Antifungal activity of plant and bacterial ureases.

Ureases (EC 3.5.1.5) are nickel-dependent metalloenzymes that catalyze the hydrolysis of urea to ammonia and carbon dioxide. Produced by plants, fungi and bacteria, but not by animals, ureases share significant homology and similar mechanisms of catalysis, although differing in quaternary structures. While fungal and plant ureases are homo-oligomeric proteins of 90 kDa subunits, bacterial ureases are multimers of two (e.g. Helicobacter pylori) or three subunit complexes. It has been proposed that in plants these enzymes are involved in nitrogen bioavailability and in protection against pathogens. Previous studies by our group have shown that plant ureases, but not a bacterial (Bacillus pasteurii) urease, display insecticidal activity. Herein we demonstrate that (Glycine max) embryo-specific soybean urease, jackbean (Canavalia ensiformis) major urease and a recombinant H. pylori urease impair growth of selected phytopathogenic fungi at sub-micromolar concentrations. This antifungal property of ureases is not affected by treatment of the proteins with an irreversible inhibitor of the ureolytic activity. Scanning electron microscopy of urease-treated fungi suggests plasmolysis and cell wall injuries. Altogether, our data indicate that ureases probably contribute to the plant arsenal of defense compounds against predators and phytopathogens and that the urease defense mechanism is independent of ammonia release from urea.

Response of major depression and Tourette's syndrome to ECT: a case report.

There have been few published reports on the use of electroconvulsive therapy in the treatment of Tourette's syndrome. We present a case of a woman with preexisting Tourette's syndrome, which had been latent for some years, that was exacerbated with the onset of a major depressive episode. Both the tics and the depressive symptoms completely remitted after eight sessions of electroconvulsive therapy. Possible mechanisms of this effect are discussed.

Adolescents in therapeutic communities.

This study was designed to compare the course of change of two groups of conduct-disordered adolescents in two theoretically distinct residential treatment programs: a Therapeutic Community and a modified Token Economy. In all, 28 clients were assessed on multiple measures at three points in the treatment process in a repeated measures design. Results of the study indicated that, despite an overall trend toward improvement in both groups, there was little significant difference between the rates of progress over time. Dropouts and nondropouts could be differentiated only by a small number of baseline scores and the amount of family contact during placement. While comparative studies in residential treatment have been lacking, it appears that a more promising approach would be to examine common features of different models. The results of this study support the need for qualitative research focusing on the interaction of client attributes and underlying components of treatment modalities.