Antioxidants L-carnitine and D-methionine modulate neuronal activity through GABAergic inhibition.

Antioxidants are well known for their neuroprotective properties against reactive oxygen species in cortical neurons and auditory cells. We recently identified L-carnitine and D-methionine to be among agents that provide such protection. Here, we investigated their neuronal modulatory actions. We used cultured neuronal networks grown on microelectrode arrays to assess the effects of L-carnitine and D-methionine on network function. Spike production and burst properties of neuronal networks were used as parameters to monitor pharmacological responses. L-Carnitine and D-methionine reduced spike activity with 100% efficacy with EC50 values of 0.22 (± 0.01) mM and 1.06 (± 0.05) mM, respectively. In the presence of 1.0-40 µM of the GABAA antagonist bicuculline, the sigmoidal concentration-response curves of both compounds exhibited stepwise shifts, without a change in efficacy. Under a maximal bicuculline concentration of 40 µM, the EC50 increased to 3.57 (± 0.26) mM for L-carnitine and to 10.52 (± 0.97) mM for D-methionine, more than a tenfold increase. The agonist-antagonist interactions with bicuculline were estimated by Lineweaver-Burk plot analyses to be competitive, corroborated by the computed dissociation constants of bicuculline. For both compounds, the effects on the network burst pattern, activity reversibility, and bicuculline antagonism resembled that elicited by the GABAA agonist muscimol. We showed that the antioxidants L-carnitine and D-methionine modulate cortical electrical spike activity primarily through GABAA receptor activation. Our findings suggest the involvement of GABAergic mechanisms that perhaps contribute to the protective actions of these compounds.

Local and systemic innate immunity in broiler chickens supplemented with yeast-derived carbohydrates.

A study was conducted to assess the effect of yeast-derived carbohydrates (YDC) on performance and innate immune responses of broiler chickens. In total, 1,080 one-day-old birds were randomly assigned to one of 3 dietary treatments (n = 360): a standard broiler diet containing monensin (control), control + bacitracin methylene disalycylate (BMD), and YDC treatment (control + YDC at 0.02%, 0.01%, and 0.005% for starter, grower, and finisher, respectively). Weekly BW, feed intake (FI), and feed conversion ratio (FCR) were recorded. Immune organ weights, gut morphology, gene expression, heterophil:lymphocyte (H:L), and serum IgG were determined at d 42. No significant difference in FCR, FI, and mortality was observed among treatments. However, BW gain in starter phase was higher in control and YDC treatments compared with BMD treatment. Ileal villi height, crypt depth, and their ratio were not significantly different among treatments, whereas villi width was lower in control and YDC treatments compared with BMD treatment. The number of goblet cells per unit area in the ileum was lower in BMD treatment compared with control and YDC treatments. Expression of TLR2b and IL-6 in the ileum and cecal tonsils was not significantly different among treatments (P > 0.05). Expression of TLR4 was downregulated in YDC treatment compared with control in the ileum. Expression of IL-12p35 and IFN-γ were downregulated in the YDC treatment only in the cecal tonsils. Compared with the control, the expression of IL-10 in both the ileum and the cecal tonsils was downregulated in YDC treatment. Serum IgG and H:L ratio were lower and higher, respectively, in the YDC treatment compared with control and BMD treatments. In conclusion, dietary inclusion of YDC affected intestinal cytokines anti-inflammatory profile on a gut location associated immune pathways manner, suggesting different immune pathways that require further studies in this field.

Innate immune response to yeast-derived carbohydrates in broiler chickens fed organic diets and challenged with Clostridium perfringens.

