Specificity of monoclonal antibodies obtained by immunization of mice with trypsin-treated group a streptococcus culture

Hybridomas producing monoclonal antibodies intensively reacting with group A streptococcus antigens in enzyme immunoassay were obtained as a result of immunizing mice with pepsin-treated cultures of group A streptococcus. All antibodies were referred to class M immunoglobulins. The reactions of monoclonal antibodies were completely inhibited by the pepsin-treated culture of group A streptococcus. The degree of inhibition with A-polysaccharide was lower, being 17.5 to 50.0 in different monoclonal antibodies. All the monoclonal antibodies obtained cross-reacted with antigens of murine and human epithelial tissues of the thymus and skin. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 11, pp. 492–495, November, 1994 Presented by A. G. Skavronskaya, Member of the Russian Academy of Medical Sciences     

Foveal contour interactions and crowding effects at the resolution limit of the visual system

We describe several experiments on contour interactions and crowding effects at the resolution limit of the visual system. As test stimuli we used characters that are often employed in optometric practice for testing visual acuity: Landolt C's, Snellen E's, and rectangular gratings. We tested several hypotheses that have been put forward to explain contour interaction and crowding effects. In Experiment 1 and Experiment 2, Landolt C's were the test stimuli, and bars, or Landolt C's, or gratings served as distractors. In Experiment 1, we showed that neither scale invariance nor spatial frequency selectivity is a characteristic of foveal crowding effects. These results allowed us to conclude that mechanisms other than lateral masking contribute to observers' performance in 'crowded' tasks. R. F. Hess, S. C. Dakin, and N. Kappor (2000) suggested that the spatial frequency band most appropriate for target recognition is shifted by the surrounding bars to higher spatial frequencies that cannot be resolved by observers. Our Experiment 2 rejects this hypothesis as the experimental data do not follow theoretical predictions. In Experiment 3, we employed Snellen E's, both as test stimuli and as distractors. The masking functions were similar to those measured in Experiment 1 when the test Landolt C was surrounded by Landolt C's. In Experiment 4, we extended the range of test stimuli to rectangular gratings; same-frequency or high-frequency gratings were distractors. In this case, if the distracting gratings had random orientation from trial to trial, the critical spacing was twice larger than in the first three experiments. If the orientation of the distractors was fixed during the whole experiment, the critical spacing was similar to that measured in the first three experiments. We suggest that the visual system can use different mechanisms for the discrimination of different test stimuli in the presence of particular surround. Different receptive fields with different spatial characteristics can be employed. To explain why crowding effects at the resolution limit of the visual system are not scale invariant, we suggest that a range of stimuli, slightly varying in size, may all be processed by the same neural channel--the channel with the smallest receptive fields of the visual system.     

Induction of autoimmunity against endogenous neuroregulators isatin and cholecystokinin as a method of modeling and correction of depressive behavior

Long-term depressive behavior was modeled via immunization of white rats with isatin (an endogenous MAO inhibitor) covalently bound to a carrier antigen. The immunization of rats against isatin and several exogenous MAO inhibitors (pargyline and deprenyl) resulted in long-term (2 months) depressive-like behavior with elements of anxiety and an increased activity of MAO in the brain. In contrast, immunization against endogenous inductors of anxiety (cholecystokinins 4 and 3) induced prolonged antidepressant and anxiolytic effects. The authors discuss the advantages of the immunochemical approach, both to modeling of depression and pathological anxiety, and to their long-lasting correction.     

Cost-effectiveness analysis of tuberculosis control policies in Ivanovo Oblast, Russian Federation. Ivanovo Tuberculosis Project Study Group.

Many of the current tuberculosis control programmes in the Russian Federation are based on costly strategies which are underfunded and use long, individualized treatment regimens. This article compares, using a cost-effectiveness analysis, the new WHO strategy implemented in the Ivanovo Oblast (case-finding among symptomatic patients (SCF) and shorter regimens) and the old strategy (active screening of the asymptomatic population (ACF) and longer regimens). The cost per case cured was calculated at different levels of cure rate (45-95%) using three scenarios to describe the new WHO strategy (use of WHO-recommended regimens and three options at increasing rates of admission) and a fourth scenario to describe the old strategy (all patients admitted for the whole treatment and longer regimens). The cost per case detected was determined by calculating the following: yield of the new and old strategy (number of examinations necessary to diagnose one case); cost of the diagnostic process; multiplying yield per cost according to the three scenarios describing the new WHO strategy and a fourth scenario describing the old strategy. In the Ivanovo Oblast the cost per case cured, at 85% cure rate level, ranged from US$ 1197 (new strategy, scenario 1 without food) to US$ 6293 (old strategy, scenario 4) the cost per case detected ranged from US$ 1581 (new strategy, scenario 1) to US$ 4000 (old strategy, scenario 4). Significant savings can result from shifting towards the new WHO strategy. Decision-makers and health administrators should be responsible for re-investing the financial and human resources mobilized by the adoption of cost-effective strategies within the TB control programme.