Cation-controlled wetting properties of vermiculite membranes and its promise for fouling resistant oil-water separation.

Manipulating the surface energy, and thereby the wetting properties of solids, has promise for various physical, chemical, biological and industrial processes. Typically, this is achieved by either chemical modification or by controlling the hierarchical structures of surfaces. Here we report a phenomenon whereby the wetting properties of vermiculite laminates are controlled by the hydrated cations on the surface and in the interlamellar space. We find that vermiculite laminates can be tuned from superhydrophilic to hydrophobic simply by exchanging the cations; hydrophilicity decreases with increasing cation hydration free energy, except for lithium. The lithium-exchanged vermiculite laminate is found to provide a superhydrophilic surface due to its anomalous hydrated structure at the vermiculite surface. Building on these findings, we demonstrate the potential application of superhydrophilic lithium exchanged vermiculite as a thin coating layer on microfiltration membranes to resist fouling, and thus, we address a major challenge for oil-water separation technology.

Correlation between in vitro and in vivo data on food digestion. What can we predict with static in vitro digestion models?

During the last decade, there has been a growing interest in understanding food's digestive fate in order to strengthen the possible effects of food on human health. Ideally, food digestion should be studied in vivo on humans but this is not always ethically and financially possible. Therefore, simple in vitro digestion models mimicking the gastrointestinal tract have been proposed as alternatives to in vivo experiments. Thus, it is no surprise that these models are increasingly used by the scientific community, although their various limitations to fully mirror the complexity of the digestive tract. Therefore, the objective of this article was to call upon the collective experiences of scientists involved in Infogest (an international network on food digestion) to review and reflect on the applications of in vitro digestion models, the parameters assessed in such studies and the physiological relevance of the data generated when compared to in vivo data. The authors provide a comprehensive review in vitro and in vivo digestion studies investigating the digestion of macronutrients (i.e., proteins, lipids, and carbohydrates) as well as studies of the bioaccessibility and bioavailability of micronutrients and phytochemicals. The main conclusion is that evidences show that despite the simplicity of in vitro models they are often very useful in predicting outcomes of the digestion in vivo. However, this has relies on the complexity of in vitro models and their tuning toward answering specific questions related to human digestion physiology, which leaves a vast room for future studies and improvements.

Peanut protein structure, polyphenol content and immune response to peanut proteins in vivo are modulated by laccase.

Food texture can be improved by enzyme-mediated covalent cross-linking of different food components, such as proteins and carbohydrates. Cross-linking changes the biological and immunological properties of proteins and may change the sensitizing potential of food allergens. In this study we applied a microbial polyphenol oxidase, laccase, to cross-link peanut proteins. The size and morphology of the obtained cross-linked proteins were analyzed by electrophoresis and electron microscopy. Structural changes in proteins were analyzed by CD spectroscopy and by using specific antibodies to major peanut allergens. The bioavailability of peanut proteins was analyzed using a Caco-2 epithelial cell model. The in vivo sensitizing potential of laccase-treated peanut proteins was analyzed using a mouse model of food allergy. Finally, peanut polyphenols were analyzed by UHPLC-MS/MS, before and after the enzymatic reaction with laccase. Laccase treatment of peanut proteins yielded a covalently cross-linked material, with the modified tertiary structure of peanut proteins, improved bioavailability of Ara h 2 (by 70 fold, p < 0.05) and modulated allergic immune response in vivo. The modulation of the immune response was related to the increased production of IgG2a antibodies 11 fold (p < 0.05) and reduced IL-13 secretion in in vitro cultured splenocytes 7 fold (p < 0.05). Analysis of the peanut polyphenol content and profile by HPLC-MS/MS revealed that laccase treatment depleted the peanut extract of polyphenol compounds leaving mostly isorhamnetin derivatives and procyanidin dimer B-type in detectable amounts. Treatment of complex food extracts rich in polyphenols with laccase results in both protein cross-linking and modification of polyphenol compounds. These extensively cross-linked proteins have unchanged potency to induce allergic sensitization in vivo, but certain immunomodulatory changes were observed.

