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PubMed2002

The effects of dry extrusion temperature of whole soybeans on digestion of protein and amino acids by steers.

Five Holstein steers (450 kg) with cannulas in the rumen, proximal duodenum, and terminal ileum were used in a 5 x 5 Latin square design to study the effects of extrusion temperature on site of digestion of nitrogenous compounds in whole soybeans. The basal diet contained 50% corn silage, 24% alfalfa hay, 16.6% corn starch, 4.05% ground corn, 1% urea, and 3.4% soybean oil. Raw soybeans or soybeans extruded at 116, 138, or 160 degrees C (diets 116, 138, and 160, respectively) replaced the soybean oil and most of the corn starch in the test diets. Total N (g/d) reaching the duodenum was 232, 293, 285, 308, and 299 for the basal, raw, 116, 138, and 160 diets, respectively. No differences were observed between the raw and extruded soybeans (P = 0.81), or for the linear or quadratic effects of extrusion temperature (P = 0.56 and P = 0.45, respectively). Nonbacterial N (g/d) reaching the duodenum was 63.1, 104.6, 106.7, 101.9, and 113.9 for the same diets, respectively, and was not influenced by extrusion or extrusion temperature. Nitrogen disappearance from the small intestine (g/d) was 150 for the basal diet, 194 for the raw soybean diet, and 187,221, and 213 for the 116,138, and 160 degrees C extruded diets, respectively; no differences were observed between the raw and the extruded soybeans, or for diets containing soybeans extruded at different temperatures. Nitrogen disappearance (% of N entering) from the small intestine was lower (P < 0.05) for steers fed the basal diet than for steers fed the soybean-supplemented diets (64.1 vs 68.5%). No differences (P > 0.10) due to extrusion temperature were detected for flows of individual, essential AA, nonessential AA, and total AA at the duodenum. As extrusion temperatures increased, there were linear increases (P < 0.10) in disappearance (g/d) of all individual AA from the small intestine except for methionine and glycine. Essential, nonessential, and total AA disappearance from the small intestine were increased linearly (P < 0.10) with increasing extrusion temperature. Extrusion of soybeans can protect soy protein against extensive ruminal degradation without compromising intestinal digestibility.

Amino Acids↗
PubMed1975

Hypernatremia following gastrointestinal bleeding in cirrhosis with ascites.

3 patients with hepatic cirrhosis and ascites underwent increased diuresis on six occasions, closely related to episodes of gastrointestinal bleeding. In each instance the increased urine volume was preceded by a sharp increase in blood urea nitrogen, presumably due to absorption of nitrogenous compounds from the gastrointestinal tract, suggesting a mechanism of osmotic diuresis. In each case there was a signigicant increase in serum sodium and osmolality, related to the greater-water-than-sodium diuresis induced by urea, which was promptly reversed by the administration of water or isotonic solution. Clinically this syndrome may be defined as the association of hypernatremia and hyperosmolality due to osmotic diuresis from urea appearing in a cirrhotic patient with ascites and gastrointestinal bleeding.

Adult↗
PubMed1988

Protective effects of thromboxane receptor blockade in splanchnic artery occlusion shock.

Splanchnic artery occlusion (SAO) followed by release of the occlusive clamps produces circulatory shock characterized by an abrupt hypotension, cardiac depression and high lethality. We studied the effects of the thromboxane receptor antagonist, BM-13505, in rats during SAO shock. Anesthetized rats subjected to total occlusion of the celiac and superior mesenteric arteries for 40 minutes developed a severe shock state following reperfusion, usually resulting in death within 90-120 minutes of release of the occlusion. BM-13505 was started at reperfusion for 10 minutes. SAO shock rats treated with BM-13505 (1 mg/kg) maintained post-reperfusion mean arterial blood pressure (MABP) at significantly higher values compared to those receiving only the vehicle (0.9% NaCl). Treatment with BM-13505 attenuated the plasma activity of the lysosomal protease cathepsin D (p less than 0.05 from vehicle) and the plasma accumulation of free amino-nitrogen compounds (p less than 0.01 from vehicle). Furthermore, the plasma activity of a myocardial depressant factor was significantly lower in BM-13505 treated rats than in non-treated rats (p less than 0.01 from vehicle). SAO shock rats treated with BM-13505 also exhibited a higher survival rate than the vehicle group (75% vs. 20%). These results suggest an important role of thromboxane A2 in the pathophysiology of SAO shock.

