bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleosides, XLVII. Syntheses, Reactions and Properties of 6- and 7-p-Bromophenyllumazine N-1-Nucleosides
Authors: Al-Masoudi Najim A. L. , Pfleiderer Wolfgang 
Published: March 2013

Summary Glycosylation of 6-(2) and 7-p-bromophenyllumazine (3) by the silyl method using 1-O-acetyl-2.3 ,5-tri-O-benzoyl-β-D-ribofuranose (6) and trimethylsilyl trifluoromethanesulfonate as catalyst proceeded regioselectively in high yields to the N-1 nucleosides (7, 11). Thiations by P4S10 or Lawesson’s reagent led to the corresponding 4-thiolumazine ribosides (9, 13). Deblocking to the free nucleosides (8, 10, 12. 14) worked best with K2CO3, in MeOH. Treatment of 9 and 13 respectively by methanolic NH3 afforded debenzoylation and di splacement of the thio-function to give the corresponding isopterin N-1 ribofuranosides (15.16). 2,2ʹ-Anhydro- nucleoside formation was achieved with 8 and 10 respectively to give 17 and 18, which formed on acid hydrolysis the 6- and 7-substituted l-~-D-arabinofuranosyl-lumazines 19 and 20.
Pregnancy Increases Urinary Neopterin Levels in Human Immunodeficiency Virus Type 1 Infection
Authors: Mayr Peter , Fuchs Dietmar , Fuith Lothar C. , Reibnegger Gilbert , Werner Ernst R. , Dapunt Otto , Wachter Helmut 
Published: March 2013

Summary Eleven mothers of 12 infants with human immunodeficiency virus type 1 (HIV-1) infection (all intravenous drug users) were followed throughout their pregnancies for evidence of clinical and immunological abnormalities. Intrauterine death occurred in one, growth retardation in 7/12 pregnancies. Moderate progression of HIV-l infection according to the Walter Reed Staging Classification was observed in 5/ 11 women during pregnancy. Two of them developed AIDS during follow up after delivery. Mean neopterin levels in the first, second and third trimester were significantly higher as compared to HIV-l seronegative pregnant women. Furthermore, concentrations of urinary neopterin increased significantly with the time of pregnancy in all HIV-1 seropositive women. Since higher urinary neopterin concentrations are predictive for more rapid disease progression in HIV infected patients the data may indicate that pregnancy increases the risk for developing AIDS. However, a possible influence of continuous drug use has to be considered.
Preparation of Isotope-labeled Dihydroneopterin 3'-Triphosphate with High Specific Activity
Authors: Katzenmeier Gerd , Schwarzkopf Bruno , Van Quang Le , Schmid Cornelia , Bacher Adelbert 
Published: March 2013

SummaryIsotope-labeled dihydroneopterin 3'-triphosphate with 3H at positions C-1' and C-2', respectively, has been prepared from isotope-labeled glucose as starting material. Glucose was first converted enzymatically to ribose 5-phosphate. GMP was subsequently obtained by the action of phosphoribosylpyrophosphate synthetase and guanosine phosphoribosyl transferase. It was subsequently phosphorylated to GTP in two steps using adenylate kinase and guanylate kinase. Dihydroneopterin triphosphate was prepared from GTP by the action of recombinant GTP-cyclohydrolase I from Escherichia coli. The method allows the incorporation of 3H and 14C isotope labels into any desired position of dihydroneopterin triphosphate. Rapid purfication procedures for phosphoribosylpyrophosphate synthetase and guanosine phosphoribosyl transferase as well as HPLC assays for their determinations are described.
Pteridines IC. Chemical Synthesis and Structural Proof of Photinuspterin
Authors: Sugimoto Takashi , Pfleiderer Wolfgang 
Published: March 2013

SummaryThe proposed structure of Photinuspterin isolated from the firefly Photinus pyralis has been proven by two unambiguous syntheses to be 6-(1-hydroxypropyl)-8-methylisoxanthopteIin (15), 8-MethylisoxanthopteIin (7) can be substituted in 6-position in a homolytic nucleophilie substitution reaction either by the 1-hydroxypropyl radical to give 15 directly or by the propionyl radical leading first to 8-methyl-6-propionyl-isoxanthopteIin (9) which was easily converted into 15 by sodium borohydlide reduction. These two approaches are of general nature and can be applied to synthesize a broad variety of 6-substituted 8-methylisoxanthopterins (8-19). The newly synthesized compounds have been characterized by elemental analysis. pKa determinations, UV and NMR spectra.
Regulation of Folate Metabolizing Enzymes In Fungus Aspergillus nidulans
Authors: Balińska Malgorzata , Natorff Renata , Paszewski Andrzej 
Published: March 2013

