Predictors of milk cortisol in North American women.

OBJECTIVES: Human milk content varies across mother-child dyads, environments, and populations. Among the hormones in milk is cortisol, a glucocorticoid; its impact on the breastfeeding child is unknown. Milk cortisol may constitute a signal to the child's developing physiology which can shape characteristics (e.g., growth, temperament) to prevailing environmental conditions. This exploratory study evaluated the maternal, breastfeeding, and infant characteristics associated with milk cortisol. METHODS: We evaluated archived milk specimens for cortisol using enzyme immunoassay and employed an information-theoretic approach to assess associations between milk cortisol and participant characteristics with linear regression modeling. Because we employed secondary data, information for some variables likely to impact milk cortisol variation (e.g., time of day, socioeconomic status, maternal or infant body mass index, milk energy density) was unavailable. RESULTS: Participants were 48 lactating mothers from upstate New York, aged 21-40 years. Milk cortisol ranged from 0.098 to 1.007 µg/dL. Child age ranged from 1 to 26 months. In linear regression employing best fit modeling criteria, milk cortisol increased with child age (B: 0.069; p: .000; a 7.1% increase in milk cortisol for each month of child age), while child symptoms of illness (B: -0.398; p: .057; a 33% decrease) and consumption of complementary foods (B: -.525; p: .020; a 41% decrease) were associated with lower milk cortisol. CONCLUSIONS: We speculate that increasing milk cortisol with child age plays a role in signaling development (e.g., as increasing independence increases risk for injury and other negative health outcomes), independent of the maternal stressors we could capture.

Adult liver transplant anesthesiology practice patterns and resource utilization in the United States: Survey results from the society for the advancement of transplant anesthesia.

INTRODUCTION: Liver transplant anesthesiology is an evolving and expanding subspecialty, and programs have, in the past, exhibited significant variations of practice at transplant centers across the United States. In order to explore current practice patterns, the Quality & Standards Committee from the Society for the Advancement of Transplant Anesthesia (SATA) undertook a survey of liver transplant anesthesiology program directors. METHODS: Program directors were invited to participate in an online questionnaire. A total of 110 program directors were identified from the 2018 Scientific Registry of Transplant Recipients (SRTR) database. Replies were received from 65 programs (response rate of 59%). RESULTS: Our results indicate an increase in transplant anesthesia fellowship training and advanced training in transesophageal echocardiography (TEE). We also find that the use of intraoperative TEE and viscoelastic testing is more common. However, there has been a reduction in the use of veno-venous bypass, routine placement of pulmonary artery catheters and the intraoperative use of anti-fibrinolytics when compared to prior surveys. CONCLUSION: The results show considerable heterogeneity in practice patterns across the country that continues to evolve. However, there appears to be a movement towards the adoption of specific structural and clinical practices.

Perioperative management of adult living donor liver transplantation: Part 1 - recipients.

Living donor liver transplantation was first developed to mitigate the limited access to deceased donor organs in Asia in the 1990s. This alternative liver transplantation option has become an established and widely practiced transplantation method for adult patients suffering from end-stage liver disease. It has successfully addressed the shortage of deceased donors. The Society for the Advancement of Transplant Anesthesia and the Korean Society of Transplant Anesthesia jointly reviewed published studies on the perioperative management of live donor liver transplant recipients. The review aims to offer transplant anesthesiologists and critical care physicians a comprehensive overview of the perioperative management of adult live liver transplantation recipients. We feature the status, outcomes, surgical procedure, portal venous decompression, anesthetic management, prevention of acute kidney injury, avoidance of blood transfusion, monitoring and therapeutic strategies of hemodynamic derangements, and Enhanced Recovery After Surgery protocols for liver transplant recipients.

Structural basis for the regulation of ß-glucuronidase expression by human gut Enterobacteriaceae.

