Functional Analysis of a Bacterial Antifreeze Protein Indicates a Cooperative Effect between Its Two Ice-Binding Domains.

Antifreeze proteins make up a class of ice-binding proteins (IBPs) that are possessed and expressed by certain cold-adapted organisms to enhance their freezing tolerance. Here we report the biophysical and functional characterization of an IBP discovered in a bacterium recovered from a deep glacial ice core drilled at Vostok Station, Antarctica (IBPv). Our study showed that the recombinant protein rIBPv exhibited a thermal hysteresis of 2 °C at concentrations of >50 µM, effectively inhibited ice recrystallization, and enhanced bacterial viability during freeze-thaw cycling. Circular dichroism scans indicated that rIBPv mainly consists of ß strands, and its denaturing temperature was 53.5 °C. Multiple-sequence alignment of homologous IBPs predicted that IBPv contains two ice-binding domains, a feature unique among known IBPs. To examine functional differences between the IBPv domains, each domain was cloned, expressed, and purified. The second domain (domain B) expressed greater ice binding activity. Data from thermal hysteresis and gel filtration assays supported the idea that the two domains cooperate to achieve a higher ice binding effect by forming heterodimers. However, physical linkage of the domains was not required for this effect.

Nutritional adequacy of a cows' milk exclusion diet in infancy.

BACKGROUND: Infants with suspected cows' milk allergy are required to follow a strict milk exclusion diet which may lead to nutritional deficiencies, especially if not supervised by a healthcare professional. The aim of this study was to assess the nutritional adequacy of a cows' milk exclusion diet in a group of UK infants over a period of 6 months. METHODS: Participants in this study are a subgroup of the Prevalence of Infant Food Allergy study, a prospective food allergy birth cohort study from the South of England. Each infant consuming a milk free diet, following advice from a specialist allergy dietitian, was matched to two control infants who were consuming an unrestricted diet, forming a nested matched case-control study. Detailed food diaries completed prospectively for 1 week per month over a 5 month period, were coded and analysed according to a standard protocol. RESULTS: The diets of 39 infants (13 milk-free and 26 controls) were assessed. Mean age at diet commencement was 14 weeks. Two of the eleven infants started on an extensively hydrolysed formula did not tolerate it and required an amino acid formula for symptom resolution. All infants had mean intakes in excess of the estimated average requirement for energy and the recommended nutrient intake (RNI) for protein, calcium, iron, selenium, zinc, vitamins A, C and E. Vitamin D intake was in excess of the RNI at all time-points, except at 44 weeks of age. Across the study period, selenium intake was higher for infants consuming a milk free diet whilst vitamin C intake was higher for infants consuming an unrestricted diet. Differences were found between the two groups for protein, calcium, iron and vitamin E intakes at differing time points. CONCLUSION: This study demonstrated that although infants consuming a milk-free diet have a nutritional intake that is significantly different to matched controls who are eating an unrestricted diet, this difference is not constant and it is not seen for all nutrients. Further research in infants without dietetic input is needed to explore the nutritional implications of unsupervised cows' milk exclusion diets.

Cows' milk exclusion diet during infancy: Is there a long-term effect on children's eating behaviour and food preferences?

BACKGROUND: Dietary restriction during infancy may influence later eating behaviour. The aim of this study was to determine whether consuming a cows' milk exclusion (CME) diet during infancy affects eating habits in later childhood, once cows' milk has been reintroduced into the diet. METHODS: Children were recruited from two large birth cohort studies in the UK. A small number of participants were recruited from allergy clinic. Two groups were recruited: an experimental group of children who had consumed a CME diet during infancy and a control group, who had consumed an unrestricted diet during infancy. Parents and children completed questionnaires regarding eating behaviour and food preferences. RESULTS: In total, 101 children of mean age 11.5 years were recruited (28 CME and 73 controls). The CME group scored significantly higher on 'slowness of eating' and on the combined 'avoidant eating behaviour' construct (p < 0.01). The number of foods avoided and symptoms was associated with higher levels of avoidant eating behaviour (p < 0.05). The CME group rated liking for several dairy foods (butter, cream, chocolate, full fat milk and ice cream) significantly lower than the control group (p < 0.05), although there were no significant differences seen for any other category of food. CONCLUSION: This study demonstrated that consuming a CME diet during infancy has persistent and long-term effects on eating habits and food preferences. To reduce future negative eating behaviours, children's exclusion diets need to be as varied as possible and reintroduction of cows' milk products closely monitored.

