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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been hypothesized that the beneficial effect on hepatic encephalopathy of lactulose or neomycin might be exerted by their effect on intermediary glutamine metabolism and ammonia generation within enterocytes. We examined glutamine consumption and the production of alanine and ammonia (net substrate exchange in nmol min-1 g-1) in isolated vascularly and luminally perfused small intestine from rats with and without pretreatment with lactulose (2.0 g/kg) or paromomycin (60 mg/kg). Without pretreatment, 50 mM lactulose or 1 mM paromomycin were equally ineffective to significantly reduce the consumption of arterial glutamine (-92 +/- 5 vs. -80 +/- 6 vs. -71 +/- 6 for controls, lactulose, or paromomycin; mean +/- SEM, n = 6 each, n.s. by analysis of variance), and the production of alanine (41 +/- 3 vs. 44 +/- 3 vs. 61 +/- 7, n.s.) or ammonia (42 +/- 6 vs. 42 +/- 6 vs. 38 +/- 6, n.s.). Similarly, glutamine utilisation, and the release of alanine and ammonia were not different after pretreatment for 10 days. Also, both agents did not reduce glutamine absorption from the lumen (-170 +/- 9 vs. -171 +/- 6 vs. -219 +/- 25, n = 5 each) or the concomitant vascular release of metabolic products alanine (92 +/- 7 vs. 78 +/- 10 vs. 77 +/- 10 vs. 77 +/- 7, n.s.) and ammonia (73 +/- 6 vs. 69 +/- 7 vs. 65 +/- 8, n.s.). Our results do not support the hypothesis, that lactulose or paromomycin reduce ammonia generation by small intestinal mucosa through a specific effect on intermediary glutamine metabolism.
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PMID:Lactulose or paromomycin do not affect ammonia generation in the isolated perfused rat small intestine. 819 8

Fecal concentrations of total short-chain fatty acids were normal in 16 patients with ileorectal anastomoses (mean +/- SEM, 99.7 +/- 10.3 mmol/L) and 28 patients with ileal pouch-anal anastomoses (138.8 +/- 8.5 mmol/L) and did not differ from those in 14 healthy noncolectomized controls (130.7 +/- 12.6 mmol/L). Acetate:propionate:butyrate:isobutyrate+valerate+isovalerate ratios were similar in the ileorectum (71:12:12:5%) and in the colorectum (66:14:13:7%) of healthy noncolectomized controls, whereas the concentration of acetate was increased at the expense of the polypeptide-derived isobutyrate, valerate, and isovalerate in the ileal pouch (77:12:11:1%). Ammonia was accordingly significantly diminished in ileal pouch contents (28.8 +/- 3.2 mmol/L vs 45.2 +/- 4.1 mmol/L in controls) in contrast to concentrations in ileorectal contents (36.2 +/- 5.3 mmol/L). Concentrations of lactate were normal and low. Twenty-four-hour productions of total short-chain fatty acids in 16.6% fecal homogenates from both groups of patients were normal. Addition of saccharides (eg, glucose, starch, pectin, ispaghula husk) increased the production of acetate, propionate, and butyrate and decreased the production of ammonia and isobutyrate, valerate, and isovalerate, which was increased in homogenates with albumin added. This pattern of substrate fermentation was similar in homogenates from ileal pouch, ileorectum, and control colorectum. In conclusion, the concentrations of short-chain fatty acids, lactate, and ammonia indicate that ileorectal fermentation resembles normal colorectal fermentation in noncolectomized healthy individuals, whereas the fermentation in ileal pouch contents seems to be more carbohydrate predominated.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Short-chain fatty acids, lactate, and ammonia in ileorectal and ileal pouch contents: a model of cecal fermentation. 827 56

We investigated the effect of resistant starch (RS) on markers of colonic protein metabolism. Eleven subjects participated in a randomized crossover study in which they consumed either high-RS (39 +/- 3 g/d, -chi +/- SEM) or low-RS (5 +/- 0.4 g/d) diets for 3 wk. All other macronutrients were kept constant. During the high-RS diet daily excretion of fecal nitrogen increased from 1.84 +/- 0.15 to 2.86 +/- 0.42 g/d (P < 0.01) and excretion of fecal phenols fell from 9.2 +/- 1.4 to 5.3 +/- 0.8 mg/d (P < 0.01). Fecal concentrations of ammonia decreased from 397 +/- 33 to 278 +/- 49 microgram/g (P < 0.01) and phenols decreased from 69 +/- 8 to 39 +/- 10 microgram/g (P < 0.001). Daily output of urinary ammonia, urea, phenols, and total nitrogen did not change significantly, but pH decreased from 6.4 +/- 0.1 to 6.2 +/- 0.1 (P < 0.05) during the high-RS period. These results suggest that RS significantly attenuates the accumulation of potentially harmful byproducts of protein fermentation in the human colon.
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PMID:Resistant starch lowers fecal concentrations of ammonia and phenols in humans. 898 33

