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1

Herpes simplex virus-mediated human hypoxanthine-guanine phosphoribosyltransferase gene transfer into neuronal cells  

SciTech Connect

The virtually complete deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT) results in a devastating neurological disease, Lesch-Nyhan syndrome. Transfer of the HPRT gene into fibroblasts and lymphoblasts in vitro and into hematopoietic cells in vivo has been accomplished by other groups with retroviral-derived vectors. It appears to be necessary, however, to transfer the HPRT gene into neuronal cells to correct the neurological dysfunction of this disorder. The neurotropic virus herpes simplex virus type 1 has features that make it suitable for use as a vector to transfer the HPRT gene into neuronal tissue. This report describes the isolation of an HPRT-deficient rat neuroma cell line, designated B103-4C, and the construction of a recombinant herpes simplex virus type 1 that contained human HPRT cDNA. These recombinant viruses were used to infect B103-4C cells. Infected cells expressed HPRT activity which was human in origin.

Palella, T.D.; Silverman, L.J.; Schroll, C.T.; Homa, F.L.; Levine, M.; Kelley, W.N.

1988-01-01

2

Ubiquitous and neuronal DNA-binding proteins interact with a negative regulatory element of the human hypoxanthine phosphoribosyltransferase gene.  

PubMed Central

The hypoxanthine phosphoribosyltransferase (HPRT) gene is constitutively expressed at low levels in all tissues but at higher levels in the brain; the significance and mechanism of this differential expression are unknown. We previously identified a 182-bp element (hHPRT-NE) within the 5'-flanking region of the human HPRT (hHPRT) gene, which is involved not only in conferring neuronal specificity but also in repressing gene expression in nonneuronal tissues. Here we report that this element interacts with different nuclear proteins, some of which are present specifically in neuronal cells (complex I) and others of which are present in cells showing constitutive expression of the gene (complex II). In addition, we found that complex I factors are expressed in human NT2/D1 cells following induction of neuronal differentiation by retinoic acid. This finding correlates with an increase of HPRT gene transcription following neuronal differentiation. We also mapped the binding sites for both complexes to a 60-bp region (Ff; positions -510 to -451) which, when analyzed in transfection assays, functioned as a repressor element analogous to the full-length hHPRT-NE sequence. Methylation interference footprintings revealed a minimal unique DNA motif, 5'-GGAAGCC-3', as the binding site for nuclear proteins from both neuronal and nonneuronal sources. However, site-directed mutagenesis of the footprinted region indicated that different nucleotides are essential for the associations of these two complexes. Moreover, UV cross-linking experiments showed that both complexes are formed by the association of several different proteins. Taken together, these data suggest that differential interaction of DNA-binding factors with this regulatory element plays a crucial role in the brain-preferential expression of the gene, and they should lead to the isolation of transcriptional regulators important in neuronal expression of the HPRT gene.

Rincon-Limas, D E; Amaya-Manzanares, F; Nino-Rosales, M L; Yu, Y; Yang, T P; Patel, P I

1995-01-01

3

Absence of hypoxanthine:guanine phosphoribosyltransferase activity in murine Dunn osteosarcoma  

SciTech Connect

The transplantable murine Dunn osteosarcoma has no detectable hypoxanthine:guanine phosphoribosyltransferase (EC 2.4.2.8) activity. This was established from the tumors directly and from tissue culture cell lines derived from the tumor using a variety of assays: e.g., no (3H)hypoxanthine uptake into tumor or tissue culture cells, no conversion of (3H)hypoxanthine to (3H)IMP by cell extracts from tumors or tissue culture cells, no growth of tissue culture cells in hypoxanthine:aminopterin:thymidine medium, and normal growth of these cells in 10 microM 6-mercaptopurine. Ten human osteosarcomas have been assayed, and two have no apparent hypoxanthine:guanine phosphoribosyltransferase enzyme activity. After high-dose methotrexate treatment in vivo, murine tumors could be selectively killed and normal tissues could be spared by using a rescue regimen of hypoxanthine-thymidine-allopurinol.

Abelson, H.T.; Gorka, C.

1983-09-01

4

Construction of a defective retrovirus containing the human hypoxanthine phosphoribosyltransferase cDNA and its expression in cultured cells and mouse bone marrow.  

PubMed Central

Defective ecotropic and amphotropic retroviral vectors containing the cDNA for human hypoxanthine phosphoribosyltransferase (HPRT) were developed for efficient gene transfer and high-level cellular expression of HPRT. Helper cell clones which produced a high viral titer were generated by a simplified method which minimizes cell culture. We used the pZIP-NeoSV(X) vector containing a human hprt cDNA. Viral titers (1 X 10(3) to 5 X 10(4)/ml) of defective SVX HPRT B, a vector containing both the hprt and neo genes, were increased 3- to 10-fold by cocultivation of the ecotropic psi 2 and amphotropic PA-12 helper cells. Higher viral titers (8 X 10(5) to 7.5 X 10(6] were obtained when nonproducer NIH 3T3 cells or psi 2 cells carrying a single copy of SVX HPRT B were either transfected or infected by Moloney leukemia virus. The SVX HPRT B defective virus partially corrected the HPRT deficiency (4 to 56% of normal) of cultured rodent and human Lesch-Nyhan cells. However, instability of HPRT expression was detected in several infected clones. In these unstable variants, both retention and loss of the SVX HPRT B sequences were observed. In the former category, cells which became HPRT- (6-thioguanine resistant [6TGr]) also became G418s, indicative of a cis-acting down regulation of expression. Both hypoxanthine-aminopterin-thymidine resistance (HATr) and G418r could be regained by counterselection in hypoxanthine-aminopterin-thymidine. In vitro mouse bone marrow experiments indicated low-level expression of the neo gene in in vitro CFU assays. Individual CFU were isolated and pooled, and the human hprt gene was shown to be expressed. These studies demonstrated the applicability of vectors like SVX HPRT B for high-titer production of defective retroviruses required for hematopoietic gene transfer and expression. Images

Chang, S M; Wager-Smith, K; Tsao, T Y; Henkel-Tigges, J; Vaishnav, S; Caskey, C T

1987-01-01

5

The effect of novel [3-fluoro-(2-phosphonoethoxy)propyl]purines on the inhibition of Plasmodium falciparum, Plasmodium vivax and human hypoxanthine-guanine-(xanthine) phosphoribosyltransferases.  

PubMed

Protozoan parasites from the Plasmodiidae family are the causative agents of malaria. Inhibition of hypoxanthine-guanine-(xanthine) phosphoribosyltransferase (HG(X)PRT) has been suggested as a target for development of new anti-malarial therapeutics. Acyclic nucleoside phosphonates (ANPs) are potent and selective inhibitors of plasmodial HG(X)PRTs. A new series of ANPs, based on the chemical structure and inhibitory activity of three ANPs, 2-(phosphonoethoxy)ethyl with either guanine or hypoxanthine as the base (PEEG and PEEHx) and 3-hydroxy-2-(phosphonomethoxy)propyl with guanine as the base (HPMPG), were prepared. These compounds are stereoisomers of 3-fluoro-(2-phosphonoethoxy)propyl (FPEPs) and 3-fluoro-(2-phosphonomethoxy)propyl (FPMPs) analogues. Both the (R)- and (S)-isomers of these fluorinated derivatives have higher Ki values (by 10- to 1000-fold) for human HGPRT and Plasmodium falciparum HGXPRT than the non-fluorinated ANPs. Possible explanations for these changes in affinity are proposed based on docking studies using the known crystal structures of human HGPRT in complex with PEEG. PMID:23850568

Baszczy?ski, Ond?ej; Hocková, Dana; Janeba, Zlatko; Holý, Antonín; Jansa, Petr; Dra?ínský, Martin; Keough, Dianne T; Guddat, Luke W

2013-09-01

6

Hypoxanthine-guanine phosphoribosyltransferase variant associated with accelerated purine synthesis.  

PubMed

We have previously described a 14-yr-old boy with hyperuricemia, renal failure, and accelerated purine production resistant in vivo and in vitro to purine analogs. This patient demonstrated normal red cell hypoxanthine-guanine phosphoribosyltransferase (HPRT) heat stability, electrophoresis at high pH, and activity at standard substrate levels. In the present report an abnormal HPRT enzyme was demonstrated by enzyme kinetic study with phosphoribosylpyrophosphate (PRPP) as the variable substrate and inhibitory studies with sodium fluoride. Apparently normal HPRT activity in a patient with hyperuricemia and gout does not exclude a functionally significant HPRT mutation. PMID:4353774

Benke, P J; Herrick, N; Hebert, A

1973-09-01

7

Multiple in vivo footprints are specific to the active allele of the X-linked human hypoxanthine phosphoribosyltransferase gene 5' region: implications for X chromosome inactivation.  

PubMed Central

Dosage compensation of X-linked genes in male and female mammals is accomplished by random inactivation of one X chromosome in each female somatic cell. As a result, a transcriptionally active allele and a transcriptionally inactive allele of most X-linked genes reside within each female nucleus. To examine the mechanism responsible for maintaining this unique system of differential gene expression, we have analyzed the differential binding of regulatory proteins to the 5' region of the human hypoxanthine phosphoribosyltransferase (HPRT) gene on the active and inactive X chromosomes. Studies of DNA-protein interactions associated with the transcriptionally active and inactive HPRT alleles were carried out in intact cultured cells by in vivo footprinting by using ligation-mediated polymerase chain reaction and dimethyl sulfate. Analysis of the active allele demonstrates at least six footprinted regions, whereas no footprints were detected on the inactive allele. Of the footprints on the active allele, at least four occur over canonical GC boxes or Sp1 consensus binding sites, one is associated with a potential AP-2 binding site, and another is associated with a DNA sequence not previously reported to interact with a sequence-specific DNA-binding factor. While no footprints were observed for the HPRT gene on the inactive X chromosome, reactivation of the inactive allele with 5-azacytidine treatment restored the in vivo footprint pattern found on the active allele. Results of these experiments, in conjunction with recent studies on the X-linked human PGK-1 gene, bear implications for models of X chromosome inactivation. Images

Hornstra, I K; Yang, T P

1992-01-01

8

Hypoxanthine phosphoribosyltransferase: radiochemical assay procedures for the forward and reverse reactions  

SciTech Connect

Simple and rapid radiochemical assay procedures for the forward (IMP synthesis) and reverse (IMP pyrophosphorolysis) reactions catalyzed by hypoxanthine phosphoribosyltransferase have been developed. Enzyme activity in the forward direction was assessed by measuring the amount of (8-/sup 14/C)IMP formed from (8-/sup 14/C)hypoxanthine following their separation by polyethyleneimine-cellulose TLC in methanol:water (1:1, v/v). (8-/sup 14/C)IMP has been synthesized from (8-/sup 14/C)hypoxanthine, using hypoxanthine phosphoribosyltransferase derived from human brain, with subsequent purification by elution from phenyl boronate-agarose. Enzyme activity in the reverse direction was assessed by measuring the amount of (8-/sup 14/C)uric acid formed from the labeled IMP following their separation by polyethyleneimine-cellulose TLC in 0.2 M LiCl saturated with boric acid (pH 4.5):95% ethanol (1:1, v/v), the transferase reaction being coupled with excess xanthine oxidase and catalase to overcome the unfavorable equilibrium.

Smithers, G.W.; O'Sullivan, W.J.

1985-02-15

9

A review of the molecular basis of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency  

Microsoft Academic Search

Hypoxanthine-guanine phosphoribosyltransferase (HPRT, EC 2.4.2.8) is a purine salvage enzyme that catalyses the conversion of hypoxanthine and guanine to their respective mononucleotides. Partial deficiency of this enzyme can result in the overproduction of uric acid leading to a severe form of gout, whilst a virtual absence of HPRT activity causes the Lesch-Nyhan syndrome which is characterised by hyperuricaemia, mental retardation,

Donna G. Sculley; Paul A. Dawson; Bryan T. Emmerson; Ross B. Gordon

1992-01-01

10

Hypoxanthine-guanine phosphoribosyltransferase. Characterization of a mutant in a patient with gout.  

PubMed Central

The mutation in a young gouty male with a partial deficiency of hypoxanthine-guanine phosphoribosyltransferase has been evaluated. The serum uric acid was 11.8 mg/100 ml, and the urinary uric acid excretion was 1,279 mg/24 h. Erythrocyte hypoxanthine-guanine phosphoribosyltransferase was 34.2 nmol/h/mg, adenine phosphoribosyltransferase was 36.5 nmol/h/mg and phosphoribosylpyrophosphate was 2.6 muM. Hypoxanthine-guanine phosphoribosyltransferase from peripheral leukocytes and cultured diploid skin fibroblasts was within the normal range, but enzyme activity in rectal mucosa was below the normal range. Initial velocity studies of the normal enzyme and the mutant enzyme from erythrocytes with the substrates hypoxanthine, guanine, or phosphoribosylpyrophosphate showed that the Michaelis constants were similar. Product inhibition studies distinguished the mutant enzyme from the normal enzyme. Hyperbolic kinetics with increasing phosphoribosylpyrophosphate were converted to sigmoid kinetics by 0.2 mM GMP with the mutant enzyme but not with the normal enzyme. The mutant erythrocyte hypoxanthine-guanine phosphoribosyltransferase was inactivated normally at 80 degrees C and had a normal half-life in the peripheral circulation. The mol wt of 48,000 was similar to the normal enzyme mol wt of 47,000. With isoelectric focusing, the mutant erythrocyte enzyme had two major peaks with isoelectric pH's of 5.50 and 5.70, in contrast to the isoelectric pH's of 5.76, 5.82, and 6.02 of the normal isozymes. Isoelectric focusing of leukocyte extracts from the patient revealed the presence of the mutant enzyme. Cultured diploid fibroblasts from the propositus appeared to function normally, as shown by the inability to grow in 50-100 muM azaguanine and by the normal incorporation of [14C]hypoxanthine into nucleic acid. In contrast, erythrocytes from the patient displayed abnormal properties, including the increased synthesis of phosphoribosylphyrophosphate and elevated functional activity of orotate phosphoribosyltransferase and orotidylic decarboxylase. These unique kinetic, physical, and functional properties provide support for heterogeneous structural gene mutations in partial deficiencies of hypoxanthine-guanine phosphoribosyltransferase.

