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At least 73 records · Page 4Linked to original sources

Demonstration of hemopoietic stem cells in the peripheral blood of baboons by cross circulation.

Baboons were given 1200 R total body irradiation from two opposing 60Co sources. Three animals were given supportive therapy only and died, as expected, within 8 days of irradiation with profound marrow hypoplasia. Five baboons were cross-circulated with unirradiated partners and died within 14 days with evidence suggestive of graft-versus-host disease. Their marrows were repopulated with hemopoietic precursor cells, and three of the five had rises in peripheral white blood cell counts to more than 1500/cu mm before death. These results are compatible with the presence of hemopoietic stem cells in the peripheral blood of a nonhuman primate, the baboon.

ABO Blood-Group System↗

Ventricular septal defect repair in a small dog using cross-circulation.

A haemodynamically significant ventricular septal defect was diagnosed in a 3-month-old male Cavalier King Charles Spaniel. A median sternotomy was performed and the 6.5 kg dog placed on cardiopulmonary bypass using pump-assisted cross-circulation. A 10 mm diameter peri-membranous ventricular septal defect was closed using a continuous suture of 4-0 polypropylene, via a 2.5 cm incision in the right ventricular outflow tract. The duration of cardiopulmonary bypass was 90 minutes. Complications in the immediate postoperative period were mild and easily managed.

Animals↗

Thyrotropin-releasing hormone-induced changes in electroencephalographic and vagal activity in the cross-circulated brain of the rat.

The effects of centrally administered thyrotropin-releasing hormone (TRH) on vagal efferent and cortical electroencephalographic (EEG) activity were assessed in rat brains which were functionally isolated from the body trunk and maintained via cross-circulation. Upon withdrawal of inputs from the trunk, cervical vagal activity was markedly attenuated. The decreased activity was partially restored by TRH with a latent period of a few minutes. On the other hand, TRH immediately but transiently augmented the fast waves of the EEG. The change in brain activity produced by TRH appears to simulate the state which makes possible the generation of vagal efferent activity even though inputs from the body trunk are withdrawn.

Animals↗

Efficacy of double filtration plasmapheretic cross-circulation using a high permeability membrane between totally hepatectomized dogs and donor pigs.

BACKGROUND: Major obstacles to develop a bioartificial liver are xenogeneic immune reactions and viral infection from donor pigs. To solve these problems, we studied the effect of xenogeneic double filtration plasmapheretic cross-circulation (DFPCC) using a high performance semipermeable membrane on totally hepatectomized dogs. METHODS: Mongrel dogs, weighing 12-15 kg, underwent total hepatectomy in one stage (n=18). One hr after total hepatectomy, the femoral vein and the jugular vein were cannulated in both dogs and pigs by using the blood access catheter tubes that were connected to the DFPCC system. In the DFPCC circuit, filtrated dog plasma and pig plasma counterflowed in a hollow fiber cartilage at a rate of 25 ml/min for 6 hr and met through a semipermeable membrane with 100 kd nominal molecular weight cut-off (n=5). In control dogs, the circuit was not connected to the pig (n=13). RESULTS: In vitro mass transfer study suggested that very little immunoglobulins crossed the semipermeable membrane. During and after 6 hr of DFPCC, anhepatic dogs had significantly lower blood ammonia and aromatic amino acid levels than did controls. DFPCC-treated dogs demonstrated decreased intracranial pressure and survived significantly longer than control dogs (20.75+/-3.80 hr vs. 14.75+/-1.30 hr, P<0.05). Histology showed no xenogeneic rejection in both dogs and pigs. CONCLUSIONS: Our DFPCC systems with a high permeability membrane demonstrated detoxification-function and contributed to intracranial decompression and longer animal survivals without adverse immune reaction and the possibility of zoonosis.

Animals↗

Pharmacological analysis of positive chrono- and inotropic responses to denopamine (TA-064) in dog cross-circulated atrial and ventricular preparations.

Positive chrono- and inotropic responses to denopamine (TA-064, (-)-(R)-1-(p-hydroxyphenyl)-2-[(3,4-dimethoxyphenethyl)amino]ethanol), a new and orally active cardiotonic agent, were investigated in the canine isolated right atrial or left ventricular preparation which was cross-circulated with blood from another support dog. Denopamine dose-dependently increased the sinus rate, right atrial and left ventricular contractile force. Denopamine was one to two orders of magnitude less potent than isoproterenol. The positive chrono- and inotropic effects of denopamine in isolated, blood-perfused right atria were dose-dependently inhibited by treatment with propranolol and atenolol. The effects of denopamine were only slightly attenuated by ICI 118,551 in doses which completely suppressed the positive chrono- and inotropic effects of procaterol. The increases in sinus rate and atrial contractility induced by denopamine were partially but significantly attenuated by treatment with imipramine in a dose which suppressed the effects of tyramine and potentiated the effects of norepinephrine. These results indicate that denopamine is a highly selective beta-1 adrenoceptor agonist in isolated, blood-perfused dog heart preparations, and they also suggest a mild catecholamine-releasing activity through tyramine-like action in isolated right atria.