Prospective food diaries demonstrate breastfeeding characteristics in a UK birth cohort.

Breastfeeding duration and exclusive breastfeeding rates are universally below those recommended by World Health Organization. Due to limitations and challenges associated with researching breastfeeding characteristics, the times when exclusivity is likely to be lost and when women are most likely to discontinue breastfeeding have not yet been identified. Prospective food diaries allow reliable description of the dynamics of breastfeeding to be made to help identify these key time periods. Food diaries detailing intake from birth until the cessation of breastfeeding were analysed for 718 infants recruited into a national arm of an international multicentre birth cohort study (EuroPrevall). Analyses included linear regression analysis and Kaplan-Meier time course analysis. Breastfeeding and exclusive breastfeeding cessation rates for younger mothers (<25 years) are high in the first few weeks after delivery but slow markedly in the period 10-12 weeks after delivery. Cessation rates are consistent from 0 to 26 weeks in older mothers. This difference in feeding patterns led to significant differences between the two different age groups at 26 weeks for breastfeeding (P = 0.006) and exclusive breastfeeding at 8 weeks (P = 0.009). Forty-nine per cent of younger mothers (<25 years) stopped breastfeeding before their infant was 3 weeks old. To increase breastfeeding duration, further work is required to investigate the attitudes and perceptions associated with such high breastfeeding cessation rates in younger mothers during these very early post-natal weeks.

Incidence and risk factors for food hypersensitivity in UK infants: results from a birth cohort study.

BACKGROUND: The prevalence of food hypersensitivity in the UK is still largely open to debate. Additionally its pathogenesis is also unclear although it is known that there are differing phenotypes. Determining its prevalence, along with identifying those factors associated with its development will help to assess its clinical importance within the national setting and also add to the debate on appropriate prevention strategies. METHODS: A population based birth cohort study conducted in Hampshire, UK as part of the EuroPrevall birth cohort study. 1140 infants were recruited with 823 being followed up until 2 years of age. Infants with suspected food reactions were assessed including specific IgE measurement and skin prick testing. Diagnosis of food hypersensitivity was by positive double-blind, placebo-controlled food challenge (DBPCFC) where symptoms up to 48 h after the end of the food challenge were considered indicative of a food hypersensitivity. Factors associated with food hypersensitivity and its two phenotypes of IgE-mediated and non-IgE-mediated disease were modelled in a multivariable logistic regression analysis. RESULTS: Cumulative incidence of food hypersensitivity by 2 years of age was 5.0 %. The cumulative incidence for individual food allergens were hens' egg 2.7 % (1.6-3.8); cows' milk 2.4 % (1.4-3.5); peanut 0.7 % (0.1-1.3); soy 0.4 % (0.0-0.8); wheat 0.2 % (0.0-0.5) and 0.1 % (0.0-0.32) for fish. The cumulative incidence of IgE-mediated food allergy was 2.6 % with 2.1 % reacting to hens' egg. For non-IgE-mediated food allergy the cumulative incidence was 2.4 % (cows' milk 1.7 %). Predictors for any food hypersensitivity were wheeze, maternal atopy, increasing gestational age, age at first solid food introduction and mean healthy dietary pattern score. Predictors for IgE mediated allergy were eczema, rhinitis and healthy dietary pattern score whereas for non-IgE-mediated food allergy the predictors were dog in the home, healthy dietary pattern score, maternal consumption of probiotics during breastfeeding and age at first solid food introduction. CONCLUSIONS: Just under half the infants with confirmed food hypersensitivity had no demonstrable IgE. In an exploratory analysis, risk factors for this phenotype of food hypersensitivity differed from those for IgE-mediated food allergy except for a healthy infant diet which was associated with less risk for both phenotypes.