Animals↗
PubMed1992

Chemolithoautotrophic assimilation of dinitrogen by Streptomyces thermoautotrophicus UBT1: identification of an unusual N2-fixing system.

Streptomyces thermoautotrophicus UBT1, which was isolated previously from a burning charcoal pile, was shown to utilize N2 as a sole nitrogen source when growing chemolithoautotrophically with CO or H2 plus CO2 under aerobic conditions at 65 degrees C. Doubling times under diazotrophic conditions were 10 h. S. thermoautotrophicus is a new CO- or H2-oxidizing, obligately chemolithoautotrophic, thermophilic, free-living, aerobic, N2-fixing streptomycete. Its ability to fix N2 was also evident from (i) the incorporation of substantial amounts of 15N2 (about 13%) into cell material, (ii) the formation of H2 during diazotrophic growth, (iii) the repression of 15N2 assimilation and H2 formation by ammonia, and (iv) culture growth yields with N2 as a nitrogen source that were significantly higher than those without any added nitrogen compounds (ca. 2.4 versus < 0.1 mg [dry weight]). The N2-fixing system of S. thermoautotrophicus exhibited several properties not apparent in the diazotrophic bacteria studied so far, since it was (i) incapable of reducing acetylene to ethylene or ethane and (ii) resistant to inhibition by acetylene or ethylene (5% [vol/vol] each), CO (40 to 70% [vol/vol]), or H2 (40% [vol/vol]). Under stringent conditions, nifH and nifDK gene probes from Klebsiella pneumoniae did not hybridize with total DNA from S. thermoautotrophicus.

Acetylene↗
PubMed2005

A novel approach to remove nitrogen in a biological aerobic filter (BAF).

Laboratory study on nitrogen removal was carried out using biological aerobic filter (BAF) fed with synthetic domestic wastewater in the temperature range of 20.5-26.5 degrees C in order to gain insight into the mechanism and the influences of operation parameters on nitrite accumulation in the biological nitrogen removal process. Influent loading with 0.26-0.62 kg (m(3)d(-1)) NH4+-N, 0.28-0.63 kg (m(3)d(-1)) TN, 1-2 m h(-1) hydraulic loading and air/ water ratio 3:1, resulted in the removal of NH4+-N and TN by 0.15-0.52 kg (m(3)d(-1)) and 0.18-0.42 kg (m(3)d(-1)) respectively. Hence BAF seems to be a promising nitrogen removal technique. The investigation of nitrite concentrations in the bulk and effluent, the profiles of inorganic nitrogen compounds and the spatial distribution of microbial populations and activity indicated that the nitrite accumulation and shortcut nitrification-denitrification had taken place in the bioreactor. No clear relationships were observed between the nitrite accumulation with the influent loading, temperature and pH value except that nitrite concentrations in the bulk increased with high back washing frequency. The results suggested that the filter structure and operation pattern were the principal factors that cause the nitrite accumulation and shortcut nitrification-denitrification occurring in the biological aerobic filter.

Bacteria↗
PubMed1990

Role of NAD-linked glutamate dehydrogenase in nitrogen metabolism in Saccharomyces cerevisiae.

