Transcriptome Analysis of Plasmodium falciparum Isolates From Benin Reveals Specific Gene Expression Associated With Cerebral Malaria.

Cerebral malaria (CM) is the severest form of Plasmodium falciparum infection. Children under 5 years old are those most vulnerable to CM, and they consequently have the highest risk of malaria-related death. Parasite-associated factors leading to CM are not yet fully elucidated. We therefore sought to characterize the gene expression profile associated with CM, using RNA sequencing data from 15 CM and 15 uncomplicated malaria isolates from Benin. Cerebral malaria parasites displayed reduced circulation times, possibly related to higher cytoadherence capacity. Consistent with the latter, we detected increased var genes abundance in CM isolates. Differential expression analyses showed that distinct transcriptome profiles are signatures of malaria severity. Genes involved in adhesion, excluding variant surface antigens, were dysregulated, supporting the idea of increased cytoadhesion capacity of CM parasites. Finally, we found dysregulated expression of genes in the entry into host pathway that may reflect greater erythrocyte invasion capacity of CM parasites.

PfEMP1 A-Type ICAM-1-Binding Domains Are Not Associated with Cerebral Malaria in Beninese Children.

PfEMP1 is the major antigen involved in Plasmodium falciparum-infected erythrocyte sequestration in cerebrovascular endothelium. While some PfEMP1 domains have been associated with clinical phenotypes of malaria, formal associations between the expression of a specific domain and the adhesion properties of clinical isolates are limited. In this context, 73 cerebral malaria (CM) and 98 uncomplicated malaria (UM) Beninese children were recruited. We attempted to correlate the cytoadherence phenotype of Plasmodium falciparum isolates with the clinical presentation and the expression of specific PfEMP1 domains. Cytoadherence level on Hbec-5i and CHO-ICAM-1 cell lines and var genes expression were measured. We also investigated the prevalence of the ICAM-1-binding amino acid motif and dual receptor-binding domains, described as a potential determinant of cerebral malaria pathophysiology. We finally evaluated IgG levels against PfEMP1 recombinant domains (CIDRα1.4, DBLß3, and CIDRα1.4-DBLß3). CM isolates displayed higher cytoadherence levels on both cell lines, and we found a correlation between CIDRα1.4-DBLß1/3 domain expression and CHO-ICAM-1 cytoadherence level. Endothelial protein C receptor (EPCR)-binding domains were overexpressed in CM isolates compared to UM whereas no difference was found in ICAM-1-binding DBLß1/3 domain expression. Surprisingly, both CM and UM isolates expressed ICAM-1-binding motif and dual receptor-binding domains. There was no difference in IgG response against DBLß3 between CM and UM isolates expressing ICAM-1-binding DBLß1/3 domain. It raises questions about the role of this motif in CM pathophysiology, and further studies are needed, especially on the role of DBLß1/3 without the ICAM-1-binding motif.IMPORTANCE Cerebral malaria pathophysiology remains unknown despite extensive research. PfEMP1 proteins have been identified as the main Plasmodium antigen involved in cerebrovascular endothelium sequestration, but it is unclear which var gene domain is involved in Plasmodium cytoadhesion. EPCR binding is a major determinant of cerebral malaria whereas the ICAM-1-binding role is still questioned. Our study confirmed the EPCR-binding role in CM pathophysiology with a major overexpression of EPCR-binding domains in CM isolates. In contrast, ICAM-1-binding involvement appears less obvious with A-type ICAM-1-binding and dual receptor-binding domain expression in both CM and UM isolates. We did not find any variations in ICAM-1-binding motif sequences in CM compared to UM isolates. UM and CM patients infected with isolates expressing the ICAM-1-binding motif displayed similar IgG levels against DBLß3 recombinant protein. Our study raises interrogations about the role of these domains in CM physiopathology and questions their use in vaccine strategies against cerebral malaria.

Moringa oleifera-rich diet and T cell calcium signaling in spontaneously hypertensive rats.