A simplified, data-constrained approach to estimate the permafrost carbon-climate feedback.

We present an approach to estimate the feedback from large-scale thawing of permafrost soils using a simplified, data-constrained model that combines three elements: soil carbon (C) maps and profiles to identify the distribution and type of C in permafrost soils; incubation experiments to quantify the rates of C lost after thaw; and models of soil thermal dynamics in response to climate warming. We call the approach the Permafrost Carbon Network Incubation-Panarctic Thermal scaling approach (PInc-PanTher). The approach assumes that C stocks do not decompose at all when frozen, but once thawed follow set decomposition trajectories as a function of soil temperature. The trajectories are determined according to a three-pool decomposition model fitted to incubation data using parameters specific to soil horizon types. We calculate litterfall C inputs required to maintain steady-state C balance for the current climate, and hold those inputs constant. Soil temperatures are taken from the soil thermal modules of ecosystem model simulations forced by a common set of future climate change anomalies under two warming scenarios over the period 2010 to 2100. Under a medium warming scenario (RCP4.5), the approach projects permafrost soil C losses of 12.2-33.4 Pg C; under a high warming scenario (RCP8.5), the approach projects C losses of 27.9-112.6 Pg C. Projected C losses are roughly linearly proportional to global temperature changes across the two scenarios. These results indicate a global sensitivity of frozen soil C to climate change (γ sensitivity) of -14 to -19 Pg C °C(-1) on a 100 year time scale. For CH4 emissions, our approach assumes a fixed saturated area and that increases in CH4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH4 emission increases of 7% and 35% for the RCP4.5 and RCP8.5 scenarios, respectively, which add an additional greenhouse gas forcing of approximately 10-18%. The simplified approach presented here neglects many important processes that may amplify or mitigate C release from permafrost soils, but serves as a data-constrained estimate on the forced, large-scale permafrost C response to warming.

Cry1Ab protein from Bacillus thuringiensis and MON810 cry1Ab-transgenic maize exerts no adjuvant effect after airway exposure.

The genetically modified (GM) maize event MON810 has been inserted with a processed version of the transgene, cry1Ab, derived from the soil bacterium Bacillus thuringiensis (Bt) to express proteins with insecticidal properties. Such proteins may introduce new allergens and also act as adjuvants that promote allergic responses. While focus has been on safe consumption and hence the oral exposure to GM food and feed, little is known regarding inhalation of pollen and desiccated airborne plant material from GM crops. The aim of this study was to investigate whether plant material from the Cry1Ab-expressing maize variety MON810, or trypsin-activated Cry1Ab (trypCry1Ab) protein produced in recombinant bacteria, may act as adjuvants against the allergen ovalbumin (OVA) in a mouse model of airway allergy. A clear proallergic adjuvant effect of the mucosal adjuvant cholera toxin (CT) was demonstrated, determined as increased specific IgE, eosinophils and Th2 cytokines in MLN cell supernates, while no elevation in OVA-specific antibodies or cytokine release from MLN cells after stimulation with OVA were observed in mice receiving Cry1Ab-containing plant materials or the trypCry1Ab protein. Our data suggest that Cry1Ab proteins had no detectable systemic adjuvant effect in mice after airway exposure. Further experiments with purified plant proteins, as well as long-term exposures needs be conducted to further evaluate exposures experienced in real-life situations.

Detection of multiple mycotoxin occurrences in soy animal feed by traditional mycological identification combined with molecular species identification.

