RESUMEN
Brain acetylcholinesterase (AChE) of some fishes from the coast of Rio de Janeiro State was studied as a possible pesticide biomarker in marine environmental monitoring. AChE specific activity in brain varied from 145 to 530 U/g of proteins and the Michaelis-Menten constant (K(M)) for acetylthiocholine varied from 104 to 291 microM among the 20 species studied. The enzyme sensitivity to methyl paraoxon, evaluated by the inhibition kinetic constants, shows that some species (Paralonchurus brasiliensis and Genidens genidens) are more sensitive (IC50-30 min=455 and 468 nM, respectively). The less sensitive Merluccius hubbsi and Percophis brasiliensis (IC50-30 min=3339 and 3259 nM, respectively) belong to the super-order Paracanthopterygii, which includes the more ancient species. On the other hand, more susceptible species belong to the super-order Acanthopterygii, which includes more recent species. These results suggest a possible evolutionary linkage for AChE sensitivity to methyl paraoxon. The application of inhibition kinetic constants for fish brain AChE in phylogenetic studies is still being investigated. The results have shown that a fish sentinel species should have the highest brain AChE level among the more sensitive ones.
Asunto(s)
Acetilcolinesterasa , Biomarcadores/análisis , Encéfalo/enzimología , Monitoreo del Ambiente/métodos , Peces/metabolismo , Plaguicidas/análisis , Contaminantes Químicos del Agua/análisis , Acetilcolinesterasa/análisis , Animales , Océano Atlántico , Brasil , Inhibidores de la Colinesterasa/metabolismo , Análisis por Conglomerados , Concentración 50 Inhibidora , Cinética , Paraoxon/análogos & derivados , Paraoxon/metabolismo , Filogenia , Especificidad de la EspecieRESUMEN
Acetylcholinesterase (AChE) sensitivity to the organophosphorus (OP) pesticide methyl-paraoxon was measured in fourteen species of Neotropical marine and freshwater fish found in the waters of Brazil. The rate constant for phosphorylation, kp, the dissociation constant, kd, the second order rate constant, ki, and the IC50 value were measured at 28 degrees C in pH 7.5 buffer for AChE extracted from brain. In addition, the substrate affinity constant, km, was measured with acetylthiocholine. The IC50 for 30 min of inhibition ranged from 123 nM (Prochilodus lineatus) to 3340 nM (Percophis brasiliensis), which corresponded to ki values of 187-6.9 mM(-1) min(-1). A 10-fold range in kp values from 0.21 min(-1) (Paralonchurus brasiliensis) to 2.1 min(-1) (Dules auriga) was associated with a 37-fold range in kd values from 4 to 150 microM. These large differences in reactivity with methyl-paraoxon were not reflected in the binding affinity for acetylthiocholine; km values were approximately 0.1-0.3 mM for all species. These results predict that the amino acid sequence involved in AChE sensitivity differs in these fishes, and that consequently some fish species may be resistant to the toxicity of methyl-paraoxon.
Asunto(s)
Acetilcolinesterasa/metabolismo , Encéfalo/enzimología , Inhibidores de la Colinesterasa/farmacología , Paraoxon/análogos & derivados , Paraoxon/farmacología , Animales , Peces , Cinética , FosforilaciónRESUMEN
The etiopathogenic features and noninvasive diagnosis of Takayasu's arteritis are reviewed in brief and the case of a young man suffering from the disease (type I in Ueno's classification) is reported.
Asunto(s)
Síndromes del Arco Aórtico/etiología , Arteritis de Takayasu/etiología , Adulto , Terapia Combinada , Humanos , Masculino , Arteritis de Takayasu/clasificación , Arteritis de Takayasu/diagnóstico , Arteritis de Takayasu/terapiaRESUMEN
After a short examination of data in the literature, the paper presents a retrospective analysis of 340 patients who underwent endoscopic examination for upper gastrointestinal haemorrhage. Among them, 123 underwent emergency and 112 elective endoscopy. A source of active or recent bleeding was identified in 87.5% of the cases. Emergency endoscopy showed a clearcut diagnostic superiority over elective endoscopy, and endoscopy as a whole was more efficient than conventional radiology. The most commonly observed bleeding lesions were found in the duodenum and stomach followed by oesophageal varices. The value of an early endoscopic approach to the diagnosis and treatment of upper gastrointestinal haemorrhage is confirmed.
Asunto(s)
Enfermedades Duodenales/diagnóstico , Endoscopía , Hemorragia Gastrointestinal/diagnóstico , Gastropatías/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Enfermedades Duodenales/complicaciones , Neoplasias Duodenales/complicaciones , Úlcera Duodenal/complicaciones , Urgencias Médicas , Várices Esofágicas y Gástricas/complicaciones , Várices Esofágicas y Gástricas/diagnóstico , Femenino , Hemorragia Gastrointestinal/etiología , Humanos , Masculino , Persona de Mediana Edad , Úlcera Péptica Hemorrágica/diagnóstico , Úlcera Péptica Hemorrágica/etiología , Estudios Retrospectivos , Gastropatías/complicaciones , Neoplasias Gástricas/complicaciones , Úlcera Gástrica/complicacionesRESUMEN
After a short introductory note on the incidence, classification and malignant potentiality of gastric polyps, according to the literature, the paper presents data on a six-year experience in gastric polypectomy involving 5942 endoscopies. The incidence of gastric polyps was 2.1%. Gastric polypectomy was performed on 84 patients with extirpation of 113 polyps. Assessments and comments are presented on the site, size, morphology, histological type, degree of dysplasia and degenerative potentiality of several types of gastric polyps. Gastric endoscopic polypectomy is a safe, economical, well-tolerated and valid methodology with considerable therapeutic possibilities and potential prophylactic actions against cancer.
Asunto(s)
Pólipos/cirugía , Gastropatías/cirugía , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Gastroscopía , Humanos , Masculino , Persona de Mediana Edad , Pólipos/patología , Gastropatías/patologíaRESUMEN
Gastric lymphomas have been easier to diagnose since the introduction of digestive endoscopy combined with multiple target biopsy and possibly macrobiopsy. Personal experience of three primary non-Hodgkin lymphomas of the stomach is reported. Analysis of this endoscopic series reveals the multiplicity and polymorphism of the lesions that are never, in any cases, pathognomic of this pathology.