Summary The regulation of methionine synthase. serine hydroxymethyltransferase. methylenetetrahydrofolate oxidorelluctase and dihydrofolate reductase in Aspergillus nidulans have been found to be controlled by endogenous pools methionine and homocysteine. Mutants impaired in sulfur metaholite repression. which have highly elevated pools of these amino acids. also show elevated levels of folate metabolizing enzymes mentioned above. This effect was found to he the result of the accumulation of endogenous homocysteine. which induces folate enzymes. High concentration (up to 5 mM) or methionine in growth medium leads to repression of these enzymes. It appears. therefore. that the levels of folate metaholizing enzymes arc determined by the ratio of cellular levels or methionine and homocysteine.
Nucleosides LIII Syntheses and Reactions of 6,7-Dipyridyllumazine and 2' -Deoxylumazine N-1 Nucleosides
Authors: Al-Masoudi Najim AL. , Pfleiderer Wolfgang 
Published: March 2013

Summary The chemical syntheses of 6,7-(α-pyridyl)-1-(2,3,5-tri-O-benzoy-β-D-ribofuranosyl)-lumazine (6) and the corresponding free nucleoside 7 are described. Thiation of 6 with P4S10 gave a salt type adduct derivative of 4-thiolumazine 8 which afforded the free nucleoside 9 on deblocking. Treatment of 8 with methanolic NH3 gave the isopterin-N-1 nucleoside 10. 2,2' -Anhydro compound 13 was obtained by the diphenyl carbonate technique and characterised as the diacetate 14. Acid hydrolysis of 14 gave the arabino-nucleoside 15. which was isolated also from hydrolysis of 14 with hydroxide ion. Reaction of 7 with acetyl bromide gave the 2'-bromo-2'-deoxy derivative 11 as minor product together with triacetate 12 as the main analogue. Reduction of the bromo function in 11 into the expected 2'-deoxy analogue during the treatment with tri-n-butyltin hydride has failed and the 2.2' -anhydro compound 15 was the only product isolated. Alternatively. the 6,7-bis-(α-pyridyl)-1-(2-deoxy-3.5-di-O-toloulyl-α and β-D-ribofuranosyl)-Iumazine (17) and (19) were synthesized from direct condensation of sugar 16 and the silylated base 4. Debolcking of 17 and 19 with sodium methoxide gave the free analogues 18 and 20 respectively.
Influence of Kynurenine, Neopterin, Noradrenaline and Pyridoxal-5-Phosphate on Cholesterol and Phospholipid Content and Phospholipid Biosynthesis in vitro
Authors: Rudzite Vera , Jurika Edite , Reibnegger Gilbert , Weiss Günter , Wachter Helmut , Fuchs Dietmar 
Published: March 2013

Summary Incorporation of fatty acids into phospholipids has been investigated using samples of rat liver tissue homogenate, Krebs-Ringer-phosphate buffer (pH = 7.4) containing 0.3% albumin, fatty acid mixture and glyceroL The addition of L-kynurenine (4 nmol/g wet weight), D-eryhro-neopterin (5 and 30 pmol/g wet weight) and noradrenaline (4 nmol/g wet weight) to incubation medium induced an increase of saturated (palmitic acid) and decrease of poly-unsaturated (linoleic and arachidonic acid) fatty acids incorporation into phospholipids. The increase of saturated fatty acids incorporation into phospholipids was more pronounced after addition of neopterin and noradrenaline to the incubation medium while the decrease of linoleic and arachidonic acid synthesis was stimulated most with kynurenine. Moreover, kynurenine stimulated whereas neopterin depressed the oleic acid incorporation into phospholipids. These changes of fatty acid incorporation into phospholipids were followed by increase of cholesterol content in samples containing kynurenine, neopterin or noradrenalin. In contrast, phospholipid content decreased in samples containing kynurenine or noradrenalin, hut was not altered by supplementation of neopterin. Since the addition of kynurenine and neopterin to incubation medium for isolated fog heart resulted in an increased noradrenaline and decreased pyridoxal-5-phosphate content in the tissue, we also added pyridoxal-5-phosphate (4 nmol/g wet weight) to incubation medium for phospholipid biosynthesis. No change of the fatty acid incorporation into phospholipids as welI as the content of phospholipids and cholesterol in samples was observed.
Neopterin, PMN Elastase, and Complement Components as Monitoring Parameters in Women with the Syndrome of Hemolysis, Elevated Liver Enzymes and Low Platelet Count
Authors: Haeger Magnus , Unander Margareta , Bengtsson Anders 
Published: March 2013