Necrotic enteritis (NE) caused by Clostridium perfringens is a reemerging disease of economic importance in areas of the world where antibiotic growth promoters have been banned. The effect of mannan-oligosaccharide (MOS) supplementation in organic diets of broilers challenged with C. perfringens on performance, gut morphology, and innate immunity was investigated. Three hundred Ross-308 broilers were fed antibiotic-free certified organic starter and grower diets. On d 14, birds were orally challenged with 1 mL of C. perfringens culture at 3 × 10(10) cfu/bird. Treatments consisted of a control no-challenge (CO; 0 g/kg of MOS in the basal diet), control challenge (COC, 0 g/kg of MOS in the basal diet), and MOS challenge (2 g/kg of MOS in the basal diet). Challenge of birds resulted in decreased feed intake and BW gain (P = 0.048 and P = 0.026, respectively). Even though supplementation of diet with MOS improved feed intake (P = 0.985), BW gain and G:F were not improved compared with those of the CO group (P = 0.026 and P = <0.001, respectively). There was no significant difference among treatments in jejunal and ileal villus height, crypt depth, and goblet cells/mm(2) (P > 0.05). Quantitative real-time PCR showed that, in the ileum, the MOS diet resulted in an upregulation of toll-like receptor (TLR)2b, TLR4, interleukin (IL)-12p35, and interferon (IFN)-γ compared with CO (P = 0.003, P = 0.018, and P = 0.024, respectively). In the cecal tonsil, challenging birds with C. perfringens resulted in an upregulation of TLR2b compared with CO (P = 0.036), and MOS resulted in an upregulation of TLR4 (P = 0.018). In conclusion, feeding a MOS-supplemented diet to C. perfringens-challenged broiler chickens did not improve performance and gut morphology-associated responses. However, MOS was capable of altering TLR and cytokine profiles, where dual TLR2 and TLR4 pathways were associated with MOS supplementation with subsequent upregulation of ileal IL-12p35 and IFN-γ, implying that MOS supplementation in C. perfringens-challenged chickens supports a proinflammatory effect via T-helper cell-1 associated pathways.

Production performance and nitrogen flow of Shaver White layers housed in enriched or conventional cage systems.

Despite the large number of studies examining the impact of cage systems on Ca and P nutrition, data are limited on the N balance of hens when housed under different systems. To this end, an experiment was conducted to assess N balance, manure characteristics, and indices of the performance of laying hens housed in 2 distinct caging systems. A total of 4,836 commercial Shaver White hens were housed in either enriched (EC) or conventional (CC) cages (average floor space per bird of 643 and 468 cm(2), respectively) under semicontrolled environmental conditions. Enriched cages provided hens with a curtained nesting area, scratch pad, and perches. Birds in both systems were phase fed similar layer diets for 11 periods (4 wk each). Data, expressed on a hen basis, were analyzed as repeated measures using the mixed model procedure of SAS. Lower feed disappearance (P < 0.01; 92.5 vs. 95.0 ± 0.6 g/d, DM basis) and manure output (P < 0.01; 79.8 vs. 91.3 ± 1.2 g/d, as-is basis, and 27.0 vs. 28.1 ± 0.2 g/d, DM basis) were observed in birds housed in EC compared with CC, respectively. Manure DM was 34.1 and 31.0 ± 0.3% for EC and CC, respectively. Egg production, feed conversion ratio, BW, egg weight, and egg mass were not significantly different between the 2 systems. Overall egg N output decreased with age for both cage systems and was not significantly different between the systems. Although no difference was observed in the overall manure N excretion (1.94 and 1.96 ± 0.02 g/d for EC and CC, respectively), hens housed in CC had a significantly (P < 0.05) higher N balance compared with those in the EC system (85.0 vs. 30.2 ± 13.6 mg/d, respectively), which could potentially be explained by a higher (P < 0.05) manure N excretion in the EC at the later stages of production. The current data provide estimates of the efficiency of N utilization in laying hens housed under different housing conditions.

Calcium and phosphorus dynamics in commercial laying hens housed in conventional or enriched cage systems.