Diet and food allergy development during infancy: birth cohort study findings using prospective food diary data.

BACKGROUND: After an era of only considering the allergenic properties of the infant diet and allergy outcomes, emerging data suggest that the overall composition of the infant diet might be a more important factor in the development of allergic disease. OBJECTIVE: We sought to assess the relationship between infant dietary patterns in the first year of life and development of food allergy by age 2 years. METHODS: We performed a nested, case-control, within-cohort study. Mothers kept prospective food diaries for the first year of life, with resultant diet data coded in a unique manner to produce new variables, which were then analyzed by using principal component analysis to identify infant feeding patterns within the study subjects. RESULTS: Principal component analysis of diet diary data from 41 infants given a diagnosis of food allergy based on results of double-blind, placebo-controlled food challenges in the first 2 years of life and their 82 age-matched control subjects provided an early infant diet pattern and an ongoing diet pattern. There was no difference between the study groups for the early infant diet pattern, but for the ongoing diet pattern, there was a significant difference between the groups (P = .001). This ongoing dietary pattern was characterized by higher intake of fruits, vegetables, and home-prepared foods, with control infants having a significantly higher healthy infant diet dietary pattern score than children who had a food allergy. CONCLUSIONS: An infant diet consisting of high levels of fruits, vegetables, and home-prepared foods is associated with less food allergy by the age of 2 years.

Introduction of complementary foods and the relationship to food allergy.

OBJECTIVES: To address questions regarding breastfeeding, complementary feeding, allergy development, and current infant-feeding recommendations. METHODS: This was a nested, case-control within a cohort study in which mothers of 41 infants diagnosed with food allergy by the age of 2 years (according to double-blind, placebo-controlled food challenge) and their 82 age-matched controls kept prospective food diaries of how their infants were fed in the first year of life. RESULTS: Infants who were diagnosed with food allergy by the time they were 2 years of age were introduced to solids earlier (≤16 weeks of age) and were less likely to be receiving breast milk when cow's milk protein was first introduced into their diet. CONCLUSIONS: This study supports the current American Academy of Pediatrics' allergy prevention recommendations and the European Society of Pediatric Gastroenterology, Hepatology and Nutrition recommendations on complementary feeding to not introduce solids before 4 to 6 months of age. It also supports the American Academy of Pediatrics' breastfeeding recommendations that breastfeeding should continue while solids are introduced into the diet and that breastfeeding should continue for 1 year, or longer, as mutually desired by mother and infant.

Supporting Positive Living and Sexual Health (SPLASH): a clinician and behavioral counselor risk-reduction intervention in a university-based HIV clinic.

Effective HIV prevention interventions with HIV-positive persons are paramount to stemming the rate of new infections. This paper describes an HIV-clinic-based demonstration project aimed at decreasing patient HIV-transmission risk behaviors and sexually transmitted infections. Systematic, computer-assisted assessment of patient risk aided primary care providers in delivering prevention messages. Patients at greater risk were referred to an HIV Prevention Specialist for behavioral counseling. Patients completed a computerized behavioral staging assessment to self-identify risk behaviors and readiness to change behaviors and counseling messages were individually tailored based on computer assessment. Challenges to project implementation: primary care provider buy-in, patient privacy concerns during risk assessment, and low participation in behavioral counseling. Forty-six percent of persons completing a risk assessment (2,124) were at risk for HIV transmission. Of 121 patients who scheduled counseling appointments, 42% completed at least one session. Despite challenges, successful implementation of a clinic-based prevention intervention is feasible, particularly with attention to patient and provider concerns.