Concentrations Of Phe Research Articles

Fullerene-associated phenanthrene contributes to bioaccumulation but is not toxic to fish.

The present study investigated the effects of aqueous fullerene suspensions (nC60 ) on the bioavailability and toxicity of phenanthrene (Phe) to junior carp (Cyprinus carpio). Bioaccumulation factors (BAFs) were calculated based on total as well as free concentrations of Phe. Equal BAF values were obtained with and without nC60 based on the total concentrations, whereas greater BAFs were found in the presence of nC60 when free Phe concentrations were applied. The results demonstrated that nC60 could act as a contaminant carrier to facilitate Phe bioaccumulation. The concentration-response relationship of induced hepatic 7-ethoxysorufin-O-deethylase activity was established in regard to the total and free concentrations of aqueous Phe solutions as well as the body residues. The concentration-response curves were reliant on the nC60 concentration when the total concentration of Phe was employed as a variable but were independent of nC60 presence when free concentration or body residue was employed as a variable, implying that the latter 2 parameters were more accurate in evaluating biological effects. Particles of C60 were mostly distributed in fish liver and intestines, which indicated the primary routine of uptake was through ingestion. Approximately 22% to 100% of the Phe-nC60 complex contributed to the bioaccumulation, whereas the complex did not contribute to the toxicity.

Tyrosine supplementation and hair coat pigmentation in puppies with black coats – A pilot study

SummaryThe appearance of a red hue to the hair in black coated cats and dogs has previously been reported as a “red hair syndrome”. Such changes in hair colour are related to an alteration in the proportions of two types of pigments produced by melanocytes; black eumelanin and brown pheomelanin. In black cats, it has been demonstrated that higher levels of phenylalanine + tyrosine (Phe+Tyr) than those recommended for growth are required to support eumelanin synthesis. The purpose of this study was to evaluate if a similar observation could be made in dogs. Twelve black coated puppies (Black Labrador retrievers and Newfoundlands) were divided into 3 groups of 4 and fed 3 diets with increasing concentrations of Phe+Tyr (A: 4 g/Mcal; B: 5.8 g/Mcal; C: 7 g/Mcal) for a period of 6 months. Quantification of plasma amino acids (Phe, Tyr, Cys) and spectrocolourimetry of hair samples from the Labrador retrievers (as the a* dimension of CIE Lab system) were performed at the beginning, during and at the end of the study. There was a significant negative linear relationship between plasma Tyr levels and a* values of hair in Labrador dogs on diets A and B, suggesting that a diet with total Phe+Tyr content of 6 g/Mcal (higher than the growth recommended allowance) was necessary to ensure an optimal black coat colour in these puppies and that levels up to 7 g/Mcal can lead to a more intense black coat colour. Moreover, similar to what was found in kittens, plasma levels of Tyr up to 54 μmol/l did not guarantee an optimal black colour coat and led to the “reddish hair” appearance in black coated puppies.

L-Glutamine deprivation induces autophagy and alters the mTOR and MAPK signaling pathways in porcine intestinal epithelial cells.

L-Glutamine (Gln) is an essential amino acid for intestinal growth and integrity. However, the underlying molecular mechanisms are not fully known. In the present study, porcine intestinal epithelial cells (IPEC-1) were used to test the hypothesis that autophagy is induced by Gln deprivation and inhibited by Gln supplementation. After a 2-day period of growth in normal medium, IPEC-1 cells were transferred to a Gln-free custom-made DMEM. Cell numbers, the distribution of autophagosomes, the abundance of the protein for an autophagy marker LC3B, as well as abundances of the mTOR and MAPK proteins during an 8-h period were determined. Furthermore, the rescue effect of 5mM Gln was evaluated. Our results showed that Gln deprivation reduced the cell number, while enhancing the accumulation of autophagosomes and the expression of LC3B-II in IPEC-1 cells within 8h. The concentrations of Glu, Asp, Cit, Arg, Leu, Ile, Val, Ala, β-Ala, Orn, Phe, Met and Ser in the culture medium were altered by Gln deprivation. Further analysis revealed that Gln deficiency inactivated, but Gln supplementation activated, the mTOR and MAPK/ERK signaling pathways. Collectively, our findings support the notion that Gln deficiency induces autophagy and disturbs amino acid metabolism in intestinal epithelial cells, as well as attenuated their mTOR and MAPK/ERK signaling pathways to inhibit protein synthesis and cell proliferation.