Moringa oleifera is a plant whose fruits, roots and leaves have been advocated for traditional medicinal uses. The physicochemical analysis shows that Moringa oleifera contains more dietary polyunsaturated fatty acids (PUFA) than saturated fatty acids (SFA). The consumption of an experimental diet enriched with Moringa oleifera extracts lowered blood pressure in spontaneously hypertensive rats (SHR), but not in normotensive Wistar-Kyoto (WKY) rats as compared to rats fed an unsupplemented control diet. Anti-CD3-stimulated T cell proliferation was diminished in both strains of rats fed the Moringa oleifera. The experimental diet lowered secretion of interleukin-2 in SHR, but not in WKY rats compared with rats fed the control diet. Studies of platelets from patients with primary hypertension and from SHR support the notion that the concentration of intracellular free calcium [Ca(2+)](i) is modified in both clinical and experimental hypertension. We observed that the basal, [Ca(2+)](i) was lower in T cells of SHR than in those of WKY rats fed the control diet. Feeding the diet with Moringa oleifera extracts to WKY rats did not alter basal [Ca(2+)](i) in T cells but increased basal [Ca(2+)](i) in SHR. Our study clearly demonstrated that Moringa oleifera exerts antihypertensive effects by inhibiting the secretion of IL-2 and modulates T cell calcium signaling in hypertensive rats.

Preferential expression of domain cassettes 4, 8 and 13 of Plasmodium falciparum erythrocyte membrane protein 1 in severe malaria imported in France.

OBJECTIVES: Severe Plasmodium falciparum malaria (SM) involves cytoadhesion of parasitized red blood cells, mediated by P. falciparum erythrocyte membrane protein 1, which is encoded by var genes. Expression of var gene group A and B or encoding domain cassettes DC4, DC5, DC8 and DC13 has been implicated in SM in African children, but no data exist in the context of imported malaria. The aim of this study was to investigate var gene expression linked to clinical presentation and host factors in SM imported into France. METHODS: Expression level of var gene groups A, B, C, var1, var2csa, var3 and var genes encoding DC4, DC5, DC8 and DC13 was measured by quantitative RT-PCR and expressed in transcript units. Seventy SM and 48 uncomplicated malaria (UM) P. falciparum cases were analysed according to disease severity, epidemiological characteristics (migrants or travellers) and anti-P. falciparum antibodies. Cluster analysis was performed to identify gene expression profiles. RESULTS: Var1 and B/C expression were higher in UM than SM (0.66 (0-1.1) and 1.88 (1.3-2.4); p <0.04, respectively). Group C expression differed between migrants and travellers (0.21 (0-0.75) versus 0 (0-0); p 0.002). Group A differed in naive and pre-exposed patients (1.1 (0.7-1.5) versus 0.4 (0-1.1); p 0.01). Population clusters revealed increased expression from group A and B var genes, and DC4, DC8 and DC13 in SM. CONCLUSIONS: These results corroborate the implication of DC4, DC8 and DC13 in severe imported malaria cases as African children, and their expression depends of host factors.

Computational Fluid Dynamic Simulations of Maternal Circulation: Wall Shear Stress in the Human Placenta and Its Biological Implications.

INTRODUCTION: In the human placenta the maternal blood circulates in the intervillous space (IVS). The syncytiotrophoblast (STB) is in direct contact with maternal blood. The wall shear stress (WSS) exerted by the maternal blood flow on the STB has not been evaluated. Our objective was to determine the physiological WSS exerted on the surface of the STB during the third trimester of pregnancy. MATERIAL AND METHODS: To gain insight into the shear stress levels that the STB is expected to experience in vivo, we have formulated three different computational models of varying levels of complexity that reflect different physical representations of the IVS. Computations of the flow fields in all models were performed using the CFD module of the finite element code COMSOL Multiphysics 4.4. The mean velocity of maternal blood in the IVS during the third trimester was measured in vivo with dynamic MRI (0.94±0.14 mm.s-1). To investigate if the in silico results are consistent with physiological observations, we studied the cytoadhesion of human parasitized (Plasmodium falciparum) erythrocytes to primary human STB cultures, in flow conditions with different WSS values. RESULTS: The WSS applied to the STB is highly heterogeneous in the IVS. The estimated average values are relatively low (0.5±0.2 to 2.3±1.1 dyn.cm-2). The increase of WSS from 0.15 to 5 dyn.cm-2 was associated with a significant decrease of infected erythrocyte cytoadhesion. No cytoadhesion of infected erythrocytes was observed above 5 dyn.cm-2 applied for one hour. CONCLUSION: Our study provides for the first time a WSS estimation in the maternal placental circulation. In spite of high maternal blood flow rates, the average WSS applied at the surface of the chorionic villi is low (<5 dyn.cm-2). These results provide the basis for future physiologically-relevant in vitro studies of the biological effects of WSS on the STB.

Socio-economic differences in healthcare access from a welfare system perspective, Italy: 2007-2010.

