Hepatic Nucleotide Research Articles

Probiotics as Potential Tool to Mitigate Nucleotide Metabolism Alterations Induced by DiNP Dietary Exposure in Danio rerio.

Diisononyl phthalate, classified as endocrine disruptor, has been investigate to trigger lipid biosynthesis in both mammalian and teleostean animal models. Despite this, little is known about the effects of DiNP exposure at tolerable daily intake level and the possible mechanisms of its toxicity. Probiotics, on the other hand, were demonstrated to have beneficial effects on the organism's metabolism and recently emerged as a possible tool to mitigate the EDC toxicity. In the present study, using a metabolomic approach, the potential hepatic sex-related toxicity of DiNP was investigated in adult zebrafish together with the mitigating action of the probiotic formulation SLAB51, which has already demonstrated its ability to ameliorate gastrointestinal pathologies in animals including humans. Zebrafish were exposed for 28 days to 50 µg/kg body weight (bw)/day of DiNP (DiNP) through their diet and treated with 109 CFU/g bw of SLAB51 (P) and the combination of DiNP and SLAB51 (DiNP + P), and the results were compared to those of an untreated control group (C). DiNP reduced AMP, IMP, and GMP in the purine metabolism, while such alterations were not observed in the DiNP + P group, for which the phenotype overlapped that of C fish. In addition, in male, DiNP reduced UMP and CMP levels in the pyrimidine metabolism, while the co-administration of probiotic shifted the DiNP + P metabolic phenotype toward that of P male and closed to C male, suggesting the beneficial effects of probiotics also in male fish. Overall, these results provide the first evidence of the disruptive actions of DiNP on hepatic nucleotide metabolism and mitigating action of the probiotic to reduce a DiNP-induced response in a sex-related manner.

Disruption of hepatic one-carbon metabolism impairs mitochondrial function and enhances macrophage activity in methionine–choline-deficient mice

One-carbon metabolism is a collection of metabolic cycles that supports methylation and provides one-carbon bound folates for the de novo synthesis of purine and thymidine nucleotides. The methylation of phosphatidylethanolamine to form choline has been extensively studied in the context of fatty liver disease. However, the role of one-carbon metabolism in supporting nucleotide synthesis during liver damage has not been addressed. The objective of this study is to determine how the disruption of one-carbon metabolism influences nucleotide metabolism in the liver after dietary methionine and choline restriction. Mice (n=8) were fed a methionine–choline-deficient or control diet for 3 weeks. We treated mice with the compound alloxazine (0.5 mg/kg), a known adenosine receptor antagonist, every second day during the final week of feeding to probe the function of adenosine signaling during liver damage. We found that concentrations of several hepatic nucleotides were significantly lower in methionine- and choline-deficient mice vs. controls (adenine: 13.9±0.7 vs. 10.1±0.6, guanine: 1.8±0.1 vs. 1.4±0.1, thymidine: 0.0122±0.0027 vs. 0.0059±0.0027 nmol/mg dry tissue). Treatment of alloxazine caused a specific decrease in thymidine nucleotides, decrease in mitochondrial content in the liver and exacerbation of steatohepatitis as shown by the increased hepatic lipid content and altered macrophage morphology. This study demonstrates a role for one-carbon metabolism in supporting de novo nucleotide synthesis and mitochondrial function during liver damage.

Metformin inhibits gluconeogenesis via a redox-dependent mechanism in vivo.

Metformin, the universal first-line treatment for type 2 diabetes, exerts its therapeutic glucose-lowering effects by inhibiting hepatic gluconeogenesis. However, the primary molecular mechanism of this biguanide remains unresolved, though it has been suggested to act, at least partially, by mitochondrial complex I inhibition. Here, we show that clinically-relevant plasma metformin concentrations achieved by acute intravenous, acute intraportal or chronic oral administration in awake normal and diabetic rats inhibit gluconeogenesis from lactate and glycerol but not from pyruvate and alanine, implicating an increased cytosolic redox state in mediating metformin’s antihyperglycemic effect. All of these effects occurred independent of complex I inhibition, evidenced by unaltered hepatic energy charge and citrate synthase flux. Normalizing the cytosolic redox state by infusion of methylene blue or substrates that contribute to gluconeogenesis independently of the cytosolic redox state abrogated metformin-mediated inhibition of gluconeogenesis in vivo. Additionally, in mice expressing constitutively active acetyl-CoA carboxylase, metformin acutely decreased hepatic glucose production and increased the hepatic cytosolic redox state without altering hepatic triglyceride content or gluconeogenic enzyme expression. These studies demonstrate that metformin, at clinically-relevant plasma concentrations, inhibits hepatic gluconeogenesis in a redox-dependent manner independent of reductions in citrate synthase flux, hepatic nucleotide concentrations, acetyl-CoA carboxylase activity, or gluconeogenic enzyme protein expression.

