Extracorporeal Perfusion System Research Articles

The emigration of lymphocytes from Peyer's patches in sheep.

The magnitude of the output of lymphocytes from Peyer's patches (PP), the morphology of the lymphocytes and their route of exit from PP has been examined in sheep. An extracorporeal perfusion system was used to selectively label a 3-4 m length of the terminal ileum of lambs at 6-10 weeks of age (the mesenteric lymph nodes had previously been excised from most lambs). This part of the intestine contains about 80% of the total PP tissue in a lamb and most of the lymphoid cells in the perfused tissue were within the PP. During a 10 min labeling period, fluorescein isothiocyanate (FITC) was added to the perfusate to label all the cells in the perfused tissues and [3H]thymidine [(3H]dThd) was added at the same time to label only those cells in the S-phase of the cell cycle. The unincorporated label was then washed from the perfused tissues, the normal blood circulation was reestablished and the lamb allowed to recover from anesthesia. It was established that the labeling was restricted to the perfused tissue and therefore that any labeled cells subsequently found elsewhere in the animal must have emigrated from the terminal ileum. During the 24 h after perfusion 1.4 X 10(9)-3.9 X 10(9) lymphoid cells (i.e. FITC labeled) left the perfused tissues via the lymph; 12-19% of these cells were either in the process of dividing or less than 24 h old (i.e. [3H] dThd labeled). The majority of the labeled cells probably came from the PP and most were classified as small lymphocytes although the [3H] dThd labeled population included a high proportion of large lymphocyte and lymphoblasts especially during the early hours after the perfusion. The labeled lymphocytes entered the blood in substantial numbers which increased linearly with time so that by 24 h about 7% of the lymphocytes in the blood were fluorescent. The numbers of newly produced cells began to increase rapidly in the blood only during the 12 h to 24 h period. The number of labeled cells in the blood was reduced by about 95% when the lymph from the perfused tissues was drained from the lamb during the experiment. This result provides clear evidence that the vast majority of all of the cells that leave the PP do so via the lymph and not via the blood.

In Situ Labelling of Bone Marrow Lymphocytes with Fluorescein Isothiocyanate for Lymphocyte Migration Studies in Pigs

In normal young pigs, the femoral artery and vein were cannulated and after occluding other vessels to one hind leg they were connected to an extracorporeal perfusion system. Fluorescein isothiocyanate (FITC) was added to the perfusate to selectively label cells in the bone marrow. Large numbers (approximately 0.9 X 10(9] of labelled lymphocytes left the bone marrow of one leg within 1 d and migrated via the blood to the bone marrow in other bones, lymph nodes, spleen, Peyer's patches and even into the thymus. On average 1.7% of the lymphocytes in the blood and about 1% within the spleen were labelled. Peyer's patches and the thymus showed very low indices. Thus the bone marrow is an integral part of the migratory route of lymphocytes. Selective labelling of bone marrow cells in their normal microenvironment with FITC is a suitable method for studies of cell migration from the bone marrow.

Selective labelling of lymphoid tissues by extracorporeal perfusion

A method for selective labelling of lymphoid tissues by means of an extracorporeal perfusion system is described. The applicability of this technique was tested by local labelling of a part of the small intestine with its mesenteric lymph nodes, spleen and bone marrow in normal young pigs. Tritiated thymidine was added to the perfusate and the selectivity of the labelling procedure tested by scintillation counting of serum samples, of specimens of lymphoid tissues and by autoradiography. There was only negligible spillover of the isotope and the perfused organs were well preserved.

Hormone secretion and glucose metabolism in islets of Langerhans of the isolated perfused pancreas from normal and streptozotocin diabetic rats.

The glucose responsiveness of alpha- and beta-cells of normal as well as untreated and insulin-treated streptozotocin diabetic rats was tested in the extracorporeal perfusion system. Also assessed was the possible in vitro effect of added insulin on the glucose sensitivity of islets from untreated diabetic animals. Insulin and glucose responsiveness of the two cell types. The rate of glucose entry islet tissue was estimated, and the effect of glucose on the tissue supply of ATP and lactate and the cyclic 3':5'-AMP level of islets was measured under the above in vitro conditions. It was demonstrated that beta-cells are more accessible to glucose than alpha-cells, that glucose entry into islet cells is not significantly modified by insulin and that glucose had no effect on ATP, lactate and cyclic 3':5'-AMP levels of islet tissue under any of the conditions investigated. High insulin in vitro elevated ATP levels of alpha-cell islets independent of extracellular glucose. Glucose caused insulin release from normal but not from diabetic islets and rapidly and efficiently suppressed stimulated glucagon secretion of the pancreas from normal and insulin treated diabetic rats. Glucose was less effective in inhibiting stimulated glucagon secretion by the pancreas from untreated diabetic rats whether insulin was added to the perfusion media or not. Therefore, profound differences of glucose responsiveness of alpha-cells fail to manifest themselves in alterations of basic parameters of glucose and energy metabolism in contrast to what had been postulated in the literature. It is however, apparent that the glucose responsiveness of alpha-cells is modified by insuling by an as yet undefined mechanism.

