The effect of intermittent versus continuous energy restriction on biomarkers of breast cancer risk

Abstract #506

Excess energy, whether it is the form of high energy diets or low energy expenditure (sedentary lifestyle), is a risk factor for breast cancer. Observational studies show that continuous energy restriction (CER) and exercise reduce risk, particularly of postmenopausal breast cancer. Animal data indicate that intermittent energy restriction (IER) may be superior or at least as effective as continuous energy restriction in preventing or reducing the growth rate of mammary tumours. IER may also be more acceptable than CER which has been difficult to implement.
 We have tested the effectiveness and acceptability of IER and have performed a randomised trial of IER (n=53) versus CER (n=54) in overweight or obese premenopausal women. Energy restriction was 25% in both arms. IER subjects had approximately 550 kcal on 2 days per week and add lib food on other days; CER subjects had approximately 1500 kcal / day over 7 days. Nineteen women (18 %) withdrew from the study before 6 months (IER = 12, CER = 7, main reasons: stress = 4, pregnancy = 3, change in employment = 3, couldn't stick to diet = 3).
 Change in weight and biomarkers for last observation carried forward are reported.
 At 6 months. Both IER and CER are effective for loss of weight -7.9 vs. - 6.7% P = 0.26 and waist circumference -6.3 vs. -5% P = 0.13, and for lowering serum levels of leptin -43.3 vs. -39.8% P = 0.53; C – reactive protein -14.8 vs.-20.3% P = 0.15 and free androgen index -9.8 vs.-14.4% P = 0.90. Both IER and CER increased circulating levels of sex hormone binding globulin + 18.1 vs. 10.8% P = 0.51, and plasma adiponectin +11 vs. +1% P = 0.09. IER is better at lowering insulin resistance at 6 months than CER -29.6 vs. -15.3 % P <0.05.
 These data indicate that 2 days IER gives similar results to CER with respect to weight loss and many of the risk parameters measured and may be an alternative approach to continuous energy restriction. The superior reductions in insulin resistance with IER which may be related to periods of very low calorie intake (approximately 70% restriction). We are waiting data of the effects of IER vs. CER on the IGF-1 axis and oxidative stress. Future studies will investigate the mechanism of IER, its optimal duration and its influence on mammary cell function.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 506.

Immunologic analysis of monoclonal and immunoglobulin E antibody epitopes on natural and recombinant Amb a 1

BACKGROUND

Amb a 1 is the major allergen from ragweed pollen and more than 90% of ragweed-allergic patients react with this protein. Although Amb a 1 was cloned and sequenced in 1991, little is known of the specificity of anti-Amb a 1 antibodies or of the immunologic properties of the recombinant allergen.

OBJECTIVE

To compare binding of monoclonal antibodies (mAb) and IgE antibodies to purified natural Amb a 1 (nAmb a 1) and recombinant Amb a 1 (rAmb a 1).

METHODS

Binding of a panel of anti-Amb a 1 mAb and IgE antibodies to nAmb a 1 or rAmb a 1 was compared by immunoblotting. Chimeric ELISA was used to measure specific IgE to these allergens using 89 ragweed-allergic sera from Austria, Italy, Canada and the United States.

RESULTS

The 8 mAb bound to a 38 kDa Amb a 1 band in ragweed pollen extract and a subset of 5 mAb also bound to the 26 kDa chain of nAmb a 1. A two-site ELISA was developed using a mAb pair, which was approximately 10-fold more sensitive to rAmb a 1. There was a significant correlation between IgE antibody binding to nAmb a 1 and rAmb a 1 (n=89, r=0.79, P<0.001). A subset of approximately 40% of patients showed greater reactivity to nAmb a 1 than to rAmb a 1.

CONCLUSIONS

The data suggest that there is less reactivity of human IgE to rAmb a 1 compared with nAmb a 1. The development of more sensitive, quantitative ELISA for Amb a 1 will require the production of new mAb especially directed against nAmb a 1.