The gut microbiota harbor diverse ß-glucuronidase (GUS) enzymes that liberate glucuronic acid (GlcA) sugars from small-molecule conjugates and complex carbohydrates. However, only the Enterobacteriaceae family of human gut-associated Proteobacteria maintain a GUS operon under the transcriptional control of a glucuronide repressor, GusR. Despite its potential importance in Escherichia, Salmonella, Klebsiella, Shigella, and Yersinia opportunistic pathogens, the structure of GusR has not been examined. Here, we explore the molecular basis for GusR-mediated regulation of GUS expression in response to small-molecule glucuronides. Presented are 2.1-Å-resolution crystal structures of GusRs from Escherichia coli and Salmonella enterica in complexes with a glucuronide ligand. The GusR-specific DNA operator site in the regulatory region of the E. coli GUS operon is identified, and structure-guided GusR mutants pinpoint the residues essential for DNA binding and glucuronide recognition. Interestingly, the endobiotic estradiol-17-glucuronide and the xenobiotic indomethacin-acyl-glucuronide are found to exhibit markedly differential binding to these GusR orthologs. Using structure-guided mutations, we are able to transfer E. coli GusR's preferential DNA and glucuronide binding affinity to S. enterica GusR. Structures of putative GusR orthologs from GUS-encoding Firmicutes species also reveal functionally unique features of the Enterobacteriaceae GusRs. Finally, dominant-negative GusR variants are validated in cell-based studies. These data provide a molecular framework toward understanding the control of glucuronide utilization by opportunistic pathogens in the human gut.

Mutational analysis confirms the presence of distal inhibitor-selectivity determining residues in B. stearothermophilus dihydrofolate reductase.

Many antibacterial and antiparasitic drugs work by competitively inhibiting dihydrofolate reductase (DHFR), a vital enzyme in folate metabolism. The interactions between inhibitors and DHFR active site residues are known in many homologs but the contributions from distal residues are less understood. Identifying distal residues that aid in inhibitor binding can improve targeted drug development programs by accounting for distant influences that may be less conserved and subject to frequent resistance causing mutations. Previously, a novel, homology-based, computational approach that mines ligand inhibition data was used to predict residues involved in inhibitor selectivity in the DHFR family. Expectedly, some inhibitor selectivity determining residue positions were predicted to lie in the active site and coincide with experimentally known inhibitor selectivity determining positions. However, other residues that group spatially in clusters distal to the active site have not been previously investigated. In this study, the effect of introducing amino acid substitutions at one of these predicted clusters (His38-Ala39-Ile40) on the inhibitor selectivity profile in Bacillus stearothermophilus dihydrofolate reductase (Bs DHFR) was investigated. Mutations were introduced into these cluster positions to change sidechain chemistry and size. We determined kcat and KM values and measured KD values at equilibrium for two competitive DHFR inhibitors, trimethoprim (TMP) and pyrimethamine (PYR). Mutations in the His38-Ala39-Ile40 cluster significantly impacted inhibitor binding and TMP/PYR selectivity - seven out of nine mutations resulted in tighter binding to PYR when compared to TMP. These data suggest that the His38-Ala39-Ile40 cluster is a distal inhibitor selectivity determining region that favors PYR binding in Bs DHFR and, possibly, throughout the DHFR family.

Physical anthropology in 1918 and the founding of the U.S. journal.

In 1918, the first issue of the American Journal of Physical Anthropology was prepared and distributed by Ales Hrdlicka, the Curator of Physical Anthropology at the Smithsonian Institution. This was a singular act, both in the general and specific sense. It was the first journal of physical anthropology published in the United States, and it was a sole effort by Hrdlicka, who was committed to promoting and recognizing physical anthropology as a new science in America. On this 100th anniversary of the founding of the journal, Hrdlicka's efforts were successful: physical/biological anthropology is a strong and timely discipline that represents a major area of scientific research today.

Coming to grips with economic development: Variation in adult hand grip strength during health transition in Vanuatu.

OBJECTIVES: To determine whether (1) maximal handgrip strength (HGS) is associated with inter-island level of economic development in Vanuatu, (2) how associations between island of residence and HGS are mediated by age, sex, body size/composition, and individual sociodeomographic variation, and (3) whether HGS is predictive of hypertension. MATERIAL AND METHODS: HGS was collected from 833 adult (aged 18 and older) men and women on five islands representing a continuum of economic development in Vanuatu. HGS was measured using a handheld dynamometer. Participants were administered in an extensive sociobehavioral questionnaire and were also assessed for height, weight, percent body fat, forearm skinfold thickness, forearm circumference, and blood pressure. RESULTS: HGS was significantly greater in men than in women regardless of island of residence. HGS was also significantly positively associated with inter-island level of economic development. Grip strength-to-weight ratio was not different across islands except in older individuals, where age-related decline occurred primarily on islands with greater economic development. HGS significantly declined with age in both men and women. CONCLUSION: HGS is positively associated with modernization in Vanuatu, but the relationship between HGS and modernization is largely due to an association of both variables with increased body size on more modernized islands. Further research on the role of individual variation in diet and physical activity are necessary to clarify the relationship between HGS and modernization.

