Outflow Line Research Articles

Fatty acid oxidation and mechanical performance of volume-overloaded rat hearts

Chronic volume overload was induced in 2-mo-old rats by surgical opening of the aortocaval fistula. Rats were killed 3 mo later and their hearts were atrially perfused. During the perfusions with 1.2 mM palmitate, mechanical performance of volume-overloaded hearts was significantly decreased both under conditions of a moderate work load and, mainly, after the clamp of the aortic outflow line. Respective O2 consumption rates as well as the rates of 14CO2 production from [U-14C]palmitate were decreased to the same extent. When 2.4 mM octanoate was used as the exogenous substrate, both the O2 consumption rates and the rates of CO2 production of volume-overloaded hearts became comparable to those of control hearts perfused with same substrate. Mechanical activity of volume-overloaded hearts returned to control values and remained stable during the entire perfusion period tested. Total tissue L-carnitine was decreased by approximately 30% in volume-overloaded hearts, which may suggest that palmitate oxidation has been limited at the level of carnitine-acylcarnitine translocase. However, our polarographic studies of the respiratory activity of isolated mitochondria indicated that the palmitoylcarnitine translocation proceeds normally. On the other hand, state 3 respiration of the mitochondria from volume-overloaded hearts supplemented with either palmitate or palmitate and L-carnitine was significantly lower than that of control ones. This may suggest that an alteration of the enzymes involved in long-chain fatty acid activation and/or long-chain fatty acyl transfer to L-carnitine has developed under conditions of chronic mechanical overloading of the heart.

The giant molecular outflow in MON R2

A large, massive outflow associated with the Mon R2 infrared cluster has been identified and mapped. The outflow line components are found to be well separated in velocity from the ambient cloud line component. These detached wings suggest high optical depths and filling factors that may be characteristic of old, evolved flows. The blueshifted lobe shows evidence of shell structure similar to that seen in the L1551 outflow. The redshifted lobe is spatially more confined in the plane of the sky and its structure is uncertain. A dense, flattened, rotating core is found near the origin of the bipolar outflow. The physical properties of this core are consistent with magnetized collapsing cloud models. The derived dynamical mass of the core, roughly 1013 solar masses, is supercritical by a factor of about 10. The large-scale velocity structure of the cloud do not appear to be consistent with such angular momentum conservation. 37 refs.

A Technique for Automatic Tubing Occlusion in Response to Air Bubble Detection When Using a Centrifugal Pump

A double acting pneumatically powered cylinder, energized by an electrically activated solenoid valve, is used to occlude the outflow line from a Bio-Medicus (a) constrained vortex pump. The cylinder is mounted on a tubing guide that is fastened to a pole clamp. A Sarns (b) air bubble detector, placed on the pump inflow line is used to provide the signal to activate the solenoid valve. The outflow occluder is capable of 100% occlusion of 3/8 × 3/32 inch Tygon tubing up to pressures of 2586 mmHg. The occluder system is able to work with many types of bubble detectors and is applicable to any form of nonocclusive pump.

Responses of the working rat heart to carbon monoxide

The effects of carbon monoxide (CO) were studied in the isolated working rat heart. Hearts removed from male laboratory rats were perfused via the left atrium with Krebs-Henseleit solution (KH) oxygenated with 95% O 2-5% CO 2 (O 2). Heart rate and arterial pressures were measured by a transducer inserted in the aortic outflow line and connected to a data logger. Aortic flow was determined by collecting the effluent from the aortic bubble trap in a graduated cylinder. Coronary flow through the pulmonary cannula was collected and measured in a graduated cylinder. After 30 min, the hearts were challenged with solutions containing either CO (5% CO-90% O 2-5% CO 2) or N 2 (5% N 2-90% O 2-5% CO 2) for 10 min (Challenge I). After recovery in O 2, the hearts were challenged with the alternate test solution (Challenge II). CO increased coronary flow (CF) and coronary flow as a percent of cardiac output (CF%) 13 and 16% respectively. N 2 had no significant effect on CF or CF%. CO and N 2 had no significant effect on heart rate, cardiac output, oxygen consumption or on aortic flow or pressure. These results indicate that vasodilation is the major response of the working heart to CO, and this response is not mediated by simple hypoxia.

Bacterial contamination of dialysate in dialysis-associated endotoxaemia

Bacteriological investigations and endotoxin (ET) determinations were performed during a routine haemodialysis session for six patients. The glucose free dialysate was prepared with untreated tap water. All patients were dialysed for 5 h. Pseudomonas aeruginosa was regularly isolated in numbers up to 10 7 cfu ml −1 from samples of the dialysate inflow, the dialysate site and the dialysate outflow. ET levels in the plasma of the patients increased continuously during haemodialysis and were always higher in the blood outflow line of the dialyzer than in the blood inflow. Despite the high bacterial counts in the dialysate and the increasing ET levels in the patients plasma neither bacteraemia nor fever was observed. The former is due to the impermeability of the dialyzer membrane for bacteria, the latter is explained by low pyrogenicity of P. aeruginosa endotoxin. Inspection of the dialyzer machines revealed that air-traps and heater-unit for the incoming (untreated) tap water before mixing with the dialysate concentrate were the only sites where high bacterial release was feasible, as this part of the machine escaped disinfection due to the construction of these devices. We recommend the regular disinfection of all parts of a dialyzer machine, including heating units, air traps and valves.

