RESUMEN
Infectious diseases are contributing to the decline of endangered amphibians. We identified myxosporean parasites, Myxidium spp. (Myxosporea: Myxozoa), in the brain and liver of declining native frogs, the Green and Golden Bell frog (Litoria aurea) and the Southern Bell frog (Litoria raniformis). We unequivocally identified two Myxidium spp. (both generalist) affecting Australian native frogs and the invasive Cane toad (Bufo marinus, syn. Rhinella marina) and demonstrated their association with disease. Our study tested the identity of Myxidium spp. within native frogs and the invasive Cane toad (brought to Australia in 1935, via Hawaii) to resolve the question whether the Cane toad introduced them to Australia. We showed that the Australian brain and liver Myxidium spp. differed 9%, 7%, 34% and 37% at the small subunit rDNA, large subunit rDNA, internal transcribed spacers 1 and 2, but were distinct from Myxidium cf. immersum from Cane toads in Brazil. Plotting minimum within-group distance against maximum intra-group distance confirmed their independent evolutionary trajectory. Transmission electron microscopy revealed that the brain stages localize inside axons. Myxospores were morphologically indistinguishable, therefore genetic characterisation was necessary to recognise these cryptic species. It is unlikely that the Cane toad brought the myxosporean parasites to Australia, because the parasites were not found in 261 Hawaiian Cane toads. Instead, these data support the enemy-release hypothesis predicting that not all parasites are translocated with their hosts and suggest that the Cane toad may have played an important spill-back role in their emergence and facilitated their dissemination. This work emphasizes the importance of accurate species identification of pathogens relevant to wildlife management and disease control. In our case it is paving the road for the spill-back role of the Cane toad and the parasite emergence.
Asunto(s)
Anuros/parasitología , Especies Introducidas , Myxozoa/fisiología , Parásitos/fisiología , Enfermedades Parasitarias en Animales/parasitología , Animales , Anuros/crecimiento & desarrollo , Australia , Axones/parasitología , Axones/patología , Encéfalo/parasitología , Encéfalo/patología , Encéfalo/ultraestructura , Brasil , ADN Ribosómico/genética , Especies en Peligro de Extinción , Genotipo , Geografía , Hawaii , Larva/parasitología , Larva/ultraestructura , Estadios del Ciclo de Vida , Hígado/parasitología , Hígado/patología , Hígado/ultraestructura , Datos de Secuencia Molecular , Vaina de Mielina/parasitología , Myxozoa/citología , Myxozoa/genética , Parásitos/citología , Parásitos/genética , FilogeniaRESUMEN
Besides their natural bird hosts, Trichobilharzia regenti cercariae are able to penetrate skin of mammals, including humans. Experimental infections of mice showed that schistosomula of this species are able to avoid the immune response in skin of their non-specific mammalian host and escape the skin to migrate to the CNS. Schistosomula do not mature in mammals, but can survive in nervous tissue for several days post infection. Neuroinfections of specific bird hosts as well as accidental mammalian hosts can lead to neuromotor effects, for example, leg paralysis and thus this parasite serves as a model of parasite invasion of the CNS. Here, we show by histological and immunohistochemical investigation of CNS invasion of immunocompetent (BALB/c) and immunodeficient (SCID) mice by T. regenti schistosomula that the presence of parasites in the nervous tissue initiated an influx of immune cells, activation of microglia, astrocytes and development of inflammatory lesions. Schistosomula elimination in the tissue depended on the host immune status. In the absence of CD3+ T-cells in immunodeficient SCID mice, parasite destruction was slower than that in immunocompetent BALB/c mice. Axon injury and subsequent secondary demyelination in the CNS were associated with mechanical damage due to migration of schistosomula through the nervous tissue, and not by host immune processes. Immunoreactivity of the parasite intestinal content for specific antigens of oligodendrocytes/myelin and neurofilaments showed for the first time that schistosomula ingest the nervous tissue components during their migration.
Asunto(s)
Infecciones Parasitarias del Sistema Nervioso Central/inmunología , Sistema Nervioso Central/parasitología , Schistosomatidae/inmunología , Infecciones por Trematodos/inmunología , Animales , Axones/parasitología , Axones/patología , Sistema Nervioso Central/inmunología , Sistema Nervioso Central/patología , Infecciones Parasitarias del Sistema Nervioso Central/etiología , Patos , Inmunidad Celular , Inmunocompetencia , Inmunohistoquímica , Inflamación/inmunología , Inflamación/parasitología , Macrófagos/inmunología , Macrófagos/parasitología , Ratones , Ratones Endogámicos BALB C , Ratones SCID , Microglía/inmunología , Microglía/parasitología , Caracoles , Infecciones por Trematodos/etiologíaRESUMEN
OBJECTIVES: The objective was to compare electrophysiologic investigations of the upper trapezius muscle (UT) after different selective neck dissections (SND) and analyze the differences between types of SND and the preservation and excision of the cervical nerves (the C2-4 rami of the cervical plexus). STUDY DESIGN: Retrospective study of 54 patients (average age, 65.1 +/- 9.6 yr, 45 males) with 70 SND. METHODS: Patients underwent needle electromyography (EMG) of the UT by 4 months after surgery. The findings were rated according to the 5 point EMG scale system from 1 (total denervation: positive sharp wave or fibrillation potential at rest and electrical silence at voluntary contraction) to 5 (normal pattern). RESULTS: The average EMG scale was 1.7 +/- 1.1, 58.6% for score 1 and only 5.7% for score 5. There was not a significant difference in the EMG scale between the types of SND, whereas the group in which the cervical nerves were excised was significantly lower than in that in which it was preserved. The average EMG scales in the former and latter were 1.5 +/- 0.8 and 2.0 +/- 1.3, 68.8%. CONCLUSIONS: The study data confirm that complete or incomplete denervation of the UT was caused by axonal injury of the spinal accessory nerve, even though it was spared, because of traction of the nerve during neck dissection. Second, the excision of the C2 to 4 rami of the cervical plexus caused worse damage of the UT. It is suggested that it is important to preserve the cervical nerves to avoid denervation of the UT.
Asunto(s)
Electromiografía/métodos , Músculo Esquelético/fisiopatología , Disección del Cuello , Nervio Accesorio/cirugía , Traumatismos del Nervio Accesorio , Potenciales de Acción/fisiología , Anciano , Axones/parasitología , Plexo Cervical/fisiopatología , Plexo Cervical/cirugía , Electromiografía/instrumentación , Femenino , Estudios de Seguimiento , Humanos , Masculino , Contracción Muscular/fisiología , Desnervación Muscular/efectos adversos , Cuello/inervación , Disección del Cuello/efectos adversos , Disección del Cuello/métodosRESUMEN
We measured the cross-sectional area (CSA) of the human tractus solitarius (HTS) with the help of an image-analyzer system on a cross section of the upper part of the medulla oblongata in 44 Japanese cadavers (22 males and 22 females) and examined the relationship between age, sex and whether the subjects were dentulous or edentulous. The results showed no significant differences between the left and right sides of the HTS in either male or female subjects. However, the size of HTS decreased slightly with age in males but not at all in females, whereas tooth loss had a definite incidence on the size of HTS in females but not in male, as the CSA was smaller in edentulous females but not in edentulous males. This would tend to indicate that a decreases in taste function is connected with the aging process in male, and with tooth loss in females.