Calcium (Ca) and phosphorus (P) dynamics in Shaver White hens (19-63 wk of age) were compared between enriched (EC) and conventional cage (CC) systems. Calcium and P intake and their levels in egg components and excreta were considered. Using commercial levels of production (4,836 hens), 10 test cages/system (24 hens/test cage) were used as replicate units. Enriched cages provided a nesting area, scratch pad, perches, and more floor space (643 cm(2)/hen ) than CC (468 cm(2)/hen). All birds were offered similar phase-fed diets based on wheat-soybean formulation and housed under semicontrolled environmental conditions for 11 periods (28 d each). Egg weight, production, and shell quality indices (egg specific gravity, shell weight, thickness, and percentage shell) were also measured. Data were analyzed as a repeated measures design using the MIXED procedure of SAS. Egg production, weight, and shell quality measurements were not significantly different between the 2 systems. On a DM basis, EC hens exhibited lower feed disappearance than CC hens (92.5 vs. 95.0 ± 0.61 g/hen per day, respectively; P < 0.01), and lower Ca and P excretions in manure compared with CC hens (Ca: 2.11 vs. 2.29 ± 0.04 g/hen per day, respectively; P: 0.619 vs. 0.643 ± 0.005 g/hen per day, respectively; P < 0.01). Even though eggs from EC compared with CC had lower Ca deposition (2.07 vs. 2.13 ± 0.01 g/hen per day, respectively; P < 0.0001) and output (38.3 vs. 38.8 ± 0.15 mg/g of egg, respectively; P < 0.05), both EC and CC systems exhibited similar Ca outputs in eggs when expressed as a proportion of Ca intake (56.5 vs. 56.6 ± 0.51% Ca intake, respectively). The overall mean P retention between EC and CC hens was not significantly different (-7.22 vs. -7.45 ± 0.71% P intake, respectively), but Ca retention was higher in EC than CC hens (-1.37 vs. -4.76 ± 0.89% Ca intake, respectively; P < 0.05). In addition to providing environmental enrichment, EC systems may help to reduce Ca and P excretions when compared with CC systems, thereby improving the utilization of these nutrients.

Characterization of folate-dependent enzymes and indices of folate status in laying hens supplemented with folic acid or 5-methyltetrahydrofolate.

The conversion of folic acid (FA) to the biologically active 5-methyltetrahydrofolate (5-MTHF) is necessary for the deposition of folate in the egg. A study was conducted to compare egg folate concentrations, indices of folate status, and activities of folate-dependent enzymes in response to equimolar intake of either FA or 5-MTHF in laying hens. Forty-eight laying hens, 24 wk of age, from 2 different strains (Shaver White and Shaver Brown) were randomly assigned to receive 1 of 3 (n = 8 per strain) dietary treatments: 1) basal diet with no supplemental folate, 2) basal diet + 10 mg/kg of FA, or 3) basal diet + 11.3 mg/kg of 5-MTHF for 3 wk. A completely randomized design with 3 dietary treatments and 2 laying hen strains in a 3 x 2 factorial arrangement was used. Data were subjected to ANOVA, using the PROC GLM procedure of SAS. Plasma homocysteine, serum, and egg folate concentrations; hepatic serine hydroxymethyltransferase; and methionine synthase activity were affected by dietary folate supplementation but not by its form (FA and 5-MTHF). Relative to control hens, plasma homocysteine was decreased (P < 0.05) by 14.2%, whereas serum and egg folate were increased (P < 0.05) by 78.3 and 61.8%, respectively, in hens consuming either folate compound. Hepatic serine hydroxymethyltransferase and methionine synthase activity were increased and decreased (P < 0.05), respectively, in folate-fed birds compared with control-fed birds. Hepatic dihydrofolate reductase was influenced by both the addition and form of dietary folate, being higher (P < 0.05) in FA-fed birds than in 5-MTHF and control-fed birds. Feed efficiency was improved (P < 0.05) in 5-MTHF-fed birds relative to FA-fed birds. Strain of hen influenced serum folate and plasma homocysteine concentrations but not other indices of folate metabolism. Overall, FA and 5-MTHF have equivalent effects in enhancing egg folate concentrations and improving folate status in laying hens. Also, supplementation and form of folate may modulate the activity of folate-dependent enzymes.

Standardized ileal amino acid digestibility in dry-extruded expelled soybean meal, extruded canola seed-pea, feather meal, and poultry by-product meal for broiler chickens.

