabajo intenta explorar las aristas centrales del fenómeno de biocombustibles, las formas de producción, así como su vinculación con la seguridad alimentaria a partir de la descripción de cuatro dimensiones interrelacionadas: la disponibilidad de los alimentos, el acceso a los mismos, la estabilidad respecto al uso de los recursos naturales y la utilización biológica de los alimentos y nutrientes. El dilema de ¶alimentos versus energía÷ seguirá siendo una incógnita hasta disponer de una plataforma sólida de estudios que analicen todos los factores relacionados al tema. Es menester el incentivo de trabajos interdisciplinarios, siendo los gobiernos los actores fundamentales.(AU)
Assuntos
Segurança Alimentar , Combustíveis não Poluentes , ArgentinaRESUMO
La elemental tarea de delimitación del concepto de biocombustible, encierra en sí misma aspectos problemáticos. Podemos referirlo como noción genérica incluyendo toda substancia orgánica utilizada por el hombre como fuente energética (ej., leña) y/o aludir al fenómeno tal como se desenvuelve en las actuales circunstancias, haciendo alusión al resultante de complejos sistemas de transformación de biomasa (ej., bioetanol, biodiesel). El debate sobre los biocombustibles ha ocupado, desde hace tiempo, un considerable espacio en los medios de divulgación (diarios, revistas, TV), pero la información es exhibida en forma desordenada, como expresión de bandos en pugna. Por un lado están aquellos que sólo parecen manifestar las bondades del modelo, aludiendo a países como Argentina (por sus características) como ejecutores privilegiados de esta nueva iniciativa. Representa una tarea ineludible encarar una visión que trascienda los planteos superficiales, aspirando a brindar evidencias claras de la etapa actual. La sola sospecha de competencia por territorio entre cultivos que tengan como destino la producción energética y aquella que persigue la obtención de alimentos, merece un riguroso examen. El presente trabajo intenta explorar las aristas centrales del fenómeno de biocombustibles, las formas de producción, así como su vinculación con la seguridad alimentaria a partir de la descripción de cuatro dimensiones interrelacionadas: la disponibilidad de los alimentos, el acceso a los mismos, la estabilidad respecto al uso de los recursos naturales y la utilización biológica de los alimentos y nutrientes. El dilema de alimentos versus energía seguirá siendo una incógnita hasta disponer de una plataforma sólida de estudios que analicen todos los factores relacionados al tema. Es menester el incentivo de trabajos interdisciplinarios, siendo los gobiernos los actores fundamentales.
Assuntos
Abastecimento de Alimentos , Combustíveis não Poluentes , ArgentinaRESUMO
Kainic acid receptor (KA-R) subunits are differentially expressed during brain development, and they modulate both neural growth and survival. High concentrations of glutamate in the brain can induce neuronal injury through these receptors, altering normal development. However, it is unclear whether KAR subunit expression itself is also modified by neonatal exposure to high glutamate. To analyze this, monosodium glutamate (4mg/g of body weight) was subcutaneously administered on postnatal days 1, 3, 5 and 7, and the expression of GluR5, GluR6, KA1 and KA2, as well as [(3)H]-kainic acid (KA-R) binding, was evaluated on postnatal days 14, 21, 30 and 60 in different regions of rat brain. As a result, high levels of GluR5 expression associated with strong [(3)H]-kainic acid binding were observed on postnatal days 30 and 60 in the cerebral cortex of rats exposed to glutamate. Similarly, the changes induced by glutamate administration in the expression of the KA1 and KA2 subunits were paralleled by those of [(3)H]-kainic acid binding in the striatum at postnatal days 21 and 30. In contrast, while KAR subunits were over expressed in the hippocampus, no changes were observed in [(3)H]-kainic acid binding in adult rats that had been exposed to glutamate. Therefore, glutamate modifies both the expression of kainic acid receptor subunits and kainic acid binding in a determined spatial and temporal manner, which may be indicative of a regional susceptibility to glutamate neurotoxicity.