SummaryPreeclampsia is a pregnancy induced hypertensive disease with an incidence of about 5% in primigravida and it significantly contributes to maternal and neonatal morbidity and mortality. The primary cause remains unknown but might be immunologic. Our previous studies have shown that complement neutrophils and macrophages are activated in preeclampsia. The present study evaluated whether the extension of the macrophage, the neutrophil and the complement activation is related to the severity of preeclampsia. Patients with severe preeclampsia. complicated by the syndrome of hemolysis. elevated liver enzymes and low platelet count (HELLP) and women with preeclampsia were studied. Women with uncomplicated pregnancies were controls. To detect activation of macrophages and polymorphonuclear neutrophils (PMN), respectively. the formations of neopterin and PMN elastase were analyzed. For evaluation of complement activation. the biologically active components C5a and the terminal C5b-9 complement complex (TCC) were determined in plasma. Patients with the HELLP syndrome had significantly elevated plasma concentrations of neopterin and C5a at delivery compared to women with preeclampsia. and compared to the controls, the HELLP group had significantly raised plasma levels of neopterin. PMN elastase. C5a and TCC. Women with preeclampsia had significantly higher plasma concentrations of neopterin and TeC at delivery as compared to the controls. In preeclamptics and HELLP patients, the plasma concentrations at delivery of PMN elastase, C5a and TCC were normalized within one week. but the plasma levels of neopterin remained elevated after one week. Neopterin, PMN
Dihydropteridine Reductase
Authors: Whiteley John M. , Varughesej Kottayil I. , Xuong Nguyen H. , Matthews David A. , Grimshaw Charles E. 
Published: March 2013

Summary During the past decade numerous advances have been made in understanding the structure, mechanism and clinical properties of dihydropteridine reductase. An attempt is made here to delineate the current status of this essential enzyme by describing its structural features, its kinetic mechanism, the cloning and expression of both rat and human enzyme forms, the solution of their crystal structures, their classification as members of a large family of short chain dehydrogenases, and finally a brief description is included indicating how current molecular biological applications have allowed the clinical definition of the aberrant form of phenylketonuria caused by a defective reductase.
Neopterin Levels In Thyroid Pseudocysts
Authors: Zaknun J. , Mayersbach P. , Moncayo R. , Fridrich L. , Wachter H. , Fuchs D. 
Published: March 2013

Summary Cystic changes of the thyroid remain a diagnostic dilemma with regard to malignancy due to insufficient information gained by fine needle aspiration, sonography and routine nuclear medicine procedures. As complementary soluble parameters we measured neopterin and thyroglobin levels in cyst fluids and in serum of 81 patients with disorders of the thyroid. Based on clinical, cytological and histological information, patients were divided into five groups. (I): Serous cysts (n=41), (II): hemorrhagic cysts (N=18), (III): cysts ' with evidence for inflammation clinically or by histology (n= 11), (IV): malignancy in cysts by histology (n = 6), (V): cysts containing "honey" like, brownish fluid of high viscosity (n = 5). Neopterin concentration in cyst fluids vs. serum in group (I) were not different, 8.8± 4.3 nmol/l in vs. 6.67± 3.34 nmol/l. In groups II-V neopterin concentration in cysts were higher than in serum, (II): 21.1 ± 18.7 nmol/l vs. 5.6± 2.56 nmol/l, (III): 30.6± 24.9 nmol/l vs. 6.1 ± 2.9 nmol/l, in (IV): 35± 23.5 vs. 10.98± 7.0 nmol/l and (V): 36.0± 23.9 vs. 5.9± 3.32 nmol/l respectively. In patients with proven benign histology at surgery, neopterin levels in cystic fluid were significantly lower than in cysts harbouring malignancy, 8.5±4.6 vs. 35.4±23.5 (Z=3,17, p=O. 0015). There were no significant differences between groups II, III IV and V regarding neopterin concentrations in cysts. Elevated serum neopterin levels were observed in 2/6 patients with aggressive thyroid cancer (group IV). However, average neopterin concentrations in serum of patients of group IV were not higher than in 15 patients from group I with benign histology (P=O.l). Significantly lower levels of thyroglobin in cyst fluid were found in group V ("honey" cysts) in comparison to all other groups pooled, 2.67± 1.82 f..lg/rnl vs. 6.76± 3.97 f..lg/ml, (Z=2.l5, p=0.031), four of five cysts in group V resolved after fine needle aspiration. We found no correlation between thyroglobin levels in cyst fluid and in serum. Our data suggest that low neopterin concentrations in cystic fluid have high negative predictive value with regard to inflammation and malignancy in thyroid cysts. In clinical settings neopterin may provide further' valuable information in the evaluation of such lesions.
Early Diagnosis of 6-Pyruvoyl-tetrahydropterin Synthase Deficiency
Authors: Shintaku Haruo 
Published: March 2013

