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1.
Burrin DG Stoll B Jiang R Petersen Y Elnif J Buddington RK Schmidt M Holst JJ Hartmann B Sangild PT 《American journal of physiology. Gastrointestinal and liver physiology》2000,279(6):G1249-G1256
We wished to determine whether exogenous glucagon-like peptide (GLP)-2 infusion stimulates intestinal growth in parenterally fed immature pigs. Piglets (106-108 days gestation) were given parenteral nutrient infusion (TPN), TPN + human GLP-2 (25 nmol. kg(-1). day(-1)), or sow's milk enterally (ENT) for 6 days. Intestinal protein synthesis was then measured in vivo after a bolus dose of [1-(13)C]phenylalanine, and degradation was calculated from the difference between protein accretion and synthesis. Crypt cell proliferation and apoptosis were measured in situ by 5-bromodeoxyuridine (BrdU) and terminal dUTP nick-end labeling (TUNEL), respectively. Intestinal protein and DNA accretion rates and villus heights were similar in GLP-2 and ENT pigs, and both were higher (P < 0.05) than in TPN pigs. GLP-2 decreased fractional protein degradation rate, whereas ENT increased fractional protein synthesis rate compared with TPN pigs. Percentage of TUNEL-positive cells in GLP-2 and ENT groups was 48 and 64% lower, respectively, than in TPN group (P < 0.05). However, ENT, but not GLP-2, increased percentage of BrdU-positive crypt cells above that in TPN piglets. We conclude that GLP-2 increases intestinal growth in premature, TPN-fed pigs by decreasing proteolysis and apoptosis, whereas enteral nutrition acts via increased protein synthesis and cell proliferation and decreased apoptosis. 相似文献
2.
Sangild PT Malo C Schmidt M Petersen YM Elnif J Holst JJ Buddington RK 《American journal of physiology. Regulatory, integrative and comparative physiology》2007,293(6):R2179-R2184
Exogenous glucagon-like peptide 2 (GLP-2) prevents intestinal atrophy and increases nutrient absorption in term newborn pigs receiving total parenteral nutrition (TPN). We tested the hypothesis that the immature intestine of fetuses and preterm neonates has a diminished nutrient absorption response to exogenous GLP-2. This was accomplished using catheterized fetal pigs infused for 6 days (87-91% of gestation) with GLP-2 (25 nmol.kg(-1).day(-1) iv; n = 7) or saline (n = 7), and cesarean-delivered preterm pigs (92% of gestation) that received TPN with GLP-2 (25 nmol.kg(-1).day(-1) iv; n = 8) or saline (n = 7) for 6 days after birth. Responses to GLP-2 were assessed by measuring intestinal dimensions, absorption of nutrients (glucose, leucine, lysine, proline) by intact tissues and brush border membrane vesicles, and abundance of sodium-glucose cotransporter mRNA. Infusion of GLP-2 increased circulating GLP-2 levels in fetuses, but did not increase intestinal mass or absorption of nutrients by intact tissues and brush border membrane vesicles, except for lysine. Administration of exogenous GLP-2 to preterm TPN-fed pigs similarly did not increase rates of nutrient absorption, yet nutrient absorption capacities of the entire small intestine tended to increase (+10-20%, P < 0.10) compared with TPN alone due to increased intestinal mass (+30%, P < 0.05). GLP-2 infusion did not increase sodium-glucose cotransporter-1 mRNA abundance in fetuses or postnatal preterm pigs. Hence, the efficacy of exogenous GLP-2 to improve nutrient absorption by the intestine of fetal and preterm pigs is limited compared with term pigs and more mature animals and humans. 相似文献
3.
Bjornvad CR Schmidt M Petersen YM Jensen SK Offenberg H Elnif J Sangild PT 《American journal of physiology. Regulatory, integrative and comparative physiology》2005,289(4):R1212-R1222
Preterm birth and formula feeding predispose to small intestinal dysfunction, which may lead to necrotizing enterocolitis (NEC). In piglets, we tested whether the physiological and environmental transitions occurring at birth affect the response of the immature intestine to enteral feeding. Pig fetuses (106 days gestation, term = 115 days) were prepared with esophageal feeding tubes and fed either sow's colostrum (n = 8) or infant formula (n = 7) in utero. After 24 h of oral feeding, the pig fetuses were delivered by cesarean section and their gastrointestinal morphology and function were compared with those of preterm newborn (NB) littermates that were not fed (n = 8) or fed colostrum (n = 7) or formula (n = 13) for 24 h after birth. Before birth, both colostrum and formula feeding resulted in marked increases in intestinal mass, brush-border enzyme activities, and plasma glucagon-like peptide 2 concentrations, to levels similar to those in NB colostrum-fed piglets. In contrast, NB formula-fed piglets showed reduced intestinal growth, decreased brush-border enzyme activities, and intestinal lesions, reflecting NEC. NB formula-fed pigs also showed impaired enterocyte endocytotic function and decreased antioxidative capacity, whereas brush-border enzyme mRNA levels were unaltered, relative to NB colostrum-fed pigs. Our results indicate that the feeding-induced growth and enzyme maturation of the immature intestine are not birth dependent. However, with a suboptimal diet (milk formula), factors related to preterm birth (e.g., microbial colonization and metabolic and endocrine changes) make the immature intestine sensitive to atrophy and development of NEC. 相似文献
4.