Soy products are a main component of animal feed. Because mycotoxins may harm farm animals, undermining productivity and health, a mycological and toxigenic screening was carried out on 36 batches used in animal feed, collected in 2008, 2009 and 2010 in Italy. The investigated mycoflora of a subset of soy seed (n = 6) suggested that Aspergillus spp. and Fusarium spp. frequently colonize soy seeds. Aflatoxins, fumonisins and deoxynivalenol were detected in 88.9%, 72.2% and 30.6% of samples, respectively. Co-occurrence of at least two toxins was observed in 72% of cases. The molecular analysis of the Fusarium spp. population identified Fusarium verticillioides as potential producers of fumonisins, but no known deoxynivalenol producers were detected. It is suggested that the widespread presence of toxins can be due to non-optimal storing conditions of the feed. Moreover, our results suggest that mycotoxin thresholds should be adapted to consider the frequent case of toxin co-occurrence. This approach would better reflect the real toxigenic risk of feedstuffs.

A standardised static in vitro digestion method suitable for food - an international consensus.

Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives that determine endpoints such as the bioaccessibility of nutrients and non-nutrients or the digestibility of macronutrients (e.g. lipids, proteins and carbohydrates) are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.

Compositional differences in soybeans on the market: glyphosate accumulates in Roundup Ready GM soybeans.

This article describes the nutrient and elemental composition, including residues of herbicides and pesticides, of 31 soybean batches from Iowa, USA. The soy samples were grouped into three different categories: (i) genetically modified, glyphosate-tolerant soy (GM-soy); (ii) unmodified soy cultivated using a conventional "chemical" cultivation regime; and (iii) unmodified soy cultivated using an organic cultivation regime. Organic soybeans showed the healthiest nutritional profile with more sugars, such as glucose, fructose, sucrose and maltose, significantly more total protein, zinc and less fibre than both conventional and GM-soy. Organic soybeans also contained less total saturated fat and total omega-6 fatty acids than both conventional and GM-soy. GM-soy contained high residues of glyphosate and AMPA (mean 3.3 and 5.7 mg/kg, respectively). Conventional and organic soybean batches contained none of these agrochemicals. Using 35 different nutritional and elemental variables to characterise each soy sample, we were able to discriminate GM, conventional and organic soybeans without exception, demonstrating "substantial non-equivalence" in compositional characteristics for 'ready-to-market' soybeans.

In Vitro Models for Studying Secondary Plant Metabolite Digestion and Bioaccessibility.

There is an increased interest in secondary plant metabolites, such as polyphenols and carotenoids, due to their proposed health benefits. Much attention has focused on their bioavailability, a prerequisite for further physiological functions. As human studies are time consuming, costly, and restricted by ethical concerns, in vitro models for investigating the effects of digestion on these compounds have been developed and employed to predict their release from the food matrix, bioaccessibility, and assess changes in their profiles prior to absorption. Most typically, models simulate digestion in the oral cavity, the stomach, the small intestine, and, occasionally, the large intestine. A plethora of models have been reported, the choice mostly driven by the type of phytochemical studied, whether the purpose is screening or studying under close physiological conditions, and the availability of the model systems. Unfortunately, the diversity of model conditions has hampered the ability to compare results across different studies. For example, there is substantial variability in the time of digestion, concentrations of salts, enzymes, and bile acids used, pH, the inclusion of various digestion stages; and whether chosen conditions are static (with fixed concentrations of enzymes, bile salts, digesta, and so on) or dynamic (varying concentrations of these constituents). This review presents an overview of models that have been employed to study the digestion of both lipophilic and hydrophilic phytochemicals, comparing digestive conditions in vitro and in vivo and, finally, suggests a set of parameters for static models that resemble physiological conditions.

Determination of atrazine and degradation products in Luxembourgish drinking water: origin and fate of potential endocrine-disrupting pesticides.

