Intravenous salbutamol caused significant increases in plasma insulin and glucose levels and a fall in serum potassium concentration in addition to tachycardia and tremor, whereas aerosol salbutamol produced only a small transient increase in the plasma glucose level. The initially raised non-esterified fatty acid levels decreased significantly after aerosol and placebo but not after intravenous salbutamol. The use of implantable neural prostheses activated by radiofrequency transmission requires that the materials in the device and the stimulation techniques are not injurious to neural tissue, particularly the neurons.
In this report, we discuss our experiences in the search for safe stimulation techniques. Acute and chronic experiments have been performed to evaluate electrode design and materials and to observe the effects of various stimulus protocols on the blood-brain barrier and brain. Neural tissue underlying the stimulated and control electrodes has been examined with both light and electron microscopy. Observations up to the present time indicate that the charge per phase is the most relevant stimulus parameter although the importance of charge density and current density cannot be underestimated.
Stimulation of the cat striate cortex with polished 1 mm2 gold, platinum, rhodium or carbon electrodes for 40h, at 50 Hz, and 0.5 msec duration, results in tissue damage at current densities of 0.6 A/cm2. In vitro gold and platinum corroded after 1,500-2,300 h of testing in simulated cerebrospinal fluid. The materials utilized are not suitable for long-term chronic electrodes for neural prosthetics.
In a previous study, the labeling pattern of three proteins (alpha, beta and gamma) in goldfish brain was found to change after the animals successfully acquired a new pattern of behavior. In the present study, these proteins were isolated from the brain cytoplasmic fraction, purified by successive gel electrophoresis and used as antigent to immunize rabbits. Antisera containing antibodies to two of the proteins (beta and gamma) were obtained. These gave single precipitin bands when plated against the antigens and a mixture of the total cytoplasmic proteins. The distribution of beta and gamma in brain subcellular fractions and in a variety of goldfish tissues was determined by immunodiffusion methods. The beta protein cross-reacted but was not identical to a widely distributed substance in plasma, liver and kidney.
Both beta and gamma appear to be species specific in that no cross-reactivity was obtained with mouse, chick or rat brain proteins. Immunological methods, in combination with double labeling experiments were used to establish that the beta and gamma antigens were proteins which were normally present in goldfish brain. Both the beta and gamma antisera were equally capable of specifically precipitating the proteins which were differentially labeled after training as well as purified proteins of the same molecular weight present in the brains of control animals.
These results suggest that the acquisition of a new pattern of behavior can increase the demand for the synthesis of specific proteins (beta and gamma) normally present in goldfish brain. Fluorescent antibody was prepared against a temperate-soil isolate of Beijerinckia obtained from a rhizosphere of rice growing in Camargue (France).
The antibody did not cross-react with any of 6 species of Azotobacter, 4 species of Beijerinckia, or 44 unidentified soil bacteria isolated from a spectrum of rhizospheres, but strongly stained the homologous Beijerinckia isolate. The isolate grew well in autoclave Camargue soil, but increased in numbers only slightly in nonsterile soil during 9 days.
Preliminary examination of rice plants grown in the laboratory in soil from which the Beijerinckia was originally isolated did not show detectable Beijerinckia in the rhizosphere. The fluorescent antibody was sufficiently sensitive and specific to permit more extensive study of Beijerinckia in relation to nitrogen fixation in the rhizospher of rice.
Extracorporeal circulation during open-heart surgery may damage cellular and humoral factors in the blood. Phagocytic functions of circulating polymorphonuclear leukocytes were investigated in 10 patients 1 day before, then 1 hour, 2, 4 and 10 days after open-heart surgery. Transient diminutions in the phagocytic capacity of polymorphs was found for Staphylococcus aureus and Escherichia coli in one patient, and E. A positive correlation was found between the duration of extracorporeal circulation and the transient diminutions in phagocytic capacity for these three patients.