Hepatic nucleotide binding oligomerization domain-like receptors pyrin domain-containing 3 inflammasomes are associated with the histologic severity of non-alcoholic fatty liver disease.

To examine the role of nucleotide binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasomes in the development of non-alcoholic fatty liver disease (NAFLD). Levels of mRNAs encoding NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain, procaspase-1, interleukin (IL)-1β, and IL-18 were quantified by real-time polymerase chain reaction in 91 liver samples and 37 blood samples from biopsy-proven patients with NAFLD. Adiponutrin (also called PNPLA3) polymorphisms (rs738409, C>G) were determined in 74 samples by genotyping assays. Serum IL-1β and IL-18 levels were measured by enzyme-linked immunosorbent assay and liver tissue caspase-1 expression by immunostaining. Hepatic NLRP3, procaspase-1, IL-1β, and IL-18 mRNA levels were significantly higher in NAFLD patients than in controls and were significantly associated with adiponutrin G alleles. Blood procaspase-1 mRNA was significantly higher in NAFLD patients than in healthy controls. Hepatic procaspase-1 and IL-1β mRNA levels correlated significantly with lobular inflammation, hepatocyte ballooning, and NAFLD activity score. Serum IL-18 levels were significantly higher in NAFLD patients than in controls, while IL-1β levels were non-significantly higher. Serum IL-1β and IL-18 concentrations correlated significantly with steatosis, NAFLD activity score, and transaminase levels. Serum IL-1β levels were significantly associated with adiponutrin G alleles. Scattered caspase-1-positive cells were present in portal tracts and inflammatory foci and around ballooning hepatocytes. Immunofluorescence staining showed that caspase-1 colocalized with the macrophage marker CD68. The NLRP3 inflammasomes are primed in the liver, influenced by adiponutrin genotypes, and activated in Kupffer cells and/or macrophages in NAFLD, leading to histological progression through IL-1β and IL-18 production.

Nicotinamide Riboside Ameliorates Hepatic Metaflammation by Modulating NLRP3 Inflammasome in a Rodent Model of Type 2 Diabetes

Low-grade chronic inflammation (metaflammation) is a major contributing factor for the onset and development of metabolic diseases, such as type 2 diabetes, obesity, and cardiovascular disease. Nicotinamide riboside (NR), which is present in milk and beer, is a functional vitamin B3 having advantageous effects on metabolic regulation. However, the anti-inflammatory capacity of NR is unknown. This study evaluated whether NR modulates hepatic nucleotide binding and oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome. Male, 8-week-old KK/HlJ mice were allocated to the control or NR group. NR (100 mg/kg/day) or vehicle (phosphate-buffered saline) was administrated by an osmotic pump for 7 days. Glucose control, lipid profiles, NLRP3 inflammasome, and inflammation markers were analyzed, and structural and histological analyses were conducted. NR treatment did not affect body weight gain, food intake, and liver function. Glucose control based on the oral glucose tolerance test and levels of serum insulin and adiponectin was improved by NR treatment. Among tested lipid profiles, NR lowered the total cholesterol concentration in the liver. Histological and structural analysis by hematoxylin and eosin staining and transmission electron microscopy, respectively, showed that NR rescued the disrupted cellular integrity of the mitochondria and nucleus in the livers of obese and diabetic KK mice. In addition, NR treatment significantly improved hepatic proinflammatory markers, including tumor necrosis factor-alpha, interleukin (IL)-6, and IL-1. These ameliorations were accompanied by significant shifts of NLRP3 inflammasome components (NLRP3, ASC, and caspase1). These results demonstrate that NR attenuates hepatic metaflammation by modulating the NLRP3 inflammasome.