Grip strength and body composition in Turkana pastoralist children and adolescents.

OBJECTIVES: In an earlier study, age changes and sex differences in grip strength were documented for adult Turkana pastoralists of Kenya (Little and Johnson, 1986). The objective here is to characterize age changes and sex differences in grip strength of Turkana children and adolescents in the context of arm lean tissue composition, and in comparison with other African, African-American, and non-Western populations. METHODS: Anthropometric measurements, derived body composition values, and grip strength measures (maximum voluntary contraction) were taken on a sample of 232 nomadic Turkana pastoralist children (94 boys and 138 girls) aged 3 to 21 years. Relationships were tested between grip strength (in Newtons) and mid-upper arm (brachium) lean tissue cross-sectional areas. Comparisons were made among several different ethnic groups. RESULTS: Turkana children and adolescents had low arm muscle (derived lean tissue) and grip strength values when compared with U.S. NHANES percentile references. Girls' percentile rankings were greater than boys' percentile rankings for muscle and for grip strength. Both boys and girls were intermediate when compared with other non-Western populations and U.S. strength grip reference values. Correlations between grip strength and arm lean tissue areas were highly significant for both boys and girls. CONCLUSIONS: The greater relative muscle size and grip strength values of late adolescent girls compared to boys is consistent with an earlier study of adults. The difference is likely to result from greater physical subsistence activity and greater access to food in girls than in boys. Several suggestions are given to explain why Turkana youths have relatively small muscle sizes.

Structural Features Essential to the Antimicrobial Functions of Human SPLUNC1.

SPLUNC1 is an abundantly secreted innate immune protein in the mammalian respiratory tract that exerts bacteriostatic and antibiofilm effects, binds to lipopolysaccharide (LPS), and acts as a fluid-spreading surfactant. Here, we unravel the structural elements essential for the surfactant and antimicrobial functions of human SPLUNC1 (short palate lung nasal epithelial clone 1). A unique α-helix (α4) that extends from the body of SPLUNC1 is required for the bacteriostatic, surfactant, and LPS binding activities of this protein. Indeed, we find that mutation of just four leucine residues within this helical motif to alanine is sufficient to significantly inhibit the fluid spreading abilities of SPLUNC1, as well as its bacteriostatic actions against Gram-negative pathogens Burkholderia cenocepacia and Pseudomonas aeruginosa. Conformational flexibility in the body of SPLUNC1 is also involved in the bacteriostatic, surfactant, and LPS binding functions of the protein as revealed by disulfide mutants introduced into SPLUNC1. In addition, SPLUNC1 exerts antibiofilm effects against Gram-negative bacteria, although α4 is not involved in this activity. Interestingly, though, the introduction of surface electrostatic mutations away from α4 based on the unique dolphin SPLUNC1 sequence, and confirmed by crystal structure, is shown to impart antibiofilm activity against Staphylococcus aureus, the first SPLUNC1-dependent effect against a Gram-positive bacterium reported to date. Together, these data pinpoint SPLUNC1 structural motifs required for the antimicrobial and surfactant actions of this protective human protein.

Design, synthesis and biological evaluation of novel aminothiazoles as antiviral compounds acting against human rhinovirus.

We describe here the design, synthesis and biological evaluation of antiviral compounds acting against human rhinovirus (HRV). A series of aminothiazoles demonstrated pan-activity against the HRV genotypes screened and productive structure-activity relationships. A comprehensive investigational library was designed and performed allowing the identification of potent compounds with lower molecular weight and improved ADME profile. 31d-1, 31d-2, 31f showed good exposures in CD-1 mice. The mechanism of action was discovered to be a host target: the lipid kinase phosphatidylinositol 4-kinase III beta (PI4KIIIß). The identification of the pan-HRV active compound 31f combined with a structurally distinct literature compound T-00127-HEV1 allowed the assessment of target related tolerability of inhibiting this kinase for a short period of time in order to prevent HRV replication.

A half century of high-altitude studies in anthropology: introduction to the plenary session.