Adrenergic beta-Antagonists↗

In vitro evaluation of cross-circulation system using semipermeable membrane combined with whole liver perfusion.

INTRODUCTION: Many types of isolated hepatocytes-based bioartificial liver have been developed. However, to maintain hepatocyte-specific functions for a long period is still a significant challenge. The possibilities of rejection or viral transmission still remain as untackled obstacles. We developed a cross-circulation system, using a semipermeable membrane combined with whole liver perfusion. Detoxifying functions of the extracorporeal porcine liver and molecular movements across the membrane were evaluated in vitro. METHODS: The hollow-fiber module has a molecular cutoff of 100 kD. A spiked solution containing 500 mL low molecular dextran solution spiked with 12 mg ammonium chloride, 500 mg D-galactose, and 300 mg lidocaine, which mimicked a patient, was recirculated through the inner fiber space. The extracorporeal liver perfusion circuit consisted of an extra-fiber spaces. A reservoir containing 1000 mL healthy pig plasma, a membrane oxygenator, and a porcine whole liver. Both circuits circulated in the opposite direction for 6 hours. RESULT: In 6 hours, 47.3% +/- 10.2% of ammonia, 89.5% +/- 1.7% of D-galactose, and 95.5% +/- 1.0% of lidocaine were eliminated from the circuits; 66.5 +/- 11.1 mg of urea were produced at the same time. Oxygen consumption was maintained between 0.248 and 0.259 mL/100 g liver/min for 6 hours. Movement of IgM was completely blocked by the 100-kD membrane, whereas albumin was freely transferred from the reservoir to the intrafiber space. CONCLUSION: The perfusion experiments showed the possibility of using a whole liver with oxygenated plasma perfusion in a bioartificial liver system in vitro.

Animals↗

Cardiac effects of propofol and its interaction with autonomic nervous system in isolated, cross-circulated canine atria.

PURPOSE: The effects of propofol on sinoatrial pacemaker activity and myocardial contractility and its interaction with the autonomic nervous system were investigated in isolated, cross-circulated right atrial canine preparations. METHODS: An isolated right atrial preparation was perfused with heparinized arterial blood from an anesthetized support dog and changes in atrial rate and atrial contractile force were recorded. RESULTS: Propofol (30-1000 microg) and thiopental (30-1000 microg), injected into the sinus node artery of the isolated atrium, induced dose-dependent decreases in atrial rate and contractile force. The negative chronotropic and inotropic effects of propofol were greater than those of thiopental. The propofol-induced negative chronotropic and inotropic responses were not inhibited by atropine. Propofol had no effects on the cardiac responses to acetylcholine, norepinephrine, and the intracardiac parasympathetic nerve stimulation which activates ganglionic nicotinic acetylcholine receptors. CONCLUSION: These results indicate that: (a) propofol directly depresses sinoatrial pacemaker activity and myocardial contractility, (b) the negative chronotropic and inotropic effects of propofol do not involve activation of muscarinic receptors, and (c) propofol has little interaction with the autonomic nervous system at the effector site.

Journal Article↗

Auditory brain-stem responses in the rat brain isolated from the body trunk and maintained via cross-circulation.

The auditory brain-stem response (ABR) recorded from the vertex of the rat was analyzed before and after the brain was functionally isolated from the body trunk and maintained via cross-circulation. The ABR profile did not change for as long as 30 min after isolating the brain. The finding indicates that this experimental procedure is useful for studying the brain devoid of input from the trunk.

Analysis of Variance↗

New index for oxygen cost of contractility from curved end-systolic pressure-volume relations in cross-circulated rat hearts.

We have already reported the linear oxygen consumption per beat (VO(2))-systolic pressure-volume area (PVA) relation from the curved left ventricular (LV) end-systolic pressure-volume relation (ESPVR) in the cross-circulated rat heart. The VO(2) intercept (PVA-independent VO(2)) is primarily composed of VO(2) for Ca(2+) handling in excitation-contraction (E-C) coupling and basal metabolism. The aim of the present study was to obtain the oxygen cost of LV contractility that indicates VO(2) for Ca(2+) handling in E-C coupling per unit LV contractility change in the rat heart. Oxygen cost of LV contractility is obtainable as a slope of a linear relation between PVA-independent VO(2) and LV contractility. We obtained a composite VO(2)-PVA relation line at a mid-range LV volume (mLVV) under gradually enhanced LV contractility by stepwise increased Ca(2+) infusion and thus the gradually increased PVA-independent VO(2) values. As a LV contractility index, we could not use E(max) (ESP-V ratio; ESP/ESV) for the linear ESPVR because of the curved ESPVR in the rat LV. A PVA at a mLVV (PVA(mLVV)) has been proposed as a good index for assessing rat LV mechanoenergetics. Since the experimentally obtained PVA(mLVV) was not triangular due to the curved ESPVR, we propose an equivalent ESP-V ratio at a mLVV, (eESP/ESV)(mLVV), as a LV contractility index. This index was calculated as an ESP-V ratio of the specific virtual triangular PVA(mLVV) that is energetically equivalent to the real PVA(mLVV). The present approach enabled us to obtain a linear relation between PVA-independent VO(2) and (eESP/ESV)(mLVV) and the oxygen cost of LV contractility as the slope of this relation.

