Browsing by Subject "arginine"
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Item A Novel Role for Arginine in Enhancing Neonatal Thermogenesis(2012-10-19) Greff, Sorin MeredithMaintenance of body temperature is one of the first and most important physiological processes that must be initiated after birth. Failure to sustain homeothermy leads to hypothermia and death. Indeed, in sheep, 40% of non-predator lamb deaths are attributed to cold and cold-related causes. Brown adipose tissue (BAT) is an essential mediator of thermogenesis in many species and is responsible for 50% of the heat generated in the newborn lamb despite comprising only 2% of body weight. Previously, we found that maternal arginine supplementation increased fetal peri-renal BAT by 62%. This observation led us to test the hypothesis that increased the amount of fetal BAT will enhance neonatal thermogenesis at birth and thus combat the effects of cold stress. Thirty-one multiparous Suffolk ewes gestating singletons and twins were assigned to receive either intravenous injections of L-arginine (27 mg/kg bodyweight; n=17) or sterile saline (n=14) three times daily from Day 75 to Day 125 of gestation (term=147). Following parturition lambs were removed from their dams, placed in a thermoneutral environment, and fed artificial colostrum on a per body weight basis. At 4 hours of age, lambs were cold challenged at 0 degrees C for 2 hours. Rectal temperatures were recorded at 15 minute intervals. At 6 hours of age all singletons and one lamb of each twin pair was sacrificed. The remaining twin lamb was challenged again at 22 hours of age for an additional 2 hours prior to necropsy. Rectal temperature was greater for the duration of both cold challenges in lambs from arginine-treated ewes than lambs from saline-treated ewes (P<0.050). Interestingly, at time of necropsy, BAT weight did not differ (P>0.10) between treatments. UCP1 mRNA levels were not affected by treatment or age (P>0.10). However, TEK, PPARGC1A, NRF1, NRF2, PPARG, ADRB3, ARG2, RPS6KA1, EIF4EBP1, ODC1 were not affected by treatment (P>0.10) but were upregulated (P<0.05) by age; being greater at 24 hours of age versus 6 hours of age. Results indicate that maternal arginine treatment results in increased neonatal thermogenesis after birth. Although the underlying mechanisms remain to be elucidated, the data reported herein represent the first step in improving neonatal survival in response to cold.Item The AAX system from Chlamydia pneumoniae(2009-12) Smith, Conor Blake; Graham, David E.; Hoffman, David; Meyer, Richard; Trent, Stephen; Whiteley, MarvinArginine uptake and degradation systems are common throughout bacteria and archaea. The genome of human pathogen Chlamydia pneumoniae encodes three proteins now called AaxA, AaxB, and AaxC which function together to take up arginine, decarboxylate it, and expel the decarboxylation product, agmatine. AaxB is the previously characterized pyruvoyl-dependent arginine decarboxylase, AaxC is an inner membrane amino acid transport protein that functions as an arginine-agmatine antiporter, and AaxA is an outer membrane porin, which facilitates the uptake of arginine and also functions as a general porin with broad specificity. C. pneumoniae is a non-typical Gram negative bacteria and an obligate intracellular parasite with a unique 2-phase life cycle. The role of this system for arginine-agmatine exchange has yet to be determined but it may function to deplete host cell arginine as a means of inactivating host inducible nitric oxide synthase (iNOS), a molecule used in the innate immune response that has been shown to have an inhibitory affect on the growth of C. pneumoniae in cell culture. AaxB and AaxC are able to complement the loss of extreme acid-resistance in E. coli mutants that lack their own system for arginine-agmatine exchange, making pH homeostasis another possible role for this system. The porin AaxA is able to enhance arginine-agmatine exchange by AaxB and AaxC in E. coli mutants as well as by the native arginine decarboxylase AdiA and the native arginine-agmatine antiporter AdiC in wild type E. coli. AaxA is not an arginine-specific porin and instead acts as a general porin with a broad specificity. AaxA discriminates only against large and negatively charged solute molecules, and therefore it may have a broad role in the uptake of various biomolecules essential for chlamydial growth in addition to its role as part of a system for arginine-agmatine exchange.Item Arginine and Conjugated Linoleic Acid Reduce Fat Mass in Rats(2010-10-12) Nall, Jennifer L.We hypothesized that subcutaneous (s.c.) adipose tissue would differ in monounsaturated (MUFA) and saturated fatty acid (SFA) composition among different depots throughout a beef carcass. To test this, 50 carcasses from a variety of breed types and backgrounds were sampled. External fat samples were collected from eight different carcass locations: round, sirloin, loin, rib, chuck, brisket, plate and flank. Samples were used to provide information on slip points, fatty acid composition and MUFA:SFA ratios. Lipids were extracted from s.c. adipose tissue by a modified chloroform:methanol procedure, and fatty acid composition and slip points were measured. The brisket was significantly lower in palmitic (16:0) and stearic (18:0) acid than the other seven sampling sites (P = 0.001). The brisket demonstrated the highest values of MUFA (P = 0.001) with the exception of possessing the lowest value of transvaccenic (18:1t11) acid (P = 0.002). There were also significant differences in the amounts of PUFA among the eight sampling sites. The lowest values were from the brisket with a mean of 25.1. The flank had the highest slip point with a mean of 39.0 (P ? 