Pineda L Sawosz E Hotowy A Elnif J Sawosz F Ali A Chwalibog A 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2012,161(3):315-319
This investigation evaluated the effects of nanoparticles of silver (AgNano) and gold (AuNano) on metabolic rate (O2 consumption, CO2 production and heat production-HP) and the development of embryos from different breeds of broiler and layer chicken. Gaseous exchange was measured in an open-air-circuit respiration unit, and HP was calculated for 10, 13, 16 and 19-day-old embryos. Relative chick and muscle weights were used as a measure of growth rate and development. AgNano but not AuNano increased the rates of O2 consumption and HP of the layer embryos. The metabolic rate of broiler embryos was not affected by either of the treatments, but it was significantly higher compared to the layer embryos. Neither of the nanoparticles promoted nor depressed growth and development of the embryos, irrespective of breed. Although the metabolic rate of AgNano-injected layer embryos was significantly increased, their BW and muscle weights at hatching were similar to those of the control group, which suggests that the concentration of AgNano used was adequate for increasing the metabolic rate but not enough to affect growth and development. The results show that AgNano could be a potential metabolic modifier for layer embryos; however, the exact mechanism of action should be elucidated in future research. 相似文献
5.
Elnif J Buddington RK Hansen NE Sangild PT 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2006,176(3):233-241
Glucocorticoids from endogenous and exogenous sources accelerate maturation of brush-border membrane (BBM) hydrolases in omnivorous
laboratory rodents and pigs. Less is known for carnivores, and whether the route of administration (oral or systemic) has
an influence. The present study examined the influence of administering cortisol (hydrocortisone succinate, 5 mg/kg-day) to
mink during postnatal week 4, just prior to weaning, on small intestine glucose and amino acid (aspartate, leucine, lysine,
methionine, proline) absorption and on the activities of BBM disaccharidases and peptidases. Kits treated with cortisol were
smaller (P<0.05), but had small intestines that were proportionally larger (P<0.05 for length and mass per kg body weight, but not for mucosal mass) than control kits with higher rates of absorption
for most nutrients, except leucine, and increased activities of most BBM hydrolases, except lactase. As a consequence, cortisol
increased hydrolytic and absorptive capacities of the entire small intestine, with the responses more pronounced when the
cortisol was given orally. These findings indicate administration of cortisol stimulates growth of the developing mink small
intestine, but does not accelerate the postnatal declines in nutrient transport, and may be a dam-to-kit signal that prepares
suckling mink to digest and absorb the adult diet. 相似文献
6.
Caroline Trebbien Gottlieb Line Elnif Thomsen Hanne Ingmer Per Holse Mygind Hans-Henrik Kristensen Lone Gram 《BMC microbiology》2008,8(1):205
Background
Host defense peptides (HDPs), or antimicrobial peptides (AMPs), are important components of the innate immune system that bacterial pathogens must overcome to establish an infection and HDPs have been suggested as novel antimicrobial therapeutics in treatment of infectious diseases. Hence it is important to determine the natural variation in susceptibility to HDPs to ensure a successful use in clinical treatment regimes. 相似文献7.
Total numbers of aerotolerant and anaerobic bacteria, and densities of Enterobacteriaceae, lactobacilli, staphylococci, salmonella and shigella, and campylobacteria were enumerated in the contents of the stomach, small intestine (and the associated mucosa), and colon of mink beginning at 2 weeks of age to adulthood, and in adults that were fed diets with different levels and types of fiber or food deprived. Highest densities of all bacterial groups were found in the colon at all ages (up to 108 cfu per g for total anaerobes), but were 2–4 orders of magnitude lower than those of other mammals. When all regions were pooled, significant age-related increases (p<0.05) were detected for anaerobes, aerobes, and staphylococci, and these coincided with the dietary shift at weaning. Enterobacteriaceae did not vary with age. Lactobacilli were never common isolates, but were detected more often after weaning, particularly in adults fed diets containing the 2 sources of fiber. Campylobacteria were detected only at 2 weeks of age, and salmonella and shigella were not isolated from any of the experimental mink. Total bacterial densities, the relative proportions of the bacterial groups, and age- and diet-related effects differ from those known for other mammals, which may be related to the carnivorous diet and rapid movement of digesta through the GIT. 相似文献
8.
