Optimization criteria and design of few-mode erbium-doped fibers for cladding-pumped amplifiers

We propose a novel optimization method that combines two design criteria to reduce the differential modal gain (DMG) in few-mode cladding-pumped erbium-doped fiber amplifiers (FM-EDFAs). In addition to the standard criterion that considers the mode intensity and dopant profile overlap, we introduce a second criterion that ensures that all doped regions have the same saturation behavior. With these two criteria, we define a figure-of-merit (FOM) that allows the design of MM-EDFAs with low DMG without high computational cost. We illustrate this method with the design of six-mode erbium-doped fibers (EDFs) for amplification over the C-Band targeting designs that are compatible with standard fabrication processes. The fibers have either a step-index or a staircase refractive index profile (RIP), with two ring-shaped erbium-doped regions in the core. With a staircase RIP, a fiber length of 29 m and 20 W of pump power injected in the cladding, our best design leads to a minimum gain of 22.6 dB while maintaining a DMGmax under 0.18 dB. We further show that the FOM optimization achieves a robust design with low DMG over a wide range of variations in signal power, pump power and fiber length

Pyridoxine (Vitamin B6) and the Glutathione Peroxidase System; a Link between One-Carbon Metabolism and Antioxidation

Vitamin B6 (B6) has a central role in the metabolism of amino acids, which includes important interactions with endogenous redox reactions through its effects on the glutathione peroxidase (GPX) system. In fact, B6-dependent enzymes catalyse most reactions of the transsulfuration pathway, driving homocysteine to cysteine and further into GPX proteins. Considering that mammals metabolize sulfur- and seleno-amino acids similarly, B6 plays an important role in the fate of sulfur-homocysteine and its seleno counterpart between transsulfuration and one-carbon metabolism, especially under oxidative stress conditions. This is particularly important in reproduction because ovarian metabolism may generate an excess of reactive oxygen species (ROS) during the peri-estrus period, which may impair ovulatory functions and early embryo development. Later in gestation, placentation raises embryo oxygen tension and may induce a higher expression of ROS markers and eventually embryo losses. Interestingly, the metabolic accumulation of ROS up-regulates the flow of one-carbon units to transsulfuration and down-regulates remethylation. However, in embryos, the transsulfuration pathway is not functional, making the understanding of the interplay between these two pathways particularly crucial. In this review, the importance of the maternal metabolic status of B6 for the flow of one-carbon units towards both maternal and embryonic GPX systems is discussed. Additionally, B6 effects on GPX activity and gene expression in dams, as well as embryo development, are presented in a pig model under different oxidative stress conditions

Effects of intramuscular injections of folic acid on folates status and growth performance of weanling pigs

In the first of two trials, 24 piglets (2 wk old) were used to measure the dose–response curve of serum folates after intramuscular injections of folic acid (0, 10, 20 or 30 mg). Administration of 10 mg of folic acid was sufficient (P &lt; 0.01) to prevent the decrease of serum folates observed 1 wk after weaning. In the second trial, 72 piglets (2 wk old) were used to study the effect of repeated intramuscular injections of folic acid (0 or 2.5 mg kg−1 of body weight) on hematological status, liver development, and concentrations of serum and hepatic folates, as well as on growth performance up to 10 wk of age. Serum and liver folates were increased (P &lt; 0.01) by repeated injections of folic acid. However, no treatment effects (P &gt; 0.10) were observed on total content of DNA, RNA and protein in the liver. Hemoglobin, hematocrit, total body weight gain, gain: feed ratio and total feed intake were also not influenced (P &gt; 0.10) by the injections of folic acid. Therefore, although a decrease in serum folates is observed during the weaning period, it does not seem to have detrimental effects on the growth performance of weanling piglets. Key words: Folic acid, folates, growth performance, piglets, weaning </jats:p

Bioavailability of Vitamin B12 from Dairy Products Using a Pig Model

The present study compares the bioavailability of vitamin B12 (B12) of dairy products or synthetic B12, using the pig as an experimental model for humans. Eleven pigs were used in a cross-over design to assess the net portal drained viscera (PDV) flux of blood plasma B12 after ingestion of tofu (TF; devoid of B12), Swiss cheese (SC), Cheddar cheese (CC), yogurt (YG), and synthetic B12 (TB12; TF supplemented with cyanocobalamin), providing a total of 25 &micro;g of B12 each. PDV blood plasma flow for SC and CC were higher than for TF and TB12 (p &le; 0.04) whereas YG was higher than TF (p = 0.05). Porto-arterial difference of blood plasma B12 concentrations were higher for CC and TB12 than for TF and YG (p &le; 0.04) but not different from SC (p &ge; 0.15). Net PDV flux of B12 was only different from zero for CC. However, the net PDV flux of B12 for CC was not different from SC or TB12. Cumulative net PDV flux of B12 for SC, TB12, and CC were 2.9, 4.4, and 8.3 &micro;g 23 h post-meal, corresponding to a bioavailability of 11.6%, 17.5%, and 33.0%, respectively. In conclusion, CC had the best bioavailability of B12 among the tested dairy products or compared to synthetic B12

