Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In two experiments with milk cows with permanent rumen fistula it was investigated whether, apart from urea being unpalatable, further physiologic parameters are responsible for the reduced feed intake. In experiment I the cows received 2, 3 resp 4% urea orally with barley coarse meal, or an equivalent amount was given continuously from the beginning of the feeding over a period of three hours through the fistula. When 2, 3 resp. 4% urea were given orally, the consumption went down in the first 30 min to 58, 52 resp. 40%. When urea was given rumenally, no depression of the consumption could be observed. There were distinct relations with the NH3-concentration in the rumen fluid. At 20 to 35 mg per 100 ml there was no resp. a slight depressioon only and at 40 mg a significant depression. When the concentration rose to greater than 50 mg, consumption was stopped. In experiment II the rumenal application of urea began two hours before the feeding. The high NH3-level shortly after the beginning of feeding (58 mg/100 ml) caused a stop in the feed consumption. No relation could be observed between the urea concentration in veinous blood and the feed intake.
 ...
PMID:[Effective factors for the reduced feed intake of milk cows fed with rations containing urea]. 50 90

The proximal tubule model of this laboratory [Am. J. Physiol. 250 (Renal Fluid Electrolyte Physiol. 19): F860-F873, 1986] has been updated to examine proposed pathways for Cl- transport. Two additional buffer pairs have been added, i.e., HCO2-/H2CO2 and NH3/NH4+. At the luminal cell membrane Cl-/HCO2- and Cl-/HCO3- exchange are considered as pathways for Cl- entry, whereas at the peritubular membrane, Cl- exit occurs by either Na(+)-2HCO3-/Cl- exchange or K(+)-Cl- cotransport. Calculations with this model indicate that absolute proximal reabsorption of both Na+ and Cl- are critically dependent on the rate of luminal Na+/H+ exchange. In contrast, increases in the coefficient for Cl-/HCO2- exchange have little impact on overall Cl- flux, but, by enhancing base secretion, limit the depression of end-proximal HCO3-. Model calculations confirm those of Preisig and Alpern (J. Clin. Invest. 83: 1859-1867, 1989) showing that their measured value of luminal membrane H2CO2 permeability is inadequate to sustain the transcellular Cl- flux as Cl-/HCO2- exchange. Conversely, with sufficiently high H2CO2 permeability, luminal Cl- uptake is enhanced along the tubule, as HCO2- secretion and luminal acidification increase luminal H2CO2 to values severalfold greater than in glomerular filtrate. At the basolateral membrane, the thermodynamic driving force across the Na(+)-2HCO3-/Cl- exchanger is small. Although its contribution to steady-state Cl- exit may be less than the K(+)-Cl- cotransporter, the Na(+)-2HCO3-/Cl- exchanger can be a mechanism by which cytosolic acidification enhances peritubular Cl- transport, when luminal acidification enhances luminal Cl- uptake. A simulation is presented in which impermeant replacement of luminal Na+ leads to enhanced convective Cl- flux across the tight junction and alkalinization of the lateral interspace. In this setting, cytosolic Cl- depletion via the Na(+)-2HCO3-/Cl- exchanger may mimic luminal membrane Na(+)-Cl- cotransport.
 ...
PMID:Chloride transport in a mathematical model of the rat proximal tubule. 144 69

