RESUMO
Administering high doses of tetanus toxin to animals produces neuromuscular blockade. Previous studies, in which specific F(ab) antibody fragments were used to mask the 50,000 MW COOH-terminal portion of the heavy chain (fragment c) on the toxin molecule, have shown that the paralyzing effect of the toxin was most probably located in an area comprising the light chain and the 50,000 MW NH2-terminal portion of the heavy chain (Fragment Ibc). In our study, the toxin was also complexed with F(ab) fragments directed to the light chain (alpha), heavy chain (beta), beta minus IIc, and with monoclonal antibodies to epitopes on IIc and beta minus IIc. Investigating the effect of the resulting complexes both in mice and on the sphincter pupillae muscle in rabbits permitted us to circumscribe further the tetanus toxin neuromuscular blocking activity in a region of the NH2-terminal fragment (Mr = 50,000) of the heavy chain (fragment beta minus IIc). Our results are consistent with the assumption that the beta minus IIc fragment is critical for the neuromuscular blockade activity of tetanus toxin. However, it cannot be ruled out that both the peripheral and central effects of the toxin result from the same portion of the toxin molecule, the nature of the action depending on where the toxin is carried after its introduction into the organism.
Assuntos
Bloqueadores Neuromusculares , Toxina Tetânica/toxicidade , Animais , Anticorpos Monoclonais/imunologia , Especificidade de Anticorpos , Complexo Antígeno-Anticorpo/isolamento & purificação , Hidrólise , Fragmentos Fab das Imunoglobulinas/imunologia , Imunoglobulina G/isolamento & purificação , Injeções Intramusculares , Camundongos , Papaína , Pupila/efeitos dos fármacos , Coelhos , Toxina Tetânica/análiseRESUMO
The University of Tennessee-Memphis (UT-M) Health Careers Exposure Program was initiated in response to the complaint of minority college students that basic medical science laboratories and clinical centers at private and state-supported health-science organizations in Tennessee were inaccessible to them as career-motivating, summer work experiences. The preceptor-apprentice relationship was the means utilized to expose and stimulate minority college students to enter health careers in this study. The formal activity was usually conducted for eight to ten weeks of summer vacation in the basic science and clinical facilities on the UT-M campus.A survey of the current career activities of former apprentices suggests that direct exposure of academically talented, minority college students to health careers is a factor that increases the number entering the health professions.
Assuntos
Negro ou Afro-Americano , Escolha da Profissão , Educação em Saúde , Humanos , Critérios de Admissão Escolar , TennesseeRESUMO
The injection into mice of small doses of tetanus toxin induces spastic paralysis as is well-known, whereas large doses of toxin produce flaccid paralysis. The hypothesis has been put forward that the type of symptoms produced may depend on the axonal transport or the lack of axonal transport of the toxin molecule to the central nervous system. In the present paper we show that the lethal flaccid paralysis occurring in mice injected with a very large dose of toxin develops in the absence of any uptake and axonal transport of the toxin molecule. We also confirm that a tetanus toxin-derived fragment, the Ibc fragment, which is not transported retrogradely, produces flaccid paralysis. The blockage with the aid of specific antibody F(ab) fragments of the area on the toxin molecule which is involved in binding and axonal transport does prevent the toxin from being transported to the CNS and causes it to produce flaccid paralysis.