Several pesticides have been hypothesized to act as endocrine-disrupting compounds, exhibiting hormonal activity and perturbing normal physiological functions. Among these, especially s-triazine herbicides have received increased attention. Despite being banned in many countries, including the European Union, atrazine is still the world's most widely used herbicide. Despite its discontinued use, considerable concentrations of atrazine and its degradation products, mainly desethylatrazine (DEA) and deisopropylatrazine (DIA), are still found in the environment, including drinking water sources. The aim of this investigation was to study concentrations of especially s-triazine herbicides and major degradation products in drinking water, including spring water, tap water and bottled water in Luxembourg. Spring water (2007/2008/2009, n = 69/69/69), tap water (2008/2009, n = 19/26), and bottled water (2007/2008/2009, n = 5/13/7) were sampled at locations in Luxembourg and investigated for pesticides by LC-ESI-MS/MS. Atrazine was the predominant triazine, detectable in many spring water locations, tap and bottled water, ranging (mean) from 0-57 (9), 0-44 (4), and 0-4 (1) ng l(-1), respectively. DEA and DIA in spring water ranged (mean) from 0-120 (19) and 0-27 (3) ng l(-1), with higher concentrations from agricultural areas and low molar ratios of DEA:atrazine <0.5 and high ratios of atrazine:nitrate suggesting point-source contamination. Levels (mean) of DEA and DIA in tap water were 0-62 (14) and 0-6 (<1) ng l(-1) and in bottled water 0-11 (2) and 0-7 (2) ng l(-1). Simazine and other triazines were detected in traces (<5 ng l(-1)). Thus, the conducted monitoring suggested the presence of low concentrations of s-triazines in raw and finished water, presumably partly due to non-agricultural contamination, with concentrations being below thresholds advocated by the European Union Directive 98/83/EC.

Retrospective evidence for a biological cost of vancomycin resistance determinants in the absence of glycopeptide selective pressures.

OBJECTIVES: To estimate the relative fitness differences between glycopeptide-resistant Enterococcus faecium (GREF) and glycopeptide-susceptible E. faecium (GSEF) from yearly surveillance data on the occurrence of GREF in Danish poultry farm environments. METHODS: A population genetic model was adapted to retrospectively estimate the biological fitness cost of acquired resistance. Maximization of a likelihood function was used to predict the longitudinal persistence of acquired resistance. RESULTS: Our analysis suggests strong selection against GREF following the 1995 ban on the glycopeptide growth promoter avoparcin. However, parameterizing the model with two selection coefficients suggesting a reduced negative effect of the acquired resistance on bacterial fitness over time significantly improved the fit of the model. Our analyses suggest that the acquired glycopeptide resistance will persist for >25 years. CONCLUSIONS: Acquired resistance determinants in commensal E. faecium populations in Danish farm environments are likely to persist for decades, even in the absence of glycopeptide use.

Genetic Fusarium chemotyping as a useful tool for predicting nivalenol contamination in winter wheat.

Fusarium graminearum [teleomorph Gibberella zeae] and Fusarium culmorum together with Fusarium poae are the main species known to produce nivalenol (NIV). The NIV content in wheat (Triticum aestivum L.) harvested in Luxembourg was investigated in 2007 and 2008 at 17 different locations. Species determination and genetic chemotyping of F. graminearum and F. culmorum were used to understand the spatial distribution of NIV producers in wheat from Luxembourg. Three hundred thirteen F. graminearum, 175 F. culmorum and 117 F. poae strains respectively were isolated. Chemotypes of the first two species were determined by PCR and confirmed on a sub-sample of single isolates by LC-MS/MS analysis. The 15-acetylated DON chemotype of F. graminearum was dominant in both years representing 94.2% of the population while the NIV chemotype represented 5.8%. The F. culmorum chemotypes were rather evenly distributed, with 3-acetylated DON and NIV profiles present with similar abundances (53.2% and 46.8%, respectively). NIV presence in wheat flour obtained from the 17 sites was correlated with the number of F. culmorum (NIV chemotype) isolated from 100 seeds, suggesting its primary role in NIV production on grains. The predictive power for identifying NIV contamination in grains based on NIV chemotype presence was confirmed by coupling the isolation procedure with a cut-off value, resulting in the successful identification (100%, p=0.008) of NIV contamination in grains collected from 9 additional experimental sites. In conclusion, the results highlight the importance of chemotyping for improved prediction of toxin contamination in wheat.