5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) Effect on Glucose Production, but Not Energy Metabolism, Is Independent of Hepatic AMPK in Vivo

Metabolic stress, as well as several antidiabetic agents, increases hepatic nucleotide monophosphate (NMP) levels, activates AMP-activated protein kinase (AMPK), and suppresses glucose production. We tested the necessity of hepatic AMPK for the in vivo effects of an acute elevation in NMP on metabolism. 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR; 8 mg·kg(-1)·min(-1))-euglycemic clamps were performed to elicit an increase in NMP in wild type (α1α2(lox/lox)) and liver-specific AMPK knock-out mice (α1α2(lox/lox) + Albcre) in the presence of fixed glucose. Glucose kinetics were equivalent in 5-h fasted α1α2(lox/lox) and α1α2(lox/lox) + Albcre mice. AMPK was not required for AICAR-mediated suppression of glucose production and increased glucose disappearance. These results demonstrate that AMPK is unnecessary for normal 5-h fasting glucose kinetics and AICAR-mediated inhibition of glucose production. Moreover, plasma fatty acids and triglycerides also decreased independently of hepatic AMPK during AICAR administration. Although the glucoregulatory effects of AICAR were shown to be independent of AMPK, these studies provide in vivo support for the AMPK energy sensor paradigm. AICAR reduced hepatic energy charge by ∼20% in α1α2(lox/lox), which was exacerbated by ∼2-fold in α1α2(lox/lox) + Albcre. This corresponded to a ∼6-fold rise in AMP/ATP in α1α2(lox/lox) + Albcre. Consistent with the effects on adenine nucleotides, maximal mitochondrial respiration was ∼30% lower in α1α2(lox/lox) + Albcre than α1α2(lox/lox) livers. Mitochondrial oxidative phosphorylation efficiency was reduced by 25%. In summary, these results demonstrate that the NMP capacity to inhibit glucose production in vivo is independent of liver AMPK. In contrast, AMPK promotes mitochondrial function and protects against a more precipitous fall in ATP during AICAR administration.

Impact of environmental estrogens on nucleotide excision repair gene expression in embryonic zebrafish

Estrogens and estrogen mimics are aquatic contaminants that can elicit a variety of deleterious effects in exposed fauna. One of the most potent xenoestrogens found in the aquatic environment is 17α-ethinylestradiol (EE2), the pharmaceutically derived semi-synthetic hormone found in oral contraceptives and hormone replacement therapies. Exposure to 100ng/L EE2 has previously been shown to profoundly decrease functional hepatic nucleotide excision repair (NER) processes in adult zebrafish in correlation with dramatic decreases in the abundance of hepatic XPC and XPA transcripts; however, its effects on these processes in embryos are currently unknown. Because developing organisms are known to have increased sensitivities to endocrine disrupting compounds such as EE2, the goal of this study was to examine the impacts of estrogen exposure on mRNA expression of these two key NER genes in zebrafish embryos during the first 4 days of development. Embryos were exposed from 0h post fertilization (hpf) to waterborne EE2, its major metabolite, estrone (E1), or combinations of the two compounds and sampled at 12, 24, 48, 72 and 96 hpf. Increased abundance of vitellogenin-1 (VTG1) mRNA, a bioindicator of estrogen exposure, was evident as early as 24 hpf in embryos that were co-exposed to EE2 and E1 and this effect was sustained throughout 96 hpf. Embryos exposed to EE2 alone exhibited elevated VTG1 beginning at 72 hpf. In contrast to observations from adult zebrafish exposed to EE2, embryos did not show any change in mRNA abundance of the excision repair gene, XPC, during the first 4days of development. However, co-exposure to EE2 and E1 elicited an increase in XPA mRNA abundance at 48 and 72 hpf, which was the opposite response as that observed in exposed adults where hepatic XPA mRNA abundance decreased after EE2 exposure. These differences between embryos and adults suggest that alteration of NER gene transcription by EE2 is operating under different stimuli during development.

Rhythmic Nucleotide Synthesis in the Liver: Temporal Segregation of Metabolites

The synthesis of nucleotides in the body is centrally controlled by the liver, via salvage or de novo synthesis. We reveal a pervasive circadian influence on hepatic nucleotide metabolism, from rhythmic gene expression of rate-limiting enzymes to oscillating nucleotide metabolome in wild-type (WT) mice. Genetic disruption of the hepatic clock leads to aberrant expression of these enzymes, together with anomalous nucleotide rhythms, such as constant low levels of ATP with an excess in uric acid, the degradation product of purines. These results clearly demonstrate that the hepatic circadian clock orchestrates nucleotide synthesis and degradation. This circadian metabolome timetable, obtained using state-of-the-art capillary electrophoresis time-of-flight mass spectrometry, will guide further investigations in nucleotide metabolism-related disorders.

