Surface-Surface Associations in Microbial Communities Populating Epithelial Habitats in the Murine Gastrointestinal Ecosystem: Scanning Electron Microscopy

Scanning electron microscopy has been used to visualize the residents of microbial communities populating habitats on epithelial surfaces in the gastrointestinal tracts of mice. In the stomach, bacteria form a dense layer on the stratified squamous epithelium of the nonsecreting area. Microbes of at least three morphological types can be seen in this layer, including short rods with round ends, rods in chains, and tapering filaments composed of repeating units of rod- or coccal-shaped elements varying in size from large at one end of the filament to small at the other end. These three forms all attach by one end to the epithelium. The latter two forms can be found only so attached; in both cases, the end is inserted into a hole or depression in the keratinized epithelium. In the small intestine, a microbe of morphology similar to that of the tapering filaments found in the stomach can be seen attached end-on to the epithelium. Again each filament has one end inserted into a hole in the epithelium. In this case, however, the repeating elements of each filament are all about the same size. In the cecum and colon, predominantly fusiform- and spiral-shaped microbes can be seen mixed together in layers on the epithelium. At least three types of fusiform-shaped microbes can be distinguished on the basis of surface texture, and one type of spiral-shaped microbe can be found. These microorganisms appear to be attached to each other and to the epithelium by weblike filaments. The numerous microbial types present in the various epithelial habitats associate intimately surface-to-surface with each other and with the epithelium. Such surface-surface association may be an important autogenic factor contributing to the stability of the murine gastrointestinal ecosystem.     

The effects of tubule orientation on fatigue crack growth in dentin

The fracture of restored teeth is a significant obstacle to lifelong oral health. Recent studies suggest that fatigue cracks originate at flaws introduced during cavity preparation and that fatigue crack growth is a principle cause of restored tooth fractures. In this study, the rate of fatigue crack growth in bovine dentin was estimated under mode I cyclic loading. Double cantilever beam (DCB) specimens were obtained from bovine molars and subjected to high cycle fatigue loading (10(5) < N < 10(6)). The fatigue crack growth rates were measured and used to estimate the crack growth exponent and coefficient according to the Paris Law. The average fatigue crack growth exponent was 4.7 +/- 0.6 for crack growth parallel to the dentin tubules, which was significantly larger than 4.3 +/- 0.5 for crack growth perpendicular to the tubules (t-test, CI > 80%). Although the crack growth rates varied considerably, there was no significant dependence on tubule orientation or tubule density. However, specific features of the fracture surfaces and tendencies for crack curving away from the tubules suggested preferential fatigue crack growth perpendicular to the dentin tubules. Results from this study are being used to guide an experimental investigation of fatigue crack growth in human dentin.     

Neuropeptide Y stimulates proliferation and migration in the 4T1 breast cancer cell line

Stress has long been thought of to be associated with increased risk of cancer. Chronic stress is associated with elevated levels of sympathetic neurotransmitter (norepinephrine and neuropeptide Y: NPY) release and immunosuppression. The expression of NPY receptors has been reported in human breast carcinomas. Recently, activation of the NPY Y5 receptor was shown to stimulate cell growth and increase migration in human breast cancer cells; however the effects of NPY have yet to be investigated in a murine model of breast cancer. Thus, the specific aims of the current study were to: (i) characterize NPY receptor expression in 4T1 breast cancer cells and orthotopic tumors grown in BALB/c mice and (ii) investigate the impact of NPY receptor activation on 4T1 cell proliferation and migration in vitro. Positive expression of NPY receptors (Y1R, Y2R and Y5R) was observed in cells and tumor tissue. As well, NPY treatment of 4T1 cells promoted a concentration-dependent increase in proliferation, through increased phosphorylation of ERK 1/2. Using NPY receptor antagonists (Y1R:BIBP3226, Y2R:BIIE0246 and Y5R:L-152,804), we found the proliferative response to be Y5R mediated. Additionally, NPY increased chemotaxis through Y2R and Y5R activation. These data are in congruence with those from human cell lines and highlight the 4T1 cell line as a translatable model of breast cancer in which the effects of NPY can be studied in an immunocompetent system.     

Validation of 3 food outlet databases: completeness and geospatial accuracy in rural and urban food environments

Despite interest in the built food environment, little is known about the validity of commonly used secondary data. The authors conducted a comprehensive field census identifying the locations of all food outlets using a handheld global positioning system in 8 counties in South Carolina (2008-2009). Secondary data were obtained from 2 commercial companies, Dun & Bradstreet, Inc. (D&B) (Short Hills, New Jersey) and InfoUSA, Inc. (Omaha, Nebraska), and the South Carolina Department of Health and Environmental Control (DHEC). Sensitivity, positive predictive value, and geospatial accuracy were compared. The field census identified 2,208 food outlets, significantly more than the DHEC (n = 1,694), InfoUSA (n = 1,657), or D&B (n = 1,573). Sensitivities were moderate for DHEC (68%) and InfoUSA (65%) and fair for D&B (55%). Combining InfoUSA and D&B data would have increased sensitivity to 78%. Positive predictive values were very good for DHEC (89%) and InfoUSA (86%) and good for D&B (78%). Geospatial accuracy varied, depending on the scale: More than 80% of outlets were geocoded to the correct US Census tract, but only 29%-39% were correctly allocated within 100 m. This study suggests that the validity of common data sources used to characterize the food environment is limited. The marked undercount of food outlets and the geospatial inaccuracies observed have the potential to introduce bias into studies evaluating the impact of the built food environment.     