Fox, I H; Dwosh, I L; Marchant, P J; Lacroix, S; Moore, M R; Omura, S; Wyhofsky, V

1975-01-01

11

Acyclic Immucillin Phosphonates: Second generation inhibitors of Plasmodium falciparum hypoxanthine-guanine-xanthine phosphoribosyltransferase  

PubMed Central

Summary Plasmodium falciparum, the primary cause of deaths from malaria, is a purine auxotroph and relies on hypoxanthine salvage from the host purine pool. Purine starvation as an antimalarial target has been validated by inhibition of purine nucleoside phosphorylase. Hypoxanthine depletion kills Plasmodium falciparum in cell culture and in Aotus monkey infections. Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) from P. falciparum is required for hypoxanthine salvage by forming inosine 5?-monophosphate, a branchpoint for all purine nucleotide synthesis in the parasite. Here we present a new class of HGXPRT inhibitors, the acyclic Immucillin phosphonates (AIPs), and cell permeable AIP prodrugs. The AIPs are simple, potent, selective and biologically stable inhibitors. The AIP prodrugs block proliferation of cultured parasites by inhibiting the incorporation of hypoxanthine into the parasite nucleotide pool and validates HGXPRT as a target in malaria.

Hazleton, Keith Z.; Ho, Meng-Chiao; Cassera, Maria B.; Clinch, Keith; Crump, Douglas R.; Rosario, Irving; Merino, Emilio F.; Almo, Steve C.; Tyler, Peter C.; Schramm, Vern L.

2012-01-01

12

Acyclic immucillin phosphonates: second-generation inhibitors of Plasmodium falciparum hypoxanthine-guanine-xanthine phosphoribosyltransferase.  

PubMed

Plasmodium falciparum, the primary cause of deaths from malaria, is a purine auxotroph and relies on hypoxanthine salvage from the host purine pool. Purine starvation as an antimalarial target has been validated by inhibition of purine nucleoside phosphorylase. Hypoxanthine depletion kills Plasmodium falciparum in cell culture and in Aotus monkey infections. Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) from P. falciparum is required for hypoxanthine salvage by forming inosine 5'-monophosphate, a branchpoint for all purine nucleotide synthesis in the parasite. Here, we present a class of HGXPRT inhibitors, the acyclic immucillin phosphonates (AIPs), and cell permeable AIP prodrugs. The AIPs are simple, potent, selective, and biologically stable inhibitors. The AIP prodrugs block proliferation of cultured parasites by inhibiting the incorporation of hypoxanthine into the parasite nucleotide pool and validates HGXPRT as a target in malaria. PMID:22726686

Hazleton, Keith Z; Ho, Meng-Chiao; Cassera, Maria B; Clinch, Keith; Crump, Douglas R; Rosario, Irving; Merino, Emilio F; Almo, Steve C; Tyler, Peter C; Schramm, Vern L

2012-06-22

13

Hypoxanthine-guanine phosphoribosyltransferase activity of blood and muscle in Duchenne dystrophy.  

PubMed

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activity was measured in red cells and in skeletal muscles of normal and Duchenne subjects. [8-14C] hypoxanthine was used as substrate, and 5-phospho-alpha-D-ribose 1-diphosphate (PRPP) was used as the ribose-5-phosphate donor. The [8-14C] inosine monophosphate (IMP) formed was separated by high-voltage electrophoresis, and radioactivity was measured by lipid scintillation counting. HGPRT activity in Duchenne and normal red-cell hemolysates was similar, but such activity was significantly higher in Duchenne than in normal muscle homogenates. Red cells of both normal and Duchenne subjects had significantly higher enzyme activity than did skeletal muscles. It is suggested that increased HGPRT activity may be involved in enhancing protein synthesis by increasing intracellular levels of purine ribonucleotides. PMID:545141

Neerunjun, J S; Allsop, J; Dubowitz, V

1979-01-01

14

Nicotinamide Phosphoribosyltransferase in Human Diseases  

PubMed Central

Nicotinamide phosphoribosyltransferase (NAMPT) was first reported as a pre-B-cell colony enhancing factor in 1994 with little notice, but it has received increasing attention in recent years due to accumulating evidence indicating that NAMPT is a pleiotropic protein such as a growth factor, a cytokine, an enzyme and a visfatin. Now, NAMPT has been accepted as an official name of this protein. Because of NAMPT’s multiple functions in a variety of physiological processes, their dysregulations have been implicated in the pathogenesis of a number of human diseases or conditions such as acute lung injury, aging, atherosclerosis, cancer, diabetes, rheumatoid arthritis and sepsis. This review will cover the current understanding of NAMPT’s structure and functions with an emphasis on recent progress of nicotinamide phosphoribosyltransferase’s pathological roles in various human diseases and conditions. Future directions on exploring its Terra incognita will be offered in the end.

Zhang, Li Qin; Heruth, Daniel P.; Ye, Shui Qing

2011-01-01

15

Crystal structures of free, IMP-, and GMP-bound Escherichia coli hypoxanthine phosphoribosyltransferase.  

PubMed

Crystal structures have been determined for free Escherichia coli hypoxanthine phosphoribosyltransferase (HPRT) (2.9 A resolution) and for the enzyme in complex with the reaction products, inosine 5'-monophosphate (IMP) and guanosine 5'-monophosphate (GMP) (2.8 A resolution). Of the known 6-oxopurine phosphoribosyltransferase (PRTase) structures, E. coli HPRT is most similar in structure to that of Tritrichomonas foetus HGXPRT, with a rmsd for 150 Calpha atoms of 1.0 A. Comparison of the free and product bound structures shows that the side chain of Phe156 and the polypeptide backbone in this vicinity move to bind IMP or GMP. A nonproline cis peptide bond, also found in some other 6-oxopurine PRTases, is observed between Leu46 and Arg47 in both the free and complexed structures. For catalysis to occur, the 6-oxopurine PRTases have a requirement for divalent metal ion, usually Mg(2+) in vivo. In the free structure, a Mg(2+) is coordinated to the side chains of Glu103 and Asp104. This interaction may be important for stabilization of the enzyme before catalysis. E. coli HPRT is unique among the known 6-oxopurine PRTases in that it exhibits a marked preference for hypoxanthine as substrate over both xanthine and guanine. The structures suggest that its substrate specificity is due to the modes of binding of the bases. In E. coli HPRT, the carbonyl oxygen of Asp163 would likely form a hydrogen bond with the 2-exocyclic nitrogen of guanine (in the HPRT-guanine-PRib-PP-Mg(2+) complex). However, hypoxanthine does not have a 2-exocyclic atom and the HPRT-IMP structure suggests that hypoxanthine is likely to occupy a different position in the purine-binding pocket. PMID:12070315

Guddat, Luke W; Vos, Siska; Martin, Jennifer L; Keough, Dianne T; de Jersey, John

2002-07-01

16

Identification of a single nucleotide change in a mutant gene for hypoxanthine-guanine phosphoribosyltransferase (HPRT Ann Arbor)  

Microsoft Academic Search

HPRTAnn Arbor is a variant of hypoxanthine (guanine) phosphoribosyl-transferase (HPRT: EC 2.4.2.8), which was identified in two brothers with hyperuricemia and nephrolithiasis. In previous studies, this mutant enzyme was characterized by an increased Km for both substrates, a normal Vmax, a decreased intracellular concentration of enzyme protein, a normal subunit molecular weight and an acidic isoelectric point under native isoelectric

Shin Fujimori; Yuji Hidaka; Beverly L. Davidson; Thomas D. Palella; William N. Kelley

1988-01-01

17

Hypoxanthine Guanine Phosphoribosyltransferase (HPRT) Deficiencies: HPRT1 Mutations in New Japanese Families and PRPP Concentration.  

PubMed

Mutation of hypoxanthine guanine phosphoribosyltransferase (HPRT) gives rise to Lesch-Nyhan syndrome, which is characterized by hyperuricemia, severe motor disability, and self-injurious behavior, or HPRT-related gout with hyperuricemia. Four mutations were detected in two Lesch-Nyhan families and two families with partial deficiency since our last report. A new mutation of G to TT (c.456delGinsTT) resulting in a frameshift (p.Q152Hfs*3) in exon 3 has been identified in one Lesch-Nyhan family. In the other Lesch-Nyhan family, a new point mutation in intron 7 (c.532 + 5G > T) causing splicing error (exon 7 excluded, p.L163Cfs*4) was detected. In the two partial deficiency cases with hyperuricemia, two missense mutations of p.D20V (c.59A > T) and p.H60R (c.179A >G) were found. An increase of erythrocyte PRPP concentration was observed in the respective phenotypes and seems to be correlated with disease severity. PMID:24940672

Yamada, Yasukazu; Nomura, Noriko; Yamada, Kenichiro; Kimura, Reiko; Fukushi, Daisuke; Wakamatsu, Nobuaki; Matsuda, Yasufumi; Yamauchi, Takahiro; Ueda, Takanori; Hasegawa, Hiroshi; Nakamura, Makiko; Ichida, Kimiyoshi; Kaneko, Kiyoko; Fujimori, Shin

2014-04-01

18

Inactive X chromosome DNA does not function in DNA-mediated cell transformation for the hypoxanthine phosphoribosyltransferase gene.  

PubMed Central

The molecular nature of the X chromosome inactivation process has been investigated by utilizing the techniques of DNA-mediated cell transformation of the X-linked hypoxanthine phosphoribosyltransferase (HPRT) locus. The findings indicate that purified DNA from the inactive X chromosome of a near-euploid mouse cell line is not functional in transformation for HPRT, but the DNA from its "homologous" active X readily elicits transformation for HPRT in the same hamster cell recipient. These findings suggest that there is a difference between the DNA, per se, of the active and inactive X at (or near) the HPRT locus and that this difference could account, at least in part, for its inactivation. Images

Liskay, R M; Evans, R J

1980-01-01

19

Kelley-Seegmiller syndrome due to a unique variant of hypoxanthine-guanine phosphoribosyltransferase: reduced affinity for 5-phosphoribosyl-1-pyrophosphate manifested only at low, physiological substrate concentrations.  

PubMed

A male child, who presented at the age of 3.5 years with acute renal failure, was diagnosed as having partial deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT; EC 2.4.2.8). The underlying HPRT mutation was unique in that the specific activity of HPRT in erythrocyte and in fibroblast lysates was normal, but the rate of uptake of hypoxanthine into nucleotides of intact cultured fibroblasts was markedly reduced (23% of normal). The low functioning of HPRT in the intact fibroblasts was associated with decreased utilization of endogenously generated hypoxanthine and with decreased utilization of the cosubstrate 5-phosphoribosyl-1-pyrophosphate (PRPP). The non-utilized hypoxanthine was excreted into the incubation medium. The accumulation of PRPP was indicated by the 2.3-fold increase in the rate of uptake of adenine into intact cell nucleotides and by the 7. 5-fold enhancement of the rate of de novo purine synthesis. Kinetic studies of HPRT activity in fibroblast lysates revealed reduced affinity of the enzyme for PRPP (apparent K(m) 500 microM in comparison to 25 microM in control lysates), manifested in low activity at low (physiological), but not at high PRPP concentrations. The apparent K(m) for hypoxanthine was normal (23 microM in comparison to 14.2 microM in control lysates). With allopurinol treatment, our patient has had no problems since presentation, and is developing normally at 5 years of age. PMID:10657589

Zoref-Shani, E; Feinstein, S; Frishberg, Y; Bromberg, Y; Sperling, O

2000-02-21

20

Lesch-Nyhan syndrome: the synthesis of inosine 5'-phosphate in the hypoxanthine-guanine phosphoribosyltransferase-deficient erythrocyte by alternate biochemical pathways.  