17α-Ethinylestradiol decreases expression of multiple hepatic nucleotide excision repair genes in zebrafish (Danio rerio)

Waterborne 17α-ethinylestradiol (EE2) alters hormone-mediated biological indicators in fish. These alterations include increased plasma vitellogenin, increased intersex individuals, decreased egg and sperm production, reduced gamete quality, and complete feminization of male fish. Together, these observations implicate aquatic estrogens in a broad range of detrimental effects on fish reproduction and fitness. In addition to impairing reproductive processes, EE2 is also a strong promoter of hepatic tumor formation. Since many ubiquitous, aquatic hepatocarcinogens form DNA adducts that are preferentially repaired by nucleotide excision repair (NER) processes, we hypothesized that EE2 may exert co-carcinogenic effects by reducing an organisms ability to repair DNA adducts via this mechanism. The present study used fluorescence-based quantitative RT-PCR to examine effects of environmentally relevant concentrations of the semisynthetic estrogen, EE2, on hepatic nucleotide excision repair (NER) gene expression. Adult male and female zebrafish (Danio rerio) were exposed to 1ng/L, 10ng/L or 100ng/L concentrations of EE2, or to a solvent control (0.05%, v/v ethanol), for 7 days with static water renewal every 24h. Effectiveness of EE2 exposure in the liver was confirmed by examining hepatic expression of two estrogen-responsive biomarkers, vitellogenin-1 and cytochrome P450-1A1 (CYP1A1). Quantitative analysis confirmed that exposure to 100ng/L EE2 caused significant decreases in transcript abundance of several hepatic NER genes in male zebrafish, including XPC (>17-fold), XPA (>7-fold), XPD (>8-fold), and XPF (>8-fold). Adult female zebrafish exhibited a four-fold decreased in XPC mRNA abundance at all exposure concentrations. Decreased mRNA abundance of NER genes was also seen to a lesser degree at lower concentrations of EE2. Adult male zebrafish showed greater reduction of hepatic NER transcript levels than their female counterparts, which is consistent with the sexually dimorphic incidence of hepatocellular carcinoma in many species. Decreased transcript levels of NER genes have been shown to be an important epidemiological marker for increased cancer risk and decreased repair capacity in humans.

Deprivation of Dietary Nucleotides Results in a Transient Decrease in Acid-Soluble Nucleotides and RNA Concentration in Rat Liver

This study examines the contribution of dietary nucleotides to liver nucleotide pools in rats. Liver acid-soluble nucleotides, DNA and RNA concentrations were monitored in two groups of rats fed either a diet supplemented with nucleotides or a diet free of nucleotides for 3 wk. Significantly lower concentrations of ATP, ADP, GTP and CDP as well as of RNA were found after 1 wk in the rats fed a nucleotide-free diet compared with those fed the nucleotide-supplemented diet; concentrations remained lower after 2 wk except for ATP and ADP. No changes over time were observed in the rats fed the nucleotide-supplemented diet. Between wk 2 and 3 an increase in both acid-soluble nucleotides and RNA was observed in the rats fed the nucleotide-free diet, reaching the values found in the rats fed the nucleotide-supplemented diet. These findings, which indicate that dietary nucleotides are utilized at least in part by the liver to maintain the cell nucleotide pools and that diets devoid of nucleotides affect hepatic nucleotide metabolism and RNA, support the hypothesis that liver nucleotide metabolism is modulated by the availability of dietary nucleotides.

Perturbations of endogenous levels of orotic acid and carcinogenesis: effect of an arginine-deficient diet and carbamyl aspartate on hepatocarcinogenesis in the rat and the mouse.