Ileal digestibility of amino acids (AA) in dry-extruded expelled soybean meal (DESBM), co-extruded canola seed-pea blend (ECSP, 50:50 wt/wt basis), poultry by-product meal (PBPM), and feather meal (FM) were determined in broiler chicks. For each ingredient, 5 samples each collected on different occasions were evaluated. Birds (n = 180 for each sample) were fed a commercial starter diet from d 1 to 15 of age followed by the test diets from d 15 to 21. Dry-extruded expelled soybean meal, ECSP, PBPM, and FM were included in the test diets at 95.3, 95.3, 38.4, and 28.4%, respectively, as the sole source of AA and balanced for minerals and vitamins. Chromic oxide (0.3%) was included in all diets as a digestibility marker. Each diet (5 per ingredient) was randomly assigned to 6 replicate cages, each with 6 birds. On d 21, birds were killed to collect ileal digesta for determining the apparent ileal AA digestibility on cage basis. The standardized ileal digestibility (SID) values were calculated using ileal endogenous AA losses previously determined in our laboratory. The apparent ileal digestibility of AA ranged from 78 to 91%, 68 to 83%, 51 to 81%, and 39 to 74% for DESBM, ECSP, PBPM, and FM, respectively. The respective ranges for SID values were 83 to 96%, 72 to 85%, 58 to 86%, and 42 to 78%. Among the indispensable AA, the lowest SID was observed for Thr in all test ingredients, whereas the highest SID was observed for Phe except in ECSP in which Arg had the highest SID. The SID of Lys (CV) were 91% (2.8%), 79% (2.0%), 78% (7.4%), and 60% (10%) for DESBM, ECSP, PBPM, and FM, respectively, whereas the SID of TSAA (CV) were 88% (4.5%), 77% (2.4%), 74% (9.0%), and 55% (18%), respectively. These SID AA data will help nutritionists to formulate broiler diets that more closely match the birds' requirements and minimize nutrient excess.

Status, perspectives and trends of satellite navigation.

This paper reviews the status of satellite navigation (as per 11 May 2020)-without claim for completeness-and discusses the various global navigation satellite systems, regional satellite navigation systems and satellite-based augmentation systems. Problems and challenges for delivering nowadays a safe and reliable navigation are discussed. New opportunities, perspectives and megatrends of satellite navigation are outlined. Some remarks are closing this paper emphasizing the great value of satellite navigation at present and in future.

Standardized ileal amino acid digestibility in wheat distillers dried grains with solubles for broilers.

A study was conducted to estimate the ileal digestibility of amino acids (AA) in 5 different samples of wheat distillers dried grains with solubles (DDGS) fed to broilers. Two hundred sixteen male Ross broiler chicks were fed a commercial starter diet from d 1 to 15 of age followed by the test diets from d 15 to 21. The 5 test diets consisted of a DDGS sample or wheat as the sole source of AA, dextrose, minerals, and vitamins. Chromic oxide (0.3%) was included in all diets as a digestibility marker. Each test diet was randomly assigned to 6 replicate cages, each with 6 birds. On d 21, birds were killed to sample ileal digesta for determining the apparent (AID) and standardized (SID) ileal AA digestibilities. The SID values were calculated using ileal endogenous AA losses previously determined in our laboratory. Among the indispensable AA in wheat DDGS, the lowest and highest AID average values were observed for Lys (35.6%) and Phe (79.2%), respectively. The most variable AID estimates of wheat DDGS samples were observed for Lys (24.4 to 45.7%), Thr (48.2 to 60.9%), and His (57.4 to 69.1%) as indispensable and Asp (32.5 to 50.9%), Gly (49.6 to 63.1%), and Ala (53.6 to 66.8%) as dispensable AA, respectively. Apparent ileal digestibility estimates of the wheat sample for Lys, Thr, His, Gly, and Ala were 77.5, 74, 83.6, 79.3, and 78.9%, respectively. All AA digestibility estimates for both AID and SID determined in wheat were higher than in wheat DDGS samples (P < 0.05). Considering both AID and SID coefficients of wheat DDGS samples, Lys was the least digestible AA, averaging 35.6 and 40.0%, respectively. Using SID values in practical diet formulation can increase accuracy, prevent overformulation of diets, and reduce cost of safety margins.

Performance and welfare of laying hens in conventional and enriched cages.