1. It has been established that chronic hyperammonaemia, whether caused by portacaval shunting or other means, leads to a variety of metabolic changes, including a depression in the cerebral metabolic rate of glucose (CMRGlc) increased permeability of the blood-brain barrier to neutral amino acids, and an increase in the brain content of aromatic amino acids. The preceding paper [Jessy, DeJoseph & Hawkins (1991) Biochem. J. 277, 693-696] showed that the depression in CMRGlc caused by hyperammonaemia correlated more closely with glutamine, a metabolite of ammonia, than with ammonia itself. This suggested that ammonia (NH3 and NH4+) was without effect. The present experiments address the question whether ammonia, in the absence of net glutamine synthesis, induces any of the metabolic symptoms of cerebral dysfunction associated with hyperammonaemia. 2. Small doses of methionine sulphoximine, an inhibitor of glutamine synthetase, were used to raise the plasma ammonia levels of normal rats without increasing the brain glutamine content. These hyperammonaemic rats, with plasma and brain ammonia levels equivalent to those known to depress brain function, behaved normally over 48 h. There was no depression of cerebral energy metabolism (i.e. the rate of glucose consumption). Contents of key intermediary metabolites and high-energy phosphates were normal. Neutral amino acid transport (tryptophan and leucine) and the brain contents of aromatic amino acids were unchanged. 3. The data suggest that ammonia is without effect at concentrations less than 1 mumol/ml if it is not converted into glutamine. The deleterious effect of chronic hyperammonaemia seems to begin with the synthesis of glutamine.
 ...
PMID:Hyperammonaemia does not impair brain function in the absence of net glutamine synthesis. 187 6

Four diets containing 15% CP were formulated to study the effects of dietary carbohydrate and protein sources on N metabolism and carbohydrate fermentation by ruminal bacteria. Diets were supplied to eight dual-flow continuous culture fermenters during three experimental periods in a randomized complete block design. Six replications were obtained for each diet. Treatments were arranged as a 2 X 2 factorial with two carbohydrate and two protein sources. Carbohydrate sources were corn and barley and protein sources were soybean meal (SBM) and fish meal (FM). Approximately 40% of the dietary CP was derived from SBM or FM and corn or barley provided 39% of dietary DM. All diets contained 15% grass hay, 20% wheat straw, and 10.1 to 15.3% solka floc (DM basis). Interactions (P less than .05) were observed between dietary carbohydrate and protein sources, resulting in a depression of VFA production (moles/day) and digestion (percentage) of ADF and cellulose when the corn-FM diet was fed. True OM digestion (percentage) was higher (P less than .05) for SBM than for FM diets and for corn than for barley diets. Although dietary CP degradation (percentage) was higher (P less than .05) for SBM than for FM diets, non-NH3 N in the effluent (grams/day) was not different among diets due to a greater (P less than .05) bacterial N flow for SBM than for FM diets. Despite the lower amino acid (AA) intake (P less than .05) for corn than for barley diets and also for FM than for SBM diets, flows (grams/day) of total AA, essential AA (EAA), and nonessential AA (NEAA) were similar (P greater than .05) among diets. However, greater (P less than .05) total AA, EAA, and NEAA flows (percentage of AA intake) were found for corn than for barley diets and for FM than for SBM diets. It is concluded, therefore, that ruminal escape protein derived from corn or FM has a significant effect on manipulating AA leaving the ruminal fermentation.
 ...
PMID:Influence of dietary protein and carbohydrate sources on nitrogen metabolism and carbohydrate fermentation by ruminal microbes in continuous culture. 206 23

Responses of dairy cows given silage diets to the intraruminal infusion of urea in progressively increasing doses were studied in four experiments, two with non-lactating cows and two with lactating cows. No clinical symptoms of NH3 toxicity were observed in any of the experiments. When urea was infused continuously, silage intake was depressed (P less than 0.05) when the total supply of N exceeded the equivalent of 250 g crude protein (CP)/kg DM in the total diet. However, when the urea load was administered twice daily, as opposed to continuously, intake depression (P less than 0.05) occurred at the equivalent of 170 g CP/kg DM. At the higher doses of urea, concentrations of NH3 in peripheral blood increased and were accompanied by increased concentrations of glucose and reduced levels of insulin in plasma. In general, responses of milk production followed those of silage intake but there was evidence of greater proportional reductions in the yield of lactose relative to that of fat and protein. It is concluded that the voluntary intake of high-protein silages may be depressed by factors associated with high rates of absorption of NH3 from the rumen.
 ...
PMID:The effects of intraruminal infusions of urea on the voluntary intake and milk production of cows receiving grass silage diets. 226 98

