Direct and indirect exposure to air pollution

Glutathione (GSH), trypanothione (T(SH)2) and glutathionyl spermidine (GSH-SP) concentrations were determined in the Tulahuén and LQ strains and the DM 28c clone of Trypanosoma cruzi. The concentrations of GSH, T(SH)2 and GSH-SP, expressed as nmol of GSH per g of parasite fresh weight, were 60.1, 397.8 and 103.9, respectively, for the Tulahuén strain. For the DM 28c clone, the values were 113.9, 677.9 and 164.1, respectively, and for the LQ strain they were 199.1, 1100.5 and 55.3, respectively. When the parasites were treated with 10 microM nifurtimox or 50 microM benznidazole for 2 h, the concentrations of all three reduced thiols decreased strongly. The total amount of T(SH)2 decreased by more than 50%. Treatment of the parasites with 5 mM buthionine sulfoximine, an inhibitor of GSH synthesis, for 6 h diminished the concentrations of the reduced thiols by between 27% and 53% with respect to the controls. Cyclohexylamine, an inhibitor of spermidine synthesis, decreased the concentrations of T(SH)2 and GSH-SP but not that of GSH. It is possible to conclude from this study that trypanothione is the most important thiol involved in the detoxication of nifurtimox and benznidazole in T. cruzi and that electrophilic reduced metabolites of both drugs are most probably conjugated with GSH, T(SH)2 and GSH-SP, thus decreasing their concentrations. GSH biosynthesis is an important drug target.     

Indium-111 chloride scanning for identification of experimental abscesses

A review of all granulomatous surgical lesions in the files of the Free University Hospital revealed four cases of histoplasmoma in which Grocott-staining procedures provided histologic confirmation of the presence of Histoplasma capsulatum bodies. The case histories have been presented briefly. A short review of the literature follows.     

Routine automated synthesis of five patented analog circuits using genetic programming

This article reports on a project in which we browsed patents issued after January 1, 2000 to commercial enterprises or university research institutions for analog electrical circuits. We then employed genetic programming to automatically design (synthesize) entities that duplicated the functionality of five post-2000 issued patents. The automated method works from a high-level statement of the circuits intended function. The article addresses the question of what is actually delivered by the operation of the artificial problem-solving method in relation to the amount of intelligence that is supplied by the humans employing the method (something we refer to as the yield of an automated method). The article also addresses the question of the routineness of the artificial problem-solving method – that is, the amount of effort required to make the transition from problem to problem within a particular domain. The conclusion is that the artificial method routinely delivers high-yield, human-competitive (i.e., previously patented) results.     

Responses of visual, somatosensory, and auditory neurones in the golden hamster's superior colliculus

1. The response characteristics of visual, somatosensory, and auditory neurones in the golden hamster's superior colliculus were investigated.2. As has been noted for other mammalian species, a distinct difference between the functional organizations of the superficial and deeper layers of the superior colliculus was observed.3. Neurones in the superficial layers were exclusively visual, with small receptive-fields, and generally did not show response decrements with repeated stimulation. The sizes of the receptive-fields did not vary appreciably as a function of retinal eccentricity.4. In the deeper layers, visual receptive-fields were large, or could not be accurately delimited, and response habituation was often evident. In addition, many cells in the deeper layers of the colliculus responded only to somatosensory stimuli. Far fewer cells, which appeared to be confined to the caudal portions of the colliculus, responded to auditory stimuli. Polymodal cells were also encountered.5. Selectivity to opposing directions of movement was tested for ninety-four visual cells. Using a ;null' criterion, 27.7% of these cells were judged to be directionally selective. A distribution of the preferred directions of these cells showed a significant preference for movement with an upper-nasal component. With a statistical criterion, 60.6% of these cells were considered to show a significant asymmetry in responding to movement in opposing directions.6. Directional selectivity was also tested for ninety-two cells following acute, unilateral, lesions of the visual cortex. For the eighty cells recorded, homolateral to the ablated cortex, 27.5% were judged as directionally selective using the statistical criterion, while 12.5% were selective with the ;null' criterion. Of the twelve cells isolated in the colliculus, contralateral to the lesions, seven were judged as directionally selective with the statistical, and three with the ;null' criterion.7. The effects of visual cortical lesions upon directional selectivity appeared to be confined to cells in the superficial layers of the colliculus. It was suggested that directional selectivity of many cells in the superficial layers of the tectum of the hamster is organized cortically.8. A clear spatial correspondence was observed for the receptive-fields of visual, somatosensory, and auditory neurones.9. As has been suggested for other species, the hamster's superior colliculus appears to play an important role in orienting the animal toward visual, somatosensory, and auditory stimuli.     

An evaluation of predicting hearing loss from the acoustic reflex

Three different formulas used in predicting hearing level from acoustic reflex data have been suggested. Acoustic reflex information is also used in predicting slope of hearing loss. Seventy-four normal and hearing-impaired persons were tested, and predictions of level and slope of hearing were compared with pure tone hearing thresholds. The results indicate that the Niemeyer-Sesterhenn and Jerger unweighted formulas yield comparable results and are preferable to the Jerger weighted formula. Predictions of slope of hearing loss are equivocal.     

Succinylcholine as a predictor in strabismus surgery

Succinylcholine was injected intraoperatively in 20 patients with congenital esotropia, before and after the surgical procedure. Regression analysis was performed to investigate the relationship between the awake pre- and postoperative alignment and the drug-induced ocular positions, under anesthesia. The postoperative succinylcholine-induced ocular position was found to be a highly significant predictor of the one week postoperative alignment (r = 0.98, p less than 0.0001). Further investigation may lead to an ability to predict the postoperative alignment intraoperatively.