Assuntos
Encéfalo , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Ácido Glutâmico/toxicidade , Receptores de Ácido Caínico/metabolismo , Fatores Etários , Animais , Animais Recém-Nascidos , Encéfalo/anatomia & histologia , Encéfalo/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Ligação Proteica/efeitos dos fármacos , Ratos , Ratos Wistar , Receptores de Ácido Caínico/genética , Trítio/farmacocinéticaRESUMO
Monosodium l-glutamate (MSG) was administered subcutaneously to male neonatal rats, and the effect on developmental profile of tyrosine hydroxylase (TH), D1, D2 receptors, and dopamine (DA) transporter expression in the striatum was examined using Western blot. In addition, TH-immunopositive neurons at substantia nigra (SN) were also examined. MSG treatment (4mg/g of body weight, administered on postnatal days 1, 3, 5, and 7) resulted in a reduction of D1 and D2 receptor expression from 30 days of age and persisted to adulthood (120 days of age), while DA transporter expression was significantly reduced from 14 days of age to adulthood. TH immunopositive neurons at SN showed a significant reduction, as well as TH expression on postnatal days 10, 30, 60, and 120 at striatum was reduced. No changes of TH were observed at 14 days of age. Results indicate that an over-stimulation of the glutamatergic system by neonatal exposure to a high glutamate concentration induces a partial loss in TH-positive neurons in the SN and an important reduction in dopaminergic markers expression in the striatum, suggesting that early excitotoxicity could contribute to developmental alterations in the nigrostriatal pathway, which may be associated with various disorders of the basal ganglia.
Assuntos
Envelhecimento/metabolismo , Corpo Estriado/metabolismo , Ácido Glutâmico/administração & dosagem , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Receptores de Dopamina D1/metabolismo , Receptores de Dopamina D2/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Envelhecimento/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Biomarcadores/metabolismo , Corpo Estriado/efeitos dos fármacos , Proteínas da Membrana Plasmática de Transporte de Dopamina , Feminino , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Injeções Subcutâneas , Masculino , Ratos , Ratos Wistar , Distribuição Tecidual/efeitos dos fármacosRESUMO
BACKGROUND: Since the time to peak analgesic effect of intravenous morphine can be longer than 40-60 min in volunteers, the goal of this study was to evaluate the effect of the timing of intraoperative morphine administration on early postoperative pain. METHODS: A total of 120 adult patients undergoing laparoscopic cholecystectomy were studied. Anaesthesia was induced with remifentanil and etomidate and maintained with remifentanil and sevoflurane/nitrous oxide. Morphine 150 micrograms kg-1 was given randomly at three different times during surgery, and a fourth group received placebo. Times to eyes opening and extubation were measured, and pain was evaluated in the post-anaesthesia care unit (PACU) using a visual analogue scale (VAS). Morphine 2-3 mg was given when the VAS score was > or = 50 mm. The four groups were, according to the time elapsed from morphine administration to the end of surgery, group 1 (n = 30): placebo; group 2 (n = 33): < 20 min; group 3 (n = 30): 20-40 min; group 4 (n = 27): > 40 min. RESULTS: Recovery from anaesthesia and pain scores were similar in all groups. However, mean (SD) morphine consumption was 5.7 (4.7) mg in group 1, 4.4 (4.2) mg in group 2, 4.7 (4.7) mg in group 3, and 2.2 (4.0) mg in group 4 (P < 0.05, group 1 vs 4). Morphine was required in only 38% of patients in group 4 compared with 83%, 67% and 69% in groups 1, 2, and 3, respectively (P < 0.01, group 1 vs 4). CONCLUSIONS: The timing of intraoperative morphine administration did not affect the early recovery from anaesthesia. However, the reduction in the number of patients requiring morphine in the PACU when morphine had been given more than 40 min before the end of surgery supports this practice, rather than administration closer to the end of surgery.
Assuntos
Analgésicos Opioides/administração & dosagem , Anestésicos Intravenosos , Morfina/administração & dosagem , Dor Pós-Operatória/prevenção & controle , Piperidinas , Adulto , Período de Recuperação da Anestesia , Colecistectomia Laparoscópica , Esquema de Medicação , Feminino , Humanos , Período Intraoperatório , Masculino , Pessoa de Meia-Idade , Medição da Dor , RemifentanilRESUMO
Monosodium L-glutamate (MSG) causes neuronal lesions in certain brain regions when systemically given to young animals. Also, when glutamate (Glu) builds up in the intersynaptic space, it induces neuroexcitatory and neurocytotoxic effects, events mediated by several Glu receptors. Some of these receptors such as NMDA and AMPA receptors are present in the very earliest developmental stages of the central nervous system and play a major role in neuronal plasticity during synaptogenesis. In this paper, the GABAergic system vulnerability was determined in terms of [3H]-GABA release during postnatal development. [3H]-GABA release on days 14, 21, 30, and 60 days after birth was assessed for the cerebral cortex (CC), hippocampus (Hp) and striatum (S) in rats perinatally treated at days 1, 3, 5, and 7 after birth with MSG. The results show a major decrease in baseline [3H]-GABA release in the CC (30 and 60 days after birth) and the Hp (beginning day 21 after birth) vs the control groups [intact rats and rats given a NaCl solution equimolar to that of MSG (eqNaCl)] while in the S baseline release remained unchanged. Stimulated [3H]-GABA release was decreased in the CC on days 14 and 21 after birth and significantly increased on day 60 after birth vs the controls. In the Hp, a decrease was seen on days 14, 21, and 60 after birth vs the controls while stimulated [3H]-GABA release was decreased in the S vs the controls at all ages studied. No significant differences in stimulated [3H]-GABA release were found between the intact group and the group treated with eqNaCl on days 30 and 60 after birth. Results show that CC, Hp and S GABAergic neurones are a major target for the effect of perinatally given MSG and suggest a possible decrease in the number of Hp GABAergic neurones while these results in CC and S suggest a modified neuronal plasticity. NMDA receptor and calcium involvement are discussed as significant mediators of these events.