We cloned GDH2, the gene that encodes the NAD-linked glutamate dehydrogenase in the yeast Saccharomyces cerevisiae, by purifying the enzyme, making polyclonal antibodies to it, and using the antibodies to screen a lambda gt11 yeast genomic library. A yeast strain with a deletion-disruption allele of GDH2 which replaced the wild-type gene grew very poorly with glutamate as a nitrogen source, but growth improved significantly when the strain was also provided with adenine or other nitrogenous compounds whose biosynthesis requires glutamine. Our results indicate that the NAD-linked glutamate dehydrogenase catalyzes the major, but not sole, pathway for generation of ammonia from glutamate. We also isolated yeast mutants that lacked glutamate synthase activity and present evidence which shows that normally NAD-linked glutamate dehydrogenase is not involved in glutamate biosynthesis, but that if the enzyme is overexpressed, it may function reversibly in intact cells.

Alleles↗
PubMed2005

Parachlorophenylalanine exacerbates oxidative stress induced by gentamicin in rats.

The present work studies the effect of parachlorophenylalanine (PCPA, 200 mg/kg intraperitoneally/48 hr for 7 days) on the oxidative stress and nephropathy induced by gentamicin (80 mg/kg intraperitoneally/daily for 7 days) in Wistar rats. The effect of PCPA on lipid peroxidation products and reduced glutathione content in renal and brain tissue, as well as on 5HT content in brain was assessed. Catalase and superoxide dismutase activities were determined in brain tissue. Blood urea nitrogen and creatinine in plasma and total protein content in urine were also measured. Gentamicin caused significant increases in proteinuria, non-protein nitrogen compounds and lipid peroxidation markers, together with decreases in both reduced glutathione content in renal and brain tissue and enzymatic activities in brain homogenates. PCPA harnessed the effect of gentamicin in the brain and the kidney, while PCPA alone induced brain oxidative stress. These results support the prooxidant action of PCPA in brain tissue and its capacity to exacerbate the oxidative stress and renal dysfunction induced by gentamicin, as well as the possible antioxidant property of serotonin.

Animals↗
PubMed1991

Regulation of glutamine synthetase activity in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 by the nitrogen source: effect of ammonium.

Glutamine synthetase activity from Synechocystis sp. strain PCC 6803 is regulated as a function of the nitrogen source available in the medium. Addition of 0.25 mM NH4Cl to nitrate-grown cells promotes a clear short-term inactivation of glutamine synthetase, whose enzyme activity decreases to 5 to 10% of the initial value in 25 min. The intracellular levels of glutamine, determined under various conditions, taken together with the results obtained with azaserine (an inhibitor of transamidases), rule out the possibility that glutamine per se is responsible for glutamine synthetase inactivation. Nitrogen starvation attenuates the ammonium-mediated glutamine synthetase inactivation, indicating that glutamine synthetase regulation is modulated through the internal balance between carbon-nitrogen compounds and carbon compounds. The parallelism observed between the glutamine synthetase activity and the internal concentration of alpha-ketoglutarate suggests that this metabolite could play a role as a positive effector of glutamine synthetase activity in Synechocystis sp. Despite the similarities of this physiological system to that described for enterobacteria, the lack of in vivo 32P labeling of glutamine synthetase during the inactivation process excludes the existence of an adenylylation-deadenylylation system in this cyanobacterium.

Ammonia↗
PubMed2003

[The nitrite accumulation in a biological aerobic filter (BAF) and the influences factors].

The nitrite accumulation in a bench-scale biological aerobic filter (BAF) for nitrogen removal was reported in this paper. The influences of operational variables on filter performance and nitrite accumulation were also investigated. The influent loading of NH4+(-)N and TN were 0.26-0.62 kg/(m3.d) and 0.28-0.63 kg/(m3.d) respectively, the hydraulic loading, gas/water ratio and temperature were 1-2 m/h, 3:1 and 20.5 degrees C-26.5 degrees C respectively, the nitrogen removal loading of NH4+(-)N, TN were among 0.15-0.52 kg/(m3.d) and 0.18-0.42 kg/(m3.d) respectively. The nitrite concentrations in the bulk and effluent, the profiles of inorganic nitrogen-compounds, the microbial populations in the reactor and their activity were investigated, suggesting that the nitrite accumulation and shortcut nitrification-denitrification took place in the bioreactor. The mechanism of nitrite accumulation and the influences of operational variables were analyzed. The backwash process was considered as the key influential factor of nitrite accumulation. It was believed that the structure feature and operational pattern were the principal factors that may result in the nitrite accumulation and shortcut nitrification-denitrification occurring in the BAF reactor.