Animals↗

Effects of intracoronary fentanyl on left ventricular mechanoenergetics in the excised cross-circulated canine heart (revised publication).

BACKGROUND: It is still unclear whether fentanyl directly alters left ventricular (LV) contractility and oxygen consumption. This is because of the difficulty in defining and evaluating contractility and energy use independently of ventricular loading conditions and heart rate in beating whole hearts. METHODS: This study was conducted to clarify the mechanoenergetic effects of intracoronary fentanyl in six excised cross-circulated canine hearts. The authors used the framework of the Emax (a contractility index)-PVA (systolic pressure-volume area, a measure of total mechanical energy)-VO2 (myocardial oxygen consumption per beat) relationship practically independent of ventricular loading conditions. The authors measured LV pressure, volume, coronary flow, and arteriovenous oxygen content difference to calculate Emax, PVA, and VO2. They first obtained the VO2-PVA relationship for varied LV volumes at control Emax. The authors then obtained the VO2-PVA relationship at a constant LV volume, whereas coronary blood fentanyl concentration was increased in steps up to 240 ng/ml. Finally, they obtained the VO2-PVA relationship for varied LV volumes at the final dose of fentanyl. RESULTS: Fentanyl at any concentrations did not significantly change Emax, PVA, and VO2 from the control. The linear end-systolic pressure-volume relations and their slopes were virtually the same between the control and fentanyl volume loading in each heart. Further, either the slope (oxygen cost of PVA) or the VO2 intercept (unloaded VO2) of the linear VO2-PVA relationship remained unchanged by fentanyl. CONCLUSIONS: These results indicate that intracoronary fentanyl produces virtually no effects on LV mechanoenergetics for a wide range of its blood concentration.

Anesthetics, Intravenous↗

The effect of lazaroid (U74500A), a novel inhibitor of lipid peroxidation, on 24-hour heart preservation. A study based on a working model using cross-circulated blood-perfused rabbit hearts.

Lazaroid, an inhibitor of iron-mediated lipid peroxidation, has been shown to reduce free radical-mediated injury after ischemia and reperfusion. We thus examined the efficacy of pretreatment with lazaroid (U74500A) in enhancing functional recovery after 24-hr heart preservation. An isolated rabbit heart model perfused with the blood from a support rabbit was used. Before preservation, either U74500A (4 mg/kg, group L; n = 6) or solvent (group S; n = 7) was given to the donor rabbit. After 24-hr preservation with UW solution at 0 degrees C, all hearts were perfused with cross-circulated blood for 60 min with the Langendorff mode followed by 40 min of the working mode. In group S, ventricular fibrillation (Vf) after reperfusion was observed in all hearts, whereas no Vf was observed in the U74500A-pretreated group. In group L, the serum creatine phosphokinase; its isozyme, troponin-T; and serum lipid peroxide levels after 10 min of reperfusion were all significantly (P < 0.05) lower than those in group S. The Frank-Starling curve (indicating the left atrial pressure-aortic flow relationship) showed a significant left and upward shift in group L compared with that in group S (P < 0.0001). The heart pretreated with U74500A showed less ischemia-reperfusion injury, better ventricular function, and a lower lipid peroxide level. We thus conclude that the inhibition of lipid peroxidation with lazaroid appears to offer some potential benefits for long-term heart preservation.

Animals↗

Evaluation of cross-circulation through circle of Willis using an ultrasonic Doppler technique. Part II. Comparison between blood flow velocity by ultrasonic Doppler flowmetry and cerebrovascular resistance.

The correlation between the increase in velocity of blood flow in both the internal carotid and vertebral arteries during a carotid compression and the cerebrovascular resistance (CVR) was investigated in 11 patients with chronic ischemic cerebrovascular disease and 4 without organic brain lesions. The velocity of blood flow was measured by an ultrasonic Doppler flowmeter. CVR was calculated from cerebral blood flow and arterial blood pressure. There was no correlation between the increased velocity of blood flow in the internal carotid and vertebral arteries and CVR. The increased velocity of blood flow in patients with low CVR was, however, significantly higher than that of patients with high CVR. The investigation of cross-circulation by ultrasonic Doppler flowmetry is a useful non-invasive method for the detection of changes in cerebral vascular resistance.

Adolescent↗