0.001). There was a high negative correlation shown between palmitoleic and stearic acid (R2 = 0.827). The brisket displayed the highest values for MUFA:SFA ratios (P = 0.001), whereas the flank was the lowest. Due to the significant differences amongst fat depots within bovine carcasses in their fatty acid composition we conclude that substantial differences exist across fat depots.Item Arginine and fetal growth in ovine models of intrauterine growth restriction(2009-05-15) Lassala, Arantzatzu LeticiaThis research was conducted to test the hypothesis that parenteralarginine supplementation is effective in enhancing birth weights of intrauterinegrowth restricted (IUGR) fetuses. Underfed and prolific ewes were used asexperimental models. The first study characterized the pharmacokinetics ofarginine and citrulline and assessed the potential of citrulline to serve as aprecursor for enhancing arginine availability in fetal and maternal plasma. Sixlate pregnant ewes and their fetuses were instrumented to access arterial andvenous circulations. Intravenous boluses of 155 mol of L-arginine-HCl or Lcitrullineper kg body weight were administered to each ewe. Administration ofcitrulline was more effective than arginine in achieving a sustained increase inconcentrations of arginine in maternal and fetal blood. Accordingly, theclearance rate of citrulline was lower and its biological half-life in maternal bloodgreater, when compared with arginine. The second experiment determined ifadministration of arginine to underfed ewes is effective in ameliorating orpreventing IUGR. Ewes were fed either 100% or 50% of the National ResearchCouncil recommended nutrient requirements for pregnant sheep. Between Day60 of pregnancy and parturition control-fed ewes received saline solution and underfed ewes received either saline solution or L-arginine-HCl solution (155mol of arginine/kg body weight) intravenously three times daily (n=5 / treatmentgroup). Birth weights of lambs were lower in saline-infused underfed ewes.There was no difference in birth weights of lambs from control-fed and argininetreatedunderfed ewes. The third experiment determined whether administrationof arginine could improve survival rates of lambs and enhance fetal growth inewes carrying multiple fetuses. Between Days 100 and 121 of pregnancy, ewesreceived an intravenous infusion of either saline solution (n= 14) or L-arginine-HCl solution (345 mol of arginine/kg body weight, n=20) three times daily.Parenteral administration of arginine increased the percentage of lambs bornalive and enhanced the birth weights of quadruplets. Collectively, these resultsindicate that 1) parenteral administration of arginine improves pregnancyoutcomes in underfed and prolific ewes; and 2) the use of arginine or citrullinemay have important implications for the design of an effective treatment forpreventing or ameliorating IUGR in mammals.Item Evaluation of amino acid supplementation of soybean-meal-based diets for hybrid striped bass(2009-05-15) Savolainen, Lea ChristineHybrid striped bass (Morone chrysops x M. saxatilis) aquaculture is a major commercial enterprise in the United States and internationally. Efforts to decrease diet costs and limit dependence on fishmeal, have led to the development of plant-based diets as an alternative aquafeed. Due to limiting concentrations of amino acids such as methionine, cystine, and taurine in plant meals such as soybean meal, supplementation of these plant-based diets with methionine or other sulfur amino acid compounds is typically required. Therefore, the current study was conducted to evaluate different amino acid supplements in soybean-meal-based diets for hybrid striped bass for possible refinement of diets and reduction of production costs. One feeding trial evaluated methionine hydroxy analog (MHA) and Mintrex? which is MHA containing chelated zinc relative to L-methionine. The second trial evaluated the effects of supplemental taurine or arginine on fish performance and potential health benefits. In the first feeding trial, a basal soybean-meal-based diet (56% soybean meal and 15% fishmeal) marginally deficient in total sulfur amino acids (TSSA) (1.10% methionine and cystine) was supplemented with either L-methionine, Mintrex? or MHA calcium salt and fed to triplicate groups of juvenile hybrid striped bass for 10 weeks. The different methionine supplements provided similar weight gain, feed efficiency ratio (FER) and protein efficiency ratio (PER) values that tended to be greater than observed in fish fed the basal diet. Mintrex? supplementation provided much higher plasma zinc concentrations compared to fish fed the other methionine supplements. In the second feeding trial, soybean-meal based diets which satisfied the requirement for TSAA were supplemented with either taurine or arginine at 1.5% of dry weight. Supplemental taurine or arginine did not