This experiment investigated the effect of intraruminal infusion of propionic acid on the net flux of nitrogenous compounds across the mesenteric- (MDV) and portal-(PDV) drained viscera of seven Friesian steers, average BW 127 kg (SEM 4.6), fed a grass-pellet diet. Each received by random allocation 0 (control), .5, or 1.0 mol of propionic acid/d for 7 d. Blood flow in mesenteric and portal veins was determined by downstream dilution of p-aminohippuric acid in order to determine net appearance rates across the gastrointestinal tissues. Net urea and ammonia flux was unaffected by propionic acid supply. Circulating plasma free amino acid concentrations were increased (P < .05) by propionic acid infusion (2,235, 2,428, and 2,427, error mean square [EMS] 44,370 microM, for control, .5, and 1.0 mol of propionic acid/d, respectively). Net amino acid flux rates were increased at the highest rate of propionic acid infusion across MDV and PDV (4.66, 3.69, and 6.11, EMS 2.98 mol/d for MDV [P < .05] and 2.98, 2.45, and 3.73, EMS 1.69 mol/d for PDV [P < .10] for control, .5, and 1.0 mol of propionic acid/d respectively). Positive venous-arterio concentration differences for peptide-bound amino acids (PBAA) across the MDV and PDV indicated net appearance across the gastrointestinal tissues, but this was not affected by propionic acid infusion. The data show that amino acid flux across postruminal tissues can be influenced by ruminal propionic acid supply and that this does not affect PBAA appearance.
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PMID:Effect of intraruminal propionic acid infusion on metabolism of mesenteric- and portal-drained viscera in growing steers fed a forage diet: II. Ammonia, urea, amino acids, and peptides. 877 5

The purpose of the present study was to examine the growth hormone (GH) response to treadmill sprinting in male (M) and female (F) sprint- and endurance-trained athletes. A group of 11 sprint-trained (ST; 6M, 5F) and 12 endurance-trained (ET; 6M, 6F) athletes performed a maximal 30-s sprint on a nonmotorized treadmill. Peak power and mean power expressed in watts or in watts per kilogram body mass were higher in ST than in ET (P < 0.01) and in the men compared to the women (P < 0.01). Serum GH was greater in ST than in ET athletes, but was not statistically significantly different between the men and the women [mean peak GH: ST 72.4 (SEM 12.5) compared to ET 26.3 (SEM 4.9) mU.1(-1), P < 0.01; men 59.8 (SEM 13.3) compared to the women 35.8 (SEM 7.4) mU.1(-1), n.s.]. Plasma ammonia and blood lactate concentrations were higher and blood pH lower during 1 h of recovery after the sprint in ST compared to ET (all P < 0.01). Multiple log linear regression showed that 82% of the variation in the serum peak GH response was explained by the peak power output and peak blood lactate response to the sprint. As serum GH was still approximately ten times the basal value in ST athletes after 1 h of recovery, it is suggested that the exercise-induced increase in GH could have important physiological effects in this group of athletes, including increased protein synthesis and sparing of protein degradation leading to maintained or increased muscle mass.
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PMID:Growth hormone responses to treadmill sprinting in sprint- and endurance-trained athletes. 892 17

