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Nutrient Metabolism and Fetal Brain Development
Published in Emilio Herrera, Robert H. Knopp, Perinatal Biochemistry, 2020
George E. Shambaugh, Boyd E. Metzger, James A. Radosevich
In the fetal brain, amino acids are utilized for biosynthesis of purines, pyrimidines, and polyamines. The de novo pathway for pyrimidine biosynthesis is summarized in Figure 3 and begins with the combination of nitrogen from glutamine with bicarbonate, a reaction catalyzed by carbamyl phosphate synthetase. Carbamyl phosphate is converted to carbamyl aspartate and dihydro orotic acid. The capacity for glutamine synthesis in the fetal brain and the low KM for glutamine make the synthesis of carbamyl phosphate an effective means for reutilizing ammonia derived from maternal gluconeogenesis or transamination of branched-chain amino acids.14 The de novo pathway for purine biosynthesis also fixes nitrogen that is spared from urea synthesis.
Diseases of the Nervous System
Published in George Feuer, Felix A. de la Iglesia, Molecular Biochemistry of Human Disease, 2020
George Feuer, Felix A. de la Iglesia
In hyperammonemia, the only established biochemical defect is the elevated blood ammonia level. This even may be associated with the deficiency of ornithine transcarbamylase or carbamyl phosphate synthetase. These enzymes are located in the liver and both types of disorders have been demonstrated. Consumption of a low-protein-containing diet reduces blood ammonia.
Structure, Function and Evolutionary Aspects of Mitochondria
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
Puja Agarwal, Mehali Mitra, Sujit Roy
Mitochondrial matrix contains a wide variety of metabolites. Pyruvate, acetyl CoA, acyl CoA, α-ketoglutarate, isocitrate, succinyl CoA, succinate, malate, fumarate and oxaloacetate are involved in citric acid cycle. L-citrulline, L-ornithine and carbamoyl phosphate are used in urea cycle. Mitochondria DNA, RNA and transfer RNA are used for protein synthesis. Another ions like Ca+2, K+, Mg+2 are also present in the matrix. Moreover CO2, H2O, O2, ATP, ADP and inorganic phosphate are present as metabolites. Enzymes like citrate synthase, Pyruvate dehydrogenase, isocitrate dehydrogenase, aconitase, α-ketoglutarate dehydrogenase, succinyl CoA synthetase, fumerase and malate dehydrogenase facilitates the TCA cycle. Transaminase facilitates amino acid production. β-oxidation uses pyruvate carboxylase, acyl CoA dehydrogenase and β-ketothiolase. The urea cycle is facilitated by carbamoyl phosphate synthetase I and ornithine transcarboxylase.
Porphyromonas gingivalis diffusible signaling molecules enhance Fusobacterium nucleatum biofilm formation via gene expression modulation
Published in Journal of Oral Microbiology, 2023
Yukiko Yamaguchi-Kuroda, Yuichiro Kikuchi, Eitoyo Kokubu, Kazuyuki Ishihara
Eighty-seven genes were downregulated (Table 2), including those encoding protein involved in de novo synthesis of purine (phosphoribosyl amine-glucine ligase, purH, class I SAM-dependent methyltransferase, phosphoribosyl glycinamide formyl transferase, purM, amidophosphoribosyltransferase, phosphoribosylaminoimidazole-succinocarboxamide synthase, purE, and phosphoribosylformylglycinamidine synthetase), proteins involved in de novo pyrimidine synthesis (bifunctional pyr operon transcriptional regulator/uracil phosphoribosyltransferase PyrR, aspartate carbamoyltransferase, dihydroorotase, glutamine-hydrolyzing carbamoyl-phosphate synthase small subunit, carbamoyl-phosphate synthase large subunit, dihydroorotate dehydrogenase electron transfer subunit, dihydroorotate dehydrogenase, orotidine 5’-phosphate decarboxylase, and orotate phosphoribosyltransferase), bioA involved in biotin metabolism, and TonB-dependent receptor.
Fermented whey modulated AFB1 and OTA-induced hepatotoxicity and nephrotoxicity in vivo. A relative and absolute quantification about sex differences
Published in Toxicology Mechanisms and Methods, 2023
Massimo Frangiamone, Alexander Yemelin, Alessandra Cimbalo, Guillermina Font, Eckhard Thines, Lara Manyes
For in vivo toxicological studies concerning mycotoxins, a main aspect to take into account is the sex-dependent response. For instance, in mice, chickens, and humans, the liver carcinogenicity of AFB1 is greater in males than in females. Similarly, OTA prompted kidney tumors much more frequently in male rats than in females (Soler and Oswald 2018; EFSA 2020a; EFSA 2020b). The beneficial effects of probiotics have been also reported to show sex-related responses (He et al. 2019; Myles et al. 2020). Furthermore, the findings achieved with animal models can be extrapolated to humans by using biological biomarkers (Kraus 2018). In this sense, carbamoyl phosphate synthetase-1 (CPS1), the most abundant protein in liver mitochondria, represents a robust biomarker to detect hepatic diseases in humans and rats (Weerasinghe et al. 2014). Likewise, kidney injury molecule 1 (KIM-1) has been accepted by the Food and Drug Administration and European Medicines Agency as a highly sensitive and specific biomarker to monitor chemical-induced kidney injury in preclinical studies (Griffin et al. 2019).
Hyperammonemia in the setting of Roux-en-Y gastric bypass presenting with osmotic demyelination syndrome
Published in Journal of Community Hospital Internal Medicine Perspectives, 2021
Carly Rosenberg, Michael Rhodes
The question we ask ourselves now is can hyperammonemia cause osmotic demyelination syndrome? A case report by Langer et al. [5] described a pediatric patient with carbamoyl phosphate synthetase deficiency who developed osmotic demyelination and transient cortical blindness after rapid correction of hyperammonemia. The hypothesized underlying mechanism was due to disruption of the blood–brain barrier and re-equilibration of osmolytes, in particular glutamine. Similarly, another case had been reported earlier by Mattson et al. [6] of a child with ornithine carbamoyl transferase deficiency who presented with hyperammonemic encephalopathy with a maximum ammonia level of 376 mmcol/L. Her ammonia was corrected with hydration and protein restriction; however, 5 days after correction of her hyperammonemia, she developed seizures and fell into a coma. MRI brain imaging ultimately revealed characteristic findings of central pontine myelinolysis.