Concerns regarding the welfare of laying hens raised in battery cages have led to the development of enriched cages that allow hens to perform natural behaviors including nesting, roosting, and scratching. This study was conducted to compare indices of production and welfare in birds housed in 2 different caging systems. Shaver White hens were housed from 21 to 61 wk in either conventional battery cages (n = 500; 10 cages; 5 hens/cage; floor space = 561.9 cm(2)/hen) or enriched cages (n = 480; 2 cages; 24 hens/cage; floor space = 642.6 cm(2)/hen) and were replicated 10 times. Enriched cages provided hens with a curtained nesting area, scratch pad, and perches. Production parameters and egg quality measures were recorded throughout the experiment. Plumage condition was evaluated at 37 and 61 wk. Bone quality traits and immunological response parameters were measured at 61 wk, and 59 and 61 wk, respectively. Hen-day egg production, feed consumption, egg weight, and percentage of cumulative mortality of laying hens were not affected by the cage designs. Specific gravity and the percentage of cracked and soft-shelled eggs were also similar between the 2 housing systems. The incidence of dirty eggs was, however, significantly higher (P < 0.0001) in enriched cages than in conventional cages. Feather scores were similar between birds except for the wing region, which was higher (P < 0.05) for hens housed in conventional cages. Bone quality measures tended to be higher for hens housed in enriched cages compared with hens in conventional cages. However, the increase was significant only for bone mineral density. Immunological response parameters did not reveal statistically significant differences. Overall, laying performance, exterior egg quality measures, plumage condition, and immunological response parameters appear to be similar for hens housed in the 2 cage systems tested. Enrichment of laying hen cages resulted in better bone quality, which could have resulted from increased activity.

Molecular profiling of angiogenesis with targeted ultrasound imaging: early assessment of antiangiogenic therapy effects.

Molecular ultrasound is capable of elucidating the expression of angiogenic markers in vivo. However, the capability of the method for volumetric "multitarget quantification" and for the assessment of antiangiogenic therapy response has rather been investigated. Therefore, we generated cyanoacrylate microbubbles linked to vascular endothelial growth factor receptor 2 (VEGFR2) and alphavbeta3 integrin binding ligands and quantified their accumulation in squamous cell carcinoma xenografts (HaCaT-ras-A-5RT3) in mice with the quantitative volumetric ultrasound scanning technique, sensitive particle acoustic quantification. Specificity of VEGFR2 and alphavbeta3 integrin binding microbubbles was shown, and changes in marker expression during matrix metalloproteinase inhibitor treatment were investigated. In tumors, accumulation of targeted microbubbles was significantly higher compared with nonspecific ones and could be inhibited competitively by addition of the free ligand in excess. Also, multimarker imaging could successfully be done during the same imaging session. Molecular ultrasound further indicated a significant increase of VEGFR2 and alphavbeta3 integrin expression during tumor growth and a considerable decrease in both marker densities after matrix metalloproteinase inhibitor treatment. Histologic data suggested that the increasing VEGFR2 and alphavbeta3 integrin concentrations in tumors during growth are related to an up-regulation of its expression by the endothelial cells, whereas its decrease under therapy is more related to the decreasing relative vessel density. In conclusion, targeted ultrasound appears feasible for the longitudinal molecular profiling of tumor angiogenesis and for the sensitive assessment of therapy effects in vivo.

Simultaneous electrophysiological and morphological assessment of functional damage to neural networks in vitro after 30-300 g impacts.