Amino acid concentrations in uterine fluid during early pregnancy differ in fertile and subfertile dairy cow strains

The objective of this study was to determine if free AA concentrations in uterine luminal fluid (ULF) and plasma differed between dairy cow strains that differ phenotypically for fertility and to evaluate the effect of the presence of a conceptus on ULF AA concentrations. Uterine luminal fluid was obtained postmortem from cows characterized on the basis of genetic ancestry as fertile (n=11) or subfertile (n=11) strains. At slaughter, cows were at a similar stage of lactation (fertile, 85±1d and subfertile, 87±1d postpartum, respectively). Cows were slaughtered on either d 17 of the estrous cycle [nonpregnant (n=10): fertile n=5; subfertile n=5] or d 17 of pregnancy [10d after embryo transfer, which was undertaken 7d after estrus (n=12, pregnant): fertile n=6, subfertile n=6]. Uterine luminal fluid was collected from each uterine horn of the pregnant (gravid and nongravid horns) and nonpregnant (horn ipsilateral and contralateral to the corpus luteum) cows. Plasma harvested on the day of slaughter and ULF samples were analyzed for AA determination using HPLC. The main effects of genetic strain, reproductive status, and their interactions on ULF and plasma AA content were tested. Additionally, the effect of uterine horn on ULF AA was tested for the pregnant and nonpregnant cows. Reproductive status had the greatest effect on AA concentrations in ULF. The concentrations of Leu, Met, Phe, Val, 1-methyhistidine, Asp, essential, ketogenic, and branched-chain AA, and those AA classified as both glucogenic and ketogenic were greater in the ULF collected from pregnant cows, with taurine being lower. Additionally, we observed effects of uterine horn and genetic strain × uterine horn interaction for ULF AA concentrations. Concentrations of the essential AA plus Met and Phe were greater in the ULF from the gravid horn, irrespective of strain. The ULF from the gravid horn of fertile cows contained the greatest concentrations of nonessential, glucogenic, branched-chain AA, and Leu, Thr, Ala, Ser, and Asp. With the exception of Asp, plasma AA profiles were not different in fertile and subfertile strains. These data support the hypothesis that reproductive status modifies the AA profiles of the ULF and that these profiles differ in fertile and subfertile genetic strains. Successful pregnancy depends on the complex interactions between the developing conceptus and uterine environment. Understanding the mechanisms contributing to maternal–conceptus communication using models with divergent fertility phenotypes could provide information regarding novel mechanisms to improve dairy cow fertility.

Autistic Symptoms in Late Diagnosed Phenylketonuric Children in Upper Egypt

Background: Phenylketonuria (PKU) is the most common metabolic cause of mental retardation. Increased concentrations of Phe in PKU have a neurotoxic effect, contributing to the structural brain damage, severe mental retardation, and psychiatric disturbances. Co-occurrence of autism and PKU has been described in several studies. The toxic levels of Phe appear to play a significant role in the development of autism symptomatology. Our objective was to assess autistic features in a cohort of late diagnosed PKU children. Methods: Thirty-two PKU pediatric patients diagnosed after the age of one year and followed up at Pediatric University Hospital, Assiut University, Egypt. DSM-IV TR and CARS were used for diagnosis and classification of autism cases. FSIQ and MRI brain were done for all cases. EEG was done for cases with convulsions. Results: Autism was present in 8 (25%) cases; 3 were females and 5 were males, 2 had severe autism and 6 had mild/moderate autism, 5 patients had classic PKU and 3 had moderate PKU, 3 cases had mild mental retardation and five have moderate mental retardation. Conclusion: Delay in the diagnosis and management of PKU leads to very high incidence of intellectual disabilities and autistic features in these patients. doi: http://dx.doi.org/10.4021/jnr221w

Phenanthrene exposure causes cardiac arrhythmia in embryonic zebrafish via perturbing calcium handling

