Transient hypercapnia reveals an underlying cerebrovascular pathology in a murine model for HIV-1 associated neuroinflammation: role of NO-cGMP signaling and normalization by inhibition of cyclic nucleotide phosphodiesterase-5.
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In vivo myocardial cell pH in the dog. Response to ischemia and infusion of alkali.
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Myocardial cell pH has been measured with 5,5-dimethyl-2,4-oxazolidinedione (DMO) in intact anesthetized dogs by a transient indicator dilution technique. Bolus injections of labeled DMO, vascular, extracellular, and water indicators were made into the anterior descending coronary artery, and blood samples were collected from the great cardiac vein. The steady-state distribution of DMO between cells and plasma was calculated from the indicator mean transit times, and the plasma pH. Myocardial cell pH was determined from the distribution value and plasma pH. Normal myocardial cell pH averaged 6.94. Changes in myocardial cell pH after infusions of acid or alkali. Myocardial ischemia induced by inflation of a coronary artery balloon resulted in progressive decreases in cellular pH to average values of 6.83 within the initial 15 min and to 6.59 within the interval between 20 and 70 min. Infusions of Na2CO3 tended to diminish intracellular acidosis although these infusions had little effect on the difference in pH between the myocardial cell and extracellular fluid. (+info)
Validation of a novel and existing algorithms for the estimation of pulse transit time: advancing the accuracy in pulse wave velocity measurement.
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Dependency of transcoronary circulatory transport function on coronary perfusion pressure and flow.
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Transcoronary circulatory transport function was computed from the dye-dilution curves recorded simultaneously at the entrance (aortic root) and exit (coronary sinus) of the coronary circulation after the injection of dye bolus into the femoral vein in open-chest dog. The effect of coronary perfusion pressure and flow on the first (delta-t) and second (deltapi2) moments of the transport function was examined before and during intra-aortic angiotensin infusion. It was observed that the relative dispersion (deltapi2 1/2/delta-t) in the canine coronary circulation is the largest among the organ-circulations that have been examined by the investigators, suggesting that cardiac wall is highly heterogeneously perfused, and that the relative dispersion was variable depending on the coronary perfusion pressure and flow. It is concluded that sole measurement of the moment of transcoronary transport function such as -t cannot be a reliable indicator of the coronary circulatory disturbances. The underlying mechanisms for the dependency of the relative dispersion on the perfusion was discussed. (+info)
Limitations of circulation time in the diagnosis of intracranial disease.
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The mode circulation time was measured using intravenously injected technetium 99(m) and a collimation system devised to discriminate between the right and left sides of the head. The results in 21 normal men were used as a basis of assessing the findings in 205 patients, made up of five diagnostic groups (ischaemia, haematoma, subarachnoid haemorrhage, intracranial tumour, and head injury). The average mode circulation time in the affected hemisphere for the three groups with vascular disease was increased, but even in these groups half the patients had a mode circulation time within 1 SD of normal mean; similar results were found for asymmetry between the hemispheres. In serial measurements in 45 patients no correlation was found between change in mode circulation time and the clinical state. That so many results are within the normal range limits the value of this method. (+info)
Aglycosylantibody. Effects of exoglycosidase treatments on autochthonous antibody survival time in the circulation.
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Rabbit anti-hapten antibodies were purified by affinity chromatography and characterized immunochemical for in vivo studies of their blood clearance rate and organ distribution after treatment with various glycosidases. Following sequential removal of sialic acid, galactose, and N-acetylglucosamine with the appropriate cellulose-immobilized exoglycosidases, the antibody populations were recharacterized, radiolabeled, and introduced intravenously into the original animals. Using double radioiodine lables it was possible to demonstrate alterations in purified antibody survival times in the circulation and altered organ distribution after glycolytic cleavage. Removal of terminal sialic acid resulted in rapid blood clearance and enhanced localization of asialoantibody in the liver. Subsequent removal of penultimate galactose residues returned both antibody survival time in the circulation and organ distribution to near normal. Removal of subpenultimate N-acetylglucosamine moieties resulted in aglycosylantibody survival values which were intermediate between asialo- and asialoagalactoantibodies. Removal of the three saccharide also increased kidney localization. The results are evaluated based on current concepts of the biological roles of protein-linked carbohydrate and plasma glycoprotein survival time in the circulation. (+info)