Immune response and leucine oxidation in oral and intravenous fed rats.

A comparison was made between oral and intravenous nutrition with respect to the route of nutrient administration on leucine oxidation and the immune response. Rats were either fed an oral liquid diet or a comparable amount of energy and amino acids by vein. Groups of rats were used daily for 7 days to determine the percentage of L-[1-14C]-leucine oxidized and the ability of the lymphocytes to respond to stimulation. The intravenous fed rats continually lost 60 to 80 mg more of nitrogen per day in the urine than oral fed rats. The percentage of C-14 from leucine found in breath in 4 h was 13 to 15% of the dose for the oral rats and 25 to 27% for the parenteral fed rats. Lymphocytes reactivity remained unchanged over 7 days for the oral fed rats while the intravenous fed rats were depressed by day 2 to 3 and remained depressed through day 7. These data indicate that nitrogen provided by vein is not handled efficiently as that taken per os, and the requirements for intravenous nutrition are different than those needed for oral food intake.

Comparison of the carcinoembryonic antigen levels by dialysis and sephadex column methods.

Duplicate plasma samples from 64 human donors were tested and compared for the levels of carcinoembryonic antigen (CEA) by the conventional dialysis and sephadex column methods. Results from the column method were similar to those from the dialysis method, with a correlation coefficient of 0.9959. In addition, the assay time by the sephadex column was only four to five hours, as compared with 18 to 24 hours for the dialysis procedure. The potential usefulness in substituting the sephadex column for the dialysis method in CEA determinations is discussed.

Identification of RNA as a complement inhibitory component in an extract of Ehrlich ascites tumor cells.

A factor capable of inhibiting complement was obtained from intact Ehrlich ascites tumor cells by mild extraction with phosphate-buffered saline (PBS). The inhibitor caused a decrease in extent of lysis of EAC14 with a concomitant extension of Tmax. EA, EAC1, EAC4 and EAC142 were all less susceptible to complement-mediated lysis after treatment with the tumor cell extract. Partial purification of a complement inhibitor was accomplished. The inhibitor was rich in RNA and its activity was totally destroyed by RNAase but not DNAase. RNA from mouse tissues, yeast, and Escherichia coli also inhibited complement hemolytic activity. The partially purified material only inhibited lysis of EAC1 and EAC14. Slow inhibition of fluid phase C1 was also demonstrated. In addition, RNA-rich partially purified tumor cell extract was capable of precipitating with purified human C1q.

Comparison between in vitro lymphocyte activity and metabolic changes in trauma patients.

This study was designed to investigate the relationship of in vitro and in vivo components of host immunocompetence and various biochemical parameters of injury. Thirteen multiple trauma victims were evaluated within 2 to 3 days postinjury while maintained on 5% glucose. The mean nitrogen balance of the patients was -18 gm/24 hr and the resting metabolic expenditure was increased 22.3%. Seventy-five per cent of the patients skin tested were anergic or relatively anergic. Patient lymphocyte response to the T cell mitogens phytohemagglutinin and concanavalin A were suppressed 45 and 48%, respectively, when compared to 24 normal healthy individuals. Total lymphocyte count (1,558) and percentage of T lymphocytes (63%) were within normal limits. The suppression of lymphocyte response to mitogens correlated by regression analysis with the negative nitrogen balances and resting metabolic expenditures in these patients (p less than 0.05). The depression of lymphocyte activity can be correlated with the catabolic response of injury in multiple trauma patients.

Comparison of the techniques used for monitoring humoral immunity in cancer patients.

The humoral immune response to tumor-associated antigens (TAA) in cancer patients undergoing immunotherapy can vary considerably. This variability is inherent from patient to patient and is also dependent on the type of assay used to measure patient antibody response to tumors. In this investigation four serological techniques, complement-dependent antibody-mediated cytotoxicity, immune adherence, complement fixation, and indirect membrane immunofluorescence, were used to assess the humoral immune response in melanoma patients receiving specific immunization with cultured allogeneic melanoma cell vaccine. Two different patterns of antibody response were elicited. One was directed against TAA and oncofetal antigens (OFA) and the other was against HLA antigens. The sensitivity and reactivity varied among the different techniques suggesting that one test or technique may not be sufficient to evaluate critically a patient's response to immunotherapy.

Aerobic physical training and alterations in pressor response during norepinephrine infusion: a controlled single-subject experiment.

To test the influence of aerobic physical training on pressor response to infused norepinephrine, the present study utilized a single subject A-B-A-B withdrawal design consisting of 9-week alternating sedentary and aerobic phases (S1, A1, S2, A2). During each 9-week phase the subject underwent infusions every 3 weeks, consisting of saline, low-dose and high-dose norepinephrine (Low-NE, High-NE). Heart rate and mean arterial blood pressure were monitored continuously; resting platelet and plasma catecholamines were also measured. Infusions were conducted 48 h from the most recent exercise bout to minimize residual effects of acute exercise. Fitness level was confirmed by VO2max during graded exercise testing at the conclusion of each 9-week phase. Blood pressure during saline did not differ between aerobic and sedentary phases. However, in all but one comparison, aerobic fitness was associated with a highly significant reduction in pressor response during Low-NE as well as High-NE. Plasma norepinephrine was higher during the two aerobic phases; platelet catecholamines and plasma epinephrine showed no reliable association with fitness. Results for this subject support an attenuation of pressor response associated with aerobic conditioning.