The effects of active recovery on metabolic and cardiorespiratory responses and power output were examined during repeated sprints. Male subjects (n = 13) performed two maximal 30-s cycle ergometer sprints, 4 min apart, on two separate occasions with either an active [cycling at 40 (1)% of maximal oxygen uptake; mean (SEM)] or passive recovery. Active recovery resulted in a significantly higher mean power output (W) during sprint 2, compared with passive recovery [W] 603 (17) W and 589 (15) W, P < 0.05]. This improvement was totally attributed to a 3.1 (1.0)% higher power generation during the initial 10 s of sprint 2 following the active recovery (P < 0.05), since power output during the last 20 s sprint 2 was the same after both recoveries. Despite the higher power output during sprint 2 after active recovery, no differences were observed between conditions in venous blood lactate and pH, but peak plasma ammonia was significantly higher in the active recovery condition [205 (23) vs 170 (20) mumol .l-1; P < 0.05]. No differences were found between active and passive recovery in terms of changes in plasma volume or arterial blood pressure throughout the test. However, heart rate between the two 30-s sprints and oxygen uptake during the second sprint were higher for the active compared with passive recovery [148 (3) vs 130 (4) beats.min-1; P < 0.01) and 3.3 (0.1) vs 2.8 (0.1) l.min-1; P < 0.01]. These data suggest that recovery of power output during repeated sprint exercise is enhanced when low-intensity exercise is performed between sprints. The beneficial effects of an active recovery are possibly mediated by an increased blood flow to the previously exercised muscle.
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PMID:Effects of active recovery on power output during repeated maximal sprint cycling. 895 94

Fast cyclic voltammetry (FCV) was used to measure electrically stimulated monoamine efflux in the rat ventral lateral geniculate nucleus (vLGN). The electrochemical characteristics of the released species resembled 5-HT but not dopamine or noradrenaline. Amine efflux was abolished by the sodium channel blocker tetrodotoxin (0.1 microM), Ro 4-1284 (1.0 microM), the fast-acting reserpine analogue, and removal of Ca2+ from the superfusate. Amine efflux was unaffected by the monoamine oxidase inhibitor clorgyline (0.1 microM). Of paroxetine (0.1 microM), desipramine (50 nM) and vanoxerine (0.5 microM), selective blockers of 5-HT, noradrenaline and dopamine uptake respectively, only paroxetine increased monoamine efflux (to 194 +/- 25%, mean +/- SEM) and prolonged the removal half-life (to 638 +/- 105%). The non-specific 5-HT1 antagonist methiothepin (0.2 microM) increased 5-HT efflux on long (20 pulses at 20 Hz) but not short trains (20 pulses at 100 Hz). When tested on pseudo-one-pulse stimulations (5 pulses, 100 Hz), the selective 5-HT1A agonist 8-OHDPAT (1.0 microM) had no effect. CP 93129 (0.3 microM), the selective 5-HT1B agonist, decreased 5-HT efflux to 37 +/- 4% of control and was antagonised by the 5-HT1B blocker isamoltane (0.5 microM) and by the 5-HT1D/B antagonist GR 127935 (50 nM). The preferential 5-HT1D agonist sumatriptan (0.5 microM) also decreased 5-HT efflux, to 55 +/- 6% and was antagonised by GR 127935 (50 nM) but not isamoltane (0.5 microM). These results suggest that 5-HT released in the vLGN can be measured by FCV. Furthermore, released 5-HT is taken up by the 5-HT transporter and may be under the influence of 5-HT1B and 5-HT1D autoreceptors.
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PMID:Serotonin efflux in the rat ventral lateral geniculate nucleus assessed by fast cyclic voltammetry is modulated by 5-HT1B and 5-HT1D autoreceptors. 902 11

The study was designed to determine urinary excretions of endogenous total, urea, ammonia and creatinine nitrogen in adult domestic cats. Endogenous urinary nitrogen metabolite excretions were determined by feeding adult cats a protein-free diet for 10 d or by regression to zero protein intake of the urinary nitrogen metabolite excretions of adult cats fed four levels of dietary protein. The mean (+/- SEM) endogenous total, urea and ammonia nitrogen excretions for the cats fed the protein-free diet were 360 (+/- 11.3), 243 (+/- 8.8) and 27.6 (+/- 1.06) mg x kg body weight(-0.75) x d(-1), respectively. Estimates of 316 (+/- 53.9), 232 (+/- 43.4) and 33.7 (+/- 5.68) mg x kg body weight(-0.75) x d(-1), respectively, were obtained using the regression technique. The differences in results between the two techniques were not statistically significant. Daily excretions of creatinine nitrogen were not significantly (P = 0.64) different between the protein-free and regression technique (mean +/- SEM, 14.4 +/- 0.49 and 15.9 +/- 1.05 mg/kg body weight(0.75), respectively). The endogenous urinary total and urea nitrogen excretion of adult domestic cats is higher than values for other mammals such as humans, dogs, rats and pigs.
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PMID:Urinary excretion of endogenous nitrogen metabolites in adult domestic cats using a protein-free diet and the regression technique. 910 14

