RESUMEN
Toxoplasma gondii is a highly prevalent protozoan parasite that infects a wide range of animals and threatens human health by contaminating food and water. A markedly limited number of clonal parasite lineages have been recognized as predominating in North American and European populations, whereas strains from South America are comparatively diverse. Here, we show that strains from North America and Europe share distinct genetic polymorphisms that are mutually exclusive from polymorphisms in strains from the south. A striking exception to this geographic segregation is a monomorphic version of one chromosome (Chr1a) that characterizes virtually all northern and many southern isolates. Using a combination of molecular phylogenetic and phenotypic analyses, we conclude that northern and southern parasite populations diverged from a common ancestor in isolation over a period of approximately 10(6) yr, and that the monomorphic Chr1a has swept each population within the past 10,000 years. Like its definitive feline hosts, T. gondii may have entered South America and diversified there after reestablishment of the Panamanian land bridge. Since then, recombination has been an infrequent but important force in generating new T. gondii genotypes. Genes unique to a monomorphic version of a single parasite chromosome may have facilitated a recent population sweep of a limited number of highly successful T. gondii lineages.
Asunto(s)
Cromosomas , Evolución Molecular , Toxoplasma/genética , Toxoplasma/patogenicidad , Toxoplasmosis Animal/parasitología , Alelos , Animales , Secuencia de Bases , Cruzamientos Genéticos , Europa (Continente) , Variación Genética , Genética de Población , Haplotipos , Intrones , Ratones , Modelos Biológicos , Datos de Secuencia Molecular , América del Norte , Filogenia , Polimorfismo de Nucleótido Simple , Recombinación Genética , Factores de Tiempo , Toxoplasma/clasificación , Toxoplasma/aislamiento & purificación , Toxoplasmosis Animal/transmisión , VirulenciaRESUMEN
Toxoplasma gondii strains differ dramatically in virulence despite being genetically very similar. Genetic mapping revealed two closely adjacent quantitative trait loci on parasite chromosome VIIa that control the extreme virulence of the type I lineage. Positional cloning identified the candidate virulence gene ROP18, a highly polymorphic serine-threonine kinase that was secreted into the host cell during parasite invasion. Transfection of the virulent ROP18 allele into a nonpathogenic type III strain increased growth and enhanced mortality by 4 to 5 logs. These attributes of ROP18 required kinase activity, which revealed that secretion of effectors is a major component of parasite virulence.
Asunto(s)
Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Protozoarias/metabolismo , Toxoplasma/enzimología , Toxoplasma/patogenicidad , Factores de Virulencia/metabolismo , Alelos , Secuencia de Aminoácidos , Animales , Animales Modificados Genéticamente , Dominio Catalítico , Mapeo Cromosómico , Cromosomas/genética , Clonación Molecular , Genes Protozoarios , Ratones , Datos de Secuencia Molecular , Movimiento , Mutación Puntual , Proteínas Serina-Treonina Quinasas/química , Proteínas Serina-Treonina Quinasas/genética , Proteínas Protozoarias/química , Proteínas Protozoarias/genética , Sitios de Carácter Cuantitativo , Toxoplasma/genética , Toxoplasma/crecimiento & desarrollo , Toxoplasmosis Animal/mortalidad , Toxoplasmosis Animal/parasitología , Transfección , Virulencia/genética , Factores de Virulencia/química , Factores de Virulencia/genéticaRESUMEN
In a study of congenital transmission during acute infection of Toxoplasma gondii, 23 pregnant Balb/c mice were inoculated orally with two cysts each of the P strain. Eight mice were inoculated 6-11 days after becoming pregnant (Group 1). Eight mice inoculated on the 10th-15th day of pregnancy (Group 2) were treated with 100 mg/kg/day of minocycline 48 h after inoculation. Seven mice inoculated on the 10th-15th day of pregnancy were not treated and served as a control (Group 3). Congenital transmission was evaluated through direct examination of the brains of the pups or by bioassay and serologic tests. Congenital transmission was observed in 20 (60.6%) of the 33 pups of Group 1, in one (3.6%) of the 28 pups of Group 2, and in 13 (54.2%) of the 24 pups of Group 3. Forty-nine Balb/c mice were examined in the study of congenital transmission of T. gondii during chronic infection. The females showed reproductive problems during this phase of infection. It was observed accentuated hypertrophy of the endometrium and myometrium. Only two of the females gave birth. Our results demonstrate that Balb/c mice with acute toxoplasmosis can be used as a model for studies of congenital T. gondii infection. Our observations indicate the potential of this model for testing new chemotherapeutic agents against congenital toxoplasmosis.
Asunto(s)
Transmisión Vertical de Enfermedad Infecciosa/prevención & control , Complicaciones Infecciosas del Embarazo , Toxoplasmosis Congénita/transmisión , Animales , Antibacterianos/uso terapéutico , Enfermedad Crónica , Modelos Animales de Enfermedad , Endometrio/patología , Femenino , Hipertrofia , Masculino , Ratones , Ratones Endogámicos BALB C , Minociclina/uso terapéutico , Miometrio/patología , Embarazo , Toxoplasmosis Congénita/prevención & control , Útero/patologíaRESUMEN
In a study of congenital transmission during acute infection of Toxoplasma gondii, 23 pregnant Balb/c mice were inoculated orally with two cysts each of the P strain. Eight mice were inoculated 6-11 days after becoming pregnant (Group 1). Eight mice inoculated on the 10th-15th day of pregnancy (Group 2) were treated with 100 mg/kg/day of minocycline 48 h after inoculation. Seven mice inoculated on the 10th-15th day of pregnancy were not treated and served as a control (Group 3). Congenital transmission was evaluated through direct examination of the brains of the pups or by bioassay and serologic tests. Congenital transmission was observed in 20 (60.6 per cent) of the 33 pups of Group 1, in one (3.6 per cent) of the 28 pups of Group 2, and in 13 (54.2 per cent) of the 24 pups of Group 3. Forty-nine Balb/c mice were examined in the study of congenital transmission of T. gondii during chronic infection. The females showed reproductive problems during this phase of infection. It was observed accentuated hypertrophy of the endometrium and myometrium. Only two of the females gave birth. Our results demonstrate that Balb/c mice with acute toxoplasmosis can be used as a model for studies of congenital T. gondii infection. Our observations indicate the potential of this model for testing new chemotherapeutic agents against congenital toxoplasmosis.