Gastric feed intolerance is not increased in critically ill patients with type II diabetes mellitus

OBJECTIVE

To examine the occurrence of feed intolerance in critically ill patients with previously diagnosed type II diabetes mellitus (DM) who received prolonged gastric feeding.

DESIGN AND SETTING

Retrospective study in a level 3 mixed ICU.

PATIENTS

All mechanically ventilated, enterally fed patients (n = 649), with (n = 118) and without type II DM (n = 531) admitted between January 2003 and July 2005.

INTERVENTIONS

Patients with at least 72 h of gastric feeding were identified by review of case notes and ICU charts. The proportion that developed feed intolerance was determined. All patient received insulin therapy.

RESULTS

The proportion of patients requiring gastric feeding for at least 72 h was similar between patients with and without DM (42%, 50/118, vs. 42%, 222/531). Data from patients with DM were also compared with a group of 50 patients matched for age, sex and APACHE II score, selected from the total non-diabetic group. The occurrence of feed intolerance (DM 52% vs. matched non-DM 50% vs. unselected non-diabetic 58%) and the time taken to develop feed intolerance (DM 62.6 +/- 43.8 h vs. matched non-DM 45.3 +/- 54.6 vs. unselected non-diabetic 50.6 +/- 59.5) were similar amongst the three groups. Feed intolerance was associated with a greater use of morphine/midazolam and vasopressor support, a lower feeding rate and a longer ICU length of stay.

CONCLUSIONS

In critically ill patients who require prolonged enteral nutrition, a prior history of DM type II does not appear to be a further risk factor for feed intolerance.

Anaesthetic considerations for patients receiving photodynamic therapy in head and neck surgery

Photodynamic therapy is an innovative modality in the treatment of malignant and non-malignant diseases. Owing to its widespread use, there will be an increase in the number of photosensitized patients presenting for both elective and emergency anaesthesia. As one of the few centres involved in providing this specialized treatment for maxillofacial conditions, we would like to highlight its main anaesthetic considerations.

Antro-pyloro-duodenal motor responses to gastric and duodenal nutrient in critically ill patients

BACKGROUND

Gastric emptying is frequently delayed in critical illness which compromises the success of nasogastric nutrition. The underlying motor dysfunctions are poorly defined.

AIMS

To characterise antro-pyloro-duodenal motility during fasting, and in response to gastric and duodenal nutrient, as well as to evaluate the relationship between gastric emptying and motility, in the critically ill.

SUBJECTS

Fifteen mechanically ventilated patients from a mixed intensive care unit; 10 healthy volunteers.

METHODS

Antro-pyloro-duodenal pressures were recorded during fasting, after intragastric administration (100 ml; 100 kcal), and during small intestinal infusion of liquid nutrient (6 hours; 1 kcal/min). Gastric emptying was measured using a (13)C octanoate breath test.

RESULTS

In healthy subjects, neither gastric nor small intestinal nutrient affected antro-pyloro-duodenal pressures. In patients, duodenal nutrient infusion reduced antral activity compared with both fasting and healthy subjects (0.03 (0-2.47) waves/min v 0.14 (0-2.2) fasting (p = 0.016); and v 0.33 (0-2.57)/min in healthy subjects (p = 0.005)). Basal pyloric pressure and the frequency of phasic pyloric pressure waves were increased in patients during duodenal nutrient infusion (3.12 (1.06) mm Hg; 0.98 (0.13)/min) compared with healthy subjects (-0.44 (1.25) mm Hg; p<0.02 after 120 minutes; 0.29 (0.15)/min; p = 0.0002) and with fasting (-0.06 (1.05) mm Hg; p<0.03 after 160 minutes; 0.49 (0.13)/min; (p = 0.0001). Gastric emptying was delayed in patients (gastric emptying coefficient 2.99 (0.2) v 3.47 (0.1); p = 0.015) and inversely related to the number of pyloric pressure waves (r = -0.563, p = 0.029).

CONCLUSIONS

Stimulation of pyloric and suppression of antral pressures by duodenal nutrient are enhanced in the critically ill and related to decreased gastric emptying.