Phenanthrene (Phe) is one of the most abundant and ubiquitous polycyclic aromatic hydrocarbons in the aquatic environment. It is known that Phe has cardiotoxic effects, but knowledge concerning the mechanism of cardiac dysfunction caused by Phe is still limited. In this study, zebrafish embryos were exposed to environmentally relevant concentrations of Phe, and an increase of an irregular rhythm was observed in Phe treated embryos. Disordered calcium (Ca2+) handling characterized by impaired sarcoplasmic reticulum Ca2+ uptake, and obvious Ca2+ accumulation in the cytoplasm was observed in rat embryonic cardiac myoblasts (H9C2) exposed to Phe. The mRNA level as well as protein expression of the SERCA2a Ca2+ pump in zebrafish hearts or H9C2 cells was significantly decreased by Phe exposure. The activity of Ca2+-ATPase in H9C2 cells was inhibited by Phe. Both the mRNA and protein levels of TBX5, a direct regulator of SERCA2a, were significantly decreased by Phe exposure. These results suggested that exposure to Phe could lead to arrhythmia in zebrafish embryos via perturbing the calcium handling pathway.

Phenanthrene causes ocular developmental toxicity in zebrafish embryos and the possible mechanisms involved

Recent studies show that polycyclic aromatic hydrocarbons (PAHs) may be a candidate cause of developmental defects of the retina, but the mechanism is still unclear. We evaluated the mechanism(s) underlying PAH-induced retinal development defects due to exposure to environmental concentrations of Phenanthrene (Phe) in zebrafish. We found that exposure to environmental concentrations of Phe caused obvious morphological changes, developmental retardation, apoptosis, and reduction of cell proliferation in the retina. Our results indicated that Phe could cause visual system developmental defects. Phe exposure up-regulated aryl hydrocarbon receptor (AhR) and microphthalmia-associated transcription factor (Mtif) expression, and down-regulated zinc finger E-box binding homeobox 1 (Zeb1) and paired box 6 (Pax6). Moreover, we demonstrated that AhR was a repressor of Zeb1. We propose that Phe's ocular toxicity is mediated by up-regulating AhR, which then down-regulates Zeb1, in turn inducing Mitf expression while inhibiting Pax6 expression.

Phenanthrene exposure produces cardiac defects during embryo development of zebrafish (Danio rerio) through activation of MMP-9

Phenanthrene (Phe) is one of the most abundant polycyclic aromatic hydrocarbons in the aquatic environment as a result of human activities. It is widely accepted that Phe has cardiotoxic effects. Even so, knowledge concerning the mechanism(s) of cardiac development toxicity is still limited. In this study, we exposed zebrafish embryos to environmentally relevant concentrations of Phe and then investigated its cardiotoxic effects and the mechanism(s) involved. Some cardiac morphogenetic defects, which was characterized by an abnormally looped and enlarged heart, dilated and thinner ventricular wall, and increased interstitial fibrosis, were observed in the Phe treated groups. The mRNA and protein expression levels of matrix metalloproteinase-9 (MMP-9), as well as the MMP-9 activity, were induced. Moreover, during co-treatment of the zebrafish embryos with MMP-9 inhibitor, the cardiac defects caused by Phe were attenuated. In addition, Phe exposure led to an up-regulation of transforming growth factor β (TGF-β), which plays a crucial role in mediating cardiac fibrosis. Taken together, our data indicated that the exposure to Phe of zebrafish embryos disrupted normal cardiac development, and that the cardiac defects induced by Phe were mediated by the MMP-9, while TGF-β was also involved in these cardiac defects.

Effects of adding protein, condensed tannins, and polyethylene glycol to diets of sheep and goats fed one-seed juniper and low quality roughage

