Preferred food rewards for laying hens in behavioural experiments.

1. Laying hens showed a clear preference for maggots over whole grain wheat, feed pellets and other food stuffs in a preference test. 2. Motivation to work for maggots in an operant conditioning task was high and unaffected by periods of food deprivation of up to 6h before testing. 3. By extrapolation, motivation to work for maggots was equivalent to the motivation of the hens to work for their normal ration after approximately 9 h food deprivation. 4. Food deprivation is a common prerequisite for laying hens in operant conditioning and other behavioural techniques but can be avoided if an attractive food, such as maggots, is used. The mild distress associated with the deprivation is thereby removed and, in the UK, the procedure would not require regulation under the Animals (Scientific Procedures) Act 1986.

Effect of tumor necrosis factor antibody given to horses during early experimentally induced endotoxemia.

OBJECTIVE: To test efficacy of murine monoclonal, rabbit polyclonal recombinant equine or human tumor necrosis factor-alpha (rETNF or rHTNF, respectively) antibodies to inhibit native equine tumor necrosis factor (TNF) activity. ANIMALS: 8 and 18 healthy adult horses for parts 1 and 2 of the study, respectively. PROCEDURES: In part 1, supernates from endotoxin-activated peritoneal macrophages were incubated with various dilutions of each rETNF antibody and subsequently tested for TNF activity. Serum was also obtained from a horse 1 hour after infusion with 20 ng of endotoxin/kg of body weight and was incubated with various dilutions of rabbit polyclonal rHTNF antibody. In part 2, 20 ng of endotoxin/kg was infused in horses during a 30-minute period. Fifteen minutes after the endotoxin infusion was initiated, 1 of 3 preparations was infused: 0.1 mg of rabbit polyclonal (rHTNF antibody/kg, 0.1 mg of human IgG/kg, or 500 ml of 5% dextrose. Clinical and hematologic data were collected for 24 hours. RESULTS: Compared with the monoclonal antibody, the rabbit polyclonal rETNF antibody was more effective in inhibiting TNF activity. The 50% effective doses of the murine monoclonal rETNF, rabbit polyclonal rETNF, and rabbit rHTNF antibodies were 1.8, 0.8, and 0.6 micrograms of antibody/ml, respectively. In part 2, endotoxin infusion resulted in significant alternations in all variables; however, differences among treatment groups were not significant. CONCLUSIONS AND CLINICAL RELEVANCE: Although murine monoclonal and rabbit polyclonal rETNF or rHTNF antibodies are capable of inhibiting native equine TNF activity in vitro, when given after initiation of endotoxemia, administration of 0.1 mg of rabbit polyclonal rHTNF/kg does not alter the response to infusion of endotoxin.

Relationships of working status and cardiac capacity to functional age before and after coronary bypass surgery.

In 77 patients having coronary bypass surgery, we evaluated the interaction between chronological age, functional age, and working status pre- and postoperatively. Preoperatively the chronological age of those not working compared to those working was 60.7 +/- 8.4 years versus 53.0 +/- 8.3 years (P less than 0.001). The preoperative functional ages were 93.5 +/- 11.5 versus 87.6 +/- 10.9 years (P less than 0.05). Postoperatively no patient who was not working preoperatively started work, although functional age improved from 93.5 +/- 11.5 to 83.2 +/- 12.8 years (P less than 0.001). Postoperatively subjects who stopped working showed similar improvement in maximal cardiac output, and maximal oxygen consumption compared to those who continued working; however, the functional age after surgery was 80.6 +/- 9.4 versus 69.6 +/- 11.6 years (P less than 0.01). This study showed a poor relationship between degree of improvement in cardiac function after bypass surgery and change in working status. However, functional age and chronological age contribute to the poor results with regard to return to work.

Psychosocial coping strategies and cardiac capacity before and after coronary artery bypass surgery.

One hundred patients, eighty-nine men and eleven women, with chronic stable angina who were previously selected for aortocoronary bypass grafting gave informed consent for non-invasive and invasive testing of hemodynamic responses to symptom-limited maximal exercise before surgery. Psychosocial coping strategies were evaluated preoperatively by structured interviews and assessment of patients perceptions of symptoms (Cornell Medical Index) and life changes (Holmes and Rahe Schedule of Recent Experiences). Preoperatively forty-one patients were "compartmentalized," forty-two "generalized" and seventeen "vacillated" according to Josten's classification of coping strategies. The Berle Index of social assets was lower and the prevalence of psychiatric symptoms (Cornell categories M to R) was greater in the vacillators preoperatively. Despite less ischemic ST depression in vacillators, no other significant physiological differences were noted between these categories preoperatively. Postoperatively more of the vacillators refused follow-up evaluation, and of vacillators who returned, only one-half were adequately revascularized at operation. Of sixty-five reevaluated after surgery, eight improved, twelve worsened and forty-five did not change classification of coping strategies, yet physiological variables of cardiac function when invasively measured in sixty patients were significantly improved in all three groups. Amounts of improvement, both absolutely and relative to sex- and age-adjusted normal values, were least in vacillators with virtually normal cardiac capacity, and/or inadequate revascularization. Compartmentalized patients were more frequently working, yet only sixty-four in all psychosocial classifications worked before surgery. After this event only forty-five resumed working; none of the non-workers or retired returned to work. Both physiologic improvement and working status were independent of postoperative psychosocial status.

Comparison of active participants and dropouts in CAPRI cardiopulmonary rehabilitation programs.

Of 547 men and 56 women enrolled up to April 1974 in Cardiopulmonary Research Institute (CAPRI) community programs for cardiopulmonary rehabilitatation, 84.5 percent had clinical manifestations of coronary heart disease. These medically supervised programs of physical training involved 30 to 60 minutes of graded levels of working, calisthenics and, if indicated, jogging for 3 mornings/week. Altogether 352 (58.4 percent) dropped out after an average of 8.6 months for men and 5.7 months for women. The remaining 230 men and 21 women remained active for 22 and 20 months, respectively. In retrospect, there were few minor differences between active participants and dropouts in physical characteristics, clinical diagnoses and responses to exercise testing on enrollment. Elapsed time to morbidity tended to be longer in active persons than in dropouts. Over one half of active men and about one third of dropouts were working. Of six early deaths, one occurred before training was instituted, and five within the first 2 weeks of training. Among men, the respective total mortality rates were 2.7 and 4.7/100 person-years for active participants and dropouts; among women, the rates were 0 and 3.8 respectively. Whereas 24 episodes of cardiac arrest occurred in 13 men, with three fatalities outside the training program, in 11 instances of exertional arrest during class training all defibrillations were successful. Without this benefit of medical supervision there would have been little difference in mortality experience.