Uptake visualization of deltamethrin by NanoSIMS and acute toxicity to the water flea Daphnia magna.

The objective of this study was to investigate the uptake of deltamethrin, an insecticide, by Daphnia magna neonates by SIMS and to compare these findings with results based on established toxicity tests. Young daphnids (aged <24 h) were exposed to 0, 50 and 200 microg L(-1) (ppb) deltamethrin. Mobile, immobile and dead animals were enumerated after 24 and 48 h following OECD 202 [OECD 202, 2004. Daphnia sp., acute immobilisation test, guideline for testing of chemicals] guidelines. The animals were embedded in epoxy resin, cut into semi-thin sections (500 nm) and placed on silicon supporters. NanoSIMS 50 (Cameca) images were made from tissues of the intestine for carbon, nitrogen (measured as CN), phosphorus and bromine. To distinguish between relative concentrations of bromine in the guts from different exposure concentrations of deltamethrin, a carbon normalization method was carried out. Both deltamethrin concentrations and time showed a significant effect on immobilization and mortality of the daphnids (P<0.0001). Bromine from deltamethrin could be visualized by NanoSIMS in all exposed gut tissues (gut wall, microvilli layer, perithropic membrane). Highest deltamethrin concentrations following (12)C normalization were found in animals exposed to 200 microg L(-1) deltamethrin, followed by 50 microg L(-1) and the control. NanoSIMS 50 was successfully used as a supplemental technique for elucidating the relation between the uptake and localization of deltamethrin and its toxicity to D. magna. These results highlight the potential usefulness of NanoSIMS to detect marker elements of xenobiotic compounds within exposed organisms, to compare relative exposure concentrations, and to locate these compounds at their original tissue location.

First Report of the Nivalenol Chemotype of Fusarium graminearum Causing Head Blight of Wheat in the Grand Duchy of Luxembourg.

Head blight caused by Fusarium graminearum is one of the major diseases of wheat (Triticum aestivum L.) in Luxembourg (2) and there is concern for mycotoxins in diseased grain. Isolates of F. graminearum have been assigned to chemotypes based on the particular toxins produced. Ten wheat fields representing different topoclimatological areas of Luxembourg were surveyed in 2007 and 2008 to determine the frequency and distribution of chemotypes. Partially blighted wheat heads were collected, and diseased grains were plated on Fusarium-selective agar (dichloran-chloramphenicol-peptone) for 12 days at 22 ± 2°C with a 12-h light period. Monoconidial isolates of F. graminearum (79 in 2007 and 85 in 2008) were obtained by conidia dilution on 2% water agar and needle selection under a microscope. F. graminearum isolates showed rapid growth on potato dextrose agar, dense aerial mycelium with red pigment deposits in the plate, macroconidia with five to six defined septa, and a basal cell with the typical foot shape. Microconidia were absent. To confirm species identification, a PCR reaction was carried out using the F. graminearum species-specific primers Fg16F (5'-CTCCGGATATGTTGCGTCAA-3') and Fg16R (5'-GGTAGGTATCCGACATGGCAA-3') according to Demeke et al. (1). Chemotype of each isolate was determined according to Ward et al. (4). In particular, PCR primer 12CON (5' CATGAGCATGGTGATGTC-3') coupled with primer 12NF (5'-TCTCCTCGTTGTATCTGG-3') and primer 3CON (5'-TGGCAAAGACTGGTTCAC-3') coupled with primer 3NA (5'-GTGCACAGAATATACGAGC-3') identified the nivalenol chemotype, primer 12CON coupled with primer 12-15F (5'-TACAGCGGTCGCAACTTC-3') and primer 3CON coupled with primer 3D15A (5'-ACTGACCCAAGCTGCCATC-3') identified the 15-acetylated deoxynivalenol (DON) chemotype, while primer 12CON coupled with primer 12-3F (5'-CTTTGGCAAGCCCGTGCA-3') and primer 3CON coupled with primer 3D3A (5'-CGCATTGGCTAACACATG-3') identified 3-acetylated DON chemotype. Reactions were repeated two times and positive controls (provided by Kerry O'Donnell, NRRL collection, Peoria, IL) and a negative control (water) were used in each reaction. Frequency of the nivalenol chemotype was found to be 2.5% in 2007 and 1% in 2008. Interestingly, the nivalenol chemotype was absent in southern Luxembourg. According to this finding, nivalenol was likely to be present at low levels in grain from Reisdorf and Echternach in 2007 (central Luxembourg) and in 2008 from grain of Troisvierges (northern Luxembourg). The remaining isolates in both years belonged to the 15-acetylated DON chemotype and the 3-acetylated DON chemotype was not detected. Compared with a previous report from the Netherlands (3), the nivalenol chemotype in Luxembourg is less frequent and widespread. To our knowledge, this is the first report of the nivalenol chemotype of F. graminearum causing head blight on wheat in Luxembourg. References:(1) T. Demeke et al. Int. J. Food Microbiol. 103:271, 2005. (2) F. Giraud et al. Plant Dis. 92:1587, 2008. (3) C. Waalwijk et al. Eur. J. Plant Pathol. 109:743, 2003. (4) T. J. Ward et al. Fung. Genet. Biol. 45:473, 2008.

