Structural modeling of functional neural pathways mapped with 2-deoxyglucose: effects of acoustic startle habituation on the auditory system

This paper describes the first application of structural modeling to neuroscience. Structural modeling (also known as path analysis) is a method to assess the relative impact of directional links in a system and how these interrelations may change under different conditions. The objective was to demonstrate how structural modeling can be used to determine the functional interrelationships between brain structures that form the auditory system. Using structural modeling, changes in auditory system 2-DG uptake were examined during long- and short-term habituation of the acoustic startle reflex. Models were based on the anatomical connections between central auditory system structures. Using functional 2-DG data, the correlations between these structures were calculated and numerical weights were computed for each anatomical link. The analysis revealed that the lemniscal path was dominant during short-term habituation, while during long-term habituation this influence was modified through extra-lemniscal pathways. The models are discussed in the context of previous findings to demonstrate how structural modeling can not only complement, but also extract more information from 2-DG mapping experiments.     

Activation-induced changes in evoked and slow brain potentials: effect of cocaine in rabbits previously subchronically treated by cocaine

To study the type of adaptive modification (tolerance vs. sensitization) in different organism's indices following intermittent cocaine (COC) administrations, acute COC (2 mg/kg, SC)-induced changes in heart and breathing rate, response to increasing noxious stimulation, spontaneous EEG and event-related evoked and slow brain potentials (ERP) registered from the occipital cortex and hippocampal CA1 region were investigated in naive rabbits and one subchronically treated with COC (6 injections at a same dose). Tolerance developed for bradycardia, depression of noxious responsiveness, cortical desynchronization and increase of main components of cortical ERP, typical to acute COC, while the changes in breathing and hippocampal ERP were stable. These changes as well as a significant increase due to COC administrations of the basal values of an animal's noxious responsiveness and increase in relative changes in main component of cortical ERP (N205) are considered as a consequence of adaptive changes in neurophysiological/neurochemical substrate accepting COC action and mediating phenomena tolerance-sensitization and dependence typical to the drug.     

Gas chromatographic analysis of the metabolic products of anaerobic bacteria. 2. Clostridia]

Qualitative and quantitative characteristics of clostridial metabolites (short-chain carbonic acids and alcohols) were analyzed in associations of these bacteria with facultative anaerobes. Various bacterial groups were found to vary as regarded the composition and quantitative ratio of the major bacterial metabolites. These data may become the criteria for the indication of pathogenic clostridia in mixed cultures after anaerobic passages for 24-48 h at 37 degrees in a medium with 1% glucose.     

Isolation and characterization of a distinct immunoregulatory isoform of alpha-fetoprotein produced by the normal fetus

In this report, we examine the functional significance of the molecular microheterogeneity of alpha-fetoprotein (AFP). In doing so, we have taken the direct approach of purifying the naturally occurring isomeric forms of fetal-derived AFP using a preparative anion exchange column linked to an automated fast protein liquid chromatography (FPLC) system followed by parallel testing of each isolated molecular variant for in vitro immunoregulatory activity. The data obtained demonstrate the presence of seven distinct variants of AFP as defined by their retention volumes on FPLC elution profiles, by their pIs on analytical IEF gels, and by Western blot analysis. Molecular mass determination by SDS-PAGE showed each isomer to be equivalent in size to 69,000-dalton native unfractionated AFP molecules. All the immunosuppressive activity of AFP was localized to a single variant representing only 6% of the total composition of native AFP. The immunoregulating isomer termed AFP-1 was the least acidic of the seven isolated variants with a pI of 5.1 and displayed a sialic acid content of 1 mol/mol of protein. The inhibitory activity of AFP-1 could be readily measured on T cell-dependent antibody synthesis, Con A-induced stimulation of Lyt-1+23- thymocyte DNA synthesis, and lymphokine-activated NK cell activity. All other isomers were without effect in these test systems. The immunosuppressive AFP-1 isomer also displayed the strongest growth-promoting influence on cultured bone marrow lymphocytes. There was no correlation between functional activity and degree of expression of sialic acid residues on the AFP molecules. These findings demonstrate that the immunoregulating function of AFP is confined to a distinct and relatively small subpopulation of native AFP molecules and should therefore contribute to the resolution of outstanding questions regarding the structure/function relationship of this onco-fetal glycoprotein.     

Common forefoot deformities. How to treat, when to refer

Initial assessment of common forefoot deformities by the primary care physician is quite feasible. A thorough history, examination of the foot with the patient standing and seated, assessment of the patient's footwear, and radiographic evaluation can often lead to gratifying relief with use of simple office measures. Even in cases that require referral to an orthopedic surgeon, interim relief of symptoms and the patient's increased awareness of the problem and its cause enhance the patient's understanding and the final outcome as well.     

ITI endosteal hollow cylinder implant systems

The endosteal hollow cylinder implant systems have been in clinical use for over 10 years. These systems incorporate advanced sophisticated biomaterials and bioengineering design concepts such as the titanium plasma spray (TPS) surface coating as well as the cylindric shape. This shape has now introduced the third dimension to dental implantology. In previous systems, such as the blade-vent, only height and width were present. Therefore, these previous systems could not be used as single-tooth replacements; also, they were not able to withstand lateral forces or torquing. In a series of cases reported from Switzerland, Sweden, Germany, and the United States, 580 hollow cylinder implants were placed for up to 10 years with an overall rate of success of 95.3 per cent.