Summary 6-Pyruvoyl-tetrahydropterin synthase (PTPS) deficiency, which used to be called dihydrobiopterin synthase deficiency, is the most common kind of tetrahydrobiopterin deficiency. Early treatment by administration of tetrahydrobiopterin and neurotransmitter precursors helps to prevent neurological injury, so prompt diagnosis of neonates with hyperphenylalaninemia discovered by screening for phenylketonuria is necessary. Three patients with PTPS deficiency were diagnosed by pteridine analysis. All patients had low biopterin and high neopterin levels in the urine, resulting in a neopterin to biopterin ratio (N/B)much higher than that of age-matched controls. The mean NIB in the parents of these patients was twice that of healthy unrelated adults. PTPS activity was measured in one of these patients with PTPS deficiency and in his family members; the patient was homozygous and his parents were heterozygous for PTPS deficiency. This result meant that N/Bcould be used as an index of PTPS activity. In healthy subjects studied cross-sectionally, urinary levels of pteridine decreased in groups of increasing age, and the same change was found in subjects with hyperphenylalaninemia studied cross-sectionally. Thus, pteridine values of patients can be compared meaningfully only with age-matched controls. The urinary N/Bis useful for the diagnosis of homozygotes and heterozygotes for PTPS deficiency.
Applicability of an Enzyme-linked Immunosorbant Assay for Neopterin Detection for Screening of Blood Donations
Authors: Mayersbach Peter , Augustin Roman , Schennach Harald , Fuchs Dietmar , Werner Ernst R. , Schonitzer Diether , Wachter Helmut , Reibnegger Gilbert 
Published: March 2013

Summary We have evaluated a new commercially available enzyme-linked immunorsorbant assay for neopterin :or its suitability in the context of screening of voluntary blood donors. The assay was performed on 1040 consecutive blood donors, and compared with radioimmunoassay and. in a fraction of 142 donors . . : Iso with high performance liquid chromatography. On repetitive assays of all donations showing a concentration exceeding 8.0 nmol/L in the initial assay. three of the radioimmunoassay results were identified as gross outliers. No such gross outliers were detected for the enzyme-linked immunosorbant assay. RegarJing the reproducibility of results exceeding a cut-off limit of \0 nmol/L neopterin. the enzyme-linked ;mmunosorbant assay was better than the radioimmunoassay. Moreover. the enzyme-linked immunosorbant assay was slightly superior to radioimmunoassay when both tests were compared with high performance liquid chromatography (based on linear regression analysis. evaluation of frequencies of concentrations bant assay was slightly superior to radioimmunoassay when both tests were compared with high performance liquid chromatography (based on linear regression analysis. evaluation of frequencies of concentrations rations. Its slight superiority compared to the conventional radioimmunoassay likely results from the higher degree of automatization employed.
Neopterin Determinations in Tuberculous Bone Infections
Authors: Peters K. M. , Schweitzer K. , Zimmermann S. , Zilkens K. W. 
Published: March 2013

Summary
In patients with tuberculous chest infections caused by intracellular Mycobacteria elevated serum neopterin levels could be found. In the present study neopterin levels were elevated in 5/6 patients with proven tuberculous bone infections as well. Neopterin determinations in serum were especially helpful for the drug monitoring of these patients. After a sufficient antituberculous therapy initially elevated neopterin levels decreased and remained within normal range. Persistent elevation of neopterin may be a hint for a resistance of the Mycobacteria.
Role of Folate in the Modulation of Lipids, Lipoproteins and Eicosanoids in Hypertension and Diabetes
Authors: Katki Khurshed A. , Viswanathan Gomathy , Noronha John M. 
Published: March 2013