PubMed

Erythrocytes, obtained from a normal adult male and from a patient with Lesch-Nyhan syndrome, were incubated with [8-14C]adenine and [8-14C]hypoxanthine (Table 1). The labeled adenine was utilized to about the same extent for the synthesis of AMP by the normal subject's and the patient's erythrocytes. Deamination of AMP to IMP occurred to about the same extent in both samples. In contrast, hypoxanthine was utilized extensively for IMP synthesis in the normal erythrocyte only. The amount of total label in the IMP was about 100 times that of the Lesch-Nyhan erythrocyte, a consequence of the deficiency of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activity in the syndrome. No significant labeling of the AMP occurred. When aliquots of erythrocytes from both sources were incubated with 4-amino-5-imidazolecarboxamide (AICA) and sodium [14C]formate, extensive labeling of the IMP occurred in normal and in Lesch-Nyhan erythrocytes. The data suggest that AICA serves as a substrate for the adenine phosphoribosyltransferase (APRT) of the Lesch-Nyhan erythrocyte and that the ribotide of AICA, 5'-phosphoribosyl-5-aminoimidazole-4-carboxamide (AICAR), undergoes formylation by labeled N10-formyl tetrahydrofolic acid formed from the reaction of sodium [14C]formate with the tetrahydrofolic acid of the cell. The formyl-AICAR undergoes ring closure to IMP by a series of reactions comparable to those described for the normal erythrocyte. When 5-amino-1-ribosyl-4-imidazolecarboxamide (rAICA) and sodium [14C]formate were incubated with erythrocyte suspensions, extensive utilization for IMP synthesis was also observed in normal erythrocytes and in erythrocytes from Lesch-Nyhan patients (Table 2). The reaction sequence is somewhat different from that of AICA. AICA is not a substrate for the purine nucleoside phosphorylase of rabbit or human erythrocytes. The mechanism of rAICA utilization is visualized as a direct phosphorylation of the ribosyl compound, possibly by the adenosine kinase of the human cell. The ribotide, AICAR, formed by this mechanism, undergoes formylation and ring closure, yielding IMP. The glutamine antagonist, diazooxonorleucine (DON), was added to aliquots of patients' cells incubated with rAICA and sodium [14C]formate. DON is an effective inhibitor of the conversion of IMP to GMP and its presence in an incubation suspension resulted in a somewhat greater radioactivity of the total cellular IMP. The extension of the current studies to Lesch-Nyhan cells in culture may serve to assist in the direct evaluation of the regulatory role of IMP in the de novo pathway of purine nucleotide biosynthesis. Because of the substrate requirements of the reactions, the metabolism of AICA and rAICA may also serve to differentiate the roles of purine nucleotides and of phosphoribosylpyrophosphate (PRPP) in the pathway regulation. The findings presented also offer a possible therapeutic approach to the early treatment of the disease in the afflicted neonate... PMID:870876

Lowy, B A; Williams, M K

1977-05-01

21

A germ line mutation within the coding sequence for the putative 5-phosphoribosyl-1-pyrophosphate binding site of hypoxanthine-guanine phosphoribosyltransferase (HPRT) in a Lesch-Nyhan patient: missense mutations within a functionally important region probably cause disease  

Microsoft Academic Search

Lesch-Nyhan syndrome caused by a complete deficiency of hypoxanthine guanine phosphoribosyltransferase (HPRT) is the result of a heterogeneous group of germ line mutations. Identification of each mutant gene provides valuable information as to the type of mutation that occurs spontaneously. We report here a newly identified HPRT mutation in a Japanese patient with Lesch-Nyhan syndrome. This gene, designated HPRT Tokyo,

Shin Fujimori; Tetsuo Tagaya; Naoyuki Kamatani; Ieo Akaoka

1992-01-01

22

Severe Gouty Arthritis and Mild Neurologic Symptoms Due to F199C, a Newly Identified Variant of the Hypoxanthine Guanine Phosphoribosyltransferase  

PubMed Central

A deficiency in hypoxanthine guanine phosphoribosyltransferase (HPRT) activity leads to overproduction of uric acid. According to the degree of enzymatic deficiency, a large spectrum of neurologic features can also be observed, ranging from mild or no neurologic involvement to complete Lesch-Nyhan disease. Herein, we describe a patient with hyperuricemia, juvenile-onset gouty arthritis, nephrolithiasis, and mild neurologic symptoms, attributed to a newly identified variant of the hprt gene, c.596T>G, resulting in the amino acid change p.F199C. Residual HPRT activity (8%) protected against severe neurologic involvement in this patient. Modeling of the mutated protein was used to predict the mechanisms that led to partial enzymatic activity. Careful neurologic examination is warranted in juvenile and middle-aged patients with gout, in order to detect mild symptoms that may lead to a diagnosis of HPRT deficiency.

Ea, Hang-Korng; Bardin, Thomas; Jinnah, H. A.; Aral, Bernard; Liote, Frederic; Ceballos-Picot, Irene

2010-01-01

23

Molecular characterization of two deletion events involving Alu -sequences, one novel base substitution and two tentative hotspot mutations in the hypoxanthine phosphoribosyltransferase (HPRT) gene in five patients with Lesch-Nyhan syndrome  

Microsoft Academic Search

Mutations identified in the hypoxanthine phosphoribosyltransferase (HPRT) gene of patients with Lesch-Nyhan (LN) syndrome\\u000a are dominated by simple base substitutions. Few hotspot positions have been identified, and only three large genomic rearrangements\\u000a have been characterized at the molecular level. We have identified one novel mutation, two tentative hot spot mutations, and\\u000a two deletions by direct sequencing of HPRT cDNA or

T. Tvrdik; Suzanne Marcus; Sai-Mei Hou; Susann Fält; Peri Noori; Natalia Podlutskaja; Folker Hanefeld; Petter Strømme; Bo Lambert

1998-01-01

24

Genetic modification of mouse bone marrow by lentiviral vector-mediated delivery of hypoxanthine-Guanine phosphoribosyltransferase short hairpin RNA confers chemoprotection against 6-thioguanine cytotoxicity.  

PubMed

We have recently developed a novel and highly efficient strategy that exclusively uses the purine analog 6-thioguanine (6TG) for both pretransplantation conditioning and post-transplantation chemoselection of hypoxanthine-guanine phosphoribosyltransferase (HPRT)-deficient bone marrow (BM). In a mouse BM transplantation model, combined 6TG preconditioning and in vivo chemoselection consistently achieved >95% engraftment of HPRT-deficient donor BM and long-term reconstitution of histologically and immunophenotypically normal hematopoiesis in both primary and secondary recipients, without significant toxicity and in the absence of any other cytotoxic conditioning regimen. To translate this strategy for combined 6TG conditioning and chemoselection into a clinically feasible approach, it is necessary to develop methods for genetic modification of normal hematopoietic stem cells (HSC) to render them HPRT-deficient and thus 6TG-resistant. Here we investigated a strategy to reduce HPRT expression and thereby confer protection against 6TG myelotoxicity to primary murine BM cells by RNA interference (RNAi). Accordingly, we constructed and validated a lentiviral gene transfer vector expressing short-hairpin RNA (shRNA) that targets the murine HPRT gene. Our results showed that lentiviral vector-mediated delivery of HPRT-targeted shRNA could achieve effective and long-term reduction of HPRT expression. Furthermore, in both an established murine cell line as well as in primary murine BM cells, lentiviral transduction with HPRT-targeted shRNA was associated with enhanced resistance to 6TG cytotoxicity in vitro. Hence this represents a translationally feasible method to genetically engineer HSC for implementation of 6TG-mediated preconditioning and in vivo chemoselection. PMID:23769104

Hacke, K; Treger, J A; Bogan, B T; Schiestl, R H; Kasahara, N

2013-06-01

25

Red blood cell hypoxanthine phosphoribosyltransferase activity measured using 6-mercaptopurine as a substrate: a population study in children with acute lymphoblastic leukaemia.  

PubMed Central

1. 6-Mercaptopurine (6-MP) is used in the continuing chemotherapy of childhood acute lymphoblastic leukaemia. The formation of red blood cell (RBC) 6-thioguanine nucleotide (6-TGN) active metabolites, not the dose of 6-MP, is related to cytotoxicity and prognosis. But there is an apparent sex difference in 6-MP metabolism. Boys require more 6-MP than girls to produce the same range of 6-TGN concentrations. Given the same dose, they experience fewer dose reductions because of cytotoxicity, and have a higher relapse rate. 2. The enzyme hypoxanthine phosphoribosyltransferase (HPRT) catalyses the initial activation step in the metabolism of 6-MP to 6-TGNs, a step that requires endogenous phosphoribosyl pyrophosphate (PRPP) as a cosubstrate. Both HPRT and the enzyme responsible for the formation of PRPP are X-linked. 3. RBC HPRT activity was measured in two populations, 86 control children and 63 children with acute lymphoblastic leukaemia. 6-MP was used as the substrate and the formation of the nucleotide product, 6-thioinosinic acid (TIA) was measured. RBC 6-TGN concentrations were measured in the leukaemic children at a standard dose of 6-MP. 4. There was a 1.3 to 1.7 fold range in HPRT activity when measured under optimal conditions. The leukaemic children had significantly higher HPRT activities than the controls (median difference 4.2 micromol TIA ml(-1) RBCs h(-1), 95% C.I. 3.7 to 4.7, P < 0.0001). In the leukaemic children HPRT activity (range 20.4 to 26.6 micromol TIA ml(-1) RBCs h(-1), median 23.6) was not related to the production of 6-TGNs (range 60 to 1,024 pmol 8 x 10(-8) RBCs, median 323). RBC HPRT was present at a high activity even in those children with low 6-TGN concentrations. 5. When HPRT is measured under optimal conditions it does not appear to be the metabolic step responsible for the observed sex difference in 6-MP metabolism. This may be because RBC HPRT activity is not representative of other tissues but it could equally be because other sex-linked factors are influencing substrate availability.

Lennard, L; Hale, J P; Lilleyman, J S

1993-01-01

26

Red blood cell hypoxanthine phosphoribosyltransferase activity measured using 6-mercaptopurine as a substrate: a population study in children with acute lymphoblastic leukaemia.  

PubMed

1. 6-Mercaptopurine (6-MP) is used in the continuing chemotherapy of childhood acute lymphoblastic leukaemia. The formation of red blood cell (RBC) 6-thioguanine nucleotide (6-TGN) active metabolites, not the dose of 6-MP, is related to cytotoxicity and prognosis. But there is an apparent sex difference in 6-MP metabolism. Boys require more 6-MP than girls to produce the same range of 6-TGN concentrations. Given the same dose, they experience fewer dose reductions because of cytotoxicity, and have a higher relapse rate. 2. The enzyme hypoxanthine phosphoribosyltransferase (HPRT) catalyses the initial activation step in the metabolism of 6-MP to 6-TGNs, a step that requires endogenous phosphoribosyl pyrophosphate (PRPP) as a cosubstrate. Both HPRT and the enzyme responsible for the formation of PRPP are X-linked. 3. RBC HPRT activity was measured in two populations, 86 control children and 63 children with acute lymphoblastic leukaemia. 6-MP was used as the substrate and the formation of the nucleotide product, 6-thioinosinic acid (TIA) was measured. RBC 6-TGN concentrations were measured in the leukaemic children at a standard dose of 6-MP. 4. There was a 1.3 to 1.7 fold range in HPRT activity when measured under optimal conditions. The leukaemic children had significantly higher HPRT activities than the controls (median difference 4.2 micromol TIA ml(-1) RBCs h(-1), 95% C.I. 3.7 to 4.7, P < 0.0001). In the leukaemic children HPRT activity (range 20.4 to 26.6 micromol TIA ml(-1) RBCs h(-1), median 23.6) was not related to the production of 6-TGNs (range 60 to 1,024 pmol 8 x 10(-8) RBCs, median 323). RBC HPRT was present at a high activity even in those children with low 6-TGN concentrations. 5. When HPRT is measured under optimal conditions it does not appear to be the metabolic step responsible for the observed sex difference in 6-MP metabolism. This may be because RBC HPRT activity is not representative of other tissues but it could equally be because other sex-linked factors are influencing substrate availability. PMID:12959304

Lennard, L; Hale, J P; Lilleyman, J S

1993-10-01

27

Identification and characterization of human uracil phosphoribosyltransferase (UPRTase)  

Microsoft Academic Search

Uracil phosphoribosyltransferase, which catalyzes the conversion of uracil and 5-phosphoribosyl-1-R-diphosphate to uridine monophosphate, is important in the pyrimidine salvage pathway and is an attractive target for rational\\u000a drug design by incorporation of prodrugs that are lethal to many parasitic organisms specifically. So far, uracil phosphoribosyltransferase\\u000a has been reported in Arabidopsis thaliana only, not in mammals. In this study, a novel

Jixi Li; Shengdong Huang; Jinzhong Chen; Zhenxing Yang; Xiangwei Fei; Mei Zheng; Chaoneng Ji; Yi Xie; Yumin Mao

2007-01-01

28

Localized Derepression on the Human Inactive X Chromosome in Mouse-Human Cell Hybrids  

Microsoft Academic Search

Evidence for derepression of the gene for hypoxanthine phosphoribosyltransferase (HPRT; IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) on the human inactive X chromosome was obtained in hybrids of mouse and human cells. The mouse cells lacked HPRT and were also deficient in adenine phosphoribosyltransferase (APRT; AMP: pyrophosphate phosphoribosyltransferase; EC 2.4.2.7). The human female fibroblasts were HPRT-deficient as a consequence of a mutation

Brenda Kahan; Robert Demars

1975-01-01

29

Genetics of Cell Surface Receptors for Bioactive Polypeptides: Binding of Epidermal Growth Factor is Associated with the Presence of Human Chromosome 7 in Human-Mouse Cell Hybrids  

Microsoft Academic Search

Mouse A9 cells, L-cell-derived mutants deficient in hypoxanthine phosphoribosyltransferase (HPRT; IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) were found to be incapable of binding 125I-labeled epidermal growth factor (EGF) to the cell surface. The A9 cells were fused with human diploid fibroblasts (WI-38) possessing EGF-binding ability, and human-mouse cell hybrids (TA series) were isolated after hypoxanthine\\/aminopterin\\/thymidine\\/ouabain selection. Analyses of isozyme markers and chromosomes

Nobuyoshi Shimizu; M. Ali Behzadian; Yoshiko Shimizu

1980-01-01

30

Structural complexes of human adenine phosphoribosyltransferase reveal novel features of the APRT catalytic mechanism.  