Inequalities between poorer and wealthier people in accessing healthcare services have been widely studied, but the mechanisms generating them are still to be fully understood. Among these, there is still a lack of evidence of relationships between health prevention/health promotion policies, welfare systems and social differences. We analysed 68 201 females from the PASSI Italian surveillance system for the years 2007-2010. The prevalence of women undergoing Pap testing was used as an example of access to preventive services. An odds ratio gradient was found with regard to different welfare system clusters: the probability of undergoing a screening test is higher for more advanced welfare systems. A strong association was found between having received a letter from the local health unit and having undergone the screening test. Significant differences still exist between high- and low-income women and their access to Italian preventive public services. As we expected, social determinants play an important role in health disparities, as these are also strongly influenced by typologies of welfare systems and by health policies.

Effects of dietary selenium supplementation on tissue selenium distribution and glutathione peroxidase activity in Chinese Ring necked Pheasants.

The objective of this study was to determine the concentration of total selenium (Se) and the proportions of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in the postmortem tissues of female pheasants (Phasianus Colchicus Torquator) offered diets that contained graded additions of selenised-enriched yeast (SY) or a single comparative dose of sodium selenite (SS). Thiobarbituric acid reactive substances (TBARS) and tissue glutathione peroxidase (GSH-Px) activity of breast (Pectoralis Major) were assessed at 0 and 5 days postmortem. A total of 216 female pheasant chicks were enrolled into the study. Twenty-four birds were euthanased at the start of the study, and samples of blood, breast muscle, leg muscle (M. Peroneus Longus and M. Gastrocnemius), heart, liver, kidney and gizzard were collected for determination of total Se. Remaining birds were blocked by live weight and randomly allocated to one of four dietary treatments (n = 48 birds/treatment) that either differed in Se source (SY v. SS) or dose (control (0.17 mg total Se/kg), SY-L and SS-L (0.3 mg/kg total Se as SY and SS, respectively) and SY-H (0.45 mg total Se/kg)). Following 42 and 91 days of treatment, 24 birds per treatment were euthanased, and samples of blood, breast muscle, leg muscle, heart, liver, kidney and gizzard were retained for determination of total Se and the proportion of total Se comprised as SeMet or SeCys. Whole blood GSH-Px activity was determined at each time point. Tissue GSH-Px activity and TBARS were determined in breast tissue at the end of the study. There were increases in both blood and tissues to the graded addition of SY to the diet (P < 0.001), but the same responses were not apparent with the blood and tissues of selenite-supplemented birds receiving a comparable dose (SY-L v. SS-L). Although there were differences between tissue types in the distribution of SeMet and SeCys, there were few differences between treatments. There were effects of treatment on erythrocyte GSH-Px activity (P = 0.012) with values being higher in treatments SY-H and SS-L when compared with the negative control and treatment SY-L. There were no effects of treatment on tissue GSH-Px activity, which is reflected in the overall lack of any treatment effects on TBARS.

Effect of dietary supplementation with selenium-enriched yeast or sodium selenite on selenium tissue distribution and meat quality in commercial-line turkeys.

The objective of this study was to determine the concentration of total selenium (Se) and proportions of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in the tissues of female turkeys offered diets containing graded additions of selenized-enriched yeast (SY), or sodium selenite (SS). Oxidative stability and tissue glutathione peroxidase (GSH-Px) activity of breast and thigh muscle were assessed at 0 and 10 days post mortem. A total of 216 female turkey poults were enrolled in the study. A total of 24 birds were euthanized at the start of the study and samples of blood, breast, thigh, heart, liver, kidney and gizzard were collected for determination of total Se. Remaining birds were blocked by live weight and randomly allocated to one of four dietary treatments (n = 48 birds/treatment) that differed either in Se source (SY v. SS) or dose (Con [0.2 mg/kg total Se], SY-L and SS-L [0.3 mg/kg total Se as SY and SS, respectively] and SY-H [0.45 mg total Se/kg]). Following 42 and 84 days of treatment 24 birds per treatment were euthanized and samples of blood, breast, thigh, heart, liver, kidney and gizzard were retained for determination of total Se and the proportion of total Se comprised as SeMet or SeCys. Whole blood GSH-Px activity was determined at each time point. Tissue GSH-Px activity and thiobarbituric acid reactive substances were determined in breast and thigh tissue at the end of the study. There were responses (P < 0.001) in all tissues to the graded addition of dietary Se, although rates of accumulation were highest in birds offered SY. There were notable differences between tissue types and treatments in the distribution of SeMet and SeCys, and the activity of tissue and erythrocyte GSH-Px (P < 0.05). SeCys was the predominant form of Se in visceral tissue and SeMet the predominant form in breast tissue. SeCys contents were greater in thigh when compared with breast tissue. Muscle tissue GSH-Px activities mirrored SeCys contents. Despite treatment differences in tissue GSH-Px activity, there were no effects of treatment on any meat quality parameter.

