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Background and Aims: Published studies repeatedly demonstrate an advantage of three-dimensional (3D) laparoscopic surgery over two-dimensional (2D) systems but with quite heterogeneous results. This raises the question whether clinics must replace 2D technologies to ensure effective training of future surgeons., Methods: We recruited 45 students with no experience in laparoscopic surgery and comparable characteristics in terms of vision and frequency of video game usage. The students were randomly allocated to 3D ( n = 23) or 2D ( n = 22) groups and performed 10 runs of a laparoscopic "peg transfer" task in the Luebeck Toolbox. A repeated-measures ANOVA for operation times and a generalized linear mixed model for error rates were calculated. The main effects of laparoscopic condition and run, as well as the interaction term between the two, were examined., Results: No statistically significant differences in operation times and error rates were observed between 2D and 3D groups ( p = 0.10 and p = 0.72, respectively). The learning curve showed a significant reduction in operation time and error rates (both p 's < 0.001). No significant interactions between group and run were detected (operation time: p = 0.342, error rates: p = 0.83). With respect to both endpoints studied, the learning curves reached their plateau at the 7th run., Conclusion: The result of our study with laparoscopic novices revealed no significant difference between 2D and 3D technology with respect to performance time and the error rate in a simple standardized test. In the future, surgeons may thus still be trained in both techniques., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sahm, Danzer, Grimm, Herrmann and Mantke.)

Reactivation of chronic toxoplasmosis resulting in Toxoplasma encephalitis (TE) is a common event in acquired immune deficiency syndrome (AIDS) patients. Conversion from Toxoplasma gondii bradyzoites to tachyzoites is a prerequisite for reactivation. Until recently, the study of stage conversion in human tissue was not possible due to the lack of antibodies that recognize stage-specific epitopes after long-term formaldehyde fixation. Using the combination of a polyclonal anti-T. gondii antibody, the cyst-stage-specific monoclonal antibody CC2, and a tachyzoite-specific polyclonal antibody (anti-SAG1, recombinant), we tried to demonstrate parasite differentiation in the brain tissue of 10 AIDS patients with clinically suspected TE. Double labeling of the stage-specific antibodies enabled us to demonstrate interconversion between tachyzoites and bradyzoites for the first time in human tissue. The study confirmed that the transformation process is nonsynchronous and that the manifestation of TE depends on the degree and site of tissue destruction caused by invading tachyzoites. The original source of tachyzoites could never be located, but a few samples suggested that tachyzoites may invade by dissemination across the blood-brain barrier. Cyst rupture as the first event in the process of reactivation was not seen. We conclude that the initial site(s) of reactivation will be destroyed by tissue-destructive tachyzoites long before clinical symptoms occur.

A murine model of pulmonary toxoplasmosis was examined morphologically and immunochemically using 3 strains of Toxoplasma gondii. BALB/c and NMRI mice were infected with tachyzoites of a virulent strain (RH) or with brain cysts of an avirulent (GAIL), or moderately virulent, strain (NED). Depending on the strain of T. gondii, the degree of infection, number of parasites, and replicative potential of T. gondii in lungs varied. In lungs of mice infected with the RH strain, the number of parasites increased in mice during the survival period. Only tachyzoites were found, as confirmed by stage-specific monoclonal antibodies. In lungs of mice infected with the GAIL strain or the NED strain, different stages of parasites were detected. Up to day 14 after infection, only tachyzoites were present, followed by bradyzoites between days 14 and 20 after infection. The number of cysts decreased and finally could not be detected in this organ. In general, the number of cysts that developed in the lungs was smaller than the number that developed in the brain.