PubMed

Adenine phosphoribosyltransferase (APRT) is an important enzyme component of the purine recycling pathway. Parasitic protozoa of the order Kinetoplastida are unable to synthesize purines de novo and use the salvage pathway for the synthesis of purine bases rendering this biosynthetic pathway an attractive target for antiparasitic drug design. The recombinant human adenine phosphoribosyltransferase (hAPRT) structure was resolved in the presence of AMP in the active site to 1.76 A resolution and with the substrates PRPP and adenine simultaneously bound to the catalytic site to 1.83 A resolution. An additional structure was solved containing one subunit of the dimer in the apo-form to 2.10 A resolution. Comparisons of these three hAPRT structures with other 'type I' PRTases revealed several important features of this class of enzymes. Our data indicate that the flexible loop structure adopts an open conformation before and after binding of both substrates adenine and PRPP. Comparative analyses presented here provide structural evidence to propose the role of Glu104 as the residue that abstracts the proton of adenine N9 atom before its nucleophilic attack on the PRPP anomeric carbon. This work leads to new insights to the understanding of the APRT catalytic mechanism. PMID:18399692

Silva, Carlos H T P; Silva, Mario; Iulek, Jorge; Thiemann, Otavio H

2008-06-01

31

Regulation of 5-phosphoribosyl 1-pyrophosphate and of hypoxanthine uptake and release in human erythrocytes by oxypurine cycling.  

PubMed

Uptake and release of purines by red blood cells has been shown to be markedly sensitive to changes in pH, inorganic phosphate (Pi), and oxygen concentration (Berman, P., Black, D., Human, L., and Harley, E. (1988) J. Clin. Invest. 82, 980-986). The mechanism of this regulation has been further studied. We have shown that incubation of red cells in medium containing xanthine oxidase rapidly and completely depletes intracellular hypoxanthine and causes accumulation of 5-phosphoribosyl 1-pyrophosphate (PRPP) at physiological Pi concentrations. Hypoxanthine release from intracellular IMP is strictly dependent on PRPP depletion, induced by either alkalinizing the cells or by adding excess adenine. Xanthine oxidase abolishes this dependence. Oxygen depletion enhances adenine uptake and prevents hypoxanthine release. The results suggest that hypoxanthine release is governed by PRPP-dependent recycling of hypoxanthine to IMP. We propose that PRPP accumulation in red cells is regulated by a substrate cycle, comprising hypoxanthine, IMP, and inosine. Cycle flux is controlled by Pi inhibition and 2,3-bisphosphoglycerate activation of purine-5'-nucleotidase, which converts IMP to inosine. Oxypurine cycling may account for the sensitive control of purine uptake and release by changes in pH and oxygen tension that occur physiologically. PMID:1691171

Berman, P A; Human, L

1990-04-25

32

Pyrophosphate interactions at the transition states of Plasmodium falciparum and human orotate phosphoribosyltransferases.  

PubMed

Orotate phosphoribosyltransferases from Plasmodium falciparum and human sources (PfOPRT and HsOPRT) use orotidine as a slow substrate in the pyrophosphorolysis reaction. With orotidine, intrinsic kinetic isotope effects (KIEs) can be measured for pyrophosphorolysis, providing the first use of pyrophosphate (PPi) in solving an enzymatic transition state. Transition-state structures of PfOPRT and HsOPRT were solved through quantum chemical matching of computed and experimental intrinsic KIEs and can be compared to transition states solved with pyrophosphate analogues as slow substrates. PfOPRT and HsOPRT are characterized by late transition states with fully dissociated orotate, well-developed ribocations, and weakly bonded PPi nucleophiles. The leaving orotates are 2.8 A distant from the anomeric carbons at the transition states. Weak participation of the PPi nucleophiles gives C1'-O(PPi) bond distances of approximately 2.3 A. These transition states are characterized by C2'-endo ribosyl pucker, based on the beta-secondary [2'-(3)H] KIEs. The geometry at the 5'-region is similar for both enzymes, with C3'-C4'-C5'-O5' dihedral angles near -170 degrees . These novel phosphoribosyltransferase transition states are similar to but occur earlier in the reaction coordinate than those previously determined with orotidine 5'-monophosphate and phosphonoacetic acid as substrates. The similarity between the transition states with different substrate analogues supports similar transition state structures imposed by PfOPRT and HsOPRT even with distinct reactants. We propose that the transition state similarity with different nucleophiles is determined, in part, by the geometric constraints imposed by the catalytic sites. PMID:20527751

Zhang, Yong; Schramm, Vern L

2010-06-30

33

Transport of adenine, hypoxanthine and uracil into Escherichia coli.  

PubMed Central

Uptake of adenine, hypoxanthine and uracil by an uncA strain of Escherichia coli is inhibited by uncouplers or when phosphate in the medium is replaced by less than 1 mM-arsenate, indicating a need for both a protonmotive force and phosphorylated metabolites. The rate of uptake of adenine or hypoxanthine was not markedly affected by a genetic deficiency of purine nucleoside phosphorylase. In two mutants with undetected adenine phosphoribosyltransferase, the rate of adenine uptake was about 30% of that in their parent strain, and evidence was obtained to confirm that adenine had then been utilized via purine nucleoside phosphorylase. In a strain deficient in both enzymes adenine uptake was about 1% of that shown by wild-type strains. Uptake of hypoxanthine was similarly limited in a strain lacking purine nucleoside phosphorylase, hypoxanthine phosphoribosyltransferase and guanine phosphoribosyltransferase. Deficiency of uracil phosphoribosyltransferase severely limits uracil uptake, but the defect can be circumvented by addition of inosine, which presumably provides ribose 1-phosphate for reversal of uridine phosphorylase. The results indicate that there are porter systems for adenine, hypoxanthine and uracil dependent on a protonmotive force and facilitated by intracellular metabolism of the free bases.

Burton, K

1977-01-01

34

Recycling nicotinamide. The transition-state structure of human nicotinamide phosphoribosyltransferase.  

PubMed

Human nicotinamide phosphoribosyltransferase (NAMPT) replenishes the NAD pool and controls the activities of sirtuins, mono- and poly-(ADP-ribose) polymerases, and NAD nucleosidase. The nature of the enzymatic transition-state (TS) is central to understanding the function of NAMPT. We determined the TS structure for pyrophosphorolysis of nicotinamide mononucleotide (NMN) from kinetic isotope effects (KIEs). With the natural substrates, NMN and pyrophosphate (PPi), the intrinsic KIEs of [1'-(14)C], [1-(15)N], [1'-(3)H], and [2'-(3)H] are 1.047, 1.029, 1.154, and 1.093, respectively. A unique quantum computational approach was used for TS analysis that included structural elements of the catalytic site. Without constraints (e.g., imposed torsion angles), the theoretical and experimental data are in good agreement. The quantum-mechanical calculations incorporated a crucial catalytic site residue (D313), two magnesium atoms, and coordinated water molecules. The TS model predicts primary (14)C, ?-secondary (3)H, ?-secondary (3)H, and primary (15)N KIEs close to the experimental values. The analysis reveals significant ribocation character at the TS. The attacking PPi nucleophile is weakly interacting (r(C-O) = 2.60 Å), and the N-ribosidic C1'-N bond is highly elongated at the TS (r(C-N) = 2.35 Å), consistent with an A(N)D(N) mechanism. Together with the crystal structure of the NMN·PPi·Mg2·enzyme complex, the reaction coordinate is defined. The enzyme holds the nucleophile and leaving group in relatively fixed positions to create a reaction coordinate with C1'-anomeric migration from NAM to the PPi. The TS is reached by a 0.85 Å migration of C1'. PMID:23373462

Burgos, Emmanuel S; Vetticatt, Mathew J; Schramm, Vern L

2013-03-01

35

Recycling nicotinamide. The transition-state structure of human nicotinamide phosphoribosyltransferase  

PubMed Central

Human nicotinamide phosphoribosyltransferase (NAMPT) replenishes the NAD pool and controls the activities of sirtuins (SIRT), mono- and poly-(ADP-ribose) polymerases (PARP) and NAD nucleosidase (CD38). The nature of the enzymatic transition-state (TS) is central to understanding the function of NAMPT. We determined the TS structure for pyrophosphorolysis of nicotinamide mononucleotide (NMN) by kinetic isotope effects (KIEs). With the natural substrates, NMN and pyrophosphate (PPi), the intrinsic KIEs of [1?-14C], [1-15N], [1?-3H] and [2?-3H] are 1.047, 1.029, 1.154 and 1.093, respectively. A unique quantum computational approach was used for TS analysis that included structural elements of the catalytic site. Without constraints (e.g. imposed torsion angles), the theoretical and experimental data are in good agreement. The quantum-mechanical calculations incorporated a crucial catalytic site residue (D313), two magnesium atoms and coordinated water molecules. The transition state model predicts primary 14C, ?-secondary 3H, ?-secondary 3H and primary 15N KIE close to the experimental values. The analysis reveals significant ribocation character at the TS. The attacking PPi nucleophile is weakly interacting (rC-O = 2.60 Å) and the N-ribosidic C1?-N bond is highly elongated at the TS (rC-N = 2.35 Å), consistent with an ANDN mechanism. Together with the crystal structure of the NMN•PPi•Mg2•enzyme complex, the reaction coordinate is defined. The enzyme holds the nucleophile and leaving group in relatively fixed positions to create a reaction coordinate with C1?-anomeric migration from nicotinamide to the PPi. The transition state is reached by a 0.85 Å migration of C1?.

Burgos, Emmanuel S.; Vetticatt, Mathew J.; Schramm, Vern L.

2013-01-01

36

Characterization of ouabain resistant, hypoxanthine phosphoribosyl transferase deficient human cells and their usefulness as a general method for the production of human cell hybrids  

Microsoft Academic Search

Ouabain resistant mutants of hypoxanthine phosphoribosyl transferase deficient HeLa cells and euploid human fibroblasts were isolated and extensively characterized. These double mutants were used to test the prediction that they would be “universal hybridizers” for intraspecific human cell hybrid production. Hybrids were selected from fusions with human cells of diverse somatic origin. In addition it was shown that multi-parental hybrids

B. Weissman; E. J. Stanbridge

1980-01-01

37

Nicotinamide Phosphoribosyltransferase in Malignancy  

PubMed Central

Nicotinamide phosphoribosyltransferase (Nampt) catalyzes the rate-limiting step of nicotinamide adenine dinucleotide (NAD) synthesis. Both intracellular and extracellular Nampt (iNampt and eNampt) levels are increased in several human malignancies and some studies demonstrate increased iNampt in more aggressive/invasive tumors and in tumor metastases. Several different molecular targets have been identified that promote carcinogenesis following iNampt overexpression, including SirT1, CtBP, and PARP-1. Additionally, eNampt is elevated in several human cancers and is often associated with a higher tumor stage and worse prognoses. Here we review the roles of Nampt in malignancy, some of the known mechanisms by which it promotes carcinogenesis, and discuss the possibility of employing Nampt inhibitors in cancer treatment.

Shackelford, Rodney E.; Mayhall, Kim; Maxwell, Nicole M.; Kandil, Emad

2013-01-01

38

Kinetic benefits and thermal stability of orotate phosphoribosyltransferase and orotidine 5?-monophosphate decarboxylase enzyme complex in human malaria parasite Plasmodium falciparum  

Microsoft Academic Search

We have previously shown that orotate phosphoribosyltransferase (OPRT) and orotidine 5?-monophosphate decarboxylase (OMPDC) in human malaria parasite Plasmodium falciparum form an enzyme complex, containing two subunits each of OPRT and OMPDC. To enable further characterization, we expressed and purified P. falciparum OPRT–OMPDC enzyme complex in Escherichia coli. The OPRT and OMPDC activities of the enzyme complex co-eluted in the chromatographic

Panan Kanchanaphum; Jerapan Krungkrai

2009-01-01

39

Human adipose tissue-derived mesenchymal stem cells expressing yeast cytosinedeaminase::uracil phosphoribosyltransferase inhibit intracerebral rat glioblastoma.  