Gene ontology analysis of expanded porcine blastocysts from gilts fed organic or inorganic selenium combined with pyridoxine

Abstract Background Gene ontology analysis using the microarray database generated in a previous study by this laboratory was used to further evaluate how maternal dietary supplementation with pyridoxine combined with different sources of selenium (Se) affected global gene expression of expanded porcine blastocysts. Data were generated from 18 gilts randomly assigned to one of three experimental diets (n = 6 per treatment): i) basal diet without supplemental Se or pyridoxine (CONT); ii) CONT + 0.3 mg/kg of Na-selenite and 10 mg/kg of HCl-pyridoxine (MSeB610); and iii) CONT + 0.3 mg/kg of Se-enriched yeast and 10 mg/kg of HCl-pyridoxine (OSeB610). All gilts were inseminated at their fifth post-pubertal estrus and euthanized 5 days later for embryo harvesting. Differential gene expression between MSeB610 vs CONT, OSeB610 vs CONT and OSeB610 vs MSeB610 was performed using a porcine embryo-specific microarray. Results There were 559, 2458, and 1547 differentially expressed genes for MSeB610 vs CONT, OSeB610 vs CONT and OSeB610 vs MSeB610, respectively. MSeB610 vs CONT stimulated 13 biological processes with a strict effect on RNA binding and translation initiation. OSeB610 vs CONT and OSeB610 vs MSeB610 impacted 188 and 66 biological processes, respectively, with very similar effects on genome stability, ceramide biosynthesis, protein trafficking and epigenetic events. The stimulation of genes related with these processes was confirmed by quantitative real-time RT-PCR. Conclusions Gene expression of embryos from OSeB610 supplemented gilts was more impacted than those from MSeB610 supplemented gilts. Whereas maternal OSeB610 supplementation influenced crucial aspects of embryo development, maternal MSeB610 supplementation was restricted to binding activity

Effects of dietary vitamin supplementation and semen collection frequency on hormonal profile during ejaculation in the boar

International audienceTo evaluate the effect of dietary and management factors on boar hormonal status during ejaculation, 39 boars were canulated to determine the profiles of luteinizing hormone (LH), follicle-stimulating hormone (FSH), 17 beta-estradiol (EA and testosterone (T) in blood plasma and seminal fluid. Prior to canulation, 18 boars were fed a basal diet (control), whereas the remainder (n = 21) were fed a basal diet supplemented with extra vitamins (supplemented). Within each dietary treatment, two regimens of semen collection were used over the 3 mo preceding the hormonal evaluation: three times per 2 wk (3/2) or three times per wk (3/1). Plasma E(2) was lower (P < 0.01) before ejaculation (232.5 +/- 22.6 pg/mL) than at the onset of ejaculation (255.2 +/- 27.1 ng/mL). Plasma T increased from 5.14 +/- 0.72, before ejaculation to 5.87 +/- 0.86 ng/mL at the onset of ejaculation in supplemented boars, whereas it decreased from 5.15 +/- 0.65 to 4.87 +/- 0.70 ng/mL in controls (diet by time, P < 0.05). At the onset of ejaculation, plasma FSH was higher in 3/2 boars (0.436 +/- 0.06 ng/mL) than in 3/1 boars (0.266 +/- 0.04 ng/mL; P < 0.05). During ejaculation, plasma LH increased linearly (P < 0.01) from 0.59 +/- 0.07 to 0.97 +/- 0.10 ng/mL, and plasma E(2) and T concentrations were correlated (r = 0.62, P < 0.01). Plasma FSH before and during ejaculation was negatively correlated with sperm production (r = -0.60, P < 0.01) and testicular weight (r = -0.50, P < 0.01). In conclusion, dietary and management factors had few impacts on hormonal profiles during ejaculation, but homeostasis of some hormones was related to some criteria of reproductive performance in boars

Additional file 3: of Gene ontology analysis of expanded porcine blastocysts from gilts fed organic or inorganic selenium combined with pyridoxine

Table S3. Description of data: Complete list of Gene Ontology terms (GORILLA and REVIGO) related with MSeB610 vs CONT, OSeB610 vs CONT, and OSeB610 vs MSeB610 comparisons. (XLSX 1678 kb