The Development of Urea Cycle Enzyme Activity
in the Liver of Foetal and Neonatal Rats

Miller, Anne; Chu, Peter

doi:10.1159/000458392

Cited by 27 publications

(14 citation statements)

References 5 publications

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“…On the basis of in vitro V max comparisons [mmol product/(h ⅐ kg 0.75 )], urea cycle flux in rat pups, adult rats, and human infants is limited by argininosuccinate synthetase (AS) (Miller and Chu 1970, Raiha and Suihkonen 1968aand 1968b, Table 2). It is interesting that the calculated urea production rate of piglets at baseline [ Fig.…”

Section: Figurementioning

confidence: 99%

“…In vitro enzyme activities have been used routinely to study the development of the urea cycle potential during gestation and after birth in rats (Kennan and Cohen 1959, Miller and Chu 1970, Raiha and Suihkonen 1968a, piglets (Kennan and Cohen 1959), and humans (Raiha and Suihkonen 1968b). In addition to being measured under nonphysiologic conditions, the liver samples used to make homogenates in previous studies on human fetuses were obtained from abortions, stillbirths, miscarriages and unexpected infant deaths.…”

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confidence: 99%

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Comparison of Total Body Urea Production Potential with Total Body Carbamoyl Phosphate Synthetase (CPS-1) Activity in Newborn Piglets Infused with Alanine at 50% of Resting Energy Expenditure for 36 Hours

Davis

Greer

Benevenga

2000

The Journal of Nutrition

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The calculated rate of urea production [U p ; mmol urea/(h ⅐ kg 0.75 )], based on urinary urea-N (UUN) excretion and changes in total body urea-N, was compared with the calculated total body V max of carbamoyl phosphate synthetase (CPS-1) of 24 neonatal piglets from four treatments as follows: 6 h baseline control (n ϭ 8), 18 h of alanine intravenously (IV) at 50% of resting energy expenditure (REE; n ϭ 4), 36 h of alanine IV at 50% of REE (n ϭ 6), or 36 h of glucose IV at 50% of REE (n ϭ 6). The following significant increases from baseline were seen in piglets infused with alanine for 36 h: 1) UUN excretion [10.6 Ϯ 5. With the exception of CPS-1 activity, significant decreases from baseline were seen in these values in piglets infused with glucose for 36 h (P Ͻ 0.05). Comparison of calculated urea production with calculated total body CPS-1 V max at baseline, 18 or 36 h after the start of infusion of alanine or glucose revealed a positive relationship (slope ϭ 0.263; P Ͻ 0.002). At all enzyme activities, infusion of alanine resulted in a significant increase in the rate of urea production compared with controls (P Ͻ 0.001). Total body CPS-1 activity varied from 1.8 to 5.8 times that of urea production, suggesting that CPS-1 did not limit urea production.

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Section: Figurementioning

confidence: 99%

mentioning

confidence: 99%

Comparison of Total Body Urea Production Potential with Total Body Carbamoyl Phosphate Synthetase (CPS-1) Activity in Newborn Piglets Infused with Alanine at 50% of Resting Energy Expenditure for 36 Hours

Davis

Greer

Benevenga

2000

The Journal of Nutrition

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“…The low activity found in early suckling suggests the existence of a mode of high nitrogen storage in the whole developing rat (Hahn and Koldovsky, 1961) intestinal glutamine synthetase activity reached a maximum between days 5 and 10 and decreased afterwards to adult levels. This increase during midlactation was related with the relative lack or urea cycle activity (Miller and Chu, 1970) during the initial stages of lactation and the need to detoxify excess ammonia produced in the gut (Arola et al, 1981a). However, this role was probably of limited effectiveness because of strong intestinal glutaminasic activity (Pinkus and Windmueller, 1977).…”

Section: Introductionmentioning

confidence: 99%

Activities of amino acid metabolizing enzymes in the stomach and small intestine of developing rats

Remesar¹,

Arola²,

Palou³

et al. 1985

Reprod. Nutr. Dévelop.