Alcohol-Attributable Cancer Deaths and Years of Potential Life Lost in the United States

Objectives. Our goal was to provide current estimates of alcohol-attributable cancer mortality and years of potential life lost (YPLL) in the United States.Methods. We used 2 methods to calculate population-attributable fractions. We based relative risks on meta-analyses published since 2000, and adult alcohol consumption on data from the 2009 Alcohol Epidemiologic Data System, 2009 Behavioral Risk Factor Surveillance System, and 2009–2010 National Alcohol Survey.Results. Alcohol consumption resulted in an estimated 18 200 to 21 300 cancer deaths, or 3.2% to 3.7% of all US cancer deaths. The majority of alcohol-attributable female cancer deaths were from breast cancer (56% to 66%), whereas upper airway and esophageal cancer deaths were more common among men (53% to 71%). Alcohol-attributable cancers resulted in 17.0 to 19.1 YPLL for each death. Daily consumption of up to 20 grams of alcohol (≤ 1.5 drinks) accounted for 26% to 35% of alcohol-attributable cancer deaths.Conclusions. Alcohol remains a major contributor to cancer mortality and YPLL. Higher consumption increases risk but there is no safe threshold for alcohol and cancer risk. Reducing alcohol consumption is an important and underemphasized cancer prevention strategy.Alcohol use is estimated to account for about 4% of all deaths worldwide.1 Research over several decades has consistently shown that alcohol increases the risk for cancers of the oral cavity and pharynx, larynx, esophagus, and liver.2–5 The biological mechanisms by which alcohol induces cancer are not fully understood, but may include genotoxic effects of acetaldehyde, production of reactive oxygen or nitrogen species, changes in folate metabolism, increased estrogen concentration, or serving as a solvent for tobacco metabolites.5The International Agency for Research on Cancer (IARC) and the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) both published comprehensive reviews of the scientific literature on alcohol and cancer risk in 2007.5–7 In addition to confirming earlier research for the previously mentioned cancers, they concluded that alcohol increases the risk for colon, rectal, and female breast cancer. (The WCRF/AICR used the term “convincing increased risk” upon judging the strength of the evidence for alcohol use with all of these cancers, with the exception of “probable increased risk” for liver cancer [both sexes] and for colorectal cancer among women.7)More recent studies have also found a positive association for colorectal8–13 and breast cancer11–14 with alcohol use. Although some researchers report a positive association between alcohol and cancers of the stomach, ovary, prostate, pancreas, bladder, or endometrium,14–21 this has not been found by others.11,22–29There have been surprisingly few efforts to ascertain the number of cancer deaths or years of potential life lost (YPLL) attributable to alcohol in the United States. To our knowledge, Rothman et al. were the first to consider this issue,3 estimating that alcohol caused 3% of US cancer deaths in 1974. Doll and Peto, in their seminal work on avoidable causes of cancer, came up with the same estimate of 3% (range = 2%–4%) for US cancer deaths in 1978.4 The Harvard Center for Cancer Prevention in 1996 reported that 3% of US cancers resulted from alcohol use but included no analyses in their report.30 Boffetta et al. estimated that for the World Health Organization region consisting of the United States, Canada, and Cuba, alcohol was responsible for 3% of cancer deaths in men and 2% in women in 2002.31Extensive research has been published over the past 30 years on alcohol use and cancer risk, including more recent studies showing an increased risk of breast and colorectal cancer. In addition, new methods have been developed to better estimate population-level alcohol consumption by demographics based on both survey and sales-based data. Therefore, a comprehensive examination of the population-wide impact in the United States was long overdue. The purpose of our study was to provide current estimates of deaths and YPLL from cancer attributable to alcohol use in the United States. We did so by using sensitivity analyses based on 2 different methodologies and 2 separate nationwide surveys.     

Multinucleated atypia of the vulva

Multinucleated atypia of the vulva (MAV) is an entity with a distinctive histologic pattern of multinucleation in the basal and middle layers of the squamous epithelium that may mimic human papillomavirus (HPV)-related squamous atypias. MAV is rarely reported in the literature, and we believe it should be considered in the differential diagnosis of flesh-colored vulvar papules and vulvar epidermal atypias with multinucleated squamous cells. We describe the case of a 49-year-old patient with the diagnosis of MAV. Results of histopathologic examination revealed a focal area of multinucleation in the basal to middle epithelial layers of the vulvar squamous epithelium, accompanied by mild hyperkeratosis and chronic inflammation. HPV was not identified in the lesion by in situ hybridization techniques.     