PubMed

Prodrug cancer gene therapy by mesenchymal stem cells (MSCs) targeted to tumors represents an attractive tool to activate prodrugs directly within the tumor mass, thus avoiding systemic toxicity. In this study, we tested the feasibility and efficacy of human adipose tissue-derived MSCs, engineered to express the suicide gene cytosine deaminase::uracil phosphoribosyltransferase to treat intracranial rat C6 glioblastoma. Experiments were designed to simulate conditions of future clinical application for high-grade glioblastoma therapy by direct injections of therapeutic stem cells into tumor. We demonstrated that genetically modified therapeutic stem cells still have the tumor tropism when injected to a distant intracranial site and effectively inhibited glioblastoma growth after 5-fluorocytosine (5-FC) therapy. Coadministration of C6 cells and therapeutic stem cells with delayed 5-FC therapy improved the survival in a therapeutic stem cell dose-dependent manner and induced complete tumor regression in a significant number of animals. Continuous intracerebroventricular delivery of 5-FC using osmotic pump reduced the dose of prodrug required for the same therapeutic effect, and along with repeated administration of therapeutic stem cells increased the survival time. Intracerebral injection of therapeutic stem cells and treatment with 5-FC did not show any detectable adverse effects. Results support the arguments to begin clinical studies for treatment of high-grade brain tumors. PMID:21732344

Altanerova, Veronika; Cihova, Marina; Babic, Michal; Rychly, Boris; Ondicova, Katarina; Mravec, Boris; Altaner, Cestmir

2012-05-15

40

Hypoxanthine-guanine phosophoribosyltransferase (HPRT) deficiency: Lesch-Nyhan syndrome  

Microsoft Academic Search

Deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) activity is an inborn error of purine metabolism associated with uric acid overproduction and a continuum spectrum of neurological manifestations depending on the degree of the enzymatic deficiency. The prevalence is estimated at 1\\/380,000 live births in Canada, and 1\\/235,000 live births in Spain. Uric acid overproduction is present inall HPRT-deficient patients and is associated

Rosa J Torres; Juan G Puig

2007-01-01

41

Kinetic benefits and thermal stability of orotate phosphoribosyltransferase and orotidine 5'-monophosphate decarboxylase enzyme complex in human malaria parasite Plasmodium falciparum.  

PubMed

We have previously shown that orotate phosphoribosyltransferase (OPRT) and orotidine 5'-monophosphate decarboxylase (OMPDC) in human malaria parasite Plasmodium falciparum form an enzyme complex, containing two subunits each of OPRT and OMPDC. To enable further characterization, we expressed and purified P. falciparum OPRT-OMPDC enzyme complex in Escherichia coli. The OPRT and OMPDC activities of the enzyme complex co-eluted in the chromatographic columns used during purification. Kinetic parameters (K(m), k(cat) and k(cat)/K(m)) of the enzyme complex were 5- to 125-folds higher compared to the monofunctional enzyme. Interestingly, pyrophosphate was a potent inhibitor to the enzyme complex, but had a slightly inhibitory effect for the monofunctional enzyme. The enzyme complex resisted thermal inactivation at higher temperature than the monofunctional OPRT and OMPDC. The result suggests that the OPRT-OMPDC enzyme complex might have kinetic benefits and thermal stability significantly different from the monofunctional enzyme. PMID:19800871

Kanchanaphum, Panan; Krungkrai, Jerapan

2009-12-11

42

Hypoxanthine-guanine phosophoribosyltransferase (HPRT) deficiency: Lesch-Nyhan syndrome  

PubMed Central

Deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) activity is an inborn error of purine metabolism associated with uric acid overproduction and a continuum spectrum of neurological manifestations depending on the degree of the enzymatic deficiency. The prevalence is estimated at 1/380,000 live births in Canada, and 1/235,000 live births in Spain. Uric acid overproduction is present inall HPRT-deficient patients and is associated with lithiasis and gout. Neurological manifestations include severe action dystonia, choreoathetosis, ballismus, cognitive and attention deficit, and self-injurious behaviour. The most severe forms are known as Lesch-Nyhan syndrome (patients are normal at birth and diagnosis can be accomplished when psychomotor delay becomes apparent). Partial HPRT-deficient patients present these symptoms with a different intensity, and in the least severe forms symptoms may be unapparent. Megaloblastic anaemia is also associated with the disease. Inheritance of HPRT deficiency is X-linked recessive, thus males are generally affected and heterozygous female are carriers (usually asymptomatic). Human HPRT is encoded by a single structural gene on the long arm of the X chromosome at Xq26. To date, more than 300 disease-associated mutations in the HPRT1 gene have been identified. The diagnosis is based on clinical and biochemical findings (hyperuricemia and hyperuricosuria associated with psychomotor delay), and enzymatic (HPRT activity determination in haemolysate, intact erythrocytes or fibroblasts) and molecular tests. Molecular diagnosis allows faster and more accurate carrier and prenatal diagnosis. Prenatal diagnosis can be performed with amniotic cells obtained by amniocentesis at about 15–18 weeks' gestation, or chorionic villus cells obtained at about 10–12 weeks' gestation. Uric acid overproduction can be managed by allopurinol treatment. Doses must be carefully adjusted to avoid xanthine lithiasis. The lack of precise understanding of the neurological dysfunction has precluded development of useful therapies. Spasticity, when present, and dystonia can be managed with benzodiazepines and gamma-aminobutyric acid inhibitors such as baclofen. Physical rehabilitation, including management of dysarthria and dysphagia, special devices to enable hand control, appropriate walking aids, and a programme of posture management to prevent deformities are recommended. Self-injurious behaviour must be managed by a combination of physical restraints, behavioural and pharmaceutical treatments.

Torres, Rosa J; Puig, Juan G

2007-01-01

43

Temporal order of replication of genes responsible for hypoxanthine phosphoribosyl transferase and Na/sup +//K/sup +/ ATPase in chemically transformed human fibroblasts  

SciTech Connect

The cytotoxic and mutagenic effects of a direct perturbation of DNA during various portions of the DNA synthetic period (S phase) of a chemically induced, transformed line (Hut-11A cells) derived from diploid human skin fibroblasts were examined. The cells were synchronized by a period of growth in low serum with a subsequent blockage of the cells at the G1/S boundary by hydroxyurea. This method resulted in over 90% synchrony, although approximately 20% of the cells were noncycling. Synchronized cells were treated for each of four 2-h periods during the S phase with 5-bromodeoxyuridine (BrdU) followed by irradiation with near-ultraviolet (UV). The BrdU-plus-irradiation treatment was cytotoxic and mutagenic, while treatment with BrdU alone or irradiation alone was neither cytotoxic nor mutagenic. The cytotoxicity was dependent upon the periods of S phase during which treatment was administered. The highest lethality was observed for treatment in early to middle S phase, particularly in the first 2 h of S phase, whereas scare lethality was observed in late S phase. The BrdU-plus-irradiation treatment induced ouabain- and 6-thioguanine-resistant mutants, while BrdU alone or irradiation alone was not mutagenic. Ouabain-resistant mutants were induced during early S phase by the BrdU-plus-irradiation treatment. 6-Thioguanine-resistant mutants, however, were induced during middle to late S phase. These results suggest that a certain region or regions in the DNA of Hut-11A cells, as designated by their specific temporal relationship in the S phase, may be more sensitive to the DNA perturbation by BrdU treatment plus near-UV irradiation for cell survival and that gene(s) responsible for Na/sup +//K/sup +/ ATPase is replicated during early S phase and gene(s) for hypoxanthine phosphoribosyl transferase is replicated during middle to late S phase.

Tsutsui, T.; Suzuki, N.; Elmore, E.; Maizumi, H.

1986-06-01

44

Induction of Mutations by Chemical Agents at the Hypoxanthine-Guanine Phosphoribosyl Transferase Locus in Human Epithelial Teratoma Cells.  

National Technical Information Service (NTIS)

Induction of 6-thioguanine (TG) resistance by chemical mutagens was examined in a line of cells derived from a human epithelial teratocarcinoma cell clone. The cells, designated as P3 cells, have a stable diploid karyotype with 46(XX) chromosomes, includi...

E. Huberman, C. K. McKeown, C. A. Jones, D. R. Hoffman, S. Murao

1984-01-01

45

Electrophoretic Variation for X Chromosome-Linked Hypoxanthine Phosphoribosyl Transferase (Hprt) in Wild-Derived Mice  

PubMed Central

An electrophoretic variation for hypoxanthine phosphoribosyltransferase, HPRT, has been identified in samples of Mus spretus, a field mouse from southern Europe and in M. m. castaneus, a house mouse from southeast Asia. These mice will interbreed with laboratory mice to produce viable, fertile F1 progeny. The variation for HPRT segregates as an X chromosome gene in F1 and backcross progeny. Linkage analysis involving the markers Pgk-1 and Ags indicated a gene order of centromere— Hprt—Pgk-1—Ags in crosses involving both stocks of wild mice.

Chapman, Verne M.; Kratzer, Paul G.; Quarantillo, Barbara A.

1983-01-01

46

Prospects for cellular mutational assays in human populations  

SciTech Connect

Practical, sensitive, and effective human cellular assays for detecting somatic and germinal mutations would have great value in environmental mutagenesis and carcinogenesis studies. Such assays would fill the void between human mutagenicity and the data that exist from short-term tests and from mutagenicity in other species. This paper discusses the following possible human cellular assays: (1) HPRT (hypoxanthine phosphoribosyltransferase) somatic cell mutation based on 6-thioguanine resistance; (2) hemoglobin somatic cell mutation assay; (3) glycophorin somatic cell mutation assay; and (4) LDH-X sperm cell mutation assay. 18 references.

Mendelsohn, M.L.

1984-06-29

47

Complementation analysis of locus for hypoxanthine guanine phosphoribosyltransferase in Chinese hamster cells  

Microsoft Academic Search

The study deals with intragenic complementation between clones of Chinese hamster cells carrying mutations in the HPRTgene. All clones were of independent origin, selected in media containing one of three purine bases: 8-azaguanine (8 AG), 6-mercaptopurine (6MP), or 6-thioguanine (6TG). Some of the clones were spontaneous, others were induced by various mutagens. To make the study less time-consuming, an experimental

Nikolai I. Shapiro; Eugeny V. Luss; Larisa V. Volkova; Helena V. Moiseenko

1985-01-01

48

Pyrophosphate Activation in Hypoxanthine-Guanine Phosphoribosyltransferase with Transition State Analogue †  

PubMed Central

Isotope-edited difference Raman and FTIR studies complemented by ab initio calculations have been applied to the transition state analogue complex of HGPRT?ImmHP?MgPPi to determine the ionic states of the 5’-phosphate moiety of ImmHP and of PPi. These measurements characterize electrostatic interactions within the enzyme active site as deduced from frequency shifts of the phosphate groups. The bound 5’-phosphate moiety of ImmHP is di-anionic, and this phosphate group exists in two different conformations within the protein complex. In one conformation, a hydrogen bond between the 5’-phosphate of ImmHP and the OH group of Tyr104 in the catalytic loop appears to be stronger. With the stronger H-bond, the OH of Tyr104 approaches one of the P••O bonds from the bridging oxygen side to cause distortion of the PO3 moiety, as indicated by a lowered symmetric P••O stretch frequency. The asymmetric stretch frequencies are similar in both phosphate conformations. Bound PPi in this complex is fully ionized to P2O74?. Bond frequency changes for bound PPi indicate coordination to Mg2+ ions but show no indication of significant P••O bond polarization. Extrapolation of these results to reaction coordinate motion for HGPRT suggests that bond formation between C1’ of the nucleotide ribose and the oxygen of PPi is accomplished by migration of the ribocation toward immobilized pyrophosphate.

Deng, Hua; Callender, Robert; Schramm, Vern L.; Grubmeyer, Charles

2010-01-01

49

A human-mouse somatic hybrid line selected for human deoxycytidine deaminase  

Microsoft Academic Search

A new selective medium has been developed for cells containing the enzyme deoxycytidine deaminase. This medium contains hypoxanthine, aminopterin, and 5-methyldeoxycytidine (HAM medium). To survive in the presence of the aminopterin, the cells must utilize deoxycytidine deaminase to convert the 5-methyldeoxycytidine to thymidine. The cells must also have thymidine kinase and hypoxanthine phosphoribosyltransferase. A mouse cell line deficient in deoxycytidine

Teh-sheng Chan; Cedric Long; Howard Green

1975-01-01

50

Expression of an X-Linked Gene from an Inactive Human X Chromosome in Mouse-Human Hybrid Cells: Further Evidence for the Noninactivation of the Steroid Sulfatase Locus in Man  

Microsoft Academic Search

Somatic cell hybrid clones were derived from the fusion of hypoxanthine phosphoribosyltransferase (HPRT; EC 2.4.2.8)-deficient mouse cells and two different human fibroblast strains, each carrying an X chromosome-autosome translocation. One of these had an X\\/11 translocation [46,X,t(X;11)(p21;q13)] and the other had an X\\/19 translocation [46,X,t(X;19)(q22;q13)]. The structurally normal human X chromosome is the late-replicating (genetically inactive) chromosome in these two

T. Mohandas; R. S. Sparkes; B. Hellkuhl; K. H. Grzeschik; L. J. Shapiro

1980-01-01

51

Interactions at the Dimer Interface Influence the Relative Efficiencies for Purine Nucleotide Synthesis and Pyrophosphorolysis in a Phosphoribosyltransferase  

SciTech Connect

Enzymes that salvage 6-oxopurines, including hypoxanthine phosphoribosyltransferases (HPRTs), are potential targets for drugs in the treatment of diseases caused by protozoan parasites. For this reason, a number of high-resolution X-ray crystal structures of the HPRTs from protozoa have been reported. Although these structures did not reveal why HPRTs need to form dimers for catalysis, they revealed the existence of potentially relevant interactions involving residues in a loop of amino acid residues adjacent to the dimer interface, but the contributions of these interactions to catalysis remained poorly understood. The loop, referred to as active-site loop I, contains an unusual non-proline cis-peptide and is composed of residues that are structurally analogous with Leu67, Lys68, and Gly69 in the human HPRT. Functional analyses of site-directed mutations (K68D, K68E, K68N, K68P, and K68R) in the HPRT from Trypanosoma cruzi, etiologic agent of Chagas disease, show that the side-chain at position 68 can differentially influence the K{sub m} values for all four substrates as well as the k{sub cat} values for both IMP formation and pyrophosphorolysis. Also, the results for the K68P mutant are inconsistent with a cis-trans peptide isomerization-assisted catalytic mechanism. These data, together with the results of structural studies of the K68R mutant, reveal that the side-chain of residue 68 does not participate directly in reaction chemistry, but it strongly influences the relative efficiencies for IMP formation and pyrophosphorolysis, and the prevalence of lysine at position 68 in the HPRT of the majority of eukaryotes is consistent with there being a biological role for nucleotide pyrophosphorolysis.