Formation of cerebrospinal fluid. Relation of studies of isolated choroid plexus to the standing gradient hypothesis.

After a brief summary of current views on the origin of cerebrospinal fluid (CSF) and the processes underlying its elaboration, the author discusses studies of isolated choroid plexus in extracorporeal perfusion systems and flux chambers. The results suggest that transependymal water flow is secondary to the electrically silent pumping of sodium. The author presents evidence in support of the standing gradient hypothesis as the structural basis of CSF secretion.

Cardiopulmonary Bypass

None of the extracorporeal perfusion systems equals the perfection of the human heart and lung. Therefore, physiological changes occur during and after surgery which may affect the patient's postoperative course and treatment. There are significant changes in the patient's clotting mechanism. This occurs, in part, because the patient is heparinized before he is placed on the pump-oxygenator. Heparinization prevents the clotting of blood in the extracorporeal circuit. Also, fresh, heparinized blood is used to replace blood loss as well as to prime the pump-oxygenator, although many institutions now use non-blood solutions for priming. After surgery is completed, the is neutralized by administration of protamine sulfate. However, is metabolized approximately half as fast as protamine. Therefore, reversal of anticoagulation is often imperfect, resulting in a heparin rebound effect which requires the administration of additional protamine( 1,2). Other changes in the patient's clotting mechanism are due to the mechanical trauma to blood cells by the pump and suction systems. Platelets are damaged and decreased, as are some of the plasma clotting factors (prothrombin and fibrinogen). Hemolysis of red blood cells occurs because of mechanical trauma and the direct exposure of blood to oxygen. Red blood cells may be hemolyzed more rapidly than the liver and kidneys can metabolize and excrete the damaged cells. If significant hemolysis occurs, a mannitolinduced diuresis is usually effective, but sludging in the renal tubules may lead to acute tubular necrosis and renal failure.

Platelet aggregate emboli produced in patients during cardiopulmonary bypass with membrane and bubble oxygenators and blood filters

The number, size, and site of formation of particulate emboli produced by three different extracorporeal perfusion systems were studied in three groups of 10 patients each. Systems that contained a bubble oxygenator and stainless steel filter (400 μ pores), a bubble oxygenator and stratified polyester urethan filter (27 μ pores in final filtration), and a spiral-coil membrane oxygenator and stratified polyester urethan filter were compared. The membrane oxygenator produced fewer emboli than did the bubble oxygenator, but the venous reservoir of the membrane oxygenator produced more emboli than did the reservoir used with the bubble oxygenator. The total number of platelet aggregate emboli produced by the two oxygenator systems did not differ. The stainless steel filter did not remove or generate platelet aggregate emboli. The stratified polyester urethan filter removed 90 per cent of emboli greater than 150 μ and 60 per cent of emboli between 50 and 150 μ in diameter but often produced emboli less than 50 μ in diameter. The perfusion systems studied did not produce significant differences in platelet counts, fibrinogen, and fibrin split product concentrations during and up to 24 hours after bypass.

Potassium transport across the choroidal ependyma

The transependymal flux of K + was studied in an extracorporeal perfusion system utilizing sheep choroid plexus. The movement of K + from blood to CSF appeared to be compatible with a Na-K pump in choroid plexus which saturated at a blood level of 3.3 meq/Kg and was adversely affected by ouabain (10 −5M) in CSF or blood. The movement of K + from CSF appeared to be by a diffusionary process which was insensitive to ouabain. These results suggest that the homeostasis of CSF K + is in part due to a Na-K pump at the blood-CSF barrier (choroid plexus).

