High concentrations of D-amino acids in human gastric juice

Nagata, Yoko; Satô, Tadashi; Enomoto, Nobuyuki; Ishii, Yutaka; Sasaki, Koichi; Yamada, Takuro

doi:10.1007/s00726-006-0262-9

Cited by 56 publications

(49 citation statements)

References 24 publications

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“…Additionally, surface expression of NMDA channels in gastric cells may constitutively facilitate the ability of dietary amino acids like glycine and glutamate, which are the NR1 and NR2 channel agonists, respectively, to have a direct effect on the rate of Ca 2+ -influx and thus on cell function and viability. NMDA channel activation by glutamate may also contribute to apoptosis rates in HP infection, since gastric juice glutamate levels are increased more than 2-fold in patients with gastritis and nearly 10-fold in HP-infected patients with early gastric cancer 36 .…”

Section: Discussionmentioning

confidence: 99%

N-methyl d-Aspartate Channels Link Ammonia and Epithelial Cell Death Mechanisms in Helicobacter pylori Infection

et al. 2011

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BACKGROUND & AIMS Helicobacter pylori infection is a risk factor for gastric cancer. Ammonia/ammonium (A/A) is a cytotoxin generated by H pylori that kills gastric epithelial cells. We investigated whether A/A cytotoxicity occurs by activating N-methyl D-aspartate (NMDA) channels, which results in Ca2+ permeation and epithelial cell death. METHODS Gastric epithelial cells were cultured to confluence and then incubated with A/A and NMDA channel or cell signaling antagonists. Cells were incubated with wild-type H pylori or mutant strains that do not produce A/A. Changes in intracellular Ca2+ were examined in living cells by confocal microscopy. Biochemical and histochemical techniques were used to examine the relationship between A/A-induced cell death and intracellular levels of Ca2+. RESULTS A/A increased Ca2+ permeation in gastric epithelial cells; the increase was blocked by NMDA receptor and cell signaling antagonists. Wild-type, but not mutant H pylori, also caused extensive Ca2+ permeation of gastric epithelial cells, which was blocked when NMDA receptor expression was repressed. Ca2+ that entered cells was initially cytoplasmic and activated proteases. Later, the Ca2+ was sequestered to cytoplasmic vacuoles that are dilatations of the endoplasmic reticulum (ER). Inositol -3-phosphate–dependent release of Ca2+ from ER and protease activity damaged mitochondria, reduced levels of ATP, and transcriptionally up-regulated cell death effectors. Expression of the NMDA receptor was altered in stomachs of mice infected with H pylori. CONCLUSIONS A/A affects gastric epithelial cell viability by allowing excessive Ca2+ permeation through NMDA channels. NMDA channels might thereby regulate cell survival and death pathways during development of gastric cancers associated with H pylori infection.

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Section: Discussionmentioning

confidence: 99%

N-methyl d-Aspartate Channels Link Ammonia and Epithelial Cell Death Mechanisms in Helicobacter pylori Infection

et al. 2011

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“…36% [45]. In addition, dAsp has also been found in human gastric juice [46], human saliva [47], and human and rat salivary glands [47][48][49]. The salivary gland is an exocrine tissue comprised of three kinds of major salivary glands (parotid gland, submandibular gland and sublingual gland) and several minor salivary glands.…”

Section: Expression and Localization Of D-asp In Mammalian Tissues Anmentioning

confidence: 98%

d-Aspartate—An important bioactive substance in mammals: A review from an analytical and biological point of view

Katane

Homma

2011

Journal of Chromatography B

113

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“…Despite being found in human bodily fluids and tissues (Nagata et al 1992(Nagata et al , 2006(Nagata et al , 2007, D-alanine (D-Ala) is not formed in the body because it is believed that humans lack D-Ala racemase. D-Ala is the most prevalent D-amino acid in higher plants (Robinson 1976), is found in high concentrations in certain mollusks (Zagon et al 1994), and is an integral part of the structure of bacterial cell walls (Zagon et al 1994).…”

Section: D-alaninementioning

confidence: 99%

Nutritional and medicinal aspects of d-amino acids

2011

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This paper reviews and interprets a method for determining the nutritional value of D-amino acids, D-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of experiments were carried out in which a molar equivalent of the test compound replaced a nutritionally essential amino acid such as L-lysine (L-Lys), L-methionine (L-Met), L-phenylalanine (L-Phe), and L-tryptophan (L-Trp) as well as the semi-essential amino acids L-cysteine (L-Cys) and L-tyrosine (L-Tyr). The results show wide-ranging variations in the biological utilization of test substances. The method is generally applicable to the determination of the biological utilization and safety of any amino acid derivative as a potential nutritional source of the corresponding L-amino acid. Because the organism is forced to use the D-amino acid or amino acid derivative as the sole source of the essential or semi-essential amino acid being replaced, and because a free amino acid diet allows better control of composition, the use of all-amino-acid diets for such determinations may be preferable to protein-based diets. Also covered are brief summaries of the widely scattered literature on dietary and pharmacological aspects of 27 individual D-amino acids, D-peptides, and isomeric amino acid derivatives and suggested research needs in each of these areas. The described results provide a valuable record and resource for further progress on the multifaceted aspects of D-amino acids in food and biological samples.

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High concentrations of D-amino acids in human gastric juice

Cited by 56 publications

References 24 publications

N-methyl d-Aspartate Channels Link Ammonia and Epithelial Cell Death Mechanisms in Helicobacter pylori Infection

N-methyl d-Aspartate Channels Link Ammonia and Epithelial Cell Death Mechanisms in Helicobacter pylori Infection

d-Aspartate—An important bioactive substance in mammals: A review from an analytical and biological point of view

Nutritional and medicinal aspects of d-amino acids

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