Until 50 years ago, high-altitude terrestrial research was conducted largely within the realm of environmental physiology, where interests were focused on physiological mechanisms and mountain exploration. Scientists from the United States, Europe, and Peru had developed sophisticated physiological models of adaptation and acclimatization to the hypoxia of high altitude, but very little research had been conducted on permanent residents, particularly natives of high altitude in the two major regions of the world-the Andes and the Himalayas. In 1962, Raul T. Baker initiated a project at the Pennsylvania State University to explore the responses of indigenous Peruvians to the major stresses at altitude: hypoxia and cold. Approaches to this early research were anthropological in perspective and centered on population-level studies with an evolutionary approach. Studies were conducted by applying a combination of physiological experimental methods, simulated field experiments, and extended anthropological field observations. Early hypotheses at this time were that heredity played a major role in the adaptive complexes in native high-altitude residents. These early hypotheses were later modified to incorporate or replace the genetic hypotheses with developmental adaptation models. A half century of research within anthropology and research in other fields has presented a vastly more complex and integrated picture of high-altitude adaptation in native residents. Recent studies incorporate physiology and oxygen transport, population and molecular genetics, reproduction, growth, and development. The history and current status of high-altitude research and its anthropological applications are treated in papers from this plenary symposium.

Ranking mAb-excipient interactions in biologics formulations by NMR spectroscopy and computational approaches.

Excipients are added to biopharmaceutical formulations to enhance protein stability and enable the development of robust formulations with acceptable physicochemical properties, but the mechanism by which they confer stability is not fully understood. Here, we aimed to elucidate the mechanism through direct experimental evidence of the binding affinity of an excipient to a monoclonal antibody (mAb), using saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopic method. We ranked a series of excipients with respect to their dissociation constant (KD) and nonspecific binding constants (Ns). In parallel, molecular dynamic and site identification by ligand competitive saturation (SILCS)-Monte Carlo simulations were done to rank the excipient proximity to the proteins, thereby corroborating the ranking by STD NMR. Finally, the excipient ranking by NMR was correlated with mAb conformational and colloidal stability. Our approach can aid excipient selection in biologic formulations by providing insights into mAb-excipient affinities before conventional and time-consuming excipient screening studies are conducted.

Joseph S. Weiner and the foundation of post-WW II human biology in the United Kingdom.

Both the United States and the United Kingdom experienced a transformation in the science of physical anthropology from the period before World War II until the post-war period. In the United States, Sherwood L. Washburn is credited with being a leading figure in this transformation. In the United Kingdom, two individuals were instrumental in bringing about a similar change in the profession. These were Joseph S. Weiner at the University of Oxford and Nigel Barnicot at the University of London, with Weiner playing the principal role as leader in what Washburn called the "New Physical Anthropology," that is, the application of evolutionary theory, the de-emphasis on race classification, and the application of the scientific method and experimental approaches to problem solving. Weiner's contributions to physical anthropology were broad-based--climatic and work physiology, paleoanthropology, and human variation--in what became known as human biology in the U.K. and human adaptability internationally. This biographical essay provides evidence for the significant influence of J.S. Weiner on the post-war development of human biology (biological or physical anthropology) inthe U.K.

Spatiotemporal impacts of COVID-19 on air pollution in California, USA.

Various recent studies have shown that societal efforts to mitigate (e.g. "lockdown") the outbreak of the 2019 coronavirus disease (COVID-19) caused non-negligible impacts on the environment, especially air quality. To examine if interventional policies due to COVID-19 have had a similar impact in the US state of California, this paper investigates the spatiotemporal patterns and changes in air pollution before, during and after the lockdown of the state, comparing the air quality measurements in 2020 with historical averages from 2015 to 2019. Through time series analysis, a sudden drop and uptick of air pollution are found around the dates when shutdown and reopening were ordered, respectively. The spatial patterns of nitrogen dioxide (NO2) tropospheric vertical column density (TVCD) show a decreasing trend over the locations of major powerplants and an increasing trend over residential areas near interactions of national highways. Ground-based observations around California show a 38%, 49%, and 31% drop in the concentration of NO2, carbon monoxide (CO) and particulate matter 2.5 (PM2.5) during the lockdown (March 19-May 7) compared to before (January 26-March 18) in 2020. These are 16%, 25% and 19% sharper than the means of the previous five years in the same periods, respectively. Our study offers evidence of the environmental impact introduced by COVID-19, and insight into related economic influences.

Raymond Pearl and the shaping of human biology.