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Summary. The activities of aspartate and alanine transaminase, serine dehydratase, arginase, glutamate dehydrogenase, adenylate deaminase and glutamine synthetase were determined in the stomach and small intestine of developing rats. Despite the common embryonic origin of the intestine and stomach, their enzymes showed quite different activity levels and patterns of development, depending on their roles. Most enzyme activities were low during late intrauterine life and after birth, attaining adult levels with the change of diet at weaning. No arginase activity was found in the stomach and no changes were detected in adenylate deaminase in the stomach or intestine throughout the period studied. Alanine transaminase, serine dehydratase and, to some extent, glutamine synthetase levels, significantly higher in late intrauterine life, decreased after birth, suggesting that the foetal stomach has a transient ability to handle amino acids.Introduction.

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“…It is through the aldolase connection that the motor force is translated into capping and redistribution of TRAP-like molecules along the parasite surface (4,22). When TRAP-like molecules engage cellular receptors, a moving junction is formed between the host-cell membrane and the parasite, and invasion follows, as originally described in Plasmodium merozoites (23). All of the components of this machinery, as well as their overall arrangement, are present in different Plasmodium invasive stages (sporozoites, merozoite, and the mosquito vector-restricted ookinetes) and are evolutionary conserved across the phylum Apicomplexa (5,20,(24)(25)(26).…”

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confidence: 98%

Aldolase provides an unusual binding site for thrombospondin-related anonymous protein in the invasion machinery of the malaria parasite

Bosch

Buscaglia²,

Krumm³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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An actomyosin motor located underneath the plasma membrane drives motility and host-cell invasion of apicomplexan parasites such as Plasmodium falciparum and Plasmodium vivax, the causative agents of malaria. Aldolase connects the motor actin filaments to transmembrane adhesive proteins of the thrombospondin-related anonymous protein (TRAP) family and transduces the motor force across the parasite surface. The TRAPaldolase interaction is a distinctive and critical trait of host hepatocyte invasion by Plasmodium sporozoites, with a likely similar interaction crucial for erythrocyte invasion by merozoites. Here, we describe 2.4-Å and 2.7-Å structures of P. falciparum aldolase (PfAldo) obtained from crystals grown in the presence of the C-terminal hexapeptide of TRAP from Plasmodium berghei. The indole ring of the critical penultimate Trp-residue of TRAP fits snugly into a newly formed hydrophobic pocket, which is exclusively delimited by hydrophilic residues: two arginines, one glutamate, and one glutamine. Comparison with the unliganded PfAldo structure shows that the two arginines adopt new sidechain rotamers, whereas a 25-residue subdomain, forming a helixloop-helix unit, shifts upon binding the TRAP-tail. The structural data are in agreement with decreased TRAP binding after mutagenesis of PfAldo residues in and near the induced TRAP-binding pocket. Remarkably, the TRAP-and actin-binding sites of PfAldo seem to overlap, suggesting that both the plasticity of the aldolase active-site region and the multimeric nature of the enzyme are crucial for its intriguing nonenzymatic function in the invasion machinery of the malaria parasite.actin ͉ Apicomplexa ͉ cell invasion machinery ͉ gliding motility ͉ induced fit

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The Development of Urea Cycle Enzyme Activity in the Liver of Foetal and Neonatal Rats

Cited by 27 publications

References 5 publications

Comparison of Total Body Urea Production Potential with Total Body Carbamoyl Phosphate Synthetase (CPS-1) Activity in Newborn Piglets Infused with Alanine at 50% of Resting Energy Expenditure for 36 Hours

Comparison of Total Body Urea Production Potential with Total Body Carbamoyl Phosphate Synthetase (CPS-1) Activity in Newborn Piglets Infused with Alanine at 50% of Resting Energy Expenditure for 36 Hours

Activities of amino acid metabolizing enzymes in the stomach and small intestine of developing rats

Aldolase provides an unusual binding site for thrombospondin-related anonymous protein in the invasion machinery of the malaria parasite

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