An Automated Microassay for Blood Ammonia

Imler, M; Frick, Alice; Schlienger, Jean-Louis; Stahl, A

doi:10.1515/cclm.1979.17.4.247

Cited by 12 publications

(13 citation statements)

References 3 publications

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“…Autoanalyzer 1 (Technicon Instruments Corp.): sampler, dialyzer at + 37 °C, oil bath + 95 °C, colorim eter, recorder, manifold as for NH4 microassay (13,20).…”

Section: Principle Of the Methodsmentioning

confidence: 99%

“…E-Alanine dehydrogenase (EC 1.4.1.1, from Bacil lus subtilis, Boehringer, Mannheim, 30 U/mg, batch 1326 039): the enzyme suspension in ammonium sul fate is dialyzed at + 4 °C against two liter changes of bidistilled water during 6 h and of phosphate buffer 20 mmol/1, pH 7.4 during 16 h, in order to remove the NH4 ions completely; this is checked as described earlier (12,13). The enzyme working solution con tains 15 U/ml of phosphate buffer 20 mmol/1, pH 7.4 (+ 37 °C).…”

Section: Principle Of the Methodsmentioning

confidence: 99%

“…Reagents for NH4 determination were described in detail earlier (13,20). Sodium tetraborate solution is…”

Section: Principle Of the Methodsmentioning

confidence: 99%

“…Both tubes are covered and incubated at + 37 °C for 30 min. With the capillary tube of the continuous flow analyzer (13), 50 pi of the incubated assay mixture is aspirated in 1 min. The capillary tube is cleared with water for 2 min before aspirating 50 /al of the control sample.…”

Section: Assay Proceduresmentioning

confidence: 99%

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Semiautomated Enzymic Microassay for Plasma L-Alanine

Stahl¹,

Frick²,

Imler³

et al. 1979

Enzyme

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Plasma L-alanine is deaminated by bacterial alanine-dehydrogenase; the resulting ammonia is dialyzed out and measured by use of a continuous flow phenol-hypochlorite colorimetric microassay. Concentrations in the range of 10 -1,000 μmol alanine/l can be determined in a 50-μl sample. The optimal conditions for the assay are specified. Study of the analytical qualities of the technique shows high specificity, good reproducibility, and a detection limit of 6 μmol/l. Usual values in human plasma from arterial or venous blood are respectively 296 ± 166 and 376 ± 214 ;umol alanine/1 (x ± 2 SD). The usual values in rats are close to those found in man.

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“…Autoanalyzer 1 (Technicon Instruments Corp.): sampler, dialyzer at + 37 °C, oil bath + 95 °C, colorim eter, recorder, manifold as for NH4 microassay (13,20).…”

Section: Principle Of the Methodsmentioning

confidence: 99%

Section: Principle Of the Methodsmentioning

confidence: 99%

“…Reagents for NH4 determination were described in detail earlier (13,20). Sodium tetraborate solution is…”

Section: Principle Of the Methodsmentioning

confidence: 99%

Section: Assay Proceduresmentioning

confidence: 99%

See 2 more Smart Citations

Semiautomated Enzymic Microassay for Plasma L-Alanine

Stahl¹,

Frick²,

Imler³

et al. 1979

Enzyme

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“…Incubations were performed at 37°C for 15-50 min and stopped with perchloric acid (neutralized with KOH) or 0.01 mm EDTA; aliquots were processed by HPLC according to Webster and Whaun [37]. The ammonium content was assayed using the hypochlorite-phenol Berthelot reaction, according to Imler et al [38].…”

Section: Enzyme Assaysmentioning

confidence: 99%

Evidence of a new phosphoryl transfer system in nucleotide metabolism

et al. 2008

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Purine nucleotides are precursors of nucleic acids and participate in many metabolic pathways as substrates, coenzymes and energy sources. Much attention has been focused on the roles and intracellular levels of AMP, ADP and ATP in various tissues under normal and pathological conditions [1][2][3]. Their relationships to genetic diseases, blood disorders, drugs, tumours and other pathologies have been studied extensively [4][5][6].Although ATP formation occurs via several wellknown mechanisms, ADP is thought to be formed only from ATP, either by the adenylate kinase reaction or by ATPase-mediated hydrolysis. The possibility that ADP can be formed by de novo synthesis from low-energy precursors has never been investigated fully. Even less studied is the possibility that ADP might be synthesized from low-energy precursors under special conditions, such as ischaemia and hypoxia, in which massive depletion of ATP and elevation of AMP are known to occur [7][8][9][10].In this article, it is shown that, under physiological conditions, ADP may be formed in mammalian tissues by the disproportionation of AMP, consistent with an AMP-AMP phosphotransferase reaction. This reaction is carried out by enzymes of purine metabolism which, under specific cellular conditions, associate in a biological network and cooperate in a reaction not reported previously. Crude rat liver extract showed AMP-AMP phosphotransferase activity which, on purification, was ascribed to a novel interaction between adenylate kinase, also known as myokinase (EC 2.7.4.3), and adenosine kinase (EC 2.7.1.20). The activity was duplicated using the same enzymes purified from recombinant sources. The reaction requires physical contact between myokinase and adenosine kinase, and the net reaction is aided by the presence of adenosine deaminase (EC 3.5.4.4), which fills the gap in the energy balance of the phosphoryl transfer and shifts the equilibrium towards ADP and inosine synthesis. The proposed mechanism involves the association of adenosine kinase and myokinase through non-covalent, transient interactions that induce slight conformational changes in the active site of myokinase, bringing two already bound molecules of AMP together for phosphoryl transfer to form ADP. The proposed mechanism suggests a physiological role for the enzymes and for the AMP-AMP phosphotransferase reaction under conditions of extreme energy drain (such as hypoxia or temporary anoxia, as in cancer tissues) when the enzymes cannot display their conventional activity because of substrate deficiency.

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Intestinal ammonium production in the rat: The role of the colon, small intestine, and circulating glutamine

et al. 1988

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The intestinal ammonium production and the intestinal uptake of circulating glutamine were investigated in anesthetized intact rats and rats with resected small intestine or colon by simultaneous measurements performed on portal and arterial blood. It was shown that ammonium release into the portal blood by the small intestine is of equal magnitude to that released by the colon, and that circulating glutamine participates in ammonium production by the small intestine. Increased levels of circulating glutamine induced by its i.v. infusion to intact rats were not accompanied by an increase in intestinal ammonium production.

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An Automated Microassay for Blood Ammonia

Cited by 12 publications

References 3 publications

Semiautomated Enzymic Microassay for Plasma L-Alanine

Semiautomated Enzymic Microassay for Plasma L-Alanine

Evidence of a new phosphoryl transfer system in nucleotide metabolism

Intestinal ammonium production in the rat: The role of the colon, small intestine, and circulating glutamine

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