scholarly journals The Effect of the GABA-A Agonist THIP on Regional Cortical Blood Flow in Humans. A New Test of Hemispheric Dominance

1988 ◽  
Vol 8 (3) ◽  
pp. 314-323 ◽  
Author(s):  
Per E. Roland ◽  
Lars Friberg
Keyword(s):  
Internal Carotid ◽  
Water Soluble ◽  
Aminobutyric Acid ◽  
Hemispheric Dominance ◽  
Synaptic Inhibition ◽  
Postsynaptic Inhibition ◽  
Gaba A ◽  
Baseline Levels ◽  
Superior Frontal Cortex

We studied the effect of a γ-aminobutyric acid (GABA)–A receptor–induced postsynaptic inhibition on regional CBF (rCBF) in awake humans. For this purpose we used a new specific GABA–A agonist, 4,5,6,7-tetrahydroisoxazolo(5,4)-pyridin-3-ol (THIP). As part of a new diagnostic procedure for the determination of which hemisphere subserved language, THIP was infused into the internal carotid artery 20 s before measurement of the rCBF. Administered by this route the THIP is distributed to the neocortex and neostriatum. THIP induced a dosage-dependent decrease of the rCBF. The rCBF decrease was not due to any direct effect on the cerebral vessels. The efficiency of the THIP-induced postsynaptic inhibition was tested by having the subjects voluntarily activate the inhibited cortex. During submaximal inhibition the subjects were able voluntarily to counteract decreases of rCBF in superior frontal cortex and motor cortex. Larger doses of THIP abolished this response and depressed the rCBF to baseline levels (20 ml/100 g/min). This was associated with 10-min total depression of function of the anterior two-thirds of the injected hemisphere. An analysis of the changes of rCBF in activated and nonactivated cortex—with and without THIP-induced inhibition—showed that it would be very unlikely that average increases in synaptic inhibition would increase rCBF in neocortical areas. Intracarotid injection of the water-soluble, nonirritative THIP is a very useful alternative to sodium amytal injection for determination of hemispheric dominance.

Studies on the Fibrinolytic System in Human Plasma: Quantitative Determination of Plasminogen Activators and Proactivators

1979 ◽  
Vol 41 (02) ◽  
pp. 365-383 ◽  
Author(s):  
C Kluft
Keyword(s):  
Pilot Study ◽  
Plasma Level ◽  
Human Plasma ◽  
Plasminogen Activators ◽  
Venous Occlusion ◽  
Quantitative Information ◽  
Optimal Recovery ◽  
Dextran Sulphate ◽  
Baseline Levels

SummaryEffects due to plasma plasminogen activators and proactivators are usually studied in assay systems where inhibitors influence the activity and where the degree of activation of proactivators is unknown. Quantitative information on activator and proactivator levels in plasma is therefore not availableStudies on the precipitating and activating properties of dextran sulphate in euglobulin fractionation presented in this paper resulted in the preparation of a fraction in which there was optimal recovery and optimal activation of a number of plasminogen activators and proactivators from human plasma. The quantitative assay of these activators on plasminogen-rich fibrin plates required the addition of flufenamate to eliminate inhibitors. The response on the fibrin plates (lysed zones) could be coverted to arbitrary blood activator units (BAU). Consequently, a new activator assay which enables one to quantitatively determine the plasma level of plasminogen activators and proactivators together is introduced.Two different contributions could be distinguished: an activity originating from extrinsic activator and one originating from intrinsic proactivators. The former could be assayed separately by means of its resistance to inhibition by Cl-inactivator. Considering the relative concentrations of extrinsic and intrinsic activators, an impression of the pattern of activator content in plasma was gained. In morning plasma with baseline levels of fibrinolysis, the amount of extrinsic activator was negligible as compared to the level of potentially active intrinsic activators. Consequently, the new assay nearly exclusively determines the level of intrinsic activators in morning plasma. A pilot study gave a fairly stable level of 100 ± 15 BAU/ml (n = 50). When fibrinolysis was stimulated by venous occlusion (15 min), the amount of extrinsic activator was greatly increased, reaching a total activator level of 249 ± 27 BAU/ml (n = 7).

Simultaneous Spectrophotometric Determination of Salbutamol by Coupling with Diazotized 4-Aminobenzoic acid

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Hind Hadi ◽  
Gufran Salim
Keyword(s):  
Pharmaceutical Preparations ◽  
Coupling Reaction ◽  
Dosage Forms ◽  
Water Soluble ◽  
Trace Determination ◽  
Aminobenzoic Acid ◽  
Optimum Conditions ◽  
Colored Product ◽  
Versus Concentration

A simple, rapid and sensitive spectrophotmetric method for trace determination of salbutamol (SAL) in aqueous solution and in pharmaceutical preparations is described. The method is based on the diazotization coupling reaction of the intended compound with 4-amino benzoic acid (ABA) in alkaline medium to form an intense orange, water soluble dye that is stable and shows maximum absorption at 410 nm. A graph of absorbance versus concentration indicates that Beer’s law is obeyed over the concentration range of 0.5-30 ppm, with a molar absorbtivity 3.76×104 L.mol-1 .cm-1 depending on the concentration of SAL. The optimum conditions and stability of the colored product have been investigated and the method was applied successfully to the determination of SAL in dosage forms.

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