Bacteria↗
PubMed1978

Nitrogen metabolism in the gut.

All three of the major human nitrogenous waste products--urea,, creatinine, and uric acid--are significantly degraded by intestinal bacteria. The breakdown products of creatinine and uric acid are not fully known, but metabolites of these complex heterocyclic nitrogen compounds may well turn out to play a role in uremic toxicity. Urea degradation is almost certainly by way of ammonia, but the exact site of urea hydrolysis in the alimentary tract is not known, and it is uncertain whether urea is the major source of intestinal ammonia. Ammonia is absorbed from the colon predominantly in unionized form, and the bicarbonate ion secreted by the colonic mucosa plays an important role in facilitating this absorption.

Ammonia↗
PubMed1976

[Influence of intestinal microflora on the amino acid composition of lamb feces].

6 conventional and 5 germfree male lambs were fed ad libitum a UHT sterilized cow milk. Body weight and food intake were recorded. Whole feces were collected for 5 consecutive days. Growth rate reached 259 g/d for the germfree. Daily fecal excretion of dry matter and nitrogenous compounds are not found different in the two groups of animals. The influence of intestinal microflora appears on the biochemical composition of the feces. As compared to the conventional fecal proteins from germfree lambs are very high in threonine and serine and low in lysine. Moreover the difference of amino acid composition between these two groups come not only from the histidine alanine and arginine composition of bacteries; it also involves the high levels of threonine serine cystine and tyrosine of the endogenous digestive proteins.

Amino Acids↗
PubMed1985

Comparative effects of protein, protein hydrolysate and amino acid diets on nitrogen metabolism of normal, protein-deficient, gastrectomized or hepatectomized rats.

The effects of diets containing protein, protein hydrolysate or an amino acid mixture on nitrogen metabolism of normal and severely protein-deficient rats and on rats after gastrectomy and hepatectomy were compared. In experiment 1, rats weighing about 80 g were fed one of three experimental diets containing casein, protein hydrolysate or an amino acid mixture for 28 d. In experiment 2, rats weighing about 270 g were fed a protein-free diet for 40 d, and then one of the above three experimental diets for 14 d. In experiment 3, rats weighing about 220 g were totally gastrectomized and fed one of the three experimental diets for 21 d. In experiment 4, rats weighing about 210 g had about 70% of the liver resected, and then were fed one of the three experimental diets for 15 d. In all four experiments, daily food intake, daily body weight gain, nitrogen balance, urinary nitrogen compounds, body composition and hematologic values were measured. In normal, protein-deficient and hepatectomized rats, most results were similar for the groups fed protein, protein hydrolysate or amino acid diets, except that urinary ammonia was higher in the group fed the amino acid diet than in the other two groups. For about 10 d after total gastrectomy, food intake and growth of the animals fed the protein diet were lower than in the other two groups.

Amino Acids↗
PubMedDate not supplied

Contributions of icy planetesimals to the Earth's early atmosphere.

Laboratory experiments on the trapping of gases by ice forming at low temperatures implicate comets as major carriers of the heavy noble gases to the inner planets. These icy planetesimals may also have brought the nitrogen compounds that ultimately produced atmospheric N2. However, if the sample of three comets analyzed so far is typical, the Earth's oceans cannot have been produced by comets alone, they require an additional source of water with low D/H. The highly fractionated neon in the Earth's atmosphere may also indicate the importance of non-icy carriers of volatiles. The most important additional carrier is probably the rocky material comprising the bulk of the mass of these planets. Venus may require a contribution from icy planetesimals formed at the low temperatures characteristic of the Kuiper Belt.