The biochemical mechanisms that limit voluntary intake of one-seed juniper by browsing ruminants are not well understood. Twelve Rambouillet ewes (78±2.3kgBW) and 12 Boer-Spanish does (54±1.4kgBW) were used in a split-plot sequence design to investigate the effects of adding protein, quebracho tannins (QTs), and polyethylene glycol (PEG) on one-seed juniper intake and preference and on ruminal VFA and plasma AA concentrations. Animals received sudangrass hay and isoenergetic basal diets (4 does and 4 ewes/diet) with either rumen degradable (RDP) or rumen undegradable (RUP) protein (12.5% CP) or no additional protein (control, 5% CP) during four 15-d periods. The control, RDP, and RUP diets were considered the main plot, whereas the four supplement treatments were analyzed as the split-plot effects. Period 1 allowed for adaptation to basal diets and served as a baseline phase. In periods 2–4, animals were offered juniper leaves and twigs (period 2), juniper plus QT (10% of basal diet; period 3), and juniper plus QT plus PEG (50g/animal; period 4). Juniper intake by sheep and goats was not affected (P>0.88) by RDP or RUP when animals were first exposed to juniper, but marginally increased (P<0.10) in period 4 (QT+PEG) regardless of the basal diet. Prior exposure to juniper did not affect (P=0.61) the preference ratio for juniper, but goats had higher preference ratio for juniper (P<0.01) when receiving PEG (period 4). Concentrations of total VFA tended to increase in sheep (P=0.10) and goats (P=0.14) fed protein supplements and molar proportions shifted toward acetate for goats fed RDP and RUP (P=0.07) and to butyrate for sheep fed RDP (P=0.01). Initial juniper exposure (period 2) elevated concentrations of acetate, propionate, and butyrate (P<0.01), but the effect was extinguished in periods 3 and 4 with addition of QT (P<0.05). Supplementation with PEG transiently mitigated the depressor effect of QT on acetate, propionate, and butyrate concentration at 12h post juniper feeding (P<0.01). RDP in goats and to a greater extent RUP in sheep increased plasma concentrations of various AA, especially the branched chained Val, Ile, and Leu (P<0.05). Plasma concentrations of several AA, including Met, Cyst, Glu, Gly, Gln, Asn, Thr, Ser, and Phe, decreased with ingestion of juniper (period 2) and juniper plus QT (period 3). Concentrations of some AA that were depressed by ingestion of juniper and QT were partially restored with supplemental PEG (P<0.05). Protein, terpenes, tannins, and PEG interacted to influence rumen VFA and plasma AA, which were related to intake of juniper and basal diets.

Effect of phenylalanine on Taxol production and antioxidant activity of extracts of suspension-cultured hazel (Corylus avellana L.) cells

Taxol is produced by a few microorganisms and plants such as yew (Taxus sp.). Recent researches have shown that hazel (Corylus avellana L.) is also able to produce Taxol. In the present study, effects of different concentrations of phenylalanine (Phe) on the production of Taxol, antioxidant activity, and cytotoxic effects of extracts of suspension-cultured hazel cells were investigated. The cells were treated with different concentrations of Phe on day 7 of subculture and were harvested on day 14. The results showed that the amounts of Taxol and antioxidant activity were increased by increasing the phenylalanine supply. Interestingly, the cytotoxic effects of hazel cell extract were even stronger than that of pure Taxol (standard), suggesting hazel cell extract as a novel and suitable probe for treating human cancer. Application of phenylalanine to hazel cells exaggerates their effects.

Protein and energy intakes affected amino acid concentrations in plasma, muscle, and liver, and cell signaling in the liver of growing dairy calves

The nutrient content of and feeding recommendations for milk replacers (MR) vary widely in North America, and acceleration of growth through manipulation of protein and energy intakes can reduce rearing costs of dairy operations. The effects of varying the protein and energy intake of MR on metabolite concentrations in plasma, liver, and muscle and the phosphorylation activity of protein kinase B (AKT) and ribosomal protein S6 (rpS6) cell signals in liver and muscle were assessed. Twenty-four newborn Holstein calves were fed 1 of 4 MR for 9wk (n=6/treatment): (1) a 20% crude protein (CP), 20% fat MR fed at 441g of dry matter (DM)/d (CON); (2) a high-protein, medium-fat MR (HPMF; 28% CP, 20% fat) fed at 951g of DM/d; (3) a high-protein, high-fat MR (HPHF; 27% CP, 28% fat) fed at 951g of DM/d; and (4) HPHF fed at 1,431g of DM/d (HPHF+). Water and starter (20% CP, 1.43% fat) were offered ad libitum and calves were fed MR twice daily. Plasma samples were obtained at 1, 5, and 9wk of age. Calves were not weaned and were slaughtered after the last blood sampling. Liver and muscle tissues were collected and analyzed for metabolite concentrations and cell signaling activity. Calves fed all treatments had lower plasma concentrations of Phe and Tyr, and a trend for lower Leu, but greater concentrations of Thr relative to calves fed CON. Calves fed all treatments had increased muscle concentrations of Met and muscle to plasma ratios of Phe, Tyr, and branched-chain amino acids compared with CON. All treatments increased liver to plasma ratios of Phe and Tyr but diminished the ratios of Met compared with CON. Phosphorylation of protein kinase B was not affected by treatment; however, relative to calves fed HPHF, HPMF and HPHF+ diets increased phosphorylation ratios of ribosomal protein S6 in the liver. Therefore, the changes in plasma and tissue concentrations and plasma to tissue ratios of amino acids were associated with enhanced growth rates. However, cell signaling activity was not consistent with accelerated growth in calves fed treatments with increased contents of energy and protein possibly due to confounding effects of diet (MR + starter) or fasting before tissue harvesting. Muscle concentrations of Met might have a regulatory role in protein synthesis in rapidly growing calves fed high levels of CP and energy.