An enigma of mild traumatic brain injury are observations of substantial behavior and performance deficits in the absence of bleeding or other observable structural damage. Altered behavior and performance reflect changes in action potential (AP) patterns within neuronal networks, which could result from subtle subcellular responses that affect synaptic efficacy and AP production. The aim of this study was to investigate and quantify network activity changes after simulated concussions in vitro and therewith develop a platform for simultaneous and direct observations of morphological and electrophysiological changes in neural networks. We used spontaneously active networks grown on microelectrode arrays (MEAs) to allow long-term multisite monitoring with simultaneous optical observations before and after impacts delivered by a ballistic pendulum (30 to 300 g accelerations). The monitoring of AP waveshape templates for long periods before and after impact provided an internal control for cell death or loss of cell-electrode coupling in the observed set of neurons. Network activity patterns were linked in real-time to high power phase contrast microscopy. There was no overt loss of glial or neuronal adhesion, even at high-g impacts. All recording experiments showed repeatable spike production responses: a loss of activity with recovery to near reference in 1 hr, followed by a slow activity decay to a stable, level plateau approximately 30-40% below reference. The initial recovery occurred in two steps: a rapid return of activity to an average 24% below reference, forming a level plateau lasting from 5 to 20 min, followed by a climb to within 10% of reference where a second plateau was established for 1 to 2 hrs. Cross correlation profiles revealed changes in firing hierarchy as well as in Phase 1 in spontaneous network oscillations that were reduced by as much as 20% 6-8 min post impact with only a partial recovery at 30 min. We also observed that normally stable nuclei developed irregular rotational motion after impact in 27 out of 30 networks. The evolution of network activity deficits and recovery can be linked with microscopically observable changes in the very cells that are generating the activity. The repeatable electrophysiological impact response profiles and oscillation changes can provide a quantitative basis for systematic evaluations of pharmacological intervention strategies. Future expansion to include fluorescent microscopy should allow detailed investigations of damage mechanisms on the subcellular level.

Pharmacodynamics of streptavidin-coated cyanoacrylate microbubbles designed for molecular ultrasound imaging.

OBJECTIVES: To assess the pharmacodynamic behavior of cyanoacrylate, streptavidin-coated microbubbles (MBs) and to investigate their suitability for molecular ultrasound imaging. MATERIALS AND METHODS: Biodistribution of MBs was analyzed in tumor-bearing mice using gamma-counting, immunohistochemistry, flow cytometry, and ultrasound. Further, vascular endothelial growth factor receptor 2-antibody coupled MBs were used to image tumor neovasculature. RESULTS: After 1 minute >90% of MBs were cleared from the blood and pooled in the lungs, liver, and spleen. Subsequently, within 1 hour a decent reincrease of MB-concentration was observed in the blood. The remaining MBs were removed by liver and spleen macrophages. About 30% of the phagocytosed MBs were intact after 48 hours. Shell fragments were found in the kidneys only. No relevant MB-accumulation was observed in tumors. In contrast, vascular endothelial growth factor receptor 2-specific MBs accumulated significantly within the tumor vasculature (P < 0.05). CONCLUSIONS: The pharmacokinetic behavior of streptavidin-coated cyanoacrylate MBs has been studied. In this context, the low amount of MBs in tumors after >5 minutes is beneficial for specific targeting of angiogenesis.

Spontaneous coordinated activity in cultured networks: analysis of multiple ignition sites, primary circuits, and burst phase delay distributions.

All higher order central nervous systems exhibit spontaneous neural activity, though the purpose and mechanistic origin of such activity remains poorly understood. We quantitatively analyzed the ignition and spread of collective spontaneous electrophysiological activity in networks of cultured cortical neurons growing on microelectrode arrays. Leader neurons, which form a mono-synaptically connected primary circuit, and initiate a majority of network bursts were found to be a small subset of recorded neurons. Leader/follower firing delay times formed temporally stable positively skewed distributions. Blocking inhibitory synapses usually resulted in shorter delay times with reduced variance. These distributions are characterizations of general aspects of internal network dynamics and provide estimates of pair-wise synaptic distances. The resulting analysis produced specific quantitative constraints and insights into the activation patterns of collective neuronal activity in self-organized cortical networks, which may prove useful for models emulating spontaneously active systems.

Dissociation constants for GABA(A) receptor antagonists determined with neuronal networks on microelectrode arrays.