Buddington RK Elnif J Puchal-Gardiner AA Sangild PT 《American journal of physiology. Regulatory, integrative and comparative physiology》2001,280(1):R241-R247
Amino acids originating from the diet are the principal metabolic fuels for the small intestine, and although the developing intestine is exposed to dramatic changes in the types and amounts of protein, there is little known about rates of amino acid absorption across the apical membrane during development. Therefore, rates of absorption were measured for five amino acids that are substrates for the acidic (aspartate), basic (lysine), neutral (leucine and methionine), and imino (proline) amino acid carriers using intact tissues from the proximal, mid-, and distal small intestines of pigs ranging in age from 90% of gestation to 42 days after birth (12 days after weaning). Rates of absorption (sum of carrier-mediated and apparent diffusion) were highest at birth (except for proline) and declined by an average of 30% during the first 24 h of suckling. There were continuing declines for leucine, methionine, and proline but not for aspartate and lysine. Due to rapid growth of the intestine, absorption capacities for all amino acids increased faster than predicted from gains in metabolic mass. Regional differences for rates of absorption were not detected until after birth, and only for aspartate and proline. Maximum rates of saturable absorption (nmol. min(-1). mg tissue(-1)) by the midintestine increased during the last 10% of gestation, were highest at birth, and then declined. The contribution of apparent diffusion to amino acid absorption was lowest at birth, then increased after onset of suckling. 相似文献
9.
DpiA binding to the replication origin of Escherichia coli plasmids and chromosomes destabilizes plasmid inheritance and induces the bacterial SOS response
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The dpiA and dpiB genes of Escherichia coli, which are orthologs of genes that regulate citrate uptake and utilization in Klebsiella pneumoniae, comprise a two-component signal transduction system that can modulate the replication of and destabilize the inheritance of pSC101 and certain other plasmids. Here we show that perturbed replication and inheritance result from binding of the effector protein DpiA to A+T-rich replication origin sequences that resemble those in the K. pneumoniae promoter region targeted by the DpiA ortholog, CitB. Consistent with its ability to bind to A+T-rich origin sequences, overproduction of DpiA induced the SOS response in E. coli, suggesting that chromosomal DNA replication is affected. Bacteria that overexpressed DpiA showed an increased amount of DNA per cell and increased cell size-both also characteristic of the SOS response. Concurrent overexpression of the DNA replication initiation protein, DnaA, or the DNA helicase, DnaB-both of which act at A+T-rich replication origin sequences in the E. coli chromosome and DpiA-targeted plasmids-reversed SOS induction as well as plasmid destabilization by DpiA. Our finding that physical and functional interactions between DpiA and sites of replication initiation modulate DNA replication and plasmid inheritance suggests a mechanism by which environmental stimuli transmitted by these gene products can regulate chromosomal and plasmid dynamics. 相似文献
10.
Buddington RK Malo C Sangild PT Elnif J 《American journal of physiology. Regulatory, integrative and comparative physiology》2000,279(6):R2287-R2296
Intestinal development is typically studied using omnivores. For comparative purposes, we examined an altricial carnivore, the mink (Mustela vison). In mink, intestinal dimensions increase up to 8 wk after birth and then remain constant (length) or decrease (mass) into maturity despite continuing gains in body mass. Rates of glucose and fructose transport decline after birth for intact tissues but increase for brush-border membrane vesicles (BBMV). Rates of absorption for five amino acids that are substrates for the acidic (aspartate), basic (lysine), neutral (leucine and methionine), and imino acid (proline) carriers increase between birth and 24 h for intact tissues before declining, but increase after 2 wk for BBMV. The proportion of BBMV amino acid uptake that is Na(+)-dependent increases during development but for aspartate is nearly 100% at all ages. Tracer uptake by BBMV can be inhibited by 100 mmol/l of unlabeled amino acid, except for lysine. BBMV uptake of the dipeptide glycyl-sarcosine does not differ between ages, is not Na(+) dependent, and is only partially inhibited by 100 mmol/l unlabeled dipeptide. Despite the ability to rapidly and efficiently digest high dietary loads of protein, rates of amino acid and peptide absorption are not markedly higher than those of other mammals. 相似文献