Phenylalanine as a hydroxyl radical-specific probe in pyrite slurries.

The abundant iron sulfide mineral pyrite has been shown to catalytically produce hydrogen peroxide (H2O2) and hydroxyl radical (.OH) in slurries of oxygenated water. Understanding the formation and fate of these reactive oxygen species is important to biological and ecological systems as exposure can lead to deleterious health effects, but also environmental engineering during the optimization of remediation approaches for possible treatment of contaminated waste streams. This study presents the use of the amino acid phenylalanine (Phe) to monitor the kinetics of pyrite-induced .OH formation through rates of hydroxylation forming three isomers of tyrosine (Tyr) - ortho-, meta-, and para-Tyr. Results indicate that about 50% of the Phe loss results in Tyr formation, and that these products further react with .OH at rates comparable to Phe. The overall loss of Phe appeared to be pseudo first-order in [Phe] as a function of time, but for the first time it is shown that initial rates were much less than first-order as a function of initial substrate concentration, [Phe]o. These results can be rationalized by considering that the effective concentration of .OH in solution is lower at a higher level of reactant and that an increasing fraction of .OH is consumed by Phe-degradation products as a function of time. A simplified first-order model was created to describe Phe loss in pyrite slurries which incorporates the [Phe]o, a first-order dependence on pyrite surface area, the assumption that all Phe degradation products compete equally for the limited supply of highly reactive .OH, and a flux that is related to the release of H2O2 from the pyrite surface (a result of the incomplete reduction of oxygen at the pyrite surface). An empirically derived rate constant, Kpyr, was introduced to describe a variable .OH-reactivity for different batches of pyrite. Both the simplified first-order kinetic model, and a more detailed numerical simulation, yielded results that compare well to the observed kinetic data describing the effects of variations in concentrations of both initial Phe and pyrite. This work supports the use of Phe as a useful probe to assess the formation of .OH in the presence of pyrite, and its possible utility for similar applications with other minerals.

Meta-analysis of the response of growing pigs to the isoleucine concentration in the diet

The efficiency of nitrogen utilization will be highest when the amino acid (AA) supply approaches the requirement of the animal. With the availability of different crystalline AA, it is theoretically possible to formulate low-protein diets for growing pigs in which seven AA are co-limiting for performance. In such a diet, the concentration of Lys, Met, Met + Cys, Thr, Trp and Val and a seventh AA would exactly match the requirement. To determine the extent to which low-protein diets can be used, it is important to have reliable information about the requirements for these AA. Isoleucine is often considered the seventh-limiting AA in diets for growing pigs; however, information about the Ile requirement is limited and sometimes conflicting. The purpose of this study was to carry out a meta-analysis of the available literature information to determine the Ile requirement in growing pigs. A total of 46 Ile dose–response experiments were identified that used at least four concentrations of Ile in the diet. Because of differences in experimental design, both the Ile concentration and the response criteria were standardized. In 13 dose–response experiments, there was no indication of a response to an increasing Ile concentration. For the other 33 experiments, a response to the increasing Ile concentration was observed and the Ile requirement estimates ranged from 53% to 114% of that of the National Research Council (1998). An Ile concentration below the requirement resulted in important reductions in both feed intake and growth. A 10% reduction in the Ile concentration (below the requirement) resulted in a 15% reduction in feed intake and a 21% reduction in daily gain. The use of blood products in the diet was the main factor determining whether a response to the Ile concentration was observed or not. Blood meal and blood cells are protein sources with a very low Ile concentration, but with high or very high concentrations of Leu, Val, Phe and His. Some of these AA compete with Ile for catabolic pathways or transport across the blood–brain barrier, thereby potentially increasing the requirement for Ile. In diets without blood products, the Ile requirement appears to be lower than the currently recommended requirement. On the basis of the outcome of this study, we recommend a Ile : Lys requirement ratio of at least 50% on a standardized ileal digestible basis.