Netrin-1 acts as a survival factor for aggressive neuroblastoma

Neuroblastoma (NB), the most frequent solid tumor of early childhood, is diagnosed as a disseminated disease in >60% of cases, and several lines of evidence support the resistance to apoptosis as a prerequisite for NB progression. We show that autocrine production of netrin-1, a multifunctional laminin-related molecule, conveys a selective advantage in tumor growth and dissemination in aggressive NB, as it blocks the proapoptotic activity of the UNC5H netrin-1 dependence receptors. We show that such netrin-1 up-regulation is a potential marker for poor prognosis in stage 4S and, more generally, in NB stage 4 diagnosed infants. Moreover, we propose that interference with the netrin-1 autocrine loop in malignant neuroblasts could represent an alternative therapeutic strategy, as disruption of this loop triggers in vitro NB cell death and inhibits NB metastasis in avian and mouse models.Dependence receptors now number more than a dozen, including deleted in colorectal cancer (DCC) (1), UNC5H (2), Patched (3), some integrins (4), neogenin (5), p75^NTR (6), RET (7), ALK (8), and TrkC (9). Although they have no structural homology (other than possibly in a domain referred to as the DART [dependence-associated receptor transmembrane] domain) (10), they all share the functional property of inducing cell death when disengaged from their trophic ligands, whereas the presence of their trophic ligands blocks this proapoptotic activity. Such receptors thus create cellular states of dependence on their respective ligands (11, 12).The prototype dependence receptors are the netrin-1 receptors. Netrin-1, a diffusible laminin-related protein, has been shown to play a major role in the control of neuronal navigation during the development of the nervous system by interacting with its main receptors, DCC (13, 14, 15) and UNC5H (16, 17). However, DCC and UNC5H (i.e., UNC5H1, UNC5H2, UNC5H3, and UNC5H4) have been shown to belong to the dependence receptor family (1, 2). This dependence effect upon netrin-1 has been suggested to act as a mechanism for eliminating tumor cells that would develop in settings of ligand unavailability (for reviews see references 18, 19). Along this line, disruption of the proapoptotic signaling of these netrin-1 receptors in the gastrointestinal tracts of mice, by netrin-1 overexpression or by inactivation of UNC5H3, is associated with intestinal tumor progression (20, 21).Thus, loss of the dependence receptors'' proapoptotic activity represents a selective advantage for tumor cells. In this respect, DCC was proposed in the early 1990s to function as a tumor suppressor gene, whose expression is lost in the vast majority of human cancers (22, 23). This hypothesis also fits with the observation that UNC5H genes are down-regulated in most colorectal tumors, hence suggesting that loss of UNC5H genes represents a selective advantage for tumor development (21, 24, 25). We have analyzed expression of netrin-1 and its receptors in neuroblastoma (NB), the most frequent extracranial solid tumor of early childhood. The aggressive and metastatic stage 4 NB displays three distinct clinical patterns at presentation and dissemination sites based on patients'' ages. Indeed, neonates and infants (<1 yr of age) with stage 4S and stage 4 without 4S features have an overall good prognosis, whereas stage 4 in children (>1 yr of age) shows a poor prognosis. We describe in this paper that, rather than the loss of netrin-1 receptor expression, a large fraction of aggressive NBs has evolved to select a gain of ligand expression that apparently represents a similar selective growth advantage. We therefore propose to use disruption of this selective advantage as an anticancer strategy in NB.     

A tool predicting future mean arterial blood pressure values improves the titration of vasoactive drugs

Background

Vasoactive drug infusion rates are titrated to achieve a desired effect, e.g., mean arterial blood pressure (MAP), rather than using infusion rates based on body weight. The purpose of this study is to evaluate a method to automatically identify a patient’s sensitivity to sodium-nitroprusside, dobutamine or dopamine and to evaluate, whether an advisory system that predicts MAP 5 min in the future enhances a clinician’s ability to titrate sodium-nitroprusside infusions.

Methods

We used published models implemented in MATLAB to simulate the response of 100 individual patients to infusions of sodium-nitroprusside, dopamine and dobutamine. The simulated patient’s sensitivity to the three drugs was identified using an adaptive filter approach, where MAP was altered in a binary stepwise fashion. Next, 9 nurses were asked to control the MAP of 6 of the simulated patients. For half of the patients, we used the identified sensitivity to predict and display MAP 5 min into the future.

Results

Identifying each individual patient’s sensitivity improved the accuracy of the MAP prediction by 75% for sodium-nitroprusside, 82% for dopamine and 52% for dobutamine over the MAP prediction based on an “average” patient’s sensitivity. The advisory system shortened the median time to reach the desired MAP from 10.2 to 4.1 min, decreased the median number of infusion rate changes from 6 to 4, and resulted in a significant reduction of mental workload and effort.

Discussion

Patient-specific drug sensitivity identifi- cation significantly improved the prediction of future MAP. By predicting and displaying the expected MAP 5 min in the future, the advisory system helped nurses titrate faster, reduced their perceived workload and might improve patient safety.