Changes in spontaneous spike activities from murine frontal cortex networks grown on microelectrode arrays were used to determine the dissociation constants of three GABA(A) antagonists: gabazine, bicuculline, and trimethylolpropane phosphate (TMPP). Networks were treated with fixed concentrations of antagonists and titrated with the GABA(A) receptor agonist muscimol. Muscimol decreased spike activity in a concentration-dependent manner with full efficacy (100% spike inhibition). A sigmoidal curve fit provided a 50% inhibitory concentration (IC(50)) of 0.14+/-0.05muM (mean+/-S.D., n=5). Increasing concentrations of the three antagonists shifted the muscimol concentration response curves (CRCs) to the right with the same efficacy. Schild plot analyses with linear regressions resulted in slopes that are statistically not different from unity and provided X-intercepts (dissociation constants) of 0.23, 0.61, and 3.98muM for gabazine, bicuculline, and TMPP, respectively. Corresponding pA2 values (-logK(B)) were 6.64, 6.21, and 5.40. The dissociation constants for gabazine and bicuculline agree well with those obtained with other methods. The TMPP K(B) has not yet been reported in the literature. The data suggest that spontaneously active networks on microelectrode arrays can be used as reliable platforms for rapid quantitative pharmacological investigations.

Comparison of various methods for endogenous ileal amino acid flow determination in broiler chickens.

The purpose of this study was to compare estimates of ileal endogenous amino acid (IEAA) losses determined in broiler chicks with a nitrogen-free diet (NFD), diets containing highly digestible proteins as intact casein or enzymatically hydrolyzed casein (EHC), and the regression method (RM). Male Ross 308 broiler chicks were fed a commercial starter diet from d 1 to 15 of age and the following test diets from d 15 to 21: NFD and diets containing 5, 10, or 15% casein or EHC as the sole protein source. All diets contained chromic oxide as a digestibility marker. Each diet was assigned to 6 replicate cages, with 10 birds each. On d 21, birds were euthanized to sample ileal digesta. Feeding increasing levels of EHC or casein linearly (P<0.0001) increased IEAA flow. Nonlinearity (P<0.05) was detected for Ile, Val, Glu, and Ser with EHC and for Met with casein. Compared with the NFD method, IEAA values extrapolated to zero EHC or casein intake were similar for all amino acids except Ile (200 vs. 321 mg/kg of DM intake), Val (270 vs. 341 mg/ kg of DM intake), Ala (217 vs. 262 mg/kg of DM intake), and Ser (343 vs. 577 mg/kg of DM intake), whose flows were higher with EHC (P<0.05). The present results show that IEAA values determined with the NFD, EHC, and casein diets, at different inclusion levels, were different for most amino acids and that, for all amino acids, the values obtained with NFD and RM involving feeding graded levels of casein or EHC were comparable. Thus, using IEAA values obtained with either the NFD or the RM to calculate standardized ileal amino acid digestibility coefficients will give similar values.

The effect of enzyme supplementation on egg production parameters and omega-3 fatty acid deposition in laying hens fed flaxseed and canola seed.

An experiment was conducted to investigate the effects of a multicarbohydrase enzyme on egg production parameters, nutrient digestibility, and egg fatty acid composition in Hy-Line CV-20 laying hens (39 to 63 wk of age) fed diets containing 150 g/kg of diet of canola seed, flaxseed, or Linpro (flaxseed:peas, 1:1 wt/wt). The diet effect on each parameter was also evaluated. Hens consuming the canola seed and Linpro diets had greater egg production, lower feed consumption, and therefore better feed conversion than those fed the flaxseed diets. Enzyme supplementation significantly increased (P < 0.01) egg production (from 78.0 to 80.9%) and improved (P < 0.001) feed conversion ratio (from 2.15 to 2.03) in hens fed flaxseed. Hens fed the canola seed and Linpro diets produced eggs with greater egg specific gravity than those from birds consuming flaxseed. Enzyme supplementation significantly increased egg specific gravity in hens fed flaxseed (from 1.0773 to 1.0800, P < 0.01) in phase I of the experiment. There was no effect of diet on fat digestibility, and similar fat digestibility values with enzyme supplementation were observed for canola seed (92.1 vs. 96.7%) and flaxseed (87.4 vs. 92.4%). Eggs produced by hens fed flaxseed had the greatest n-3 fatty acid content (562 mg/60 g of egg) when compared with those from hens consuming canola seed (207 mg/60 g of egg) or Linpro (427 mg/60 g of egg). Enzyme supplementation increased the egg n-3 content for the flaxseed diet (from 546 to 578 mg/60 g of egg; P = 0.01) and for the Linpro diet (from 415 to 438 mg/60 g of egg; P = 0.05). In addition, enzyme addition increased the egg docosahexaenoic acid content from 91.8 to 101.9 mg/60 g of egg (P < 0.01) and from 89.4 to 96.8 mg/60 g of egg (P = 0.01) for the flaxseed and Linpro diets, respectively. When compared with canola seed, long-term feeding of flaxseed to laying hens resulted in reduced egg production and eggshell quality. Enzyme supplementation had positive effects on feed utilization, eggshell quality, and n-3 fatty acid deposition in the egg.