NanoSIMS 50 elucidation of the natural element composition in structures of cyanobacteria and their exposure to halogen compounds.

AIMS: NanoSIMS (secondary ion mass spectrometry) is a powerful technique for mapping the elemental composition of a variety of small-scale samples (e.g. in Material Research, Cosmochemistry and Geology). However, its analytical features are making it also valuable to address biological questions. We demonstrate the ability of the NanoSIMS 50 to map elements at subcellular lateral resolution (approx. 50 nm) within cyanobacteria (Anabaena sp. and Cylindrospermum alatosporum) and its feasibility to investigate the uptake of bromine-containing substances (NaBr and deltamethrin). METHODS AND RESULTS: Elemental maps of O, N, P and S were obtained from semi-thin sections of different cell types (chemically fixed and resin-embedded heterocysts, akinetes and vegetative cells). NanoSIMS enabled the detection of various characteristic cell sub-structures and inclusions. A homogenous bromine distribution was detected following NaBr and deltamethrin exposure, at Br-concentrations of 0.05, 0.5 (NaBr) and 0.0025 mmol l(-1) (deltamethrin). CONCLUSIONS: NanoSIMS allowed study of the mapping of common elements in cyanobacterial cells and the uptake of NaBr and deltamethrin. SIGNIFICANCE AND IMPACT OF THE STUDY: These results highlight the potential usefulness of NanoSIMS analysis for tracking elements within cell structures at the nanoscale and the ability to detect marker elements of xenobiotic compounds within exposed organisms.

First Report of Fusarium Head Blight on Winter Wheat in the Grand Duchy of Luxembourg.

Following a comparatively mild winter (1.9°C above average [2000-2007]), Fusarium head blight (FHB) on winter wheat was observed during the 2007 season in 17 sites representing all three districts of Diekirch, Grevenmacher, and Luxembourg. The cultivars encountered were diverse and included Achat, Akteur, Aron, Bussard, Cubus, Enorm, Exclusiv, Flair, Rosario, Tommi, and Urban. The preceding crops were maize (six sites), rapeseed (three sites), and one site each of pea, triticale, winter barley, and winter wheat. Rainfalls recorded during the flowering period (June 1-23, mean June 12 for GS 65) ranged from 13 to 62 (mean 38) mm. An overall prevalence of FHB (percentage of infected spikes) of 8.9 ± 15.5% (mean ± SD) and a severity (percentage of infected grains per spike) of 21.0 ± 17.8% were recorded. A significant difference in FHB severity was observed between the cantons north and south of Luxembourg City, 13.4 ± 13.1% (range 0.01 to 46.4) and 35.1 ± 18.1% (range 6.2 to 61.9), respectively (Man-Whitney, P = 0.027), indicating the importance to take regional specificities such as topoclimatological aspects into account. Maize as a preceding crop resulted in significant higher prevalence of FHB as opposed to the other crops (5.9 ± 1.6% versus 3.3 ± 2.2%, Man-Whitney, P = 0.022).