Raymond Pearl (1879-1940) was a significant figure in the field of biology. He founded the journal Human Biology and almost single-handedly promoted and established the scientific discipline of human biology. His scientific versatility was one of his most important features during the first four decades of the 20th century, and he played a major role in developing the fields of biodemography, human population biology, human life-cycle and life span approaches, fertility, growth, the biology of longevity and senescence, and mortality. He was one of the earliest biologists to combine biometric analyses and experimental studies to explore the dimensions of human biology. Pearl also was broadly educated in the arts, music, literature, history, the classics, and science. His writing was sophisticated and often witty, and his views were sometimes provocative and controversial. His network of colleagues and friends among the literary and science worlds was substantial. The following biographical memoir of Raymond Pearl is designed to commemorate the 80th anniversary of the founding of his journal Human Biology and is a tribute to this great scientist. Pearl's sudden death at age 61 truncated a scientific career that was one of the most productive of the 20th century.

Evolutionary Strategies for Body Size.

Humans show marked variation in body size around the world, both within and among populations. At present, the tallest people in the world are from the Netherlands and the Balkan countries, while the shortest populations are central African Pygmies. There are genetic, genetic plasticity, developmental, and environmental bases for size variation in Homo sapiens from the recent past and the present. Early populations of Homo species also have shown considerable size variation. Populations from the present and the past are also marked by sexual dimorphism, which, itself, shows group variation. There is abundant evidence for the effects of limited food and disease on human growth and resultant adult body size. This environmental influence has been reflected in "secular trends" (over a span of years) in growth and adult size from socioeconomic prosperity or poverty (availability of resources). Selective and evolutionary advantages of small or large body size also have been documented. Heritability for human height is relatively great with current genome-wide association studies (GWAS) identifying hundreds of genes leading to causes of growth and adult size variation. There are also endocrinological pathways limiting growth. An example is the reduced tissue sensitivity to human growth hormone (HGH) and insulin-like growth factor (IGF-1) in Philippine and African hunter-gatherer populations. In several short-statured hunter-gatherer populations (Asian, African, and South American), it has been hypothesized that short life expectancy has selected for early maturity and truncated growth to enhance fertility. Some island populations of humans and other mammals are thought to have been selected for small size because of limited resources, especially protein. The high-protein content of milk as a staple food may contribute to tall stature in East African pastoral peoples. These and other evolutionary questions linked to life history, male competition, reproduction, and mobility are explored in this paper.

Blood pressure and lifestyle on Saba, Netherlands Antilles.

During the 20th century, infectious disease morbidity and mortality generally waned whereas chronic degenerative diseases posed a growing burden at the global level. The population on Saba, Netherlands Antilles has recently experienced such an epidemiologic transition, and hypertension was reported to be extraordinarily high, although no prevalences have been reported and relationships with lifestyle factors associated with rapid modernization have not been explored. In this study, a medical and demographic questionnaires, as well as body composition and blood pressure measures were collected from 278 Saban men and women aged 18-91 years. When age and sex adjusted, 48% of the population was hypertensive. Age, BMI, and Afro-Caribbean descent were all associated with higher blood pressures. In a second phase, 124 individuals of the 278 were invited to receive a longer questionnaire on individual exposure to modernizing influences such as travel and education. Higher blood pressure was associated with having lived in fewer different places in the past; those who stayed only on Saba or Statia had higher blood pressures than those who had also lived in more modernized areas. However, this was no longer statistically significant after adjustment for age and BMI. Lifestyle incongruity was positively associated with higher blood pressure in that those with more discord between material wealth and income were more likely to be hypertensive, and this remained statistically significant after adjustment for age and adiposity. In summary, hypertension is highly prevalent on Saba and tended to be associated with greater age, adiposity, Afro-Caribbean ancestry, and lifestyle incongruity.

Testing longitudinal associations between executive function and academic achievement.

