ABSTRACT
Estudios histológicos previos, realizados en el nervio ciático de ratone chagásicos crónicos, demostraron degeneración axonal y desmielinización. Con el fin de investigar los cambios funcionales en el nervio ciático y en músculos inervados por él, se estudiarón 14 ratones infectados, 12 meses antes de los experimentos, con tripomastigotes (clon K-98 de CA-I). Se exploró la actividad electromiográfica en los músculos isquiotibiales y la latencia y amplitud del potencial de nervio "in vivo". Como grupo control se emplearon 13 ratos de igual edad y peso. El electromiograma mostró que una parte de las unidades motoras funcionantes habían aumentado su amplitud, duración y número de fases de sus potenciales, señalando aumento del tamaño de sus territorios, hecho que sugiere reinervación muscular a partir del envío de colaterales axónicas hacia fibras musculares previamente denervadas. El potencial de acción del nervio ciático evidenció, en los animales infectados, disminución de su amplitud y prolongación de su latencia. Esta observación señala reducción del número de axones funcionantes en el nervio y desmielinización de las fibras remantes. Los hallazgos electrofisiológicos hechos en el nervio coinciden con las descripciones histológicas anteriores y proveen evidencia adicional del estado funcional de las fibras que lo integran en el modelo experimental de esta parasitosis (AU)
Subject(s)
Animals , Mice , Chagas Disease/complications , Peripheral Nervous System Diseases/parasitology , Sciatic Nerve/physiopathology , Action Potentials/physiology , Electrophysiology , Electromyography , Disease Models, Animal , Mice, Inbred C3HABSTRACT
Estudios histológicos previos, realizados en el nervio ciático de ratone chagásicos crónicos, demostraron degeneración axonal y desmielinización. Con el fin de investigar los cambios funcionales en el nervio ciático y en músculos inervados por él, se estudiarón 14 ratones infectados, 12 meses antes de los experimentos, con tripomastigotes (clon K-98 de CA-I). Se exploró la actividad electromiográfica en los músculos isquiotibiales y la latencia y amplitud del potencial de nervio "in vivo". Como grupo control se emplearon 13 ratos de igual edad y peso. El electromiograma mostró que una parte de las unidades motoras funcionantes habían aumentado su amplitud, duración y número de fases de sus potenciales, señalando aumento del tamaño de sus territorios, hecho que sugiere reinervación muscular a partir del envío de colaterales axónicas hacia fibras musculares previamente denervadas. El potencial de acción del nervio ciático evidenció, en los animales infectados, disminución de su amplitud y prolongación de su latencia. Esta observación señala reducción del número de axones funcionantes en el nervio y desmielinización de las fibras remantes. Los hallazgos electrofisiológicos hechos en el nervio coinciden con las descripciones histológicas anteriores y proveen evidencia adicional del estado funcional de las fibras que lo integran en el modelo experimental de esta parasitosis
Subject(s)
Animals , Mice , Chagas Disease/complications , Sciatic Nerve/physiopathology , Peripheral Nervous System Diseases/parasitology , Disease Models, Animal , Electromyography , Electrophysiology , Action Potentials/physiologyABSTRACT
Early histological studies carried out in the sciatic nerve of mice chronically infected with Trypanosoma cruzi showed demyelination and scanty axonal degeneration. The experiments reported in this paper were designed to assess the functional state of the sciatic nerve and of some of the muscles it supplies. For these purposes 14 mice were infected with trypomastigotes (clon K-98, CA-I strain) 12 months before the investigation. Results were compared with 13 normal mice matched by age and weight. Hamstring muscles were studied electromyographically by means of a fine coaxial needle electrode and the sciatic nerve action potential characteristics were recorded with surface electrodes. All the experiments were carried out in vivo. In the infected mice the electromyogram showed that some motor unit potentials has enlarged amplitude and duration and increased number of phases, suggesting that the size of their territories had been enlarged, probably through axonal collateral sproutings and reinnervation of muscle fibers previously relinquished by their original innervation. The sciatic nerve action potential of the infected animals showed diminished amplitude and prolonged latency. These features signal reduced number of functional axons within the nerve and demyelination of the remaining conducting fibers. These findings are in line with the histological evidences of the involvement of the peripheral nervous system in Chagas disease and give additional information about the functional state of the peripheral nerves in the experimental model.
