Understanding mechanisms and the role of differentiation in pathogenesis of Toxoplasma gondii: a review

Parasite differentiation from proliferating tachyzoites into latent bradyzoites is central to pathogenesis and transmission of the intracellular protozoan pathogen Toxoplasma gondii. The presence of bradyzoite-containing cysts in human hosts and their subsequent rupture can cause life-threatening recrudescence of acute infection in the immunocompromised and cyst formation in other animals contributes to zoonotic transmission and widespread dissemination of the parasite. In this review, we discuss the evidence showing how the clinically relevant process of bradyzoite differentiation is regulated at both transcriptional and post-transcriptional levels. Specific regulatory factors implicated in modulating bradyzoite differentiation include promoter-based cis-elements, epigenetic modifications and protein translation control through eukaryotic initiation factor -2 (eIF2). In addition to a summary of the current state of knowledge in these areas we discuss the pharmacological ramifications and pose some questions for future research.

Helicobacter pylori detection in gastric biopsies, saliva and dental plaque of Brazilian dyspeptic patients

Helicobacter pylori is an important human pathogen that causes chronic gastritis and is associated with the development of peptic ulcer disease and gastric malignancies. The oral cavity has been implicated as a potential H. pylori reservoir and may therefore be involved in the reinfection of the stomach, which can sometimes occur following treatment of an H. pylori infection. The objectives of this paper were (i) to determine the presence of H. pylori in the oral cavity and (ii) to examine the relationship between oral H. pylori and subsequent gastritis. Gastric biopsies, saliva samples and dental plaques were obtained from 78 dyspeptic adults. DNA was extracted and evaluated for the presence of H. pylori using polymerase chain reaction and Southern blotting methods. Persons with gastritis were frequently positive for H. pylori in their stomachs (p < 0.0001) and there was a statistically significant correlation between the presence of H. pylori in gastric biopsies and the oral cavity (p < 0.0001). Our results suggest a relationship between gastric infection and the presence of this bacterium in the oral cavity. Despite this, H. pylori were present in the oral cavity with variable distribution between saliva and dental plaques, suggesting the existence of a reservoir for the species and a potential association with gastric reinfection.

Passive lipoidal diffusion and carrier-mediated cell uptake are both important mechanisms of membrane permeation in drug disposition.

Recently, it has been proposed that drug permeation is essentially carrier-mediated only and that passive lipoidal diffusion is negligible. This opposes the prevailing hypothesis of drug permeation through biological membranes, which integrates the contribution of multiple permeation mechanisms, including both carrier-mediated and passive lipoidal diffusion, depending on the compound's properties, membrane properties, and solution properties. The prevailing hypothesis of drug permeation continues to be successful for application and prediction in drug development. Proponents of the carrier-mediated only concept argue against passive lipoidal diffusion. However, the arguments are not supported by broad pharmaceutics literature. The carrier-mediated only concept lacks substantial supporting evidence and successful applications in drug development.

4-7-19, stade Pershing, [Lawrence] Shields, Américain, à l'arrivée de la course de relais de 3000 m [des Jeux interalliés, le n°835 William C. Gray, membre du relais américain, lève le poing en signe de victoire] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54716

[1-6-19, l'Américain Earl William] Eby gagnant du 400 m [championnats de l'armée américaine à Colombes] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54199

[1-6-19, l'Américain Earl William] Eby gagnant du 400 m [championnats d'athlétisme de l'armée américaine à Colombes] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54198

[Earl William] Eby, Américain, 2ème, [Daniel Leslie] Mason, Nouvelle-Zélande, 1er du 800 [mètres des Jeux interalliés, stade Pershing, le 4 juillet 1919] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54702