Children with higher levels of executive function (EF) skills consistently demonstrate higher levels of academic achievement. Despite the consistency of these associations, fundamental questions remain about whether efforts to improve an individual child's EF skills result in corresponding improvements in his or her academic performance. In the absence of experimental evidence, developmentalists have used repeated measures designs to test the nature, magnitude, and direction of the associations between EF skills and academic achievement. In contrast to previous studies, this study described how between- and within-person associations between EF and achievement address different questions. Using data from a subsample of participants (N = 6,040) from the Early Childhood Longitudinal Study-Kindergarten, 2010-2011 (ECLS-K:2011) cohort, we estimated a series of latent growth curve models with structured residuals to test the between and within-person associations between 2 dimensions of EF (working memory, cognitive flexibility) and 2 domains of academic achievement (math, reading). Whereas between-person associations between EF and achievement were large (φ = .55-.91), the within-person associations were small (ßs = -.10-.25). Within-person effects of earlier reading achievement on later EF skills was the most consistent finding. Results were unchanged when analyses were repeated using the subset of children who were eligible for free and reduced-price lunch, a proxy for low socioeconomic households. Results are discussed with respect to interest in improving EF skills as a means for facilitating school outcomes. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Mouse Gut Microbiome-Encoded ß-Glucuronidases Identified Using Metagenome Analysis Guided by Protein Structure.

Gut microbial ß-glucuronidase (GUS) enzymes play important roles in drug efficacy and toxicity, intestinal carcinogenesis, and mammalian-microbial symbiosis. Recently, the first catalog of human gut GUS proteins was provided for the Human Microbiome Project stool sample database and revealed 279 unique GUS enzymes organized into six categories based on active-site structural features. Because mice represent a model biomedical research organism, here we provide an analogous catalog of mouse intestinal microbial GUS proteins-a mouse gut GUSome. Using metagenome analysis guided by protein structure, we examined 2.5 million unique proteins from a comprehensive mouse gut metagenome created from several mouse strains, providers, housing conditions, and diets. We identified 444 unique GUS proteins and organized them into six categories based on active-site features, similarly to the human GUSome analysis. GUS enzymes were encoded by the major gut microbial phyla, including Firmicutes (60%) and Bacteroidetes (21%), and there were nearly 20% for which taxonomy could not be assigned. No differences in gut microbial gus gene composition were observed for mice based on sex. However, mice exhibited gus differences based on active-site features associated with provider, location, strain, and diet. Furthermore, diet yielded the largest differences in gus composition. Biochemical analysis of two low-fat-associated GUS enzymes revealed that they are variable with respect to their efficacy of processing both sulfated and nonsulfated heparan nonasaccharides containing terminal glucuronides.IMPORTANCE Mice are commonly employed as model organisms of mammalian disease; as such, our understanding of the compositions of their gut microbiomes is critical to appreciating how the mouse and human gastrointestinal tracts mirror one another. GUS enzymes, with importance in normal physiology and disease, are an attractive set of proteins to use for such analyses. Here we show that while the specific GUS enzymes differ at the sequence level, a core GUSome functionality appears conserved between mouse and human gastrointestinal bacteria. Mouse strain, provider, housing location, and diet exhibit distinct GUSomes and gus gene compositions, but sex seems not to affect the GUSome. These data provide a basis for understanding the gut microbial GUS enzymes present in commonly used laboratory mice. Further, they demonstrate the utility of metagenome analysis guided by protein structure to provide specific sets of functionally related proteins from whole-genome metagenome sequencing data.

Comparison of three strategies to delineate the bowel for whole pelvis IMRT of prostate cancer.

PURPOSE: To compare three different contouring approaches of the bowel before and during whole pelvis IMRT of localized prostate cancer. MATERIALS: Nine patients were randomly selected among those treated for localized prostate cancer at UTMB from March 2004 to August 2006. On the planning CT, besides the usual organs at risk (OAR), for each patient we contoured the bowel according to three different definitions: each bowel segment ('BS'); 'BS+1', BS uniformly expanded by 1cm; intestinal cavity ('IC') or the 'container' of the bowel loops up to the pelvic/abdominal walls. For each patient we generated three rival plans each considering a different bowel definition, otherwise identical. Provided that the same target coverage and other OAR spare had been achieved, plans were compared for their ability to minimize bowel dose at planning. Furthermore, after co-registering 6 weekly CT to the initial planning CT for each patient, we investigated which of the three definitions would allow the best bowel protection also during treatment. RESULTS: All definitions provided a very similar average bowel DVH at planning. During treatment BS allowed an average approximately 20 cc more of bowel to receive at least 45 Gy over BS+1 and IC (p=0.008 and 0.029, respectively); on the contrary bowel V45 between IC and BS+1 were not significantly different (p=0.65). CONCLUSION: A definition that takes into account internal organ motion is warranted to maximize bowel protection during treatment.