Oral and intravenous l‐[1‐13C]phenylalanine delivery measure similar rates of elimination when gastric emptying and splanchnic extraction are accounted for in adult mixed hounds1–4

There are few reported estimates of amino acid (AA) kinetics in adult mammals and none exist in adult dogs. The study objectives were to evaluate the use of oral isotope delivery in contrast to the more commonly used intravenous (IV) delivery to estimate AA kinetics in adult dogs and to estimate splanchnic extraction and gastric emptying using a commonly accepted mathematical model. Dogs received 25 × 1/2-hourly meals (13 g/kg BW/day) and either an oral or IV bolus of l-[1-(13) C]Phe (12 mg/kg BW). Blood samples were taken immediately before each feeding. Concentrations of plasma Phe were measured using liquid chromatography-tandem mass spectrometry. There were no differences in baseline plasma Phe concentrations (34 μm ± 0.61), Phe distribution volume, Phe pool size and rate constants between dogs when the tracer was administered IV or orally (p > 0.25). Decay curve for plasma l-[1-(13) C]Phe differed between IV and oral dosing protocols with IV dosing fit best using a two-compartment model. Phe disappeared from plasma at a mean rate of 2.8%/min. Estimates of gastric emptying and splanchnic extraction did not differ based on oral or IV tracer dosing when the decay curves were fit with the two-compartment model (p > 0.40). The half-life for gastric emptying was 18 min, and first-pass Phe extraction by the splanchnic bed was 24% of the dietary Phe. These results suggest that oral isotope dosing can be used as an alternative to IV isotope dosing in studies that utilize a primed, constant dosing approach to measure protein and amino acid kinetics.

Effect of biosynthetic intermediates and citrate on the phenyllactic and hydroxyphenyllactic acids production by Lactobacillus plantarum CRL 778

To evaluate the influence of biosynthetic precursors, intermediates and electron acceptors on the production of antifungal compounds [phenyllactic acid (PLA) and hydroxyphenyllactic acid (OH-PLA)] by Lactobacillus plantarum CRL 778, a strain isolated from home-made sourdough. Growth of fermentative activity and antifungal compounds production by Lact. plantarum CRL 778 were evaluated in a chemically defined medium (CDM) supplemented with biosynthetic precursors [phenylalanine (Phe), tyrosine (Tyr)], intermediates [glutamate (Glu), alpha-ketoglutarate (α-KG)] and electron acceptors [citrate (Cit)]. Results showed that the highest PLA production (0.26 mmol l(-1)), the main antifungal compound produced by Lact. plantarum CRL 778, occurred when greater concentrations of Phe than Tyr were present. Both PLA and OH-PLA yields were increased 2-folds when Cit was combined with α-KG instead of Glu at similar Tyr/Phe molar ratio. Similarly, glutamate dehydrogenase (GDH) activity was significantly (P < 0.01) stimulated by α-KG and Cit in Glu-free medium. Phe was the major stimulant for PLA formation; however, Cit could increase both PLA and OH-PLA synthesis by Lact. plantarum CRL 778 probably due to an increase in oxidized NAD(+). This effect, as well as the GDH activity, was enhanced by α-KG and down regulated by Glu. This is the first study where the role of Glu and GDH activity in the PLA and OH-PLA synthesis was evidenced in sourdough lactic acid bacteria (LAB) using a CDM. These results contribute to the knowledge on the antifungal compounds production by sourdough LAB with potential applications on the baked goods.