provide any improvements in weight gain, FER, PER or survival compared to the basal diet. Thus, taurine or arginine supplementation of soybean-meal-based diets does not appear warranted. However, sulfur amino acid supplementation of plant-based diets is critical, and Mintrex? appears to be an effective supplement to meet the methionine and zinc needs of hybrid striped bass.Item Evaluation of Potential Dietary Arginine-Lysine Antagonism in Red Drum Sciaenops ocellatus(2013-09-03) Fauzi, Ichsan ATwo feeding trials were conducted to evaluate possible dietary arginine-lysine antagonisms in the red drum (Sciaenops ocellatus). In the first feeding trial, seven dietary treatments with arginine levels of 1.0, 1.25, 1.5 (previously established requirement), 1.75, 2.0, 2.5 and 3.0% of dry diet with lysine at the previously established requirement of 1.6%, and three diets with arginine at 1.75% and lysine at 1.75, 2.05 and 2.65% of dry diet were evaluated. In the second trial, similar treatments were used except the highest level of arginine (2.8% of dry diet) was combined with a higher level of lysine (2.5% of dry diet) to evaluate low and high levels of arginine and lysine in a factorial arrangement. Each feeding trial was conducted with juvenile red drum in 38-L aquaria connected as a recirculating system with the first trial continuing for 9 weeks and the second trial for 8 weeks. In the first feeding trial, fish were stocked as groups of 12 fish initially averaging 1.57 g/fish and in the second trial groups consisted of 15 fish initially averaging 2.51 g/fish. The feeding rate was initially set at 6% of body weight per day and adjusted equally among dietary treatments as the fish grew to maintain a level close to satiation without overfeeding. Results from both feeding trials indicated that red drum fed the lowest dietary arginine level had the lowest weight gain. Other parameters such as feed efficiency, protein retention and plasma amino acid concentrations also showed that high levels of dietary arginine did not significantly increase fish performance or interfere with lysine utilization. In terms of dietary lysine, increasing concentrations above the previously determined requirement level tended to increase growth performance of the fish, although a significant difference was only found in the first trial. Therefore, based on the results of both feeding trials, no antagonism between dietary arginine and lysine was evident in red drum.Item Influence of Maternal Plane of Nutrition and Arginine Supplementation on Mares and Their Foals: Glucose and Insulin Dynamics(2012-10-19) Hanson, AndreaThirty-two Quarter horse mares (468 to 668 kg BW; 3 to 19 yr) were utilized in a randomized complete block design. Animals were blocked by expected foaling date and randomly assigned to treatments within block. Treatments began 110 d prior to expected foaling date and were arranged as a 2 x 2 factorial consisting of two planes of nutrition, moderate (Mod; 0.5% BW as fed grain/d) or high (High; 1% BW as fed grain/d) and two levels of L-arginine supplementation, 0.21 g/kg BW/d (Arg) or no supplemental Arg (Con; L-alanine to maintain isonitrogenous diets). Mares were housed by block, allowed ad libitum access to water and coastal bermudagrass (Cynodon dactylon) hay, and fed commercial grain twice daily in individual stalls. A modified frequent sampling i.v. glucose tolerance test (FSIGT) was performed on mares during the 11th month gestation and on foals at 5 and 30 d of age. Jugular catheters were placed 1 h before FSIGT, and horses were allowed ad libitum access to bermudagrass hay and water throughout. After a baseline plasma sample was collected, a glucose bolus of 0.3 g/kg BW was administered. Blood samples were collected at 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, and 19 min. At minute 20, an insulin bolus of 30 mU/kg BW was administered. Blood samples continued to be collected at 22, 23, 24, 25, 27, 30, 35, 40, 50, 60, 70, 80, 90, 100, 120, 150, and 180 min. Samples were placed into tubes containing sodium heparin, immediately placed on ice, and centrifuged within 20 min. Plasma was then collected, placed in microtubes and frozen at -20 degrees C for later analysis. Glucose concentrations were analyzed using a colorimetric assay and insulin concentrations determined using a commercial RIA kit. There was no influence of dietary treatment on mare glucose area under the curve (AUCg) or peak glucose (PG) and insulin (PI) concentrations (P >= 0.55). Mare insulin area under the curve (AUCi) tended to be influenced by the interaction between nutritional plane and ARG supplementation (P <= 0.06) with HighCon mares having greater AUCi than ModCon (P <= 0.05), and HighCon mares having greater AUCi than mares fed HighArg (P <= 0.05). Foal AUCg, AUCi, and PI were not influenced by maternal diet. However, PG concentration in foals tended to be influenced by mare AA supplementation with foals from Con mares having higher concentrations compared to Arg (P <= 0.09) An influence of age was observed on foal AUCg and AUCi. Foal AUCg was greater at 5 d compared to 30 d (P <= 0.003). Foal AUCi tended to be greater at 30 d compared to 5 d (P <= 0.08). Data suggest maternal plane of nutrition and arginine supplementation can alter mare and foal glucose and insulin dynamics.