Functional structure of cortical neuronal networks grown in vitro.

We apply an information-theoretic treatment of action potential time series measured with microelectrode arrays to estimate the connectivity of mammalian neuronal cell assemblies grown in vitro. We infer connectivity between two neurons via the measurement of the mutual information between their spike trains. In addition we measure higher-point multi-information between any two spike trains, conditional on the activity of a third cell, as a means to identify and distinguish classes of functional connectivity among three neurons. The use of a conditional three-cell measure removes some interpretational shortcomings of the pairwise mutual information and sheds light on the functional connectivity arrangements of any three cells. We analyze the resultant connectivity graphs in light of other complex networks and demonstrate that, despite their ex vivo development, the connectivity maps derived from cultured neural assemblies are similar to other biological networks and display nontrivial structure in clustering coefficient, network diameter, and assortative mixing. Specifically we show that these networks are weakly disassortative small-world graphs, which differ significantly in their structure from randomized graphs with the same degree. We expect our analysis to be useful in identifying the computational motifs of a wide variety of complex networks, derived from time series data.

Pharmacological response sensitization in nerve cell networks exposed to the antibiotic gentamicin.

Gentamicin is an aminoglycoside antibiotic that is used in clinical, organismic, and agricultural applications to combat gram-negative, aerobic bacteria. The clinical use of gentamicin is widely linked to various toxicities, but there is a void in our knowledge about the neuromodulatory or neurotoxicity effects of gentamicin. This investigation explored the electrophysiologic effects of gentamicin on GABAergic pharmacological profiles in spontaneously active neuronal networks in vitro derived from auditory cortices of E16 mouse embryos and grown on microelectrode arrays. Using the GABAA agonist muscimol as the test substance, responses from networks to dose titrations of muscimol were compared in the presence and absence of 100µM gentamicin (the recommended concentration for cell culture conditions). Spike-rate based EC50 values were generated using sigmoidal fit concentration response curves (CRCs). Exposure to 100µM gentamicin exhibited a muscimol EC50±S.E.M. of 80±6nM (n=10). The EC50 value obtained in the absence of gentamicin was 124±11nM (n=10). The 35% increase in potency suggests network sensitization to muscimol in the presence of gentamicin. Action potential (AP) waveform analyses of neurons exposed to gentamicin demonstrated a concentration-dependent decrease in AP amplitudes (extracellular recordings), possibly reflecting gentamicin effects on voltage-gated ion channels. These in vitro results reveal alteration of pharmacological responses by antibiotics that could have significant influence on the behavior and performance of animals.

Total dust and endotoxin in poultry operations: comparison between cage and floor housing and respiratory effects in workers.

OBJECTIVE: The objective of this study was to assess respiratory outcomes and environmental exposure levels of workers in cage-housed and floor-housed poultry operations. METHODS: Poultry operations were evaluated for total dust, endotoxin, and ammonia, and respiratory symptoms and lung function tests of workers were conducted. RESULTS: Workers in floor-housed poultry operations had significantly greater exposures to total dust and ammonia, whereas workers from cage-housed poultry operations reported greater frequency of current and chronic symptoms overall and significantly greater current and chronic phlegm (39% vs 18% and 40% vs 11%, respectively). Endotoxin concentration (EU/mg) was a significant predictor (P = 0.05) of chronic phlegm for all poultry workers. CONCLUSIONS: Greater endotoxin concentration in the presence of significantly lower total dust, in conjunction with greater respiratory symptoms in workers from cage-housed poultry operations, as compared with workers from floor-housed poultry operations, appears to indicate that differences in environmental exposures may impact respiratory outcomes of workers.