Neuropsychological outcome of NTBC-treated patients with tyrosinaemia type 1

Corinne De Laet, Vanessa Terrones Munoz, Jaak Jaeken, Baudouin FranAois, Dietbrandt Carton, Etienne M Sokal, Bernard Dan, Philippe J Goyens 1 Nutrition and Metabolism Unit, H pital Universitaire des Enfants Reine Fabiola, Universit Libre de Bruxelles (ULB), Brussels, Belgium. 2 Centre for Metabolic Diseases, University Hospital Gasthuisberg, Leuven, Belgium. 3 Pinocchio Centre for Inborn Metabolic Diseases, Esperance Hospital, Li ge, Belgium. 4 Centre for Metabolic Diseases, Ghent University Hospital, Ghent, Belgium. 5 Paediatric Department, St Luc Clinics, Brussels, Belgium. Correspondence to: corinne.delaet@huderf.be

Polycyclic aromatic hydrocarbons in fish and crayfish from the Calumet region of southwestern Lake Michigan

We identified and quantified polyaromatic hydrocarbons (PAHs) in six aquatic taxa from the Calumet region of southwestern Lake Michigan in order to examine their differential exposure to and health risks from PAH. There was a high degree of variation in PAH concentrations across and within sites. Mean concentrations of total PAH were high in alewife (1,064 ng/g) and minnows (345 ng/g) collected from the Indiana Ship Canal, when compared to other taxa and locations. Concentrations of PAH in sunfish were relatively low (10 to 79 ng/g), even where environmental concentrations were elevated. In sunfish, regardless of location, concentrations of CHR, FLA, FLU, PHE and PYR were high whereas DBA, IPE, BAP, BBF, BGP and BKF concentrations were low. PAH concentrations in crayfish exceeded those of other taxa at three of four locations where they co-occurred. PAH profiles were similar in crayfish, sunfish and minnows from locations where sediment concentrations were low. Profiles for crayfish and minnows from a location where sediment concentrations were elevated displayed lower concentrations of ACY, and higher concentrations of BAA, BBF, and BKF, than those from the other three locations. In contrast, the profiles in sunfish from those three locations were similar. The PHE/ANT and FLA/PYR ratios for crayfish, minnows and sunfish suggested that the primary sources at most locations were pyrogenic, although some sites had strong petrogenic influences. Toxic equivalency factors in biota generally reflected the magnitude of sediment contamination. In three of four locations where they co-occurred, TEQs were higher in crayfish than in sunfish and minnows. Sunfish had higher TEQs than minnows at most, though not all, locations; TEQs were notably higher in minnows as compared to sunfish from the Little Calumet River. The selection of aquatic species as sentinels of PAH exposure and risks needs to consider differences in ecologies of taxa as well as the relative magnitude of sediment contamination.

Effect of protein source on nitrogen balance and plasma amino acids in exercising horses

Plasma AA in horses fed either an all-hay or a hay and grain diet in a traditional format have not been investigated. Eight horses were divided into 2 groups: a hay group fed only grass hay or a hay and a grain group (HG) fed in a crossover design for two 5-wk periods. After the first period, horses were fasted overnight, followed by feeding with blood sampling every hour for 6 h. A 4-d total fecal and urine collection to evaluate N balance followed. A 10-d washout period separated the 5-wk feeding periods, during which horses switched diets. The second period was also followed by fasting, feeding, blood sampling, and a 4-d collection period. Horses consumed 840 g of CP in the hay group and 865 g of CP in the HG group. Horses in the hay group had a 2.4 ± 2.4 g/d N balance, which was not different from 0 (P = 0.34), whereas horses in the HG group had 5.4 ± 2.4 g/d N balance, which was different from 0 (P = 0.045). Fecal N excretion was greater for the hay group compared with the HG group (hay = 51.1 ± 1.3 g/d and HG = 45.5 ± 1.3 g/d; P = 0.011), and urine N excretion was greater for the HG group compared with the hay group (hay = 79.3 ± 2.8 g/d and HG = 89.2 ± 2.8 g/d; P = 0.026). Plasma AA concentrations were greater in the HG group compared with the hay group for Met (P = 0.001), Lys (P = 0.001), Ile (P = 0.047), Arg (P < 0.001), Gln (P = 0.009), and Orn (P = 0.002). Plasma concentrations were less for the HG group compared with the hay group for Thr (P < 0.001) and Ala (P < 0.001). Plasma concentrations of urea were greater for the HG group compared with the hay group (P < 0.001), whereas 3-methyl-histidine concentrations were greater for the hay group compared with the HG group (P < 0.001). The effect of diet on the excretion of N via feces vs. urine in the hay and HG groups is typical. The early increases in the plasma concentrations of Met, Val, Ile, Leu, Phe, Lys, Arg, and Ala during the postfeeding phase are most likely due to increased foregut digestibility as well as a greater quality AA profile in the grain. The greater concentrations of Thr, Leu, and Val later in the postfeeding phase for the hay group most likely reflects slower digestion because of prolonged consumption time compared with the HG group. Improved N balance observed in the HG group supports the fact that the HG group had more available AA via the AA profile and foregut digestibility of the HG diet. Despite the fact that both groups consumed similar amounts of CP, the AA profile and availability affected N balance.