Effects of atmospheric ammonia (NH3) on the nasal mucosa and somatic growth were investigated in pigs exposed to 4 NH3 concentrations (0; 25; 50; and 100 ppm) for 6 days in a specifically designed air-pollutant exposure chamber. Nasal lavage (NAL) was applied to quantify the ammonia-induced inflammatory response by measuring the number of neutrophils and the albumin (porcine serum albumin) concentration in the NAL liquid. In control pigs, these variables remained unchanged throughout the exposure period. In all other groups, an important ammonia concentration-related increase was recorded. The equation of the linear regression line established between the mean values of the number of neutrophils (x 10(3)) per milliliter of NAL liquid (y) recorded at the end of the exposure period and the ammonia concentrations (ppm) was: y = 69.7 + 3.3 [NH3] (r = 0.979; P < 0.020). The increase in the neutrophil count was significant (P < 0.05) at concentrations as low as 25 ppm. For albumin concentration nanograms per milliliter, the corresponding equation was: y = 574 + 14.3 [NH3] (r = 0.953; P < 0.045). However, the first significant change (P < 0.05) in this variable was only obtained for the higher concentration (100 ppm). In exposed pigs, a concentration-related depression of somatic growth was observed. The equation of the regression line plotted relating the individual values of the changes in body weight gain recorded over the exposure period expressed as percentage of the initial body weight (y) and the ammonia concentration was: y = 3.507-0.203 [NH3] + 0.001 [NH3]2 (r = 0.55; P < 0.010).(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Quantitative assessment of aerial ammonia toxicity to the nasal mucosa by use of the nasal lavage method in pigs. 780 5

An inverse relation is known to link blood potassium with renal synthesis and the release of ammonia. Given the liability of hyperammonemia for precipitating hepatic encephalopathy (HE), 28 patients affected by stage I HE were equally divided into two groups and maintained up to their death at the highest (5.4-5.5 mEq/l) or the lowest (3.5-3.6 mEq/l) normokalemia levels. When compared with the lowest normokalemia group, the highest one showed an early, albeit transient, improvement in the mental state (as assessed by both EEG and psychiatric investigations) and to a lesser extent in hepatic functions (as assessed by the variations in serum bilirubin, GPT, GGT and plasma prothrombin time). In the highest normokalemia group the survival was also prolonged. The cause of this improvement may be related to the induced decrease in blood pH, the consequent depression of renal ammoniagenesis and the rise in the arterial and urine NH+4/NH3 ratios. These factors reduce the entry of ammonia into the cells and enhance the urinary excretion of this metabolite, respectively.
 ...
PMID:The importance of the highest normokalemia in the treatment of early hepatic encephalopathy. 816 17

Newborn Holstein calves (n = 75) were blocked by date of birth and sex and assigned randomly to one of eight isonitrogenous starters that contained protein and starch sources of different ruminal availabilities. Soybean meal or soybeans roasted to an exit temperature of 146 degrees C, raw or conglomerated corn, and urea at 1% of DM or no urea were used in a 2 x 2 x 2 factorial arrangement. The conglomeration process consisted of grinding the grain, adding water, pelleting the mixture, and roasting, which increased the degree of starch gelatinization fivefold. Starters were fed for ad libitum intake from 0.5 to 8 wk. Urea supplementation of conglomerated corn starters depressed performance, but the depression was greater when conglomerated corn was used with soybean meal than when it was used with roasted soybeans. Ruminal NH3 and plasma urea increased with increased RDP in starters, but the response varied according to corn type and soy protein source. Urea supplementation depressed plasma Lys, doubled plasma Cit with soybean meal and conglomerated corn starters, but depressed plasma Cit with roasted soybeans and conglomerated corn starters. Conglomerated corn depressed plasma Val and Gly, and roasted soybeans increased plasma Phe. Performance was similar when calves consumed starters containing ruminally synchronous or asynchronous CP and starch sources.
 ...
PMID:Ruminal availabilities of protein and starch: effects on growth and ruminal and plasma metabolites of dairy calves. 870 89

