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Biomedical subjects

J B Justice

Publications and source records attributed to J B Justice.

100 records · Page 6Linked to original sources
PubMed1983

Model studies for brain dialysis.

A dialysis cannula suitable for perfusing deep brain structures in animals is described and characterized in a series of model experiments. The effects of flow rate, concentration, variations in cannula construction, barriers to diffusion and pumping technique on the recovery of tryptophan from aqueous solutions at 37 degrees C were examined. The 200 micron diameter dialysis cannula gave good recoveries which varied from about 8% at 6 microliter/min to almost 90% at 0.15 microliter/min. Prepurification of the extracellular fluid by dialysis allows the sample loop of a high performance liquid chromatograph to be incorporated in the outflow line of the cannula for direct injection of dialysates.

Animals↗
PubMed1982

Behavioral observation and intracerebral electrochemical recording following administration of amphetamine in rats.

Intracerebral electrochemistry (chronoamperometry) was performed on rats that were administered 1, 4, and 8 mg/kg doses of amphetamine. Graphpoxy working electrodes were implanted bilaterally in nucleus accumbens (ACC) and ventral anterior stratum (VAS). Following drug injection, locomotor and stereotyped behaviors were observed. Intracerebral electrochemical signals reliably increased following injection of amphetamine. The magnitude of these increases did not change significantly across the dose range tested for VAS electrodes. ACC electrodes had increases similar in magnitude to VAS electrodes at 1 and 4 mg/kg. At 8 mg/kg increases obtained from ACC electrodes were significantly lower than those recorded from VAS. Onset of the change in electrochemical signal paralleled the onset of activity or stereotypy but the subsequent declines in signal and behavior were only loosely correlated. At the 4 mg/kg dose, the magnitude of signal increase from striatum was negatively correlated with indices of stereotypy and positively correlated with locomotor counts.

Amphetamine↗
PubMed1981

Gas chromatographic-mass spectrometric determination of glutamic acid decarboxylase activity in subregions of rat brain.

A quantitative gas chromatographic--mass spectrometric method has been developed for the determination of glutamic acid decarboxylase (GAD) activity in subregions of rat brain. The five subregions analyzed, weighing approximately 2.51 mg each, were globus pallidus, entopeduncular nucleus, ventromedial thalamus, and substantia nigra medical and lateral. The activity of the GAD enzyme has been determined indirectly by measurement of gamma-aminobutyric acid (GABA) using gamma-[2,2-2H2] aminobutyric acid as the internal standard. Both compounds were quantitatively converted to trimethylsilyl-GABA and trimethylsilyl-[2H2]GABA in 90 min with hexamethylchlorosilane, trimethylchlorosilane, pyridine and N,O-bis(trimethylsilyl)trifluoroacetamide silylating agents. Using selective ion monitoring and electron impact ionization at 70 eV, the limit of detection was 15 ng GABA per mg tissue. This method is compared with a fluorimetric procedure.

Animals↗
PubMed1981

Determination of dopamine, homovanillic acid and 3,4-dihydroxyphenylacetic acid in rat brain striatum by high-performance liquid chromatography with electrochemical detection.

Two procedures using liquid chromatography with electrochemical detection are described for the determination of dopamine (DA) and its two acidic metabolites, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC), in subregions of rat striatum and nucleus accumbens. A strong cation-exchange column was used for DA analysis and a C18 reversed-phase column was used for the analysis of the metabolites. Effects of pH, temperature and percentage of methanol on the retention time of HVA and DOPAC were studied. Levels of these compounds in the subregions of rat stratum and nucleus accumbens are reported.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1980

Gas chromatographic-mass spectrometric determination of dopamine in subregions of rat brain.

A quantitative gas chromatographic-mass spectrometric assay was developed for the determination of dopamine in subregions of rat brain. Five tissue punches weighing approximately 1.7 mg each were taken from the nucleus accumbens and four neostriatal regions differing in anterior-posterior level. The dopamine extracted from the tissue was treated with pentafluoropropionic anhydride (PFP) and quantitatively formed dopamine-(PFP)3. The derivatizing procedure took 15 min and the retention time for dopamine-(PFP)3 and its deuterated analogue [1,1,2,2-2H4]dopamine-(PFP)3) was 120 sec. Selective ion monitoring was utilized to monitor the gas chromatographic effluent. Ions were generated by electron impact ionization. The assay was able to measure concentrations of 1 nanogram dopamine per milligram protein. An anterior-posterior gradient of dopamine was observed in the striatum. This assay should be useful in studies examining the effects of experimental manipulations on dopamine content in relatively small areas of brain tissue.

Animals↗
PubMed1980

An automated electrochemical method for in vivo monitoring of catecholamine release.

A computer-controlled electrochemical system for the in vivo monitoring of catecholamines and their metabolites is described. The system is composed of a microcomputer, real time interface board, and a commercial electrochemical instrument. The method and theory of the electrochemical technique are explained and details concerning the construction of the electrodes are given. Descriptions of the hardware and software are also provided. Experimental results are presented to demonstrate the use of the system for long-term in vivo monitoring and for detecting the change in the level of oxidizable species after amphetamine administration.

Animals↗
PubMed1978

A Fujita--Ban structure--activity analysis of 44 steroids.

A Fujita--Ban structure--activity analysis has been performed on 44 steroids with a common pregn-4-ene-3,20-dione structure. The measured biological activity was glycogen deposition in the liver, expressed relative to the activity of cortisol. Substituents are at positions 2, 6, 9alpha, 11beta, 16alpha, 17, and 21. Substituents of positions 2, 6, and 17 accounted for 60% of the total variance. The substituents with significance at the p less than 0.01 level were 6alpha-hydrogen, 6alpha-methyl, 2alpha-hydrogen, 9alpha-fluorine, and 9alpha-hydrogen.

Animals↗