Optokinetic stimulation rehabilitation in preventing seasickness.

OBJECTIVES: Seasickness occurs when traveling on a boat: symptoms such as vomiting are very disturbing and may be responsible for discontinuing travel or occupation and can become life-threatening. The failure of classical treatment to prevent seasickness has motivated this retrospective study exploring optokinetic stimulation in reducing these symptoms. PATIENTS AND METHODS: Experimental training of 75 sailors with optokinetic stimulation attempted to reduce seasickness manifestations and determine the factors that could predict accommodation problems. RESULTS: Eighty percent of the trained subjects were able to return on board. No predictive factors such as sex, occupation, degree of illness, number of treatment sessions, time to follow-up, and age were found to influence training efficacy. CONCLUSION: Optokinetic stimulation appears to be promising in the treatment of seasickness. Nevertheless, statistically significant results have yet to demonstrate its efficacy.

Modification of aflatoxin B1 and ochratoxin A toxicokinetics in rats administered a yeast cell wall preparation.

The cell wall of Saccharomyces cerevisiae can bind mycotoxins in vitro, but there is scarce information on whether this property decreases the absorption of mycotoxins in vivo. The effect of a yeast cell wall preparation (YCW) on toxicokinetics and balance excretion (urine and faeces) of aflatoxin B(1) (AFB1) and ochratoxin A (OTA) was tested in rats after oral administration of each toxin. The (3)H-labelled mycotoxins were used at low doses. Co-administration of YCW with AFB1 decreased the extent, but not the rate, of absorption. Concurrently, radioactivity excreted in faeces increased by up to 55% when compared with controls, whilst the excretion in urine decreased (p < 0.05). The effect of YCW on OTA was less marked, although it increased radioactivity excretion in faeces (up to 16%; p < 0.05) it did not result in changes in urine and toxicokinetic parameters. The in vivo effect is in agreement with the reported in vitro binding ability for these toxins (AFB1 > OTA). In conclusion, these results indicate that YCW could be used to protect monogastric animals against exposure to low dietary levels of selected mycotoxins.

Metabolic and hematological profiles in mature horses supplemented with different selenium sources and doses.

This study was conducted to determine the effects of dietary Se source and dose on metabolic and hematological profiles, and their relationships with oxidative status in horses. Twenty-five mature horses were blocked by BW and randomly allocated to 1 of 5 dietary treatments: negative control (CTRL: 0.085 mg of Se/kg of DM), 3 different dietary concentrations of organic Se provided by Se yeast (SY02, SY03, and SY04 containing 0.2, 0.3, and 0.4 mg of total Se/kg of DM, respectively), and 1 positive control provided by sodium selenite (SS03 containing 0.3 mg of total Se/kg of DM). Horses were fed the same basal diet (6 kg of grass hay and 3 kg of concentrate per horse daily) and received their respective treatments for a continuous period of 112 d. Jugular venous blood samples were collected before the morning feed on d 0, 28, 56, 84, and 112. Whole blood was analyzed for hematological profile, and plasma was analyzed for metabolites of energy, protein, and mineral metabolism; enzymatic activities and metabolites related to liver and muscle damage; and markers of inflammatory and oxidative status. Plasma metabolites related to energy, protein, and mineral metabolism, acute phase proteins, and enzyme activities related to hepatocellular, hepatobiliary, and muscle damage were not affected by Se source or dose. There were no differences among treatments in either reactive oxygen metabolites or thiol group concentrations in plasma. However, a linear decrease (P < 0. 01) in plasma total antioxidants was observed with increasing Se yeast supplementation. Furthermore, total antioxidant concentrations were less in SY03 than SS03 horses (P < 0.05), and were less in SY03 and SY04 than CTRL horses (P < 0.05). These results could be interpreted as an improvement in the preventive antioxidant systems of horses fed Se yeast. Total white blood cell count was not affected by treatment. There was a tendency for horses receiving greater concentrations of Se yeast to have greater lymphocyte counts (P = 0.09), with greater lymphocyte counts in blood of SY03 vs. SS03 horses (P < 0.05). Despite the lack of effect of Se source and dose on markers of inflammatory and liver status, the hematological profile seems to indicate an immunomodulatory action, as shown by mild changes in the white blood cell populations in response to Se yeast inclusion.

Effect of live yeast culture supplementation on hindgut microbial communities and their polysaccharidase and glycoside hydrolase activities in horses fed a high-fiber or high-starch diet.

