Evagination of metacestodes of the WFU strain of Taenia crassiceps and evaluation of the impact of immune suppression of hamsters during tapeworm development.

Taeniosis-cysticercosis caused by Taenia crassiceps (Zeder, 1800) is a useful experimental model for biomedical research, in substitution of Taenia solium Linnaeus, 1758, studied during decades to develop effective vaccination, novel anti-helminthic drugs and diagnostic tools. Cysticercosis in mouse (Mus musculus Linnaeus) is achieved by the larval subculturing of the Wake Forest University (WFU) strain of T. crassiceps. Golden hamster, Mesocricetus auratus (Waterhouse), has been shown to be the most suitable host for adult forms of parasite in experimental taeniosis. Metacestodes of T. crassiceps WFU multiply by budding without restrictions once inoculated into the mouse, while the number of tapeworms developed from these larvae in hamsters remains highly variable. Three objectives have been proposed to improve the infection of T. crassiceps WFU in hamsters: (1) to re-evaluate the need of immune suppression; (2) to investigate the advantage of infecting hamsters with metacestodes with in vitro protruded scolices; and (3) to compare a number of tapeworms developed from metacestodes subcultured in hamsters against those proliferated in mice. Our results demonstrated that when the evagination of murine metacestodes was high, the number of T. crassiceps WFU adults obtained from hamsters was also high. Immunosuppressive treatment remains relevant for this experimental rodent model. The hamster-to-hamster cysticercosis-taeniosis by T. crassiceps overcame the mouse-to-hamster model in the yield of adult specimens. In vitro scolex evagination and metacestode asexual proliferation in hamsters place this rodent model by T. crassiceps WFU as the most affordable experimental models with taeniids.

Esporotricosis: la micosis subcutánea más frecuente en México / Sporotrichosis: the most frequent subcutaneous mycosis in Mexico

Resumen La esporotricosis es una micosis causada por especies del complejo Sporothrix schenckii. Basado en estudios epidemiológicos y moleculares. Se reconocen seis especies de Sporothrix como causantes de la esporotricosis humana. Algunas especies de este complejo, tienen un potencial zoonótico relevante para la transmisión al humano, y muchas otras son exclusivamente fitopatógenas. Es considerada la micosis subcutánea más frecuente en México. El principal mecanismo de infección es el traumatismo con pérdida de continuidad de la piel seguido por la contaminación con el hongo Sporothrix spp. Las principales formas clínicas son la esporotricosis linfangítica, la forma cutánea fija y la forma diseminada. Los procedimientos de laboratorio más útiles para confirmar el diagnóstico, son el cultivo de especímenes como exudado y tejido, así como el estudio histopatológico. La forma parasitaria está representada por levaduras en el tejido o exudados. Los medicamentos más útiles en el tratamiento son el yoduro de potasio y el itraconazol. La prevención es difícil; sin embargo, el uso de equipo protector durante las actividades laborales puede contribuir a evitar este padecimiento.

Abstract Sporotrichosis is a mycosis caused by fungal species that are part of the Sporothrix schenckii complex. Epidemiological and molecular studies have found only six species of the Sporothrix schenckii complex that cause infections in humans. Some species of this complex have a relevant zoonotic potential for transmission to humans, and some others only have phytopathogenic properties. It is considered the most frequent form of subcutaneous mycosis in Mexico. The main mechanism of infection a wound with loss of continuity of the skin followed by contamination with the fungus Sporothrix spp. The main clinical manifestations are lymphangitic sporotrichosis, fixed skin manifestation and disseminated manifestation. The most useful laboratory procedures to confirm the diagnosis are the cultivation of specimens such as exudate and tissue, as well as the histopathological study. The parasitic manifestation is represented by yeasts in the tissue or exudates. The most useful medications for its treatment are potassium iodide and itraconazole. Prevention is difficult; however, the use of protective equipment during work activities can help prevent this condition.

Linajes madurativos de las células que regeneran al hígado / Maturative lineages of cells that regenerate the liver

Resumen Diferentes linajes de las células hepáticas participan en la regeneración del hígado y los hepatocitos guiescentes pueden responder ante un daño hepático leve con división celular moderada, mientras gue las células troncales y progenitoras responderán para una amplia restitución del parénquima hepático severamente dañado. Ocho linajes madurativos se sitúan dentro del hígado con diferente grado de madurez. Cuatro de ocho subpoblaciones gue presentan marcadores para células troncales o progenitoras se ubican en nichos intrahepáticos como los canales de Hering y la vena porta, estructuras en las gue pueden continuar su diferenciación si se recibe algún estímulo. Recientemente se describió un nuevo nicho entrahepático con una composición celular heterogénea ubicado entre los grandes duetos biliares y en el páncreas. Las células gue se encuentran en estos compartimentos expresan marcadores tempranos de células troncales y se consideran como precursores de las células troncales hepáticas.

Abstract Different cellular lineages participate in liver regeneration. Quiescent hepatocytes may respond to a mild liver injury with moderate cell division. Meanwhile, stem and progenitor cells are responsible for the large restitution of a severe damaged organ. Eight matu rational lineages are in the liver, each one with a different maturity grade. Four subpopulations out of eight express stem or progenitor cell markers are found within intrahepatic niches such as the canals of Hering and the portal vein. Each structure is able to continue its differentiation if a stimuli is received. Recently, a new extra-hepatic stem niche with a heterogeneous cellular composition was found between the large biliary ducts and the pancreas. Stem or progenitor cells contained in these compartments express early stem markers and are considered as a precursor of hepatic stem cells.

Methoxychlor and Vinclozolin Induce Rapid Changes in Intercellular and Intracellular Signaling in Liver Progenitor Cells.

Methoxychlor (MXC) and vinclozolin (VIN) are well-recognized endocrine disrupting chemicals known to alter epigenetic regulations and transgenerational inheritance; however, non-endocrine disruption endpoints are also important. Thus, we determined the effects of MXC and VIN on the dysregulation of gap junctional intercellular communication (GJIC) and activation of mitogen-activated protein kinases (MAPKs) in WB-F344 rat liver epithelial cells. Both chemicals induced a rapid dysregulation of GJIC at non-cytotoxic doses, with 30 min EC50 values for GJIC inhibition being 10 µM for MXC and 126 µM for VIN. MXC inhibited GJIC for at least 24 h, while VIN effects were transient and GJIC recovered after 4 h. VIN induced rapid hyperphosphorylation and internalization of gap junction protein connexin43, and both chemicals also activated MAPK ERK1/2 and p38. Effects on GJIC were not prevented by MEK1/2 inhibitor, but by an inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC), resveratrol, and in the case of VIN, also, by a p38 inhibitor. Estrogen (ER) and androgen receptor (AR) modulators (estradiol, ICI 182,780, HPTE, testosterone, flutamide, VIN M2) did not attenuate MXC or VIN effects on GJIC. Our data also indicate that the effects were elicited by the parental compounds of MXC and VIN. Our study provides new evidence that MXC and VIN dysregulate GJIC via mechanisms involving rapid activation of PC-PLC occurring independently of ER- or AR-dependent genomic signaling. Such alterations of rapid intercellular and intracellular signaling events involved in regulations of gene expression, tissue development, function and homeostasis, could also contribute to transgenerational epigenetic effects of endocrine disruptors.

Taenia crassiceps: in vivo and in vitro models.

Taenia crassiceps is a cestode parasite of wild and domestic animals that rarely affects humans; it has been widely used as an experimental model. The asexual proliferation by budding is a useful attribute of T. crassiceps cysticerci, which allows the various strains to be maintained indefinitely in the peritoneal cavity of inbred mice. Over the last 50 years, experimental results using larval and adult stages of T. crassiceps have yielded much information on the morphology, infectivity, proliferation dynamics, host immune response, endocrinological responses and vaccine research, all of which have contributed to our knowledge of cestode biology.

Evagination and infectivity of Taenia crassiceps cysticerci in experimental animals.

Cysticerci of Taenia crassiceps reproduce asexually by exogenous budding in the rodent intermediate host, and can experimentally develop to the adult stage within the small intestine of golden hamsters. In the present study, we report the loss of cysticercus infectivity for hamsters after maintaining the strain for 4 yr by consecutive peritoneal passage in mice. Larval infectivity was restored after a cysticercus from the WFU strain developed into a gravid tapeworm after being passaged through a dog. The eggs of this tapeworm were infective for mice, which subsequently developed cysticerci with renewed capability for infecting experimental hamsters. An in vitro evagination assay was also conducted using eleventh-generation WFU strain cysticerci, as well as second- and fourth-generation dog-derived cysticerci. Significantly higher (P < 0.0001) evagination was observed for 5-mo-old dog-derived and WFU infrapopulations when compared with respective evagination values for 9- and 12-mo-old infrapopulations. The extent of evagination was linked to the capacity of cysticerci to infect hamsters, so that greater evagination resulted in a higher infectivity for hamsters and vice versa.

Taeniid tapeworm responses to in vitro glucose.

Experimental taeniid strobilae from Taenia solium and T. crassiceps (WFU strain) were incubated for 0-72 h in 0, 5 or 20 mM glucose solutions and further exposed for 15 min to the gap junction fluorochrome Lucifer Yellow. Frozen sections were obtained from each worm and observed under an epifluorescent microscope. Worm sections from strobilae incubated with glucose, revealed intense fluorescence in the base of the tegumentary surface, suggesting that this tissue behaves as a gap junction complex. Fluorescence intensity differences between control worms not exposed to glucose and worms incubated with glucose, were highly significant. The results demonstrate that under in vitro conditions, glucose is taken up along the whole strobilar tegument in both taeniid species, suggesting, that although taeniids attached to the duodenum probably take up most of their nutrients directly from the mucosal wall, the capacity for absorbing glucose along the tegumentary surface is always active and may increase the survival capacity of these intestinal worms by promoting glucose absorption at other points in the intestinal lumen.

Antigenic proteins associated with calcareous corpuscules of taenia solium: partial characterization of a calcium-binding protein.

BACKGROUND: A protein fraction was isolated from calcareous corpuscles of Taenia solium cysticerci. The antigens in this fraction were recognized in ELISA and Western blot assays by all sera from a group of patients with active neurocysticercosis (NC) and were not recognized by the sera from patients with other neurological disorders. Western blot analysis also showed that several high molecular weight proteins were strongly recognized by antibodies in all the neurocysticercotic patient sera, suggesting a potential for serological diagnosis of neurocysticercosis. METHODS: In order to characterize these antigenic proteins, we used a monoclonal antibody raised against a high MW calcium-binding protein associated with calcareous corpuscles of Echinococcus granulosus (EgCaBP1). RESULTS: Western blot assays revealed the recognition of a protein band of about 260 kDa, appearing within the range of the high MW antigens recognized by the NC sera. Several cDNA clones were isolated through screening of a T. solium metacestode library with a DNA probe for EgCaBP1, containing partial coding sequences showing about 88% identity with the protein of E. granulosus. Moreover, a recombinant product expressed in bacteria from the partial coding sequence of T. solium showed the ability to bind Ca2+ and was recognized by the monoclonal antibody. This recombinant calcium-binding protein of T. solium was not recognized by the NC patient sera by ELISA and Western blot. CONCLUSIONS: Antigenic proteins in the calcareous corpuscles of T. solium metacestodes deserve further analysis as candidates in the development of diagnostic tools for neurocysticercosis.