Feeding excess orotic acid (OA) in the diet promotes the carcinogenic process in different organs including the liver. A number of metabolic and genetic disorders are associated with increased synthesis of endogenous OA and some of these disorders appear to pose an increased risk of liver cancer development. This study therefore examines whether excess OA of endogenous origin also exerts a promoting effect on hepatocarcinogenesis in the mouse and the rat. Increased endogenous synthesis of OA was achieved by (i) feeding a diet deficient in arginine (AD) and (ii) feeding excess dietary carbamylaspartate (CA), a precursor for the synthesis of OA. A single dose of diethylnitrosamine (DENA) was given i.p. to male Fischer 344 rats (200 mg/kg) or to male DBA/2 mice (90 mg/kg). One week later they were placed on either AD diet or the same diet supplemented with 1.35% arginine (AS) for a total of 4 weeks. Two-thirds partial hepatectomy (PH) was performed at the end of the second week. All animals were then transferred to a control semisynthetic basal diet for a total of 20 weeks before they were killed. The results indicated that AD diet increased the incidence of hepatic nodules in both rats (percentage area occupied by nodules was 4.7 +/- 0.4 in the AD group compared to a control value of 0.7 +/- 0.5) and mice (4/10 mice had nodules > 5 mm diameter in the AD group while none in the AS group had such large nodules). In another experiment male Fischer 344 rats similarly initiated with DENA were exposed to either basal diet or basal diet containing 2% CA for 4 weeks coupled with PH performed at the end of the second week. This regimen was followed by 20 weeks of feeding basal diet to both groups. Rats given CA developed larger hepatic foci and nodules (0.84 +/- 0.56 mm3) compared to the control group, which was fed basal diet throughout the experiment (0.07 +/- 0.03 mm3). Further, both AD diet and dietary CA, like dietary OA, induced an increase in hepatic uridine nucleotides. Taken together, these results suggest that increased levels of endogenously synthesized OA, like exogenously supplied excess OA, can induce an imbalance in hepatic nucleotide pools and can exert a promoting effect on hepatocarcinogenesis.

A novel hepatic nucleotide is correlated with the carbohydrate induction of messenger ribonucleic acid-S14.

To determine whether the rapid response of hepatic mRNA-S14 to carbohydrate feeding was associated with an alteration in a specific hepatic nucleotide, acid extracts of liver tissue were analyzed by ion-paired reverse phase HPLC. A nucleotide present in nanomoles per g quantity correlated with the induction of this mRNA by sucrose. Four hours after sucrose feeding the content of this compound was 7 times greater than that in fasted rats. Furthermore, the response was rapid, attaining maximal levels 30 min after feeding, and remaining elevated for at least 4 h. The content of this nucleotide also correlated with the content of mRNA-S14 in the steady state, with the lowest levels of both mRNA-S14 and this nucleotide in fasted rats, intermediate levels in rats maintained on a regular chow diet, and the highest levels in rats fed a 60% sucrose diet for 4 days. Lastly, while the response of mRNA-S14 to thyroid hormone and sucrose is synergistic, the thyroidal state does not influence the response of this compound to sucrose. Thus, the interaction of thyroid hormone and sucrose on mRNA-S14 is distal to the generation of this compound. Based on the UV spectrum, HPLC retention, and [3H]adenosine labeling, this compound contains adenine. However, it is not any of the common adenine-containing mono- or oligonucleotides. These data indicate that a novel hepatic nucleotide is induced by sucrose and raise the possibility that this nucleotide is responsible for the induction of carbohydrate-responsive mRNAs.

Regulation of purine and pyrimidine metabolism by insulin and by resistance to tiazofurin