Assuntos
Envelhecimento , Animais Recém-Nascidos , Encéfalo/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Glutamato de Sódio/farmacologia , Ácido gama-Aminobutírico/metabolismo , Animais , Córtex Cerebral/metabolismo , Corpo Estriado/metabolismo , Hipocampo/metabolismo , Ratos , Ratos Wistar , Cloreto de Sódio/farmacologia , TrítioRESUMO
A prospective study of speech outcome and maxillofacial growth was carried out in cleft palate patients. Seventy-six cleft palate patients were randomly selected for the study group; 41 patients were operated on at 12 months of age, and 35 patients were operated on at 6 months of age. All patients were followed until they were 4 years of age. All patients underwent a complete speech evaluation, videonasopharyngoscopy, videofluoroscopy, and maxillofacial assessment. The rate of velopharyngeal insufficiency did not differ between the two groups (17 to 19 percent; p > 0.05). However, phonologic development was significantly better (p < 0.05) in the patients operated on at 6 months of age. Furthermore, none of the patients operated on at 6 months of age showed compensatory articulation disorder. In contrast, 62 percent of the patients with postoperative velopharyngeal insufficiency operated on at 12 months of age showed compensatory articulation disorder (p < 0.05). Maxillofacial assessment showed that there were non-significant differences (p > 0.05) in maxillofacial growth in both groups of patients. All patients showed similar degrees of maxillary collapse (p > 0.05). The results of this study suggest that cleft palate repair performed at 6 months of age significantly enhances speech outcome and prevents compensatory articulation disorder.
Assuntos
Transtornos da Articulação/etiologia , Fenda Labial/cirurgia , Fissura Palatina/cirurgia , Desenvolvimento Maxilofacial/fisiologia , Complicações Pós-Operatórias/etiologia , Transtornos da Articulação/fisiopatologia , Cefalometria , Pré-Escolar , Fenda Labial/fisiopatologia , Fissura Palatina/fisiopatologia , Endoscopia , Feminino , Seguimentos , Humanos , Lactente , Masculino , Faringe/fisiopatologia , Faringe/cirurgia , Fonação/fisiologia , Complicações Pós-Operatórias/fisiopatologia , Testes de Articulação da Fala , Insuficiência Velofaríngea/fisiopatologia , Insuficiência Velofaríngea/cirurgia , Gravação em VídeoRESUMO
The effects of NMDA receptor antagonists on the convulsant action of the administration of 4-aminopyridine in the rat lateral cerebral ventricle (i.c.v. injection) and motor cerebral cortex (i.cx. injection) were studied. 4-Aminopyridine administration in both regions induced various preconvulsive symptoms, such as salivation, tremors, chewing and rearing, followed by continuous clonic convulsions and, only after i.c.v. injection, running fits and generalized tonic convulsions. This behavioral pattern appeared 5-9 min after administration of 4-aminopyridine and persisted for 100-150 min. 4-Aminopyridine also generated epileptiform electroencephalographic (EEG) discharges characterized by isolated spikes, poly-spikes and spike-wave complexes, which began some seconds after administration of the drug and were present for more than 2 h. The NMDA receptor antagonists (+/-)-3-(2-carboxy-piperazin-4-yl)-propyl-1-phosphonic acid (CPP), (+/-)-2-amino-7-phosphono-heptanoic acid (AP7) and (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801) clearly protected against some of the behavioral alterations induced by i.c.v. 4-aminopyridine, particularly the tonic convulsions, but were less effective against those produced by i.cx. 4-aminopyridine. These antagonists also delayed the appearance of EEG epileptiform discharges, reduced its amplitude, frequency and duration, and blocked their propagation to other cortical regions after i.cx. 4-aminopyridine. These results, together with previous data showing that 4-aminopyridine stimulates the release of glutamate in vivo, suggest that an excessive glutamatergic neurotransmission involving NMDA receptors is implicated in 4-amino-pyridine-induced seizures.