Four cecum and right ventral colon-fistulated horses were assigned in a 4 x 4 Latin square design and fed a high-fiber (HF) or a high-starch (HS) diet with or without 10 g of Saccharomyces cerevisiae (SC; CBS 493.94) containing 4.5 x 10(9) cfu/g. The HF and HS diets consisted of pelleted feeds and long wheat straw (18.0 and 3.5 g of DM.kg(-1) of BW.d(-1), respectively) given in 2 equal meals to provide an NDF:starch ratio of 3.5 and 1.0, respectively. After a 21-d adaptation period intestinal contents were collected 4 h after the morning meal on d 23 and 25 to determine bacterial and SC concentrations. Polysaccharidase activities (CMCase, xylanase, amylase) and activities of glycoside hydrolases (alpha-l-arabinosidase, beta-d-cellobiosidase, beta-d-glucosidase, beta-d-xylosidase) were determined in liquid-associated bacteria (LAB) and solid-adherent bacteria (SAB) isolated from both compartments. Lactobacilli were increased in the cecum (P = 0.012) and colon (P = 0.086) when starch intake increased, whereas total anaerobes, cellulolytics, and streptococci did not change in either compartment. In yeast-supplemented horses, SC concentrations were greater in cecum (4.4 x 10(6) cfu/mL) than in right-ventral colon (5.6 x 10(4) cfu/mL) and did no change with diet. Concentrations of lactobacilli and lactic-acid utilizers were greater (P = 0.099 and 0.067, respectively) in the cecum but remained similar in the colon of SC-supplemented horses. The CMCase activities of SAB were not affected by diet. Colonic xylanase activities of SAB were reduced (P = 0.046) by starch addition, but no change was seen in the cecum. All SAB glucoside hydrolase activities in the cecum and colon, except beta-d-xylosidase in the cecum, were decreased when starch intake was increased. The LAB CMCase (P = 0.049 in the colon) and xylanase (P = 0.021 in the cecum; P < 0.001 in the colon) activities decreased with starch intake. No effect of starch on LAB or SAB amylase activity was observed. Addition of SC improved SAB CMCase in the cecum (P = 0.019) and colon (P = 0.037) as well as beta-d-cellobiosidase (P = 0.002) and beta-d-glucosidase (P = 0.041) in the cecum. Only xylanase in the cecum (P = 0.015) and beta-d-xylosidase in the cecum (P = 0.028) were improved with SC, whereas colonic LAB alpha-amylase activity was significantly decreased (P = 0.046). Most enzymes involved in plant cell wall digestion were increased after SC addition. This fact may contribute to explain a better digestion of fiber that has been previously reported in SC-supplemented horses.

Meta-analysis of the influence of Saccharomyces cerevisiae supplementation on ruminal parameters and milk production of ruminants.

The effects of yeast supplementation on intake, production, and rumen fermentation characteristics have been widely studied, but results are inconsistent between different studies. A quantitative meta-analysis was applied to 110 papers, 157 experiments, and 376 treatments dealing with yeast supplementation in ruminants. The objective was first to highlight the major quantitative effects of live yeast supplementation on intake, rumen fermentation, and milk production, and second, to identify major differences in experimental conditions between studies that can affect the response to treatment. Some of these experimental conditions are referred to as interfering factors. Yeast supplementation increased rumen pH (+0.03 on average) and rumen volatile fatty acid concentration (+2.17 mM on average), tended to decrease rumen lactic acid concentration (-0.9 mM on average), and had no influence on acetate-to-propionate ratio. Total-tract organic matter digestibility was also increased by yeast supplementation (+0.8% on average). Yeast supplementation increased dry matter intake (DMI; +0.44 g/kg of body weight; BW), milk yield (+1.2 g/kg of BW), and tended to increase milk fat content (+0.05%), but had no influence on milk protein content. Dose effects of yeast supplementation, expressed as log(10) [1+(cfu per 100 kg of BW)], globally confirmed the qualitative effects observed in the first analysis. The positive effect of yeast supplementation on rumen pH increased with the percentage of concentrate in the diet and with the DMI level. It was negatively correlated with the level of dietary neutral detergent fiber (NDF). The positive effect of yeast supplementation on rumen volatile fatty acid concentration increased with DMI and crude protein levels. The positive effect of yeast supplementation on organic matter digestibility increased with the percentage of concentrate and NDF in the diet. The negative effect of yeast supplementation on lactic acid concentration tended to decrease when the DMI level and the percentage of concentrate in the diet increased. The effects of interfering factors were globally similar when either dose effect or qualitative effect of yeast was taken into account. Although rumen fermentation efficiency per se was not measured, these results suggest an improvement in rumen fermentation by yeast supplementation. This effect could, however, be modulated by several different factors such as DMI, percentage of concentrate or NDF in the diet, or species.