The purpose of this investigation was to clucidate the factors that regulate the pattern of gene expression in purine and pyrimidine metabolism in normal liver and hepatoma. For this purpose, the action of a hormone, insulin, and the development of resistance to a chemotherapeutic agent, tiazofurin, were studied. 1. 1.|This investigation brought detailed evidence showing that in the rat insulin exerted a profound effect on liver purine and pyrimidine metabolism by regulating the concentrations of nucleotides through controlling the activities of strategic enzymes involved in their biosynthesis. 2. 2.|When rats were made diabetic by alloxan treatment, in the average liver cell concentrations at ATP, GTP, UTP and CTP decreased to 66, 62, 54 and 63%, respectively, of those of normal liver. Administration of insulin for 2 days returned the hepatic nucleotide concentrations to normal range; further insulin treatment for an additional 5 days raised the concentrations of ATP, GTP, UTP and CTP to 197.352, 412 and 792% of values observed in the liver of diabetic rats. 3. 3.|In diabetic rats the hepatic activities of OMP decarboxylase, orotate phosphoribosyltransferase, uridine phosphorylase, uridine-cytidine kinase and uracil phosphoribosyltransferase decreased to 44, 48, 70, 36 and 41% of the activities of normalliver. Insulin treatment for 2 days returned activities to normal range. Continued insulin treatment for an additional 5 days increased the enzymic activities to 3.9- to 5.3-fold of those of the liver of the diabetic rats. The regulation by insulin treatment of the activities of enzymes of de novo and salvage synthesis of UMP should explain, in part at least, the decline and increase of the uridylate pool in diabetes and after insulin treatment. 4. 4.|In the diabetic rat hepatic CTP synthetase, the rate-limiting enzyme of CTP biosynthesis, decreased to 53% and insulin administration for 2 days restored activity to normal range. Insulin treatment for an additional 5 days increased the synthetase activity to 4-fold of the values of the diabetic liver. Thus, the behavior of liver CTP synthetase activity is tightly linked with that of the CTP pool. 5. 5.|In the diabetic rat liver, the activity of IMP dehydrogenase, the rate-limiting limiting enzyme of GTP biosynthesis, decreased to 24% of that of the normal liver. Insulin administration for 2 days returned the activity to normal range, yielding a 4.5-fold increase in the activity from the diabetic to the insulin-treated state. The decline of IMP dehydrogenase activity in diabetes and its restoration by insulin treatment indicates that the behavior of this enzyme is closely linked with that of the GTP pool. 6. 6.|Because the major action of insulin on liver has been thought to occur in carbohydrate metabolism, the impact of insulin administration in the rat was compared on carbohydrate-metabolizing and on purine and pyrimidine synthesizing liver enzymic activities. In the diabetic rat, the hepatic activities of glucokinase, pyruvate kinase and glucose-6-phosphate dehydrogenase decreased to 20, 30 and 65% of those of the normal rat liver. The hepatic enzymes of purine and pyrimidine biosynthesis declined to 54 to 85% with the exception of IMP dehydrogenase, carbamoyl-phosphate synthetase II and aspartate carbamoyltransferase which decreased to 14 to 28% of the activity of normal rat liver. Insulin administration restored enzymic activities to normal range in 2 days. The insulin-induced increases in the carbohydrate enzymic activities were 2.5- to 6.5-fold. A similar extent of increases was observed for most of the nucleic acid synthetic enzymes. These results indicated that some of the insulin-induced rises inhepatic enzymic activities in purine and pyrimidine biosynthesis are comparable to those for the classically recognized inductions in glycolytic and pentose phosphate enzyme activities. 7. 7.|The reprogramming of gene expression in cancer cells was examined in a variant of hepatoma 3924A cells in tissue culture which was resistant to the C-nucleoside, tiazofurin. In the hepatoma cells a biochemical program emerged that was characterized by a decrease in the transport of tiazofurin, in the content of TAD, the active metabolite of tiazofurin, and in the de novo synthesis of IMP to 2-, 2- and 4.7-fold of the activities of sensitive cells. By contrast, the pools of guanylates, the activities of IMP dehydrogenase, the guanylate salvageand that of the ratio of salvage to de novo synthesis were elevated 3-, 2.6-, 2.8- and 4.8-fold of those of the sensitive cells. Thus, the resistance to tiazofurin in hepatoma cells is expressed by an integrated reprogramming of gene expression.

Depletion of cytidine triphosphate as a consequence of cellular uridine triphosphate deficiency