Effects of feeding triticale dried distillers grains plus solubles as a nitrogen source on productivity of lactating dairy cows

The objective of this study was to compare triticale dried distillers grains plus solubles (TDDGS) as a source of dietary N with other high-protein feeds commonly used in North America: corn dried distillers grains plus solubles (CDDGS), canola meal (CM), and soybean meal (SBM). Rumen degradable protein (% of crude protein, CP) after 16h of incubation in the rumen was higher for CDDGS and TDDGS (69.3% and 64.5%, respectively) than for CM (62.2%) and SBM (53.0%). For the lactation study, experimental diets were formulated to supply 30% of dietary CP from TDDGS, CDDGS, CM, or SBM. These diets contained 22.3% forage neutral detergent fiber and approximately 19.2% CP and were fed to 12 multiparous Holstein cows (130±40 d in milk) in a 4 × 12 Latin rectangle design with 21-d periods. Neither dry matter intake nor milk yield was affected by treatment, averaging 25.5 and 35.5kg/d, respectively. Plasma concentrations of Arg, Lys, and Thr were greater for cows fed CM or SBM compared with those fed TDDGS or CDDGS, whereas plasma concentrations of Leu and Phe were lower for cows fed CM or SBM compared with those fed TDDGS or CDDGS. Cows fed CDDGS had lower milk CP yield compared with cows fed CM (1.07 vs. 1.16kg/d). Contrarily, milk CP and milk lactose yields were not different for cows fed TDDGS compared with CM or SBM. These data suggest that TDDGS can replace CM or SBM in the diets of lactating dairy cows without adverse effects on production. Furthermore, although dried distillers grain has been generally accepted as a feed high in ruminal undegradable protein, CDDGS and TDDGS used in the present study had high in situ ruminal degradable crude protein. Further investigation is warranted to determine the extent of variation in ruminal protein degradation among different types of dried distillers grains.

Oligodendrocyte development and myelinogenesis are not impaired by high concentrations of phenylalanine or its metabolites

Phenylketonuria (PKU) is a metabolic genetic disease characterized by deficient phenylalanine hydroxylase (PAH) enzymatic activity. Brain hypomyelination has been reported in untreated patients, but its mechanism remains unclear. We therefore investigated the influence of phenylalanine (Phe), phenylpyruvate (PP), and phenylacetate (PA) on oligodendrocytes. We first showed in a mouse model of PKU that the number of oligodendrocytes is not different in corpus callosum sections from adult mutants or from control brains. Then, using enriched oligodendroglial cultures, we detected no cytotoxic effect of high concentrations of Phe, PP, or PA. Finally, we analyzed the impact of Phe, PP, and PA on the myelination process in myelinating cocultures using both an in vitro index of myelination, based on activation of the myelin basic protein (MBP) promoter, and the direct quantification of myelin sheaths by both optical measurement and a bioinformatics method. None of these parameters was affected by the increased levels of Phe or its derivatives. Taken together, our data demonstrate that high levels of Phe, such as in PKU, are unlikely to directly induce brain hypomyelination, suggesting involvement of alternative mechanisms in this myelination defect.