Manipulations of pH and electrical gradients in a perfused preparation were used to analyze the factors controlling ammonia distribution and flux in trout white muscle after exercise. Trout were exercised to exhaustion, and then an isolated-perfused white muscle preparation with discrete arterial inflow and venous outflow was made from the posterior portion of the tail. The tail-trunks were perfused with low (7.4)-, medium (7.9)-, and high (8.4)-pH saline, achieved by varying HCO3- concentration ([HCO3-]) at constant Pco2. Intracellular and extracellular pH, ammonia, CO2, K+, Na+, and Cl- were measured. Muscle intracellular pH was not affected by changes in extracellular pH. Increasing extracellular pH caused a decrease in the transmembrane NH3 partial pressure (PNH3) gradient and a decrease in ammonia efflux. When extracellular K+ concentration was increased from 3.5 to 15 mM in the medium-pH group, a depolarization of the muscle cell membrane potential from -92 to -60 mV and a 0.1-unit depression in intracellular pH occurred. Ammonia efflux increased despite a marked reduction in the PNH3 gradient. Amiloride (10(-4) M) had no effect, indicating that Na+/H(+)-NH4+ exchange does not participate in ammonia transport in this system. A comparison of observed intracellular-to-extracellular ammonia distribution ratios with those modeled according to either pH or Nernst potential distributions supports a model in which ammonia distribution across white muscle cell membranes is affected by both pH and electrical gradients, indicating that the membranes are permeable to both NH3 and NH4+. Membrane potential, acting to retain high levels of NH4+ in the intracellular compartment, appears to have the dominant influence during the postexercise period. However, at rest, the pH gradient may be more important, resulting in much lower intracellular ammonia levels and distribution ratios. We speculate that the muscle cell membrane NH3-to-NH4+ permeability ratio in trout may change between the rest and postexercise condition.
 ...
PMID:Ammonia movement and distribution after exercise across white muscle cell membranes in rainbow trout. 885 99

A 4 x 4 Latin square experiment was conducted to examine abomasal passage of biogenic amines in steers fed silage and their related effects on intake, digestibility, and digestive function. Thirty percent of the dry matter (DM) in the diets consisted of alfalfa forage, which was fed as either hay or silage. The DM from alfalfa silage DM was substituted at 0, 33, 67, and 100% for DM from alfalfa hay and was fed to four ruminally and abomasally cannulated steers. The roughage component of the diet constituted 50% of the DM and consisted of 60% alfalfa silage or hay and 40% tropical corn silage. The concentrate was composed mainly of ground corn. The concentrations of putrescine and cadaverine in abomasal digesta increased as alfalfa silage in the diet increased. Abomasal recovery of biogenic amines, a product of their concentration in abomasal digesta and the passage of DM through the abomasum, was negatively correlated with intake. Abomasal recovery of most amines was 5 to 20% of intake. Abomasal recovery of cadaverine was correlated with depressed intake. Total DM intake was reduced 8.3 to 25.8% as the proportion of alfalfa silage in the diet increased. Frequency of reticular contractions, intake, ruminal DM digestibility, ruminal outflow, volatile fatty acids, and total tract DM digestibility decreased in steers fed diets that contained more alfalfa silage. Ruminal fluid pH and NH3 concentration increased in steers fed more alfalfa silage; however, mass and the DM percentage of ruminal contents decreased linearly. Postprandial insulin concentrations were quadratically related to the proportion of alfalfa hay or silage in the diet. Intraruminal metabolism of biogenic amines is extensive based on the relatively low quantities recovered in abomasal digesta; however, the amounts recovered in abomasal digesta were related to intake depression and associated physiological effects.
 ...
PMID:Biogenic amines in silage, apparent postruminal passage, and the relationship between biogenic amines and digestive function and intake by steers. 974 85


1 2 Next >>