Summary Besides elevated levels of lipids and lipoproteins, ievels of the physiological amino acid homocysteine as well as whole blood folates are now known to play a role in atherogenesis. The role of folates in atherosclerosis is rather peculiar in that it helps to catalyse the remethylation of homocysteine (a proatherogenic agent) to methionine thus preventing the accumulation of homocysteine in plasma and hence its antiatherogenic role. We estimated whole blood folate levels of 69 normotensive, 34 diabetic and 94 hypertensive individuals and have attempted to correlate these values with lipid and non-lipid parameters. Whole blood levels of simple, conjugated and total folates were significantly higher among the diabetics as well as the hypertensives when compared to the normotensives. In all the study groups, levels of conjugated folates correlated significantly to those of total folates even after adjustments for age and body mass index were introduced. Among the normotensive individuals the significance of the inverse correlation between simple folates and total cholesterol/high density lipoprotein cholesterol ratio was lost after adjusting for age and body mass index. Levels of total and conjugated folates were positively correlated to plasma levels of thromboxane B2 among the diabetics. In the same group the positive correlation between total folates and thromboxane B2 and that between total folates and the eicosanoid ratio remained significant even after adjustments for age and body mass index were introduced. None of the other metabolic variables correlated with whole blood levels of simple folates in any of the study groups.
Degeneration of Rat Retina is Paralleled by an Imbalance of the Redox Mechanism of Pteridines
Authors: Cremer-Bartels Gertrud 
Published: March 2013

Summary
The RCS rat suffers from a genetic degeneration of retinal cell We have examined the pattern of oxidized and reduced monapterin and biopterin in retinas from RCS retinas and controls. The ratio of oxidized monapterin to reduced monapterin was significantly increased compared to controls. Since oxidized pterins have been shown to affect the enzyme (HIOMT) to successivly increase the content of melatonin, it can be suggested that destruction of visual cells by light exposure is based on an increase in melatonin content. Consequently, a lack of dihydro-d-monapterin reductase is postulated to be causative in the pathway for blinding in RCS rats.
Time Course of Neopterin and Cytokines After an Extreme Bicycle Race at Moderate Altitude
Authors: Deetjen Christian , Mair Johannes , Herold Manfred , Wiedermann Franz , Hobisch-Hagen Petra , Jelkmann Wolfgang , Hoffmann Georg , Schobersberger Wolfgang 
Published: March 2013

Summary Endurance exercise induces several alterations in the immune and hematological system. At present it is unknown whether exercise under hypoxic conditions can modulate these changes. We investigated the effects of a prolonged endurance bicycle exercise in 8 healthy athletes (Oetztal Bicycle Marathon, OEBM; distance 230 km; vertical displacement 5000 m) on serum concentrations of interleukin-I[3 (IL-If3), interleukin- 6 (IL-6), tumor necrosis factor-a (TNF-a), neopterin as well as erythropoietin (EPO). Blood was collected before (A), immediately after the race (B), one (C), two (D), three (E) as well as five (F) days after the OEBM. We could demonstrate that IL-6 was increased significantly after exercise termination, whereas IL-I[3 and TNF-a were unchanged. Neopterin was significantly elevated from B to D, indicating an activation of the cellular immune system. Serum EPO was significantly increased from day 1 to day 5 after exercise which might reflect the combination of hypoxia and postexercise hemodilution.
The Influence of Kynurenine and Its Metabolites on Lipid Metabolism
Authors: Rudzite Vera , Jurika Edite , Jirgensons Janis , Herpfer Inga , Weiss Günter , Wachter Helmut , Fuchs Dietmar 
Published: March 2013

Summary Incorporation of fatty acids into phospholipids has been investigated using samples of rat liver tissue homogenate, Krebs-Ringer-phosphate buffer (pH=7.4) containing 0.3% albumin, fatty acid mixture and glycerol. The addition of L-kynurenine (4 nmoljg wet weight) to incubation medium induced an increase of palmitic, oleic and linolenic acid and decrease of linoleic and arachidonic acid incorporation into phospholipids. These changes of fatty acid incorporation into phospholipids were followed by increase of cholesterol and decrease of phospholipids content in samples. The addition of 3-hydroxykynurenine (1.8 and 4 nmoljg wet weight), 3-hydroxyanthranilic acid (2.2 and 4 nmoljg wet weight) ,1n..:l quinolinic acid (2.4 and 4 nmoljg wet weight) to incubation medium for phospholipid biosynthesis ill vitro induced a decrease of stearic, palrnitic and linoleic acid and an increase of oleic and especially arachidonic acid incorporation into phospholipids. These changes were accompanied by a decrease of cholesterol content in samples. The influence of kynurenine on fatty acid incorporation into phospholipids was similar to that of neopterin observed earlier. The other tryptophan degradation products behaved similar to the reduced pteridine derivatives. Our results allow to suggest that L-kynurenine decreases, while 3-hydroxykynurenine, 3-hydroxyanthranilic acid and quinolinic acid increase membrane fluidity in the studied concentrations.