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This work is a study of the metabolic disorder due to ammonium toxicity in cucumber (Cucumis sativus L. cv. suisei No. 2) leaves. The cucumber was cultured with 20 and 200 mg/1 NH3-N for 5 days. In the first half of this experiment, the plant leaves were photosynthesized for 3 hours to study the distribution of 14C in starch and other fractions. The incorporation of photosynthesized 14C into not only starch but also other higher polymers was suppressed by ammonium toxicity. On the other hand, the rate of 14C incorporation in 80 % ethanol soluble fraction was higher in the treatment of 200 mg/1 NH3-N. In the latter half of experiment, phosphate esters in the leaves were analyzed by column chromatography. The opposing contents of uridine diphosphoglucose (UDPG) and the uridine compound containing sugar or sugar derivative (UDPX) were determined by different ammonia levels. Toxicity of ammonia resulted in an increase of UDPG and a decrease of UDPX. The level of ATP was not changed so much. The content of glucose-6-phosphate (G-6-P) in injured plants was lower than that of normal plants, while glucose-1- phosphate (G-l-P) and fructose-6-phosphate (F-6-P) were higher in injured plants. These results further suggested the disorder of carbohydrate metabolism due lo ammonium toxicity which was reported previously. [ABSTRACT FROM AUTHOR]

Proton magnetic resonance spectra of 30 adenine nucleosides have been obtained in dilute (0.001 to 0.05 M) aqueous or dimethyl sulfoxide solutions and have been analysed with respect to structure- dependent variations of the purine proton chemical shifts. In ²H2O the resonance signal of H-8 shows a marked dependence upon the nature of substituents linked to C-4' of adenine ribofuranoside derivatives and upon the presence of a 2': 3'-O-isopropylidene group while H-2 is relatively unaffected. Therefore the chemical shift difference, δH-8 - δH-2 = Δδ, may serve as an indicator of intramolecular ribose-base interact ons. Δδ varies with the chemical nature of C-4' or C-5' substituents in the order: ammonium, sulfonium (0 ppm) gauche, gauche C-5' conformation. In dimethyl sulfoxide, basically the same situation exists but different substituents exhibit smaller individual Δδ variations than in water, indicating different solvation shells. In this solvent two additional conformation-stabilizing contributions can be recognized, viz, an interaction of the bridge oxygen (O-4') of ribose with adenine, and a hydrogen bond between H-8 and a 5'- carboxylate anion. This energetic stabilisation of the anti and g,g-conformers by most types of adenosine C-5' substituents supports the "rigidity" concept of nucleotides, extending it to the nucleoside level. The only exception found is 5'-nitromethyladenosine in which ultraviolet, circular dichroism and magnetic resonance spectra suggest rotation of the adenine base to a "non-classical" conformation due to base-chain &pie;-electron interaction. The anti-conformation of the adenosine derivatives used in this study can in some cases be correlated with their enzymatic deamination by adenosine and AMP aminohydrolase. [ABSTRACT FROM AUTHOR]

The actions of intra- and extracellularly applied ammonium ions were studied on membrane potentials of the isolated crayfish stretch receptor neuron. In accordance with results obtained from cat spinal motoneurons, ammonium produced a gradual and reversible shift of the IPSP reversal potential towards the resting potential following both kinds of application. In the concentrations tested extracellularly (3 to 15 mM/l), passive membrane properties, spike generation and inhibitory synaptic transmission showed no alterations. The transient shifts of resting potential and spike amplitude that followed intracellular ammonium injection are comparable with those of injected sodium ions in some respect. Further evidence results for an outwardly directed chloride pump which normally maintains the ionic gradient for hyperpolarizing inhibition. [ABSTRACT FROM AUTHOR]

This article presents information on the paper "Inactivation of Hexavalent Chromium," by M.H. Samitz, E. Epstein and S. Katz that was published in a 1962 issue of the periodical "Archives of Dermatology." An antichrome agent consisting of sodium pyrosulfite, tartaric acid, glucose and ammonium chloride inactivated and removed hexavalent chromium from all the materials including skin.