Measurement of emboli in extracorporeal perfusion systems

Measurement of emboli in extracorporeal perfusion systems

Extracorporeal perfusion of dog and monkey brain during circulatory arrest

<h2>Abstract</h2> Cerebral viability (as evidenced by the persistence of EEG activity) has been maintained <i>in situ</i> for many hours by utilizing simplified extracorporeal (pump-oxygenator) perfusion systems to provide cephalo-cerebral circulation, in cardiac-arrested canine and monkey preparations. Additional studies using unicarotid mechanical perfusion and EEG monitoring demonstrated the limitations at present characterizing the pumping elements utilized in isolated cerebral perfusion.

Preparation and mechanical perfusion of the isolated monkey brain.

ABSTRACT An isolated monkey brain model viably sustained by a mechanical extracorporeal perfusion system employing Dextran diluted subhuman primate blood has been developed. Each isolated brain is instrumented for continuously monitoring electrical activity (depth and cortical), ventricular pressure as well as intracerebral temperature and arterial (Circle of Willis) pressure. Employing EEG criteria the isolated brain approaches during the initial 60 to 90 minutes of perfusion the neurophysiological and metabolic performance of the intact brain. After the second hour of perfusion these preparations demonstrate accelerating electrical failure with an associated rise in excess lactate and a topographical cortical appearance consistent with developing cerebral oedema. The solutions to problems of surgical isolation of the brain and design of extracorporeal perfusion support systems for this delicate organ as well as the performance of the isolated monkey brain are reviewed.

Effects of shock and anoxia on nucleotides and creatine phosphate in the isolated brain of the dog.

AbstractSurgically isolated canine brains were maintained with compatible donor blood from an extracorporeal perfusion system. Small samples of frozen cerebral cortex were removed with a newly‐developed Freon cryoprobe and were analysed for acid‐soluble nucleotides, creatine phosphate and inorganic phosphate. Most animals were in the early stages of shock unless they had received preoperative α‐adrenergic blockade with phenoxybenzamine hydrochloride (Dibenzyline). Values for high‐energy phosphates were in the normal range only when the animal had been premedicated with phenoxybenzamine hydrochloride. During a 4‐min period of anoxia (induced by blood which had been equilibrated with 95% N2 and 5% CO2), the cerebral cortex rapidly became iso‐electric, and the levels of creatine phosphate and ATP decreased concomitantly with increases in levels of ADP and Pi. These electrical and chemical changes were rapidly and completely reversed by reoxygenation. The levels of high‐energy phosphates provide a sensitive criterion of functional adequacy that may be more readily quantitated than cerebral electrical activity (EEG). EEG recovery did not correlate closely with rephosphorylation.

Renal excretion of bilirubin by the rat.

ARTICLESRenal excretion of bilirubin by the ratMA Ali, and BH BillingMA Ali, and BH BillingPublished Online:01 Jun 1968https://doi.org/10.1152/ajplegacy.1968.214.6.1340MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByBilirubin Metabolism and Jaundice23 October 2017Bilirubin Metabolism and Jaundice31 October 2011Alginate-encapsulated Human Hepatoblastoma Cells in an Extracorporeal Perfusion System Improve Some Systemic Parameters of Liver Failure in a Xenogeneic ModelArtificial Organs, Vol. 28, No. 5Renal failure complicating obstructive jaundiceThe American Journal of Surgery, Vol. 157, No. 2Renal handling of bilirubin photoderivativesExperientia, Vol. 43, No. 8Bilirubin metalbolism in cholestasisMolecular Aspects of Medicine, Vol. 9, No. 5Kidney function in the severely jaundiced dogThe American Journal of Surgery, Vol. 140, No. 3 More from this issue > Volume 214Issue 6June 1968Pages 1340-1345 Copyright & PermissionsCopyright © 1968 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1968.214.6.1340PubMed5649489History Published online 1 June 1968 Published in print 1 June 1968 Metrics

Technique Has Advantages Of Hypothermia, Perfusion

Functional renal homografts have been obtained as long as 14 hours postmortem by the medical group working with transplantation procedures at the University of Colorado School of Medicine and the Denver VA Hospital. The technique they use incorporates the advantages of both hypothermia and perfusion. In addition to two cadaveric renal transplantations, the four liver transplantations performed recently by the group afforded an opportunity for clinical application of the technique. In earlier experimental trials, dogs were sacrificed after aortic and inferior vena caval catheters had been inserted through the femoral artery and vein. The catheters were connected to an extracorporeal perfusion system consisting of a disposable bubble oxygenator, a single DeBakey pump, and a heat exchanger. Venous outflow was by gravity drainage. The oxygenator was primed with lactated Ringer's solution in all experiments except two hepatic transplants in which 5% dextrose in water was used. The perfusate was precooled to