Asunto(s)
Animales , Femenino , Embarazo , Ratones , Minociclina/uso terapéutico , Complicaciones del Embarazo , Tetraciclinas/uso terapéutico , Toxoplasmosis Congénita/tratamiento farmacológico , Útero/patología , Western Blotting , Enfermedad Crónica , Endometrio/patología , Ensayo de Inmunoadsorción Enzimática , Técnica del Anticuerpo Fluorescente Indirecta , Hipertrofia , Ratones Endogámicos BALB C , Miometrio/patología , Toxoplasmosis Congénita/inmunología , Toxoplasmosis Congénita/prevención & controlRESUMEN
Serum samples of five goats inoculated with Toxoplasma gondii were analyzed using the enzyme linked immunosorbent assay (ELISA), indirect hemagglutination (IHA) and western blotting (WB). Antibodies detected by ELISA peaked between 19 and 62 days after inoculation and persisted throughout the experiment with no association to parasitaemia. Using WB, the main antigens detected had molecular weights of approximately 68, 62, 50, 48, 42, 34, 28, 26, 22 and 19 kDa. Antibody titers of between 1:256 and 1:32000 were observed using IHA, with a significant drop in activity after treatment with 2-mercapto-ethanol between days 12 and 48. This coincided with the parasitaemic period that occurs between 5 and 64 days after inoculation.
Asunto(s)
Anticuerpos Antiprotozoarios/biosíntesis , Enfermedades de las Cabras/inmunología , Toxoplasma/inmunología , Toxoplasmosis Animal/inmunología , Animales , Anticuerpos Antiprotozoarios/sangre , Antígenos de Protozoos/sangre , Western Blotting/veterinaria , Electroforesis en Gel de Poliacrilamida/veterinaria , Ensayo de Inmunoadsorción Enzimática/veterinaria , Cabras , Pruebas de Hemaglutinación/veterinaria , Peso MolecularRESUMEN
Carotid surgery is frequently associated with postoperative blood pressure alterations. The role of baroreceptors with regard to these alterations was assessed in 50 patients by determining the pre- and postoperative mechanoreceptor sensitivity after Valsalva maneuver and intravenous injections of angiotensin and nitroglycerine as described by Smyth, Sleight and Pickering. In addition, blood pressure was monitored perioperatively and renin and aldosterone levels were measured. In patients with arterial hypertension a postoperative increase of receptor reactivity can be seen necessitating a reduction of antihypertensive therapy in more than 50% of cases. In normotensive patients no uniform response can be observed. A possible explanation for this effect might be the local increase of pressure in the operated vascular segment. The postoperative reintegration of receptor areas which had been adjusted to a reduced pressure level might induce a more sensitive response than can be seen for the remaining receptors, which usually are less responsive in hypertensive patients.
Asunto(s)
Presión Sanguínea/fisiología , Estenosis Carotídea/fisiopatología , Estenosis Carotídea/cirugía , Complicaciones Posoperatorias/fisiopatología , Presorreceptores/fisiopatología , Reflejo/fisiología , Anciano , Arteria Carótida Interna/inervación , Arteria Carótida Interna/cirugía , Femenino , Humanos , Hipertensión/fisiopatología , Masculino , Persona de Mediana Edad , Maniobra de Valsalva/fisiología , Sistema Vasomotor/fisiopatologíaRESUMEN
In the period between 1985-1986 137 patients underwent simple nerve decompression by division of the carpal ligament as therapy for carpal tunnel syndrome. In a long-term follow-up it was possible to control the results of 61 cases. Beside two patients all showed an absolutely satisfying result, subjectively as well as electroneurophysiologically. Therefore we can recommend simple ligament division as a safe and quick method for the therapy of carpal tunnel syndrome.
Asunto(s)
Síndrome del Túnel Carpiano/cirugía , Ligamentos Articulares/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Síndrome del Túnel Carpiano/fisiopatología , Femenino , Humanos , Masculino , Nervio Mediano/fisiopatología , Persona de Mediana Edad , Complicaciones Posoperatorias/fisiopatología , Tiempo de Reacción/fisiología , Estudios Retrospectivos , Transmisión Sináptica/fisiologíaRESUMEN
"The purpose of this article is to provide an explanation of the recent decline of fertility in Switzerland with a saturation model. This process, which can be observed in the majority of highly developed countries since about 1965, is part of a long-term process of limitation of births." Factors considered in the model include the segregation between the work place and household, the development of social security systems, excessive consumption, and changing values. The model attempts to show that individuals are experiencing increasing structural and cultural tensions due to an increase in the impact of such factors that lead them to react in a variety of ways, some of which can affect the number and timing of births. The author suggests that both the fertility level and fertility decline have different determinants and concludes that fears of the "dying out" of the Swiss population are premature. (SUMMARY IN ENG AND FRE)