The Km-values for ammonium and bicarbonate in carbamoylphosphate synthesis are 1.1 mM and 5.3 mM respectively at saturation with ATP and acetylglutamate. The are independent of the concentration of the second substrate. The same Km for bicarbonate is found in the hydrolysis of ATP, which is catalyzed by the enzyme in the absence of ammonium. The [32P]orthophosphate- ATP-exchange, which is very slow, requires bicarbonate and ammonium. With these findings, the following mechanisms for the C—N-ligase step(s) of the enzyme are possible: (a) enzyme-bound carbamate is formed by a simultaneous reaction of ATP, bicarbonate and ammonium; (b) at first enzyme-bound "active CO2" is formed in a rapid and reversible reaction, which releases both the ATP-products, ADP and orthophosphate only upon the reaction with ammonium. Possible structures for this intermediate would be carboxyphosphate plus ADP and the addition compound of bicarbonate with ATP (with penta-coordinated phosphorus). The participation of biotin was excluded. As can be estimated from the kinetic findings, only a small fraction of the enzyme molecules would ever be charged with "active CO2": the half-time of its decomposition, as calculated from the ATPase activity, would be ≤ 2 sec. [ABSTRACT FROM AUTHOR]

Discusses the study "Precipitating Factors in the Development of Hepatic Coma Including Preliminary Observations of Serum Ammonium Levels," presented at the Third Annual Convention of the American College of Gastroenterology in New York City on October 15-17, 1956. Diagnosis of liver disease; Precipitating factors in the development of coma; Suggested therapy to induce hepatic coma.

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The article presents a study on the responses of the Deschampsia flexuosa, Rumex acetosa, Scabiosa columbaria, Nardus stricta and Sesleria albicans seedlings grown in solution culture whose source of nitrogen was either the nitrate or the ammonium form. The objective of the study was to test the hypothesis that some calcifuge species grow better when nitrogen is available in the ammonium form, that some calcicoles grow better when the nitrate form is available, and that widely tolerant species respond equally well to either form of nitrogen. Results suggest that the species responded as predicted, and although the concentration of the major nutrients in the culture solutions was from five to several hundred times higher than in soil solutions, the ecological implications are strong.

Apparent K[SUBm] values for nitrite reductase, glutamic dehydrogenase, and nitrate reductase are of the order 10[SUP-4] molar for nitrite, ammonia, and nitrate, respectively while half-saturation constants for the corresponding uptake mechanisms approximate 10[SUP-6] molar. Ammonium and nitrate are accumulated in the vacuolated cells of the diatom (about 10 and 40 mmoles/liter cell volume, respectively) and these intracellular pools serve as substrate for the assimilatory enzymes. Nitrite is either not accumulated or is concentrated in a very small cellular compariment. Ammonium and nitrate in the external medium exert modifying effects on uptake and assimilatory mechanisms which can be distinguished from effects of the ions accumulated within the cells. Several of these effects are described and fitted into a general scheme of nitrogen assimilation by D. brightwellii. [ABSTRACT FROM AUTHOR]

Ferric ammonium citrate, haematin hydrochloride, soluble haematin, lysed mouse red ceils and a variety of purified haemoglobins abolished the protective effect of Pasteurella septica antiserum in mice when the iron compounds were injected intraperitoneally with P. septica. Ferric ammonium citrate was less effective than haematin or lysed red ceils when the dose of P. septica was reduced to less than 105, The ability of lysed red cells to abolish protection was greatly reduced if given 4 hours or more after infection. P. septica grew rapidly in unimmunized normal mice. In passively immunized mice the number of viable bacteria declined rapidly after infection. In passively immunized mice given haematin or lysed red cells the growth of bacteria was identical to that seen in unprotected normal mice. Large numbers of dead P. septica or carbon particles did not interfere with passive protection. [ABSTRACT FROM AUTHOR]

Chlamydomonas reinhardi did not assimilate nitrate or ammonium unless a suitable source of carbon was provided. Suitable sources were CO2 in light or, in darkness, acetate or the carbon reserves accumulated in nitrogen-starved cells. Illuminated cells in which CO2 assimilation was prevented by DCMU did not assimilate either nitrate or ammonium but did so when acetate was added; the rate of nitrogen assimilation was faster than with acetate in darkness and it is suggested that light promoted nitrogen assimilation by photophosphorylation. The assimilation of nitrate was inhibited by addition of either ammonium or nitrite and that of nitrite by addition of ammonium. Experimental evidence indicated that products of ammonium assimilation, rather than ammonium itself, were inhibiting. [ABSTRACT FROM AUTHOR]

The article focuses on phosphorus in human saliva. It states that calcium and phosphorus are closely related to the development and growth of teeth and bones. It mentions that there are several forms of salivary phosphorus, and that total phosphorus content can be determined through wet or dry ashing methods. It comments that phosphorus fractions can be isolated through the precipitation of phosphorus using ammonium followed by a gravimetric determination.