An in VITRO Test of the Efficacy of the Perioexr CAPD Filterset

In an attempt to reduce the incidence of peritonitis caused by contamination during CAPD bag change procedures, Millipore (Bedford, Mass) developed the Peridex R CAPD filterset. Using the bacterium Serratia marcescens as the challenge organism, this filterset has been evaluated in vitro during 30 days of mock CAPD conducted in our laboratory. S. marcescens was chosen because it has been shown to remain viable in peritoneal dialysis (PD) fluid for more than 30 days. During the test period, the membrane filter and bypass lines were separated to allow identification of the route of bacterial invasion; in essence, two artificial peritoneal cavities were created. The membrane filter, composed of 0.22 [IJ.]m cellulose ester, maintained sterility of the filtered dialysate (n = 5) during the test period. However, the one-way bypass valve had a 60% failure rate by day 18, allowing the test organism to enter the other peritoneal cavity. Under the conditions of this study, the CAPD filterset was shown to be bacteriologically safe for up to 17 days, since contamination was detected following the 18th overnight dwell. Therefore we recommend that filtersets be changed twice monthly to prevent peritonitis due to touch contamination, resulting from failure of the one-way bypass valve on the dialysate outflow line.

Gravity Wastewater Collection Systems Optimization

A computer algorithm for the selection of optimal depth‐diameter combinations for all links of a complete gravity wastewater collection system has been developed using dynamic programming. The algorithm incorporates two subprocesses P1 and P2. The subprocesses P1 generates all feasible designs of inflowing lines at a junction manhole whereas P1 uses these feasible designs to provide the upstream invert level of the outflow line, simultaneously solving the matching problem encountered at each junction manhole. The problem of dimensionality has been minimized by exploiting the characteristic features of wastewater collection system. The optimal design for a 10.7 km long collection system at Indian Institute of Technology, Bombay with 52 lines, 245 links, 224 ordinary manholes and 21 junction manholes has been compared with conventional design to bring out that the algorithm requires small computer memory, small execution time and leads to optimal solution of a complete gravity wastewater collection system.

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°C were examined. The 200 μm diameter dialysis cannula gave good recoveries which varied from about 8% at 6 μl/min to almost 90% at 0.15 μl/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.

The investigation of a compressible laminar boundary layer past an elliptical cone

The self-similar boundary layer on a sharp circular cone was calculated first by Vvedenskaya[1]. The boundary layer equations were solved in a plane containing an outflow line which lies in this case in the symmetry plane at the leeward side, and after that a solution was constructed by using a marching method along a circumferential coordinate. The calculation results for the boundary layer on an elliptic cone were presented in Bashkin's papers [2–4]. However, only the middle angles of attack (30–50°) were considered. where the outflow line of an external stream is located in the windward symmetry plane, and the flow pattern in the boundary layer is analogous to that of the circular cone. In the present the laminar boundary layer on an elliptic cone is studied for a wide range of angles of attack. The boundary layer has been calculated at small incidence when the outflow of an external flow were located out of the symmetry plane. In this case the equations are solved first in the plane containing the outflow line and then the solutions were constructed by a marching method along a circumferentialcoordinate to the windward and leeward symmetry planes. The distribution of the skin-friction coefficients and the Stanton's numbers on a cone surface was given. The similarity solution of a set of boundary layer equations was obtained for thin cones at large incidence when the stream on the windward side of the cone was directed to the cone nose. The calculations of the laminar boundary layer at hypersonic velocities were carried out to include the real equilibrium properties of the air.

Preservation of platelet function and number by prostacyclin during cardiopulmonary bypass

Thirty-four dogs underwent total cardiopulmonary bypass for 1 or 2 hours with a bubble oxygenator and cardiotomy suction. The dogs were divided into three groups: control dogs which received heparin alone, dogs which received prostacyclin (PGI2) and heparin, and dogs which received prostacyclin alone. PGI2 was given as a bolus (6 to 60 microgram) and then as a constant infusion (0.2 to 0.8 microgram/kg/min) in the venous outflow line. The pump flows were equal in the three groups. PGI2 as a bolus led to transient hypotension, and 60 microgram reduced cardiac output temporarily. During cardiopulmonary bypass, dogs treated with prostacyclin and heparin had low mean arterial perfusion pressures which responded to fluid infusion or phenylephrine. After 1 hour of cardiopulmonary bypass and reversal with protamine, dogs treated with prostacyclin and heparin had shorter bleeding times (p < 0.02) and better platelet function than control animals. After 2 hours, they had normal platelet number, but only half showed preservation of platelet function. When heparin was omitted, PGI2 preserved platelet number, but consumption coagulopathy developed, with prolonged prothrombin, partial thromboplastin, and bleeding times and decreased fibrinogen levels. PGI 2 preserves platelet number and function but may cause hypotension, and it cannot replace heparin in cardiopulmonary bypass.

Influence of Carotid Baroreceptors and Vasoactive Drugs on Systemic Vascular Volume and Venous Distensibility

Changes in systemic vascular volume, in venous return, and in the distensibility of the venous system were studied in an experimental canine preparation. The use of an extracorporeal circulation permitted complete exclusion of the heart and lungs and allowed continuous measurement of alterations of intravascular blood volume and of venous return to the oxygenator. Brief occlusion of the venous outflow line permitted the inscription of venous pressure-volume curves. Hypotension in the isolated carotid sinuses, the administration of catecholamines or of acetylcholine resulted in venoconstriction, evidenced by a decrease in vascular volume, an increase in venous return, and flattening of the venous occlusiou curves. Conversely, carotid sinus hypertension or the administration of trimethaphan produced venodilatation, a decline in venous return, and an increase in vascular volume. The significance of these observations in the regulation of cardiac output is discussed.