Canyuk, Bhutorn; Medrano, Francisco J.; Wenck, MaryAnne; Focia, Pamela J.; Eakin, Ann E.; Craig III, Sydney P. (UNC); (Connecticut)

2010-03-05

52

Effect of hypoxanthine, antioxidants and allopurinol on cholinesterase activities in rats.  

PubMed

In the present study, we investigate the in vitro effect of hypoxanthine on acetylcholinesterase and butyrylcholinesterase activities in the hippocampus, striatum, cerebral cortex and serum of 15-, 30- and 60-day-old rats. Furthermore, we also evaluated the influence of antioxidants, namely ?-tocopherol (trolox) and ascorbic acid, and allopurinol to investigate the possible participation of free radicals and uric acid in the effects elicited by hypoxanthine on these parameters. Acetylcholinesterase and butyrylcholinesterase activities were determined according to Ellman et al. (Biochem Pharmacol 7:88-95, 1961), with some modifications. Hypoxanthine (10.0 ?M), when added to the incubation medium, enhanced acetylcholinesterase activity in the hippocampus and striatum of 15- and 30-day-old rats and reduced butyrylcholinesterase activity in the serum of 60-day-old rats. The administration of allopurinol and/or antioxidants partially prevented the alterations caused by hypoxanthine in acetylcholinesterase and butyrylcholinesterase activities in the cerebrum and serum of rats. Data indicate that hypoxanthine alters cholinesterase activities, probably through free radicals and uric acid production since the alterations were prevented by the administration of allopurinol and antioxidants. It is presumed that the cholinesterase system may be associated, at least in part, with the neuronal dysfunction observed in patients affected by Lesch-Nyhan disease. In addition, although extrapolation of findings from animal experiments to humans is difficult, it is conceivable that these vitamins and allopurinol might serve as an adjuvant therapy to avoid progression of brain damage in patients affected by this disease. PMID:23400363

Wamser, Morgahna Nathalie; Leite, Eduardo Fernandes; Ferreira, Vinícius Vialle; Delwing-de Lima, Daniela; da Cruz, José Geraldo Pereira; Wyse, Angela T S; Delwing-Dal Magro, Débora

2013-09-01

53

Hereditary xanthinuria. Evidence for enhanced hypoxanthine salvage.  

PubMed Central

We tested the hypothesis that there is an enhanced rate of hypoxanthine salvage in two siblings with hereditary xanthinuria. We radiolabeled the adenine nucleotide pool with [8-14C]adenine and examined purine nucleotide degradation after intravenous fructose. The cumulative excretion of radioactivity during a 5-d period was 9.7% and 9.1% of infused radioactivity in the enzyme-deficient patients and 6.0 +/- 0.7% (mean +/- SE) in four normal subjects. Fructose infusion increased urinary radioactivity to 7.96 and 9.16 X 10(6) cpm/g creatinine in both patients and to 4.73 +/- 0.69 X 10(6) cpm/g creatinine in controls. The infusion of fructose increased total urinary purine excretion to a mean of 487% from low-normal baseline values in the patients and to 398 +/- 86% in control subjects. In the enzyme-deficient patients, the infusion of fructose elicited an increase of plasma guanosine from undetectable values to 0.7 and 0.9 microM. With adjustments made for intestinal purine loss, these data support the hypothesis that there is enhanced hypoxanthine salvage in hereditary xanthinuria. Degradation of guanine nucleotides to xanthine bypasses the hypoxanthine salvage pathway and may explain the predominance of this urinary purine compound in xanthinuria.

Mateos, F A; Puig, J G; Jimenez, M L; Fox, I H

1987-01-01

54

Over-expression of nicotinamide phosphoribosyltransferase in ovarian cancers.  

PubMed

Nicotinamide phosphoribosyltransferase (Nampt) catalyzes the rate-limiting step of nicotinamide adenine dinucleotide (NAD(+)) synthesis and is required for cell growth, survival, DNA replication and repair, and angiogenesis. Nampt expression increases gene expression which promotes cell survival and increases SirT1 activity, promoting angiogenesis, and it is increased in several human malignancies. Recently, others have shown that ovarian serous adenocarcinomas (OSAs) express high levels of activated Stat3. Since Nampt expression is increased by Stat3, we hypothesized that Nampt protein might be highly expressed in OSAs. Using tissue microarray (TMA) and the avidin-biotin complex immunohistochemical technique we examined Nampt expression in 47 samples of benign ovarian tissue and 49 samples of ovarian serous adenoacarcinomas. Our data show that Nampt protein expression is significantly increased in OSAs as compared to benign ovarian tissue (0.49+/-0.12 benign vs. 4.78+/-0.46 malignant; +/-standard error of the mean). This is the first report demonstrating Nampt overexpression in OSA, which may shed light on the pathogenesis of OSA. Further studies of the role of Nampt overexpresion in OSA may shed light on the prognosis and clinical course of OSA. Last, since an effective pharmacologic Nampt inhibitor is currently in clinical use, further studies of Nampt overexpression in OSA may be used in selecting patients for Nampt inhibitor therapy. PMID:20606733

Shackelford, Rodney E; Bui, Marilyn M; Coppola, Domenico; Hakam, Ardeshir

2010-01-01

55

Molecular changes in UV-induced and gamma-ray-induced mutations in human lymphoblastoid cells.  

PubMed

We have characterized the structural changes in the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene of 14 UV-induced, 15 gamma-ray-induced and 17 spontaneous mutants of human lymphoblastoid cells selected for 6-thioguanine (6TG) resistance. Southern blot analysis using the full-length HPRT cDNA as a probe revealed that 29% (5/17) of the spontaneous mutants contained detectable alterations in their restriction fragment patterns. Among the 15 mutants induced by gamma rays, 7 (47%) had such alterations indicative of large deletions in the HPRT gene. In contrast, all 14 UV-induced mutants exhibited hybridization patterns indistinguishable from those of the wild-type cells. These results suggest that UV is likely to induce point mutations at the HPRT locus on the human chromosome and that the molecular mechanism of UV-induced mutation is quite different from that of ionizing radiation-induced mutation or spontaneous mutation in human cells. PMID:1973821

Tachibana, A; Ohbayashi, T; Takebe, H; Tatsumi, K

1990-06-01

56

Point mutations in the guanine phosphoribosyltransferase from Giardia lamblia modulate pyrophosphate binding and enzyme catalysis.  

PubMed

Guanine phosphoribosyltransferase (GPRTase) from Giardia lamblia, an enzyme required for guanine salvage and necessary for the survival of this parasitic protozoan, has been kinetically characterized. Phosphoribosyltransfer proceeds through an ordered sequential mechanism common to many related purine phosphoribosyltransferases (PRTases) with alpha-D-5-phosphoribosyl-1-pyrophosphate (PRPP) binding to the enzyme first and guanosine monophosphate (GMP) dissociating last. The enzyme is a highly unique purine PRTase, recognizing only guanine as its purine substrate (K(m) = 16.4 microM) but not hypoxanthine (K(m) > 200 microM) nor xanthine (no reaction). It also catalyzes both the forward (kcat = 76.7 s-1) and reverse (kcat = 5.8.s-1) reactions at significantly higher rates than all the other purine PRTases described to date. However, the relative catalytic efficiencies favor the forward reaction, which can be attributed to an unusually high K(m) for pyrophosphate (PPi) (323.9 microM) in the reverse reaction, comparable only with the high K(m) for PPi (165.5 microM) in Tritrichomonas foetus HGXPRTase-catalyzed reverse reaction. As the latter case was due to the substitution of threonine for a highly conserved lysine residue in the PPi-binding loop [Munagala et al. (1998) Biochemistry 37, 4045-4051], we identified a corresponding threonine residue in G. lamblia GPRTase at position 70 by sequence alignment, and then generated a T70K mutant of the enzyme. The mutant displays a 6.7-fold lower K(m) for PPi with a twofold increase in the K(m) for PRPP. Further attempts to improve PPi binding led to the construction of a T70K/A72G double mutant, which displays an even lower K(m) of 7.9 microM for PPi. However, mutations of the nearby Gly71 to Glu, Arg, or Ala completely inactivate the GPRTase, suggesting the requirement of flexibility in the putative PPi-binding loop for enzyme catalysis, which is apparently maintained by the glycine residue. We have thus tentatively identified the PPi-binding loop in G. lamblia GPRTase, and attributed the relatively higher catalytic efficiency in the forward reaction to the unusual loop structure for poor PPi binding in the reverse reaction. PMID:10092838

Page, J P; Munagala, N R; Wang, C C

1999-02-01

57

Molecular characterization of 15 rearrangements among 90 human in vivo somatic mutants shows that deletions predominate.  

PubMed Central

Ninety hypoxanthine phosphoribosyltransferase-deficient mutants were isolated from lymphocytes of 31 individuals drawn from both control populations and populations exposed to low doses of ionizing radiation. Southern analysis of the DNA revealed altered hybridization patterns in 15 mutants. Of these, 14 changes consisted of deletions of 2 to 40 kilobases or more. Images

Bradley, W E; Gareau, J L; Seifert, A M; Messing, K

1987-01-01

58

The kinetics of hypoxanthine efflux from the rat brain.  

PubMed

The brain efflux of radiolabelled hypoxanthine in the rat was rapid in the first minute after injection [K(eff)(i)=0.21+/-0.06 min(-1)], which was saturable with a V(max)=13.08+/-0.81 nM min(-1) g(-1), and a high K(m,app) (67.2+/-13.4 microM); the K(i,app) for inosine was 31.5+/-7.6 microM. Capillary depletion analysis indicated that hypoxanthine accumulates in neurons and glia with the time. From cross-inhibition studies with different purines and pyrimidines, it suggests that these molecules could also be important substrates for this carrier. PMID:11311886

Redzic, Z B; Isakovic, A; Segal, M B; Thomas, S A; Rakic, L M

2001-04-27

59

Low-potential amperometric enzyme biosensor for xanthine and hypoxanthine.  

PubMed

The bacterial xanthine dehydrogenase (XDH) from Rhodobacter capsulatus was immobilized on an edge-plane pyrolytic graphite (EPG) electrode to construct a hypoxanthine/xanthine biosensor that functions at physiological pH. Phenazine methosulfate (PMS) was used as a mediator which acts as an artificial electron-transfer partner for XDH. The enzyme catalyzes the oxidation of hypoxanthine to xanthine and also xanthine to uric acid by an oxidative hydroxylation mechanism. The present electrochemical biosensor was optimized in terms of applied potential and pH. The electrocatalytic oxidation response showed a linear dependence on the xanthine concentration ranging from 1.0 × 10(-5) to 1.8 × 10(-3) M with a correlation coefficient of 0.994. The modified electrode shows a very low detection limit for xanthine of 0.25 nM (signal-to-noise ratio = 3) using controlled potential amperometry. PMID:23134312

Kalimuthu, Palraj; Leimkühler, Silke; Bernhardt, Paul V

2012-12-01

60

Hypoxanthine-guanine phosphoribosylotransferase deficiency--the spectrum of Polish mutations.  