Effect of low vitamin A diets with high-moisture or dry corn on marbling and adipose tissue fatty acid composition of beef steers.

Angus-cross steers (n = 165; 295 +/- 16 kg of BW) were used evaluate the effect of low vitamin A diets with high-moisture corn (HMC) or dry corn (DC) on marbling and fatty acid composition. Steers were allotted to 24 pens (7 steers/pen), such that each pen had the same average initial BW. Treatments were randomly allotted to the pens. The experiment had a completely randomized design, with a 2 x 2 factorial arrangement of treatments: low vitamin A (Lo, no supplemental vitamin A) and HMC (LoHMC); LoDC; high vitamin A (Hi, supplemented with 2,200 IU of vitamin A/kg of DM) and HMC (HiHMC); and HiDC. Diets contained 76% corn, 10% corn silage, 11% protein supplement, and 3% soybean oil (DM basis). Samples of feed ingredients were collected for carotenoid analysis. Blood samples were collected for serum retinol determination. Steers were slaughtered after 145 d on feed. Carcass characteristics and LM composition were determined. Samples from the s.c. fat depot were analyzed for fatty acid composition. High-moisture corn had a greater vitamin A content, based on its carotenoid content, than DC (614 vs. 366 IU/kg of DM, P < 0.01). No vitamin A x corn type interactions were detected for feedlot performance, carcass characteristics, or serum, s.c. fat, or liver retinol concentration. Average daily gain, DMI, and G:F were not affected by vitamin A (P > 0.05). Marbling score and USDA quality grade were greater (P < 0.05) in Lo vs. Hi steers. Hot carcass weight, backfat, and yield grade were not affected by the treatments (P > 0.05). Vitamin A and corn type did not affect LM composition (DM, ash, CP, or ether-extractable fat, P > 0.05). Vitamin A supplementation increased (P < 0.06) serum retinol on d 112 and 145 and increased (P < 0.01) liver retinol at slaughter (Lo = 38.7 vs. Hi = 102.9 mug/g). The s.c. fat retinol concentrations were less (P < 0.01) for Lo (0.8 mug/g) than for Hi (1.4 mug/g) at slaughter. Cell diameter of adipocytes in the i.m. depot was not affected by dietary vitamin A (P > 0.05). A vitamin A x corn type interaction was observed (P < 0.05) for the s.c. fat cellularity. Feeding HMC increased the number of cells per square millimeter when Lo diets were fed (LoHMC = 128 vs. LoDC = 100 cells/mm(2), P < 0.05), but not when Hi diets were fed (HiHMC = 109 vs. HiDC = 111 cells/mm(2), P > 0.05). The CLA content of adipose tissue was not affected by the treatments. Regardless of the corn type used, feeding low vitamin A diets for 145 d to Angus-cross steers increased marbling and quality grade without affecting yield grade, animal health, or performance.

Pseudotumor cerebri caused by isotretinoin.

A 16-year-old girl treated with isotretinoin at a dosage of 0.7 mg per kg each day experienced severe headaches and impaired night vision two months after the start of therapy. Bilateral papilledema and narrowing of the lateral ventricles of the brain were found. Pseudotumor cerebri and impaired night vision abated when isotretinoin was discontinued and systemic corticosteroids (dexamethasone) were administered.