Effect of selenium source and dose on selenium status of mature horses.

This study was conducted to determine the effects of either dietary Se source or dose on the Se status of horses. Twenty-five mature horses were blocked by BW and randomly allocated to 1 of 5 dietary treatments that comprised the same basal diet that differed only in Se source or dose. Treatments were as follows: negative control (0.085 mg of Se/kg of DM), 3 different dietary concentrations of supplemental organic Se (Se yeast; 0.2, 0.3, and 0.4 mg of total Se/kg of DM), and positive control (0.3 mg of total Se/kg of DM) supplemented with Na selenite. Horses initially received the control diet (6 kg of grass hay and 3 kg of concentrate per horse daily) for 56 d to allow diet adaptation. After the period of diet adaptation, horses were offered their respective treatments for a continuous period of 112 d. Jugular venous blood samples were collected before the morning feed on d 0, 28, 56, 84, and 112. Whole blood and plasma were analyzed for total Se, glutathione peroxidase activity in whole blood (GPX-1) and plasma, and thyroid hormones (thyroxine and triiodothyronine) in plasma. The proportion of total Se as selenomethionine (SeMet) or selenocysteine in pooled whole blood and plasma samples was determined on d 0, 56, and 112. Data were analyzed as repeated measures. Total Se in blood and plasma and GPX-1 activity were greater in all supplemented horses (P < 0.001, except P < 0.01 for GPX-1 in horses supplemented with the least dose of Se yeast) with a linear dose effect of Se yeast for whole blood and plasma Se (P < 0.001) and a quadratic dose effect (P < 0.05) for whole blood GPX-1 activity. A plateau for total Se in plasma was achieved within 75 to 90 d, although this was not observed in blood total Se or GPX-1 activity. On d 84 and 112, horses supplemented with Se yeast showed greater total Se in blood (P < 0.05) compared with horses supplemented with Na selenite, and a source effect (P < 0.05) was observed in the relationship between total blood Se and GPX-1 activity. Selenocysteine (the predominant form of Se in whole blood and plasma) increased in all horses supplemented with Se. The SeMet content of whole blood and plasma increased in horses supplemented with Se yeast, but it was not observed in those supplemented with selenite. The rate of increase in SeMet over time was greater in whole blood (P < 0.05) and plasma (P = 0.10) with the Se yeast product. In conclusion, Se yeast was more effective than Na selenite in increasing total Se in blood, mainly as consequence of a greater increase of the proportion of Se comprised as SeMet, but it did not modify GPX-1 activity.

Effects of selenium source and level of supplementation on the performance and meat quality of lambs.

Objective of this study was to evaluate the performance, the quality and oxidative stability of meat, the total Se and specific selenoamino-acids content of muscle of lambs that were fed diets supplemented from different Se sources and at different levels. Forty-eight Apennine lambs 30day old (12.78±0.94kg) received, during a 63day period, a total mixed ration (TMR) which was either Se unsupplemented (Control group - background only- 0.13mg/kg Se) or supplemented with Na selenite (0.30mg/kg Se as sodium selenite) or selenium enriched yeast (0.30mg/kg and 0.45mg/kg Se as Se-yeast). Growth performance, feed to gain ratio, carcass and meat quality (pH, drip and cooking losses, colour, GSH-Px activity and chemical analysis) did not show any difference between the treatments. Meat colour and oxidative stability during 9 days of refrigerated storage were unaffected by dietary supplementation, suggesting that, at the levels of Se used in this experiment, dietary Se, even from an organic source, had limited potential for reducing lipid oxidation. Selenium supplementation raised the Se content in muscle (P<0.001) with the greatest increase when Se-yeast was fed. Although selenite increased total Se, it did not influence total or specific selenoamino-acids in this tissue. On the contrary, Se-yeast supplementation led to an increase in muscle Se-methionine content. We conclude that Se supplementation can increase significantly muscle Se levels and produce, particularly when Se-yeast is fed, a source of Se enriched meat as Se-methionine.

Effect of dietary supplementation with selenium-enriched yeast or sodium selenite on selenium tissue distribution and meat quality in beef cattle.