PubMed

Hypoxanthine-guanine phosphoribosyltransferase (HPRT; EC 2.4.2.8) deficiency (OMIM 308000) is an inborn error of purine metabolism. The defect causes three overlapping clinical syndromes: Lesch-Nyhan disease (LND; OMIM 300322), HPRT-related hyperuricaemia with neurologic dysfunction (HRND) and hyperuricaemia alone (HRH; OMIM 300322). During the period 1977-2007, 18 patients belonging to 12 Polish families and one Latvian family with HPRT deficiency have been identified. The majority of patients had a typical LND phenotype, three patients were classified as HRH and one patient as an intermediate phenotype (HRND). Genetic analysis revealed 12 different HPRT1 mutations, five of them being unique. In two typical Lesch-Nyhan families a novel single-base substitution, c.220T>G (p.Phe74Val), and a deletion of seven nucleotides, c.395_401del7 (p.Ile132LysfsX3), were found. Another novel single-base substitution, c.295T>G (p.Phe99Val), was identified in a patient with severe partial deficiency of HPRT with neurological dysfunction. In patients belonging to the HRH group, two transitions were detected: c.481G>A (p.Ala161Thr) and c.526C>T (p.Pro176Ser). Other mutations identified in Polish patients, c.131A>G (p.Asp44Gly), c.222C>A (p.Phe74Leu), c.385-1G>A (p.Asn129_Glu134del), c.482C>A (p.Ala161Glu), c.508C>T (p.Arg170Ter) and c.569G>A (p.Gly190Glu), have been reported previously in unrelated patients and are located within one of the clusters of hot spots of the HPRT1 gene (exons 3, 7 and 8). Patients with partial phenotypes presented mutations predicted to permit some degree of residual enzyme function (single-base substitutions). All mutations, except c.508C>T (p.Arg170Ter), were found in single families only, indicating the lack of any common mutation causing HPRT deficiency in Poland. PMID:19016344

Jurecka, A; Popowska, E; Tylki-Szymanska, A; Kubalska, J; Ciara, E; Krumina, Z; Sykut-Cegielska, J; Pronicka, E

2008-12-01

61

Regulatory elements in the introns of the human HPRT gene are necessary for its expression in embryonic stem cells  

SciTech Connect

The authors have examined the expression of transfected human hypoxanthine phosphoribosyltransferase minigenes (HPRT) in mouse embryonic stem (ES) cells. cDNA constructs of this gene that have been successfully used in somatic cell lines failed to confer hypoxanthine/aminopterin/thymidine (HAT) resistance in ES cells. In contrast, constructs containing introns 1 and 2 from the HPRT gene produced a high frequency of HAT-resistant colonies. This observation allowed them to identify two sequences in these introns that influence expression of the HPRT gene in ES cells. One element, located in intron 2, is required for effective HPRT expression in thee cells; the other element, located in intron 1, acts as an enhancer of HPRT expression. Using this information, they have constructed an HPRT minigene that can be used for either positive or negative selection in ES cell experiments. This dual capability allows the design of in-out procedures to create subtle changes in target genes by homologous recombination with the aid of this selectable minigene.

Reid, L.H.; Smithies, O.; Koller, B.H. (Univ. of North Carolina, Chapel Hill (USA)); Gregg, R.G. (Univ. of Wisconsin, Madison (USA))

1990-06-01

62

Adenine phosphoribosyltransferase (APRT) deficiency: identification of a novel nonsense mutation  

PubMed Central

Background Adenine phosphoribosyltransferase deficiency (APRTD) is an under estimated genetic form of kidney stones and/or kidney failure, characterized by intratubular precipitation of 2,8-dihydroxyadenine crystals (2,8-DHA). Currently, five pathologic allelic variants have been identified as responsible of the complete inactivation of APRT protein. Case presentation In this study, we report a novel nonsense mutation of the APRT gene from a 47- year old Italian patient. The mutation, localized in the exon 5, leads to the replacement of a cytosine with a thymine (g.2098C?>?T), introducing a stop codon at amino acid position 147 (p.Gln147X). This early termination was deleterious for the enzyme structural and functional integrity, as demonstrated by the structure analysis and the activity assay of the mutant APRT protein. Conclusion These data revealed that the p.Gln147X mutation in APRT gene might be a new cause of APRT disease.

2014-01-01

63

Expression of thymidylate synthase and orotate phosphoribosyltransferase in thymic carcinoma  

PubMed Central

Thymic carcinoma is a rare thymic epithelial tumor in which chemotherapy for advanced disease has not yet been established. Thymidylate synthase (TS) and orotate phosphoribosyltransferase (OPRT) protein expression levels in thymic carcinoma were evaluated as possible indicators of the anticancer activity of 5-fluorouracil (5-FU) drugs using immunohistochemistry (IHC). A total of 24 samples of thymic carcinoma were used in the present study. The tumor sections were immunohistochemically stained for TS and OPRT. As a comparison with thymic carcinoma, we also assessed the TS and OPRT protein expression levels in 55 lung cancer samples. The TS expression was positive in 12 of 24 thymic carcinoma samples (50%) and OPRT expression was positive in 10 (42%). The association between TS and OPRT expression and Masaoka stages of thymic carcinoma was analyzed. The TS and OPRT expressions in stage IV were significantly higher compared to that in stages I, II or III. We also compared the TS and OPRT expression levels between thymic carcinoma and lung cancer (33 adenocarcinomas and 22 squamous cell carcinomas). TS expression in thymic carcinoma was significantly lower compared with lung squamous cell carcinoma. OPRT expression in thymic carcinoma was significantly higher compared to lung adenocarcinoma. The combination of a relatively low expression of TS and high expression of OPRT suggests an improved antitumor effect of 5-FU drugs in thymic carcinoma compared to in lung carcinoma.

YOKOTA, KEISUKE; SASAKI, HIDEFUMI; OKUDA, KATSUHIRO; SHITARA, MASAYUKI; HIKOSAKA, YU; MORIYAMA, SATORU; YANO, MOTOKI; FUJII, YOSHITAKA

2012-01-01

64

Altered kinetic properties of a mutant adenine phosphoribosyltransferase.  

PubMed

Three siblings in a Japanese family experienced recurrent 2,8-dihydroxyadenine urolithiasis despite the presence of adenine phosphoribosyltransferase (APRT) activities in the hemolysates (19.9% to 28.2% of normal value). However, studies on viable T cells from these patients indicated that APRT was not functional in viable cells. Further analysis of the partially purified enzymes from hemolysates disclosed that patient's APRT had a reduced affinity to 5-phosphoribosyl-1-pyrophosphate (PRPP). Seven healthy members of this family whose APRT functioned normally in viable T cells had the erythrocyte enzyme levels between the patients and normal individuals (38.2% to 65.6%), suggesting that they are carriers of the defective gene. These results indicate that the defective gene code a unique mutant APRT with a reduced affinity to PRPP, and the patients are homozygotes. The mutant enzyme was also shown to be more heat-stable than normal enzyme. However, since mutant enzyme, unlike normal enzyme, was insensitive to the stabilization effect of PRPP, the latter became more heat-stable than the former when the heat treatment was performed in the presence of PRPP. This type of defect with alterations in the kinetic and physical properties of APRT as described here is likely to be a common type of APRT deficiency in Japan. PMID:2418331

Fujimori, S; Akaoka, I; Takeuchi, F; Kanayama, H; Tatara, K; Nishioka, K; Kamatani, N

1986-02-01

65

Molecular, kinetic and thermodynamic characterization of Mycobacterium tuberculosis orotate phosphoribosyltransferase.  

PubMed

Tuberculosis (TB) is a chronic infectious disease caused mainly by Mycobacterium tuberculosis. The worldwide emergence of drug-resistant strains, the increasing number of infected patients among immune compromised populations, and the large number of latent infected individuals that are reservoir to the disease have underscored the urgent need of new strategies to treat TB. The nucleotide metabolism pathways provide promising molecular targets for the development of novel drugs against active TB and may, hopefully, also be effective against latent forms of the pathogen. The orotate phosphoribosyltransferase (OPRT) enzyme of the de novo pyrimidine synthesis pathway catalyzes the reversible phosphoribosyl transfer from 5'-phospho-?-D-ribose 1'-diphosphate (PRPP) to orotic acid (OA), forming pyrophosphate and orotidine 5'-monophosphate (OMP). Here we describe cloning and characterization of pyrE-encoded protein of M. tuberculosis H37Rv strain as a homodimeric functional OPRT enzyme. The M. tuberculosis OPRT true kinetic constants for forward reaction and product inhibition results suggest a Mono-Iso Ordered Bi-Bi kinetic mechanism, which has not been previously described for this enzyme family. Absence of detection of half reaction and isothermal titration calorimetry (ITC) data support the proposed mechanism. ITC data also provided thermodynamic signatures of non-covalent interactions between substrate/product and M. tuberculosis OPRT. These data provide a solid foundation on which to base target-based rational design of anti-TB agents and should inform us how to better design inhibitors of M. tuberculosis OPRT. PMID:22075667

Breda, Ardala; Rosado, Leonardo Astolfi; Lorenzini, Daniel Macedo; Basso, Luiz Augusto; Santos, Diógenes Santiago

2012-02-01

66

Nicotinamide phosphoribosyltransferase (NAMPT) activity is essential for survival of resting lymphocytes.  

PubMed

NAD biosynthesis is emerging as a key regulator of immune cell functions. Accordingly, inhibitors of the NAD-synthesizing enzyme nicotinamide phosphoribosyltransferase (NAMPT) have anti-inflammatory effects, counteract hematological malignancies and are being tested in clinical trials. Still, their effect on different cell types still waits to be fully investigated. Here we show that the NAMPT inhibitor FK866 induces NAD depletion in various mouse organs but selectively causes dramatic atrophy of the spleen red pulp. Accordingly, in cultured mouse lymphocytes exposed to FK866, NAD contents drop to 50% of basal values within 2 days, a condition sufficient to prompt complete cell death. Cultures of human lymphocytes are more resistant to FK866 and sustain a 50% NAD reduction for 5 days before dying. Death of both cell types can be prevented by different NAD precursors, indicating critical NAD homeostasis in lymphocytes. Indeed, inhibition of the NAD-consuming enzyme poly(ADP-ribose) polimerase-1 suffices to prevent FK866-induced NAD depletion and death of both lymphocyte types. Poly(ADP-ribose) polymerase-1-null lymphocytes also undergo lower NAD depletion and reduced cell death when exposed to the drug. At variance with other cell types, neither apoptosis nor autophagy are exclusively responsible for lymphocyte death by FK866, consistent with a general impairment of lymphocyte homeostasis following NAD depletion. Data demonstrate a unique sensitivity of resting lymphocytes to NAD-depleting agents, providing new hints of relevance to lymphocyte biology and therapeutic interventions with NAMPT inhibitors. PMID:24275857

Pittelli, Maria; Cavone, Leonardo; Lapucci, Andrea; Oteri, Claudia; Felici, Roberta; Niccolai, Elena; Amedei, Amedeo; Chiarugi, Alberto

2014-02-01

67

Measurement of transcribed human X-chromosomal DNA sequences transferred to rodent cells by chromosome-mediated gene transfer.  

PubMed Central

Transfer of genetic information can be effected by incubation of cultured eucaryotic cells with isolated metaphase chromosomes. In most cases, a resulting transformed cell contains only a fragment of a donor chromosome. The amount of transferred donor DNA has been quantified in 11 independent mouse A9 transformants by nucleic acid hybridization analysis. Each transformant had been selected for hprt (hypoxanthine phosphoribosyltransferase; EC 2.4.2.8) transfer and contained part of the human X chromosome. A labeled probe of transcribed human X-chromosomal DNA was prepared by hybridization of nick-translated unique-sequence human DNA with whole cellular RNA from a human-mouse hybrid cell line, A9/HRBC2-A, containing a single human chromosome., X. The amount of human X-chromosomal DNA in the transformants was quantitated by comparing the hybridization of this probe with transformant and A9/HRBC2-A DNAs. Two unstable transformants which had a microscopically detectable donor chromosome fragment contained 15% of the human X-chromosomal single-copy DNA. Four other unstable transformants contained 4 to 7% of human X-chromosomal DNA sequences. The transferred DNA was below the level of detection in three other unstable and in all three stable transformants. We conclude that the initial transfer event can introduce a substantial amount of genetic information but only smaller amounts of DNA are stably incorporated by integration.

McBride, O W; Olsen, A S; Aulakh, G S; Athwal, R S

1982-01-01

68

Localization of human gene loci using spontaneous chromosome rearrangements in human-Chinese hamster somatic cell hybrids.  

PubMed Central

Analysis of human-Chinese hamster somatic cell hybrids with spontaneously derived chromosome structural changes has provided data for the regional and subregional localization of gene loci which have previously been assigned to human chromosomes 2, 12, and X. Correlation of the expression of human gene loci with the human chromosome complements present in somatic cell hybrids indicates that the cytoplasmic malate dehydrogenase (MDH1) locus is in the 2p23yields2pter region, and red cell acid phosphatase (AcP1) is at or adjacent to 2p23. The cytoplasmic isocitrate dehydrogenase (IDH1) locus is at or adjacent to 2q11, peptidase B (Pep B) is at or adjacent to 12q21, lactate dehydrogenase B (LDH B) is in the 12q21yiedls12pter region, glucose-6-phosphate dehydrogenase (G6PD) is in the Xq24yieldsXqter region, and the gene loci for phosphoglycerate kinase (PGK), alpha-galactosidase (alpha-gal), and hypoxanthine guanine phosphoribosyltransferase (GPRT) are in the Xp21yieldsXq24 region. Images Fig. 1 Fig. 2 Fig. 3

Hamerton, J L; Mohandas, T; McAlpine, J

1975-01-01

69

Ultrafast electronic deactivation dynamics of the rare natural nucleobase hypoxanthine  

NASA Astrophysics Data System (ADS)

The electronic deactivation of the 6-oxopurine derivative hypoxanthine, its nucleoside inosine and the nucleotide inosine monophosphate have been studied by femtosecond time-resolved spectroscopy after ??? photoexcitation at ? = 260 nm. The development of a highly sensitive parallel broadband (near-UV/VIS) and single-color (deep-UV) transient absorption setup enabled us to monitor the excited-state decay and the ground-state recovery dynamics in one and the same experiment. The measurements revealed similar relaxation behavior, with time constants of ?1 ? 0.1 ps, ?2 ? 0.21 ± 0.08 ps and ?3 ? 1.8 ± 0.4 ps, for all three investigated molecules. The observed dynamics are assumed to take place through a conical intersection involving an out-of-plane puckering mode of the six-membered ring similar to guanine.

