Inhibitors of the NMDA-Nitric Oxide Signaling Pathway Protect Against Neuronal Atrophy and Synapse Loss Provoked by l-alpha Aminoadipic Acid-treated Astrocytes

The impact of treating astrocytes with the astrocytic toxin l-alpha amino adipic acid (L-AAA) on neuronal outgrowth, complexity and synapse formation was assessed, using a model of astrocyte-neuronal interaction. Treatment of rat primary cortical neurons with conditioned media (CM) derived from astrocytes treated with L-AAA reduced neuronal complexity and synapse formation. L-AAA provoked a reduction in the expression of glial fibrillary acid protein (GFAP) and a reduction in ATP-linked mitochondrial respiration in astrocytic cells. As the NMDA-R/PSD-95/NOS signaling pathway is implicated in regulating the structural plasticity of neurons, treatment of neuronal cultures with the neuronal nitric oxide synthase (nNOS) inhibitor 1-[2-(trifluoromethyl)phenyl] imidazole (TRIM) [100 nM] was assessed and observed to protect against L-AAA-treated astrocytic CM-induced reduction in neuronal complexity and synapse loss. Treatment with the NMDA-R antagonist ketamine protected against the CM-induced loss of synapse formation whereas the novel PSD-95/nNOS inhibitors 2-((1H-benzo[d] [1,2,3]triazol-5-ylamino) methyl)-4,6-dichlorophenol (IC87201) and 4-(3,5-dichloro-2-hydroxy-benzylamino)-2-hydroxybenzoic acid (ZL006) protected against synapse loss with partial protection against reduced neurite outgrowth. Furthermore, L-AAA delivery to the pre-limbic cortex (PLC) of mice was found to increase dendritic spine density and treatment with ZL006 reduced this effect. In summary, L-AAA-induced astrocyte impairment leads to a loss of neuronal complexity and synapse loss in vitro and increased dendritic spine density in vivo that may be reversed by inhibitors of the NMDA-R/PSD-95/NOS pathway. The results have implications for understanding astrocytic-neuronal interaction and the search for drug candidates that may provide therapeutic approaches for brain disorders associated with astrocytic histopathology.

Direct detection of Pneumocysytis carinii in outdoor air: preliminary results of a field study

P. carinii causes pneumonia in immunocompromised patients. New studies are suggestive of the de novo infections. Although P. carinii is believed to be ubiquitous it has not been detected directly from outdoor air. Therefore, outdoor air samples (n = 20) of 5 m3 were collected onto gelatin filters (pore size: 3 microns) on a cemetery using a suction pump (Sartorius MD8). Five samples were silver-stained, five samples were stained with an indirect immunfluorescence test kit, the remaining ten samples were stained with the combinations of the two individual stains. In a total of 100 m3 outdoor air one cyst resembling P. carinii was detected by the methenamine silver stain. Other cells not resembling P. carinii were found with a silver stained cell wall and positive fluorescence. The natural reservoir of P. carinii remains unknown. The indirect immunfluoresence which is common in the clinical laboratory is probably not specific enough for environmental samples.

Genotoxic activity of important nitrobenzenes and nitroanilines in the Ames test and their structure-activity relationship

The most important commercially available nitro- and aminobenzenes and the explosive trinitrobenzene were tested for mutagenicity in the Salmonella typhymurium TA 98 and TA 100 both in the absence and presence of S 9. Ten of the 14 compounds tested (71%) were mutagenic. All the substances showed positive results in TA 98 and 4 substances were also mutagenic in TA 100. The three diaminobenzenes and 4-nitroaniline were mutagenic only with metabolic activation. All other compounds did not require the addition of S 9. Only nitrobenzene, 1,2-dinitrobenzene, aniline and 2-nitroaniline were negative in both strains. In summary, all substances that are derived from nitrobenzene or aniline by addition of a nitro group in the meta- or para-position were mutagenic, whereas nitrobenzene and aniline themselves and their ortho-derivates were nonmutagenic. The possible relationships between the position of the substituents and the mutagenicity are discussed.

Gait characteristics in multiple sclerosis: progressive changes and effects of exercise on parameters

This study determines the characteristics of the multiple sclerosis gait, identifies the progressive gait changes associated with this degenerative disease, and determines the effects of an aquatic exercise program on gait parameters. Eleven patients with multiple sclerosis volunteered to participate and were filmed three times during a 10 week period with a Locam camera at 100 frames/s. During the testing period, subjects participated in an aquatic exercise program. In addition, they were rated according to the Kurtzke Scale for Evaluating Disability in Multiple Sclerosis. Results indicated that these patients with MS have shorter stride lengths, slower free speed walking rates, and higher cadence than do persons without MS. Knee and ankle joint rotation were characterized by lower than normal excursion with less vertical lift of the center of gravity and greater trunk lean than normal. Significant correlations between the Kurtzke Scale and gait parameters were indicated for step length and hip and ankle joint excursion. The aquatic exercise program appeared to have had no effect on the studied gait parameters.