Earth, Planet↗
PubMed1975

The effect of different feeds, including those containing soya-bean products, on the passage of digesta from the abomasum of the preruminant calf.

1. The effects of various factors on rates of flow and composition of digesta leaving the abomasum of preruminant calves were studied. The possible relation of some of these effects to the development of serum antibodies to certain dietary constituents has also been examined. Two situations were distinguished: (a) unsensitized responses, shown by calves receiving milk protein or soya-bean products for the first one or two occasions; (b) sensitized responses, shown by calves receiving certain soya-bean products, after a number of these feeds had been given. 2. For unsensitized calves, the rate of flow of total digesta from the abomasum was greater in the first few hours after a feed consisting of a mineral solution was given, than after cow's milk was given. This difference wasapparently due to differences in the composition of digesta entering the duodenum. Total digesta flows after giving synthetic milk feeds, prepared from different protein sources, were similar to those after cow's milk was given. 3. For sensitized calves, rates of flow of total digesta from the abomasum were greatly affected by the nature of the protein source used in the diet. Soya-bean flour (heated or unheated) generally caused inhibition of flow for some hours after feeding; a soya-bean protein isolate (isoelectric) had a similar but smaller effect, but a soya-bean concentrate (prepared by alcohol extraction of a soya-bean flour) and milk protein had little or no effect. The inhibition, believed to be a sign of more general disorders, appeared to be caused by a factor entering the duodenum which induced a change in the way in which the calf responded, probably as the result of a gastrointestinal allergy. 4. Calves given soya-bean flour or a soya-bean protein isolate (isoelectric) in their diets for several weeks, showed respectively high and low titres of serum antibodies to an antigen prepared from soya-bean flour. Calves given alcohol-extracted soya-bean concentrate had no similar antibodies. 5. In addition to variations in total digesta flow, dietary nitrogen compounds were held up in the abomasum to different extents after different feeds. After a whole-milk feed or a synthetic feed prepared from casein, a slow, steady release of N occurred over at least 9 h. N hold-up after giving soya-bean-containing feeds was slight for the soya-bean flour, but extremely marked for the soya-bean protein isolate (isoelectric). The latter hold-up was followed after several hours by a rapid outflow of N from the abomasum.

Abomasum↗
PubMed2006

Uric acid recycling in the shield bug, Parastrachia japonensis (Hemiptera: Parastrachiidae), during diapause.

Nymphs of the univoltine shield bug, Parastrachia japonensis grow by feeding on the drupes of their sole food plant, which are available for only 2 weeks a year. The new adults soon enter a reproductive diapause and survive without feeding for at least 10 months up to 2 years. Uric acid was found to be the predominant component among four waste nitrogenous compounds, i.e., uric acid, allantoin, allantoic acid and urea in the body of both nymphs and adults in all stages, and to be predominantly excreted by the nymphs and reproductive adults. However, adults in diapause excreted negligible amounts of these compounds. Erwinia-like bacteria were found exclusively in the cecum of midgut, in which three uricolytic enzymes, i.e., uricase, allantoinase and allantoicase were detected. Ninety % of adults in diapause could survive on water for 9 months, but those given 0.02% rifampicin aqueous solution all died within this period, with significant reduction of the bacteria and uricase activity in the cecum. Rifampicin treatment resulted in a considerable reduction of free amino acids, especially proline in the hemolymph. These results suggest that uric acid is recycled as an amino acid source with the aid of Erwinia-like bacteria, and uricase functions as a key enzyme for this process.

Animals↗
PubMed2004

Altered nitrogen metabolism associated with de-differentiated suspension cultures derived from root cultures of Datura stramonium studied by heteronuclear multiple bond coherence (HMBC) NMR spectroscopy.

