Clinical evaluation of setting pump occlusion by the dynamic method: effect on flow.

Pump manufacturers recommend setting roller pump occlusion such that the level of a 100 cm column of crystalloid drops 2.5 cm/min (Sarns, 8000 Modular Perfusion System, operator's manual, roller pump software version 2.3L. May 1993; 2.1-2.14). Though this almost occlusive setting ensures accurate pump flow, it has been shown to cause more hemolysis than nonocclusive pumps (Noon GP, Kane LE, Feldman L et al. Reduction of blood trauma in roller pumps for long-term perfusion. World J Surg 1985; 9: 65-71). We conducted a clinical study (n = 19) to compare the standard occlusion method with the dynamic method and to determine the accuracy of flow for the nonocclusive pump. Standard occlusion was set by clamping the pump tubing distal to the arterial line filter and timing the drop in pump outlet pressure as indicated by a pressure transducer connected to the filter. The occlusion setting, expressed in mmHg/s, was recorded for each roller at two specific points along the raceway. The pump was then set nonocclusively with the dynamic method using the Better Header (BH) (Circulatory Technology, Oyster Bay, NY, USA). Readings of the change in pressure in the same two selected points on the raceway were taken. The latter was repeated after discontinuation of bypass. Flow was recorded throughout the procedure from both roller pump output display and a flow meter (Model #109 Transonic, Ithaca, NY, USA). The average drop in pump outlet pressure for the standard method was 1.3 +/- 4.0 (range 0-18 mmHg/s), and for the dynamic method was 38 +/- 28 (range 1.2-89 mmHg/s). Off bypass, the average reading was 44 +/- 38 (range 2.0-103 mmHg/s). Regression analysis indicates that patient flow, when corrected for retrograde flow by the dynamic method, equals 1.003 x revolutions per minute + 40 ml/min (r2 = 0.964). The average error between indicated pump flow, corrected for retrograde flow, was -1% (range from -6.7 to 6.6%). We conclude that the BH allows nonocclusive setting (30 times less than our standard method) without sacrificing pump flow accuracy.

Antibody-dependent lymphocyte cytotoxicity against cells expressing Epstein-Barr virus antigens.

Antibody-dependent lymphocyte cytotoxicity (ADLC) was demonstrated against Epstein-Barr virus (EBV)-infected RAJI cells with peripheral with peripheral blood lymphocytes from EBV-infected donors. No cytotoxic activity was detected against unifected RAJl cells. The results indicated that this antibody-mediated cytotoxic reaction was directed against the same EBV-induced membrane antigens (MA) previously defined by the membrane immunofluorescence (MF) assay. Antibody to EBV-associated early antigens did not participate in this in vitro reaction. Antibody titers to EBV-induced MA were significantly higher by the ADLC assay in comparison with the MF test. A preliminary study showed no relationship between high antibody titers and the presence of EBV-associated malignancies. The possible in vivo significance of this immune reaction was discussed.

Augmentation of lymphocyte cytotoxicity by antibody to herpesvirus saimiri associated antigens.

Sera from owl monkeys infected with Herpesvirus saimiri (HVS) mediated antibody-dependent lymphocyte cytotoxicity (ADLC) against virus-infected owl monkey kidney cells. Peripheral blood lymphocytes from rhesus monkeys served as effector cells in this cytotoxic assay. ADLC titers increased along with membrane immunofluorescence (MF) titers but among some sera, the ADLC titers were much higher than expected from the MF titers, suggesting that multiple serum factors were involved in mediating ADLC in this system. Absorption of both low and high titered sera with HVS-infected owl monkey kidney cells removed all ADLC activity. Preliminary results from serial serum samples from two infected monkeys that developed leukemia and/or lymphoma demonstrated that ADLC but not MF titers increased to high titers with progression of disease and followed essentially a different kinetic pattern than that noted by MF. The possible significance of these findings in relation to malignant disease induced by this virus is discussed.

Infection of capuchin monkeys (Cebus albifrons) with Herpesvirus saimiri.

Herpesvirus saimiri (HVS) induced persistent, clinically inapparent infections of long-term duration in capuchin monkeys (Cebus albifrons). The infections were characterized by development of antibody to HVS-associated antigens and recovery of low levels of virus-genome-carrying lymphocytes in the peripheral blood. Peripheral lymphocyte counts remained in low-normal to normal ranges and no physical signs of lymphoma were evident. Prednisolone treatment caused immunosuppression in one monkey; this was accompanied by a progressive loss of humoral antibody to HVS-associated antigens, but neoplastic disease did not develop.

Concentration of oncogenic herpesviruses by methyl alcohol precipitation.

Oncogenic herpesviruses, like many other viruses, can be concentrated effectively from large volumes of culture fluids by precipitation with methanol with good recovery of infectivity.