Röttger, Katharina; Siewertsen, Ron; Temps, Friedrich

2012-05-01

70

Phenotype and Genotype Characterization of Adenine Phosphoribosyltransferase Deficiency  

PubMed Central

Adenine phosphoribosyltransferase (APRT) deficiency is a rare autosomal recessive disorder causing 2,8-dihydroxyadenine stones and renal failure secondary to intratubular crystalline precipitation. Little is known regarding the clinical presentation of APRT deficiency, especially in the white population. We retrospectively reviewed all 53 cases of APRT deficiency (from 43 families) identified at a single institution between 1978 and 2009. The median age at diagnosis was 36.3 years (range 0.5 to 78.0 years). In many patients, a several-year delay separated the onset of symptoms and diagnosis. Of the 40 patients from 33 families with full clinical data available, 14 (35%) had decreased renal function at diagnosis. Diagnosis occurred in six (15%) patients after reaching ESRD, with five diagnoses made at the time of disease recurrence in a renal allograft. Eight (20%) patients reached ESRD during a median follow-up of 74 months. Thirty-one families underwent APRT sequencing, which identified 54 (87%) mutant alleles on the 62 chromosomes analyzed. We identified 18 distinct mutations. A single T insertion in a splice donor site in intron 4 (IVS4 + 2insT), which produces a truncated protein, accounted for 40.3% of the mutations. We detected the IVS4 + 2insT mutation in two (0.98%) of 204 chromosomes of healthy newborns. This report, which is the largest published series of APRT deficiency to date, highlights the underdiagnosis and potential severity of this disease. Early diagnosis is crucial for initiation of effective treatment with allopurinol and for prevention of renal complications.

Bollee, Guillaume; Dollinger, Cecile; Boutaud, Lucile; Guillemot, Delphine; Bensman, Albert; Harambat, Jerome; Deteix, Patrice; Daudon, Michel; Knebelmann, Bertrand

2010-01-01

71

Adenine phosphoribosyltransferase deficiency as a rare cause of renal allograft dysfunction.  

PubMed

Adenine phosphoribosyltransferase deficiency is a rare autosomal recessive disorder manifesting as urolithiasis or crystalline nephropathy. It leads to the generation of large amounts of poorly soluble 2,8-dihydroxyadenine excreted in urine, yielding kidney injury and in some patients, kidney failure. Early recognition of the disease, institution of xanthine analog therapy to block the formation of 2,8-dihydroxyadenine, high fluid intake, and low purine diet prevent CKD. Because of symptom variability and lack of awareness, however, the diagnosis is sometimes extremely deferred. We describe a patient with adenine phosphoribosyltransferase deficiency who was diagnosed during evaluation of a poorly functioning second kidney allograft. This report highlights the risk of renal allograft loss in patients with undiagnosed adenine phosphoribosyltransferase deficiency and the need for improved early detection of this disease. PMID:24459232

Kaartinen, Kati; Hemmilä, Ulla; Salmela, Kaija; Räisänen-Sokolowski, Anne; Kouri, Timo; Mäkelä, Satu

2014-04-01

72

Studies of the locus for androgen receptor: localization on the human X chromosome and evidence for homology with the Tfm locus in the mouse.  

PubMed Central

We have established a cell line from mouse kidney cells expressing the tfm mutation and showed that these cells lack androgen binding activity. A subclone of these simian virus 40 (SV40)-transformed cells (6TGR-SV-tfm) selected in 6-thioguanine and lacking hypoxanthine phosphoribosyltransferase was used to produce a series of mouse--human hybrids containing the normal human X chromosome or various X autosome-translocation chromosomes (expressing only segments of the human X chromosome). When the androgen receptor locus (AR) was present in the hybrid, the number of receptor sites and kinetics of binding were similar to that in the human parental cells. Analysis of hybrids with partial human X chromosomes by using assays for X chromosome-linked enzymes and for the androgen receptor protein indicate that the AR locus on the human X chromosome is near the centromere between Xq13 and Xp11 and is proximal to the locus for phosphoglycerate kinase. Hybrids derived from 6TGR-SV-tfm mouse cells and human labial fibroblasts from an XY individual with the ar- form of androgen insensitivity have no binding activity. The lack of complementation indicates that the X chromosome-linked mutations in mouse and man affect homologous loci and supports the evolutionary conservation of X chromosomal loci in mammals; however, the position of the locus on the human X chromosome indicates that intrachromosomal rearrangement has occurred.

Migeon, B R; Brown, T R; Axelman, J; Migeon, C J

1981-01-01

73

Preparation and screening of an arrayed human genomic library generated with the P1 cloning system  

SciTech Connect

The authors describe here the construction and initial characterization of a 3-fold coverage genomic library of the human haploid genome that was prepared using the bacteriophase P1 cloning system. The cloned DNA inserts were produced by size fractionation of a Sau3AI partial digest of high molecular weight genomic DNA isolated from primary cells of human foreskin fibroblasts. The inserts were cloned into the pAd10sacBII vector and packaged in vitro into P1 phage. These were used to generate recombinant bacterial clones, each of which was picked robotically from an agar plate into a well of a 96-well microtiter dish, grown overnight, and stored at -70{degrees}C. The resulting library, designated DMPC-HFF No. 1 series A, consists of {approximately}130,000-140,000 recombinant clones that were stored in 1500 microtiter dishes. To screen the library, clones were combined in a pooling strategy and specific loci were identified by PCR analysis. On average, the library contains two or three different clones for each locus screened. To date the authors have identified a total of 17 clones containing the hypoxanthine-guanine phosphoribosyltransferase, human serum albumin-human {alpha}-fetoprotein, p53, cyclooxygenase I, human apurinic endonuclease, {beta}-polymerase, and DNA ligase I genes. The cloned inserts average 80 kb in size and range from 70 to 95 kb, with one 49-kb insert and one 62-kb insert. 19 refs., 3 figs., 1 tab.

Shepherd, N.S.; Perogner, B.D.; Coulby, J.N.; Ackerman, S.L.; Vaidyanathan, G.; Sauer, R.H.; Balkenhol, T.C.; Sternberg, N. [Dupont Merck Pharmaceutical Co., Wilmington, DE (United States)]|[Central Research and Development Engineering Department and Service Division, Wilmington, DE (United States)

1994-03-29

74

Defects in purine nucleotide metabolism lead to substantial incorporation of xanthine and hypoxanthine into DNA and RNA.  

PubMed

Deamination of nucleobases in DNA and RNA results in the formation of xanthine (X), hypoxanthine (I), oxanine, and uracil, all of which are miscoding and mutagenic in DNA and can interfere with RNA editing and function. Among many forms of nucleic acid damage, deamination arises from several unrelated mechanisms, including hydrolysis, nitrosative chemistry, and deaminase enzymes. Here we present a fourth mechanism contributing to the burden of nucleobase deamination: incorporation of hypoxanthine and xanthine into DNA and RNA caused by defects in purine nucleotide metabolism. Using Escherichia coli and Saccharomyces cerevisiae with defined mutations in purine metabolism in conjunction with analytical methods for quantifying deaminated nucleobases in DNA and RNA, we observed large increases (up to 600-fold) in hypoxanthine in both DNA and RNA in cells unable to convert IMP to XMP or AMP (IMP dehydrogenase, guaB; adenylosuccinate synthetase, purA, and ADE12), and unable to remove dITP/ITP and dXTP/XTP from the nucleotide pool (dITP/XTP pyrophosphohydrolase, rdgB and HAM1). Conversely, modest changes in xanthine levels were observed in RNA (but not DNA) from E. coli lacking purA and rdgB and the enzyme converting XMP to GMP (GMP synthetase, guaA). These observations suggest that disturbances in purine metabolism caused by known genetic polymorphisms could increase the burden of mutagenic deaminated nucleobases in DNA and interfere with gene expression and RNA function, a situation possibly exacerbated by the nitrosative stress of concurrent inflammation. The results also suggest a mechanistic basis for the pathophysiology of human inborn errors of purine nucleotide metabolism. PMID:22308425

Pang, Bo; McFaline, Jose L; Burgis, Nicholas E; Dong, Min; Taghizadeh, Koli; Sullivan, Matthew R; Elmquist, C Eric; Cunningham, Richard P; Dedon, Peter C

2012-02-14

75

Inhibition of Nicotinamide Phosphoribosyltransferase Reduces Neutrophil-Mediated Injury in Myocardial Infarction  

PubMed Central

Abstract Aims: Nicotinamide phosphoribosyltransferase (Nampt) is a key enzyme for nicotinamide adenine dinucleotide (NAD+) biosynthesis, and recent evidence indicates its role in inflammatory processes. Here, we investigated the potential effects of pharmacological Nampt inhibition with FK866 in a mouse myocardial ischemia/reperfusion model. In vivo and ex vivo mouse myocardial ischemia/reperfusion procedures were performed. Results: Treatment with FK866 reduced myocardial infarct size, neutrophil infiltration, and reactive oxygen species (ROS) generation within infarcted hearts in vivo in a mouse model of ischemia and reperfusion. The benefit of FK866 was not shown in the Langendorff model (ex vivo model of working heart without circulating leukocytes), suggesting a direct involvement of these cells in cardiac injury. Sera from FK866-treated mice showed reduced circulating levels of the neutrophil chemoattractant CXCL2 and impaired capacity to prime migration of these cells in vitro. The release of CXCL8 (human homolog of murine chemokine CXCL2) by human peripheral blood mononuclear cells (PBMCs) and Jurkat cells was also reduced by FK866, as well as by sirtuin (SIRT) inhibitors and SIRT6 silencing, implying a pivotal role for this NAD+-dependent deacetylase in the production of this chemokine. Innovation: The pharmacological inhibition of Nampt might represent an effective approach to reduce neutrophilic inflammation- and oxidative stress-mediated tissue damage in early phases of reperfusion after a myocardial infarction. Conclusions: Nampt inhibition appears as a new strategy to dampen CXCL2-induced neutrophil recruitment and thereby reduce neutrophil-mediated tissue injury in mice. Antioxid. Redox Signal. 18, 630–641.

Bauer, Inga; Braunersreuther, Vincent; Bruzzone, Santina; Akhmedov, Alexander; Luscher, Thomas F.; Speer, Timo; Poggi, Alessandro; Mannino, Elena; Pelli, Graziano; Galan, Katia; Bertolotto, Maria; Lenglet, Sebastien; Garuti, Anna; Montessuit, Christophe; Lerch, Rene; Pellieux, Corinne; Vuilleumier, Nicolas; Dallegri, Franco; Mage, Jacqueline; Sebastian, Carlos; Mostoslavsky, Raul; Gayet-Ageron, Angele; Patrone, Franco; Mach, Francois; Nencioni, Alessio

2013-01-01

76

Sequence-Specific Correction of Genomic Hypoxanthine-Guanine Phosphoribosyl Transferase Mutations in Lymphoblasts by Small Fragment Homologous Replacement  

PubMed Central

Oligo/polynucleotide-based gene targeting strategies provide new options for achieving sequence-specific modification of genomic DNA and have implications for the development of new therapies and transgenic animal models. One such gene modification strategy, small fragment homologous replacement (SFHR), was evaluated qualitatively and quantitatively in human lymphoblasts that contain a single base substitution in the hypoxanthine-guanine phosphoribosyl transferase (HPRT1) gene. Because HPRT1 mutant cells are readily discernable from those expressing the wild type (wt) gene through growth in selective media, it was possible to identify and isolate cells that have been corrected by SFHR. Transfection of HPRT1 mutant cells with polynucleotide small DNA fragments (SDFs) comprising wild type HPRT1 (wtHPRT1) sequences resulted in clones of cells that grew in hypoxanthine-aminopterin-thymidine (HAT) medium. Initial studies quantifying the efficiency of correction in 3 separate experiments indicate frequencies ranging from 0.1% to 2%. Sequence analysis of DNA and RNA showed correction of the HPRT1 mutation. Random integration was not indicated after transfection of the mutant cells with an SDF comprised of green fluorescent protein (GFP) sequences that are not found in human genomic DNA. Random integration was also not detected following Southern blot hybridization analysis of an individual corrected cell clone.

Bedayat, Babak; Abdolmohamadi, Alireza; Ye, Lin; Maurisse, Rosalie; Parsi, Hooman; Schwarz, Jennifer; Emamekhoo, Hamid; Nicklas, Janice A.; O'Neill, J. Patrick

2010-01-