De-differentiation of transformed root cultures of Datura stramonium has previously been shown to cause a loss of tropane alkaloid synthetic capacity. This indicates a marked shift in physiological status, notably in the flux of primary metabolites into tropane alkaloids. Nitrogen metabolism in transformed root cultures of D. stramonium (an alkaloid-producing system) and de-differentiated suspension cultures derived therefrom (a non-producing system) has been compared using Nuclear Magnetic Resonance (NMR) spectroscopy. (15)N-Labelled precursors [((15)NH(4))(2)SO(4) and K(15)NO(3)] were fed and their incorporation into nitrogenous metabolites studied using Heteronuclear Multiple Bond Coherence (HMBC) NMR spectroscopy. In both cultures, the same amino acids were resolved in the HMBC spectra. However, marked differences were found in the intensity of labelling of a range of nitrogenous compounds. In differentiated root cultures, cross-peaks corresponding to secondary metabolites, such as tropine, were observed, whereas these were absent in the de-differentiated cultures. By contrast, N- acetylputrescine and gamma-aminobutyric acid (GABA) accumulated in the de-differentiated cultures to a much larger extent than in the root cultures. It can therefore be suggested that the loss of alkaloid biosynthesis was compensated by the diversion of putrescine metabolism away from the tropane pathway and toward the synthesis of GABA via N-acetylputrescine.

Alkaloids↗
PubMed2003

Competition of the natural and manmade biotic cycles in the closed aquatic system.

This study addresses competition between the Paramecium bursaria and zoochlorella-endosymbiosis and the infusoria Paramecium caudatum in a closed aquatic system. The system is a natural model of a simple biotic cycle. P. bursaria consumes glucose and oxygen released by its zoochlorella and releases nitrogenous compounds and carbon dioxide necessary for algal photosynthesis. P. caudatum was fed on bacteria. It was shown that the infusoria P. bursaria united in one cycle with Chlorella had a higher competitive ability than P. caudatum. With any initial percentage of the infusoria in the mixed culture, the end portion of P. bursaria reached 90-99%, which was significantly higher than the end potion of the P. caudatum population. It is assumed that the sustenance expenditures of P. caudatum were greater than those of the endosymbiotic paramecium, i.e. the closing of the components into a biotic cycle leads to a decrease in sustenance expenditures.

Animals↗
PubMed1965

AMINO ACID UTILIZATION BY ALCALIGENES VISCOLACTIS FOR GROWTH AND SLIME PRODUCTION.

Punch, J. D. (University of Minnesota, St. Paul), J. C. Olson, Jr., and J. V. Scaletti. Amino acid utilization by Alcaligenes viscolactis for growth and slime production. J. Bacteriol. 89:1521-1525. 1965.-The ability of Alcaligenes viscolactis to utilize amino acids in a basal salts solution (K(2)HPO(4), KH(2)PO(4), MgSO(4), MnSO(4), FeSO(4), NaCl) was studied. Of 27 amino acids, only l-asparagine, l-glutamic acid, l-aspartic acid, l-glutamine, l-proline, and l-tyrosine supported growth sufficient to give a viscous supernatant solution. l-Proline and l-tyrosine, singly or combined, fulfilled the carbon, nitrogen, and energy requirements for growth and slime production. None of eight inorganic nitrogenous compounds supported growth with lactose as the carbon source. The addition of l-asparagine, l-aspartic acid, or l-glutamine to l-tyrosine or l-proline, singly or combined, did not increase growth or slime production, indicating no nutritional interactions among these amino acids. Neither lactose nor glucose was found to be required or utilized by A. viscolactis in a medium containing basal salts, l-proline, l-tyrosine, and lactose or glucose. This was established by the fact that total carbohydrate and total reducing activity remained constant during growth and slime production.

Alcaligenes↗