FEBS LettersVolume 103, Issue 1 p. 165-167 Full-length articleFree Access Depletion of cytidine triphosphate as a consequence of cellular uridine triphosphate deficiency Hanspeter Henninger, Hanspeter Henninger Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGSearch for more papers by this authorAxel Holstege, Axel Holstege Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGSearch for more papers by this authorBrigitte Herrmann, Brigitte Herrmann Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGSearch for more papers by this authorTongtavuch Anukarahanonta, Tongtavuch Anukarahanonta Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGSearch for more papers by this authorDietrich O.R. Keppler, Corresponding Author Dietrich O.R. Keppler Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGTo whom reprint requests and correspondence should be addressedSearch for more papers by this author Hanspeter Henninger, Hanspeter Henninger Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGSearch for more papers by this authorAxel Holstege, Axel Holstege Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGSearch for more papers by this authorBrigitte Herrmann, Brigitte Herrmann Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGSearch for more papers by this authorTongtavuch Anukarahanonta, Tongtavuch Anukarahanonta Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGSearch for more papers by this authorDietrich O.R. Keppler, Corresponding Author Dietrich O.R. Keppler Biochemisches Institut, Universität Freiburg im Breisgau, Hermann-Herder-Str. 7, D-7800 Freiburg, FRGTo whom reprint requests and correspondence should be addressedSearch for more papers by this author First published: July 01, 1979 https://doi.org/10.1016/0014-5793(79)81273-9Citations: 6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References 1 K. Decker, D. Keppler, J. Rudigier, W. Domschke, Z. Physiol. Chem., 352, (1971), 412– 418. 2 D. Keppler, J. Pausch, K. Decker, J. Biol. Chem., 249, (1974), 211– 216. 3 Y.M. Rustum, Anal. Biochem., 90, (1978), 289– 299. 4 W. Domschke, D. Keepler, E. Bischoff, K. Decker, Z. Physiol. Chem., 352, (1971), 275– 279. 5 D. Keepler, K. Gawehn, K. Decker, H.U. Bergmeyer Methods of Enzymatic Analysis (1974), Academic Press New York 2172– 2178. 6 D.F. Smith, E.F. Walborg jr, J.P. Chang, Cancer Res., 30, (1970), 2306– 2309. 7 D. Keppler, D.F. Smith, Cancer Res., 34, (1974), 705– 711. 8 D. Keepler, Cancer Res., 37, (1977), 911– 917. 9 D. Keppler, FEBS Lett., 73, (1977), 263– 266. 10 E.P. Anderson, R.W. Brockman, Biochim. Biophys. Acta, 91, (1964), 380– 386. 11 P.G.W. Plagemann, R. Marz, R.M. Wohlhueter, J. Cell. Physiol., 97, (1978), 49– 72. 12 C.R. Savage, H. Weinfeld, J. Biol. Chem., 245, (1970), 2529– 2535. 13 C. Scholtissek, Biochim. Biophys. Acta, 277, (1972), 459– 465. 14 C.M. Janeway, S. Cha, Cancer Res., 37, (1977), 4382– 4388. 15 E.C. Cadman, D.E. Dix, R.E. Handschumacher, Cancer Res., 38, (1978), 682– 688. 16 E. Cadman, F. Eiferman, R. Heimer, L. Davis, Cancer Res., 38, (1978), 4610– 4617. Citing Literature Volume103, Issue1July 01, 1979Pages 165-167 ReferencesRelatedInformation

Increased serum urate in galactosemia patients after a galactose load: a possible role of nucleotide deficiency in galactosemic liver injury.

Five galactosemic and 5 normal children received an oral load of galactose under standardized conditions. The maximal blood galactose level after 1.5 hours was 12.6 +/- 2.0 (S.D.) mmol/l in individuals with a deficiency of uridylyl transferase (EC2.7.7.12) as compared to 5.8 +/- 1.2 (S.D.) mmol/l in the controls. The concentration of serum urate in galactosemics increased to 155% of the fasting level (P less than 0.005); no rise was detectable in the controls. The elimination of urate with the urine was augmented by the same amount in both groups. Our studies provide evidence for an increased catabolism of hepatic nucleotides. This may lead to a deficiency of nucleotides which is proposed as a cause of galactosemic liver injury.

Hepatic Nucleotide Levels and NAD-synthesis as Influenced by Dietary Orotic Acid and Adenine

A simplified method is described for quantitating the effect of dietary orotic acid on the hepatic concentrations of adenine, guanine and uracil nucleotides in the rat. Within 16 hours after addition of 1% orotic acid to the diet, hepatic uracil nucleotide concentrations are 4 times normal, and concentrations of acid-soluble adenine, guanine and oxidized pyridine nucleotides have begun to decrease, coincident with a previously reported decrease in plasma lipid concentrations. Minimum values are observed after about 4 days. These effects of orotic acid are all rapidly reversed when 0.25% adenine sulfate is added to the diet. Addition of nicotinamide or nicotinic acid restores to normal only the depressed pyridine nucleotide concentration. Nicotinamide and nicotinic acid mononucleotide administered parenterally induce a 2- to 2.5-fold increase in hepatic oxidized pyridine nucleotide concentration of normal rats, but they have only slight effects in rats fed 1% orotic acid for 72 hours. The efficacy of nicotinamide in orotic acid-fed rats is improved by the administration of adenine. Depressed synthesis of pyridine nucleotides in rats fed orotic acid appears to reflect a relative unavailability of acid-soluble adenine nucleotides due either to an inhibition of purine synthesis de novo or increased competition for adenine by other metabolic pathways.