Crossbred sheep (n 16, 8.5 months of age and 33 (SE 0.9) kg) were used in a 21 d experiment (2 x 2 factorial) to determine effects on net flux of nutrients across the portal-drained viscera (PDV) and liver of ad libitum consumption of bermudagrass (Cynodon dactylon; B) v. ryegrass (Lolium multiflorum)-wheat (Triticum aestivum; RW) hay, coarsely chopped (CC) or finely ground and pelleted (GP). Crude protein concentrations were 86, 81, 113 and 119 g/kg and neutral-detergent fibre concentrations were 710, 688, 654 and 672 g/kg (dry matter basis) for B-CC, B-GP, RW-CC and RW-GP respectively. Digestible energy intake (6.0, 9.6, 10.2 and 13.8 MJ/d) differed (P < 0.01) with grass source and form, and digestible N intake values were 4.4, 7.0, 8.4 and 14.1 (SEM 0.82) g/d for B-CC, B-GP, RW-CC and RW-GP diets respectively. Consumption of O2 by the PDV (118, 165, 144 and 155 mmol/h) and splanchnic bed (196, 273, 247 and 266 mmol/h for B-CC, B-GP, RW-CC and RW-GP respectively) was greater (P = 0.07) for GP than for CC. The ratio splanchnic heat energy production: digestible energy intake was greater (P = 0.06) for B than for RW (0.374, 0.300, 0.278 and 0.219 for B-CC, B-GP, RW-CC and RW-GP respectively). alpha-Amino-N release by the PDV (P < 0.01; 11.6, 12.8, 23.0 and 18.7 mmol/h) and uptake by the liver (P = 0.07; 15.2, 6.1, 17.0 and 19.3 mmol/h for B-CC, B-GP, RW-CC and RW-GP respectively) were greater for RW than for B. Release of NH3-N by the PDV was greater (P = 0.02) for CC than for GP (12.5, 6.2, 15.7 and 8.9 mmol/h), and hepatic urea-N release differed between grass sources (P = 0.03) and physical forms (P = 0.07; 22.6, 12.7, 31.4 and 24.8 mmol/h for B-CC, B-GP, RW-CC and RW-GP respectively). In conclusion, decrease in forage particle size elicited by grinding and pelleting did not affect the difference between grass sources in splanchnic tissue heat energy production relative to digestible energy intake.
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PMID:Net flux of nutrients across splanchnic tissues in wethers consuming grasses of different sources and physical forms ad libitum. 917 96

Exposure to swine confinement buildings has a negative impact on respiratory health. A short exposure to this environment results in an acute airway inflammatory response. The present study was performed to confirm and further define the acute effects of working in a swine building, and to determine whether these effects are reproducible. Seven previously nonexposed normal subjects underwent evaluations that included hourly measurement of forced expiratory volume in one second (FEV1), methacholine challenge (the provocative concentration producing a 20% fall in FEV1 (PC20)), bronchoalveolar lavage (BAL), nasal lavage (NL), and blood analyses, before (control) and after each of two 5 h exposures to a swine building environment. The exposures were conducted 8 days apart. The levels of total dust, endotoxins, and ammonia (NH3) in the confinement building were measured on each day of exposure. Both exposures resulted in a significant reduction in FEV1 (mean+/-SEM change in FEV1: control = 7+/-2%; exposure 1 = 15+/-3%; exposure 2 = 23+/-3%), decrease in PC20 (median value (25th-75th percentile): 223 (23-256), 20 (15-198) and 20 (11-71), respectively; p=0.05) and increase in BAL cells (129+/-20, 451+/-43 and 511+/-103x10(3) cells x mL(-1), respectively) and NL cells (6+/-4, 126+/-58 and 103+/-26x10(3) cells x mL(-1), respectively), mostly neutrophils. Levels of interleukin-8 (IL-8), but not interleukin-1 (IL-1) or tumour necrosis factors (TNF-alpha), increased both in BAL and nasal fluids with exposure. In normal naive subjects, repeated exposure to the environment of a swine building induced a marked and reproducible reduction in forced expiratory volume in one second, increase in airway responsiveness, and increased neutrophilic inflammatory response. These results could not be accounted for by any of the environmental factors measured.
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PMID:Effects of repeated swine building exposures on normal naive subjects. 923 Feb 40


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