The objective was to determine the concentration of total Se and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in postmortem tissues of beef cattle offered diets containing graded additions of selenized enriched yeast (SY; Saccharomyces cerevisiae CNCM I-3060) or sodium selenite (SS). Oxidative stability and tissue glutathione peroxidase (GSH-Px) activity of edible muscle tissue were assessed 10 d postmortem. Thirty-two beef cattle were offered, for a period of 112 d, a total mixed ration that had been supplemented with SY (0, 0.15, or 0.35 mg of Se/kg of DM) or SS (0.15 mg of Se/kg of DM). At enrollment (0 d) and at 28, 56, 84, and 112 d following enrollment, blood samples were taken for Se and Se species determination, as well as whole blood GSH-Px activity. At the end of the study beef cattle were killed and samples of heart, liver, kidney, and skeletal muscle (LM and psoas major) were retained for Se and Se species determination. Tissue GSH-Px activity and thiobarbituric acid reactive substances were determined in skeletal muscle tissue (LM only). The incorporation into the diet of ascending concentrations of Se as SY increased whole blood total Se and the proportion of total Se comprised as SeMet, as well as GSH-Px activity. There was also a dose-dependent response to the graded addition of SY on total Se and proportion of total Se as SeMet in all tissues and GSH-Px activity in skeletal muscle tissue. Furthermore, total Se concentration of whole blood and tissues was greater in those animals offered SY when compared with those receiving a comparable dose of SS, indicating an improvement in Se availability and tissue Se retention. Likewise, GSH-Px activity in whole blood and LM was greater in those animals offered SY when compared with those receiving a comparable dose of SS. However, these increases in tissue total Se and GSH-Px activity appeared to have little or no effect in meat oxidative stability.

Subclinical doses of T-2 toxin impair acquired immune response and liver cytochrome P450 in pigs.

This study was designed to investigate the effect of subclinical doses of T-2 toxin on liver drug-metabolizing enzymes and the immune response. Pigs were offered over a 28-day period either a control diet or diets contaminated with 540, 1324 or 2102microg pure T-2toxin/kg feed. Pigs were immunized with ovalbumin and subsequent humoral and cellular immune responses measured. Monooxygenase and transferase enzyme activities and protein expression were investigated in liver tissue samples. Pigs fed 1324 or 2102microg T-2toxin/kg feed exhibited reduced anti-ovalbumin antibody production without significant alteration to specific lymphocyte proliferation. The livers of pigs exposed to T-2 toxin presented normal cytochrome P450 content, UGT 1A and P450 2B, 2C or 3A protein expression, and glutathione- and UDP glucuronosyl-transferase activities. However, P450 1A related activities (ethoxyresorufin O-deethylation and benzo-(a)-pyrene hydroxylation) were reduced for all pigs given T-2 toxin, with P450 1A protein expression decreased in pigs fed the highest dose. In addition T-2 toxin exposure reduced certain N-demethylase activities. The results of this study confirm the immunotoxic properties of T-2 toxin, in particular toward the humoral immune response. The reduction of monooxygenase activities, even though the liver presented no tissue lesion or lipid peroxidation, suggests possible deleterious interactions of T-2 toxin with these enzymes.

Tolerance of ruminant animals to high dose in-feed administration of a selenium-enriched yeast.

The objective of the study was to determine if there were adverse effects on animal health and performance when a range of ruminant animal species were fed at least 10 times the maximum permitted European Union (EU) Se dietary inclusion rate (0.568 mg of Se/kg of DM) in the form of Se-enriched yeast (SY) derived from a specific strain of Saccharomyces cerevisiae, CNCM I-3060. In a series of studies, dairy cows, beef cattle, calves, and lambs were offered a control diet that contained no Se supplement or a treatment diet that contained the same basal feed ingredients plus a SY supplement that increased total dietary Se from 0.15 to 6.25, 0.20 to 6.74, 0.15 to 5.86, and 0.14 to 6.63 mg of Se/kg of DM, respectively. The inclusion of the SY supplement increased (P < 0.001) whole-blood Se concentrations, reaching maximum mean values of 716, 1,505, 1,377, and 724 ng of Se/mL for dairy cattle, beef cattle, calves, and lambs, respectively. Seleno-methionine accounted for 10% of total whole-blood Se in control animals, whereas the proportion in SY animals ranged between 40 and 75%. Glutathione peroxidase (EC 1.11.1.9) activity was greater (P < 0.05) in SY animals compared with controls. A range of other biochemical and hematological parameters were assessed, but few differences of biological significance were established between treatment groups. There were no differences between treatment groups within each species with regard to animal physical performance or overall animal health. It was concluded that there were no adverse effects on animal health, performance, and voluntary feed intake with the administration of at least 10 times the EU maximum, or approximately 20 times the US Food and Drug Administration permitted concentration of dietary Se in the form of SY derived from a specific strain of Saccharomyces cerevisiae CNCM I-3060.

Effect of live yeast culture supplementation on apparent digestibility and rate of passage in horses fed a high-fiber or high-starch diet.

Eight crossbred male horses aged 12 +/- 5 yr and with BW of 305 +/- 18 kg were used in pairs in a 4 x 4 Latin square design with 4 ground and pelleted diets. Each pair included a cecum and right ventral colon-fistulated animal and a cecal-fistulated animal. The 4 horse diets were a high-fiber diet (HF+0) based on dehydrated alfalfa, a high-starch diet based on barley and wheat bran (HS+0), and the HF or HS diets supplemented with Saccharomyces cerevisiae (SC) CBS 493.94 (HF+SC and HS+SC). The probiotic preparation contained 4.5 x 10(9) cfu/g of live yeast mixed with the culture medium, and was top-dressed onto the feed pellets at a rate of 10 g/d, equally distributed between the 2 daily meals. All 4 diets were offered in the same quantities (18.0 g of pelleted feed DM + 3.5 g of long wheat straw/kg of BW per d). Each of the 4 experimental treatments was divided into a 21-d period of diet adaptation followed by a 10-d period of total fecal collection for digesta flow rate and apparent digestibility measurements. Three markers were used to measure mean retention time (MRT) of the feed particles: Yb bound to the pelleted feeds for MRT in the whole digestive tract (MRT(Yb)), Eu bound to the pelleted feeds, and Dy bound to the fecal particles for MRT in the hindgut (MRT(Eu) and MRT(Dy)). Apparent digestibilities of DM, OM, and CP were greater (P < 0.001) in the HS than HF diet, independently of SC supplementation, whereas ADF digestibility was greatest in the HF diet (P = 0.035). Cellulolytic activity estimated through the in vitro disappearance rate of the dietary ADF fraction (IVAD(ADF)) was less (P < 0.001) in the HS than the HF diet. There was no dietary effect on NDF digestibility due to the longer MRT(Eu) of small particles in the hindgut (P = 0.036), which compensated for the lower fibrolytic activity expressed per unit of time in the HS compared with the HF diet. Supplementation with SC improved ADF digestibility (P = 0.038) and stimulated DM (P = 0.030) and NDF (P = 0.038) intakes, but had no effect on the MRT of solid digesta. The absence of any significant diet x SC interaction supports the strategy of using SC to stimulate cellulose digestion and improve the nutritional status of horses under both HF and HS diets.

Selenium supplementation of lactating dairy cows: effects on milk production and total selenium content and speciation in blood, milk and cheese.

Forty multiparous Holstein cows were used in a 16-week continuous design study to determine the effects of either selenium (Se) source, selenised yeast (SY) (derived from a specific strain of Saccharomyces cerevisiae CNCM I-3060) or sodium selenite (SS), or Se inclusion rate in the form of SY in the diets of lactating dairy cows on the Se concentration and speciation in blood, milk and cheese. Cows received ad libitum a total mixed ration (TMR) with a 1 : 1 forage : concentrate ratio on a dry matter (DM) basis. There were four diets (T1 to T4), which differed only in either source or dose of Se additive. Estimated total dietary Se for T1 (no supplement), T2 (SS), T3 (SY) and T4 (SY) was 0.16, 0.30, 0.30 and 0.45 mg/kg DM, respectively. Blood and milk samples were taken at 28-day intervals and at each time point there were positive linear effects of Se in the form of SY on the Se concentration in blood and milk. At day 112, blood and milk Se values for T1 to T4 were 177, 208, 248 and 279 ± 6.6 and 24, 38, 57 and 72 ± 3.7 ng/g fresh material, respectively, and indicate improved uptake and incorporation of Se from SY. In whole blood, selenocysteine (SeCys) was the main selenised amino acid and the concentration of selenomethionine (SeMet) increased with the increasing inclusion rate of SY. In milk, there were no marked treatment effects on the SeCys content, but Se source had a marked effect on the concentration of SeMet. At day 112, replacing SS (T2) with SY (T3) increased the SeMet concentration of milk from 36 to 111 ng Se/g and its concentration increased further to 157 ng Se/g dried sample as the inclusion rate of SY increased further (T4) to provide 0.45 mg Se/kg TMR. Neither Se source nor inclusion rate affected the keeping quality of milk. At day 112, milk from T1, T2 and T3 was made into a hard cheese and Se source had a marked effect on total Se and the concentration of total Se comprised as either SeMet or SeCys. Replacing SS (T2) with SY (T3) increased total Se, SeMet and SeCys content in cheese from 180 to 340 ng Se/g, 57 to 153 ng Se/g and 52 to 92 ng Se/g dried sample, respectively. The use of SY to produce food products with enhanced Se content as a means of meeting the Se requirements is discussed.