ABSTRACT
Este estudio fue diseñado buscando un método sencillo que permitiera evaluar el compromiso denervatorio o muscular primario en la infección experimental con T. cruzi. Para ello se empleó la exploración electromiográfica convencional de los músculos isquiotibiales de una de las patas en diferentes cepas de ratones infectados con 3 cepas de T. cruzi. Se estudiaron las siguientes asociaciones entre parásitos y huéspedes: Tulahuén (Tul) y C3H/HeN, C57Bl, Balb/c ó Swiss; CA-I y C3H/HeN, Rockland, NIH; RA y C3H/HeN, Rockland. Los ratones se infectaron con tripomastigotes sanguíneos de t. cruzi administrados por vía intraperitoneal. En el electromiograma fueron estudiadas la amplitud, duración y número de fases de los potenciales de undad motora aislados. Se observó que la cepa Tul inducía alteraciones de tipo denervatório en ratones C3H/HeN y C57BI y que igual acontecía con la cepa RA en ratones C3H/HeN. Modificaciones sugestivas de daño muscular primario se vieron en la asociación parásito CA-I y huéspede C3H/HeN y entre CA-I y HIH. La metodología empleada demostró ser de utilidad práctica para la rápida detección del tipo de compromiso de la unidad motora en las infecciones murinas experimentales con T. cruzi (AU)
Subject(s)
Comparative Study , Animals , Male , Mice , Trypanosoma cruzi/pathogenicity , Mice, Inbred Strains/parasitology , Peripheral Nervous System Diseases/parasitology , Chagas Disease/parasitology , Denervation , Electromyography , Injections, Intraperitoneal , Muscles/innervation , Muscles/parasitology , Peripheral Nervous System Diseases/genetics , Species Specificity , Trypanosoma cruzi/classification , Trypanosoma cruzi/growth & development , Virulence , Chagas Disease/genetics , Mice, Inbred Strains/geneticsABSTRACT
Este estudio fue diseñado buscando un método sencillo que permitiera evaluar el compromiso denervatorio o muscular primario en la infección experimental con T. cruzi. Para ello se empleó la exploración electromiográfica convencional de los músculos isquiotibiales de una de las patas en diferentes cepas de ratones infectados con 3 cepas de T. cruzi. Se estudiaron las siguientes asociaciones entre parásitos y huéspedes: Tulahuén (Tul) y C3H/HeN, C57Bl, Balb/c ó Swiss; CA-I y C3H/HeN, Rockland, NIH; RA y C3H/HeN, Rockland. Los ratones se infectaron con tripomastigotes sanguíneos de t. cruzi administrados por vía intraperitoneal. En el electromiograma fueron estudiadas la amplitud, duración y número de fases de los potenciales de undad motora aislados. Se observó que la cepa Tul inducía alteraciones de tipo denervatório en ratones C3H/HeN y C57BI y que igual acontecía con la cepa RA en ratones C3H/HeN. Modificaciones sugestivas de daño muscular primario se vieron en la asociación parásito CA-I y huéspede C3H/HeN y entre CA-I y HIH. La metodología empleada demostró ser de utilidad práctica para la rápida detección del tipo de compromiso de la unidad motora en las infecciones murinas experimentales con T. cruzi
Subject(s)
Animals , Male , Mice , Mice, Inbred Strains/parasitology , Chagas Disease/parasitology , Peripheral Nervous System Diseases/parasitology , Trypanosoma cruzi/pathogenicity , Mice, Inbred Strains/genetics , Denervation , Chagas Disease/genetics , Electromyography , Species Specificity , Injections, Intraperitoneal , Muscles/innervation , Muscles/parasitology , Peripheral Nervous System Diseases/genetics , Trypanosoma cruzi/classification , Trypanosoma cruzi/growth & development , VirulenceABSTRACT
This study has been designed to find an easy method to evaluate the motor unit alterations induced during experimental T. cruzi infections. Different mouse strains infected with three strains of T. cruzi were used to perform conventional needle electromyography, in one of the lower limb hamstring muscles; amplitude, duration and number of phases of single motor unit potentials were measured. The following parasite strain to mouse strain relationship was investigated, in mice inoculated intraperitoneally with bloodstream forms of T. cruzi: Tulahuen and C3H/HeN, C57Bl, Balb/c, Swiss; CA-I and C3H/HeN, Rockland, NIH; RA and C3H/HeN, Rockland. T. cruzi-induced denervating alterations were found in both C3H/HeN and C57Bl mice infected with the Tulahuen strain, as well as in C3H/HeN mice inoculated with the CA-I strain. Moreover, CA-I trypomastigotes could produce primary muscle changes in C3H/HeN and NIH mice. The technique employed in this investigation proved to be an easy and adequate way to detect changes within the motor unit during T. cruzi infection in mice.
ABSTRACT
Trypomastigotes of the CA-I strain of Trypanosoma cruzi, which is practically non-lethal for mice, exhibited adhered antibodies when harvested 25-28 days pi and handled at 4 degrees C, whereas at 37 degrees C they became negative within 10-15 min. Mice injected with these tryp pre-incubated with anti-RA rabbit serum (shown to contained neutralizing antibodies against the homologous strain) developed a significantly lower parasitemia than controls while those pre-incubated with anti-CA-I serum showed only a delay in the parasitemia pattern. Neutralizing activity was undetectable in anti-CA-I rabbit and mouse sera when the test was performed under standard conditions against RA-tryp. On the other hand, neutralizing antibodies were demonstrated in few anti-CA-I mouse serum samples against RA strain when the test was performed increasing the sensitivity in order to reach no more than 75
lethality for controls. In these cases, a close relationship between [quot ]infective dose size-immune response achieved[quot ] was found, being only a narrow range of inocula able to trigger detectable neutralizing activity (10(4) CA-I tryp inoculum). Variations in the degree of neutralizing activity as a function of the infective doze size was also demonstrated for anti-RA mouse sera and, despite every antiserum prepared with this T. cruzi strain was reactive, the best values were proved for those prepared with inocula up to 10(2) tryp. Above optimal parasite dose size, both strains induced a drop of neutralizing activity.
ABSTRACT
A method to isolate T. cruzi bloodstream forms was designed taking advantage of Percoll self-generated gradients and isopycnic centrifugation, resulting in a good resolution between parasites and host cells. Purified parasites incorporated 3H-uridine giving values of 23
precipitable by TCA. Viability of the parasites was totally preserved as evidenced by the [quot ]in vivo[quot ] infectivity assays.
ABSTRACT
The protein protector requirements for CA-I and RA T. cruzi trypomastigotes were standardized. The CA-I trypomastigotes needed a supplement of 5
serum or 5
bovine albumin in the washing and/or resuspending solutions to preserve their viability. For RA trypomastigotes, requirements were in the order of 1
. Trypomastigotes viability was determined by motility at the fresh microscopic observation and by mouse inoculation. This is a further demonstration of the particular behaviour reported for the CA-I bloodstream forms compared with those of RA.
ABSTRACT
Differential reduced minus oxidized (Red-Ox) or reduced. CO minus reduced (Red. CO-Red) spectra of Trypanosoma cruzi metacyclic trypomastigotes (Tulahuen strain), revealed the presence of cytochromes aa3, b, c5 5 8, o and possibly d (Fig. 1). Mitochondrial membranes from the epimastigote form of the parasite showed similar cytochrome spectra (Fig. 2A). Extraction of the mitochondrial membranes with guanidine and cholate, and spectroscopy of the cytochrome o -cyanide derivative proved that this cytochrome is an integral constituent of the mitochondrial membranes (Figs. 2B and 4, and Table 1). Contamination of the investigated samples with hemoglobin, peroxidase, catalase, cytochrome P-420, cytochrome P-450 or culture medium hemoproteins was ruled out by filtering the cells and mitochondrial membranes on Sephadex G-50, or by differential spectroscopy of pigments, or by differential centrifugations of samples. Investigation of pyridine-hemochromes revealed hemes A, B, C and D (Fig. 3), thus confirming the presence of the postulated cytochromes. Comparative spectroscopy of a series of T. cruzi stocks (including Tulahuen and Y strains), many of them obtained from acute or chronic forms of Chagas disease, revealed significant variability in the cytochrome content (Table 2). Taking cytochromes o and b as standard for comparison, the epimastigotes samples could be grouped as follows (in parenthesis number of passages through the culture medium): 1) stocks with a relatively high content of cytochromes b and o, prevailing the former (stocks Y (116), RA (114), AF, FN, TN and MG (14 y 16); 2) stocks with a relatively low content of both cytochromes: Y (119), AWP and UP; 3) stocks with a low content of cytochrome b, without cytochrome o: CA-I and CA-I (V); 4) stocks without cytochromes: Y(117 and 118) and RA(113). In some strains (e.g. Y and RA), significant variation of cytochrome content in different stocks of the same isolate was observed (Table 2), but the Tulahuen strain proved to be less variable. Comparison of cytochrome distribution and other properties of parasites, namely, lethality for mice and morphology, did not allow to establish positive correlations.
ABSTRACT
Growth and differentiation patterns induced by T. infestans whole hemolymph as well as by hemocyte free or hemocyte and quinone free samples were similar; these results indicate that neither hemocytes nor quinones interfered in the duplication of epimastigotes or in their differentiation to metacyclic forms. The minimum amount required to induce differentiation was 2
, lacking inhibitory effect even when assayed at a concentration of 30
. Differentiation was reached simultaneously with the exponential growth period of the culture up to 80
.
ABSTRACT
La hemolinfa total de T. infestans, asi como las variantes libres de hemocitos, o libres de hemocitos y quinonas, indujeron curvas de crecimiento y diferenciacion del T. cruzi semejantes cuando se utilizaron como suplemento del medio de Grace modificado, indicando que la presencia de hemocitos y quinonas no influyen en el proceso de multiplicacion de los epimastigotes ni en su diferenciacion a metaciclicos. La cantidad minima de cualquiera de las variantes para lograr diferenciacion fue del 2%, no detectandose efecto inhibitorio aun en concentraciones del 30%. Esta diferenciacion se produjo durante la fase de crecimiento exponencial del cultivo alcanzado aproximadamente un 80%
Subject(s)
Hemolymph , Triatoma , Trypanosoma cruziABSTRACT
La hemolinfa total de T. infestans, asi como las variantes libres de hemocitos, o libres de hemocitos y quinonas, indujeron curvas de crecimiento y diferenciacion del T. cruzi semejantes cuando se utilizaron como suplemento del medio de Grace modificado, indicando que la presencia de hemocitos y quinonas no influyen en el proceso de multiplicacion de los epimastigotes ni en su diferenciacion a metaciclicos. La cantidad minima de cualquiera de las variantes para lograr diferenciacion fue del 2%, no detectandose efecto inhibitorio aun en concentraciones del 30%. Esta diferenciacion se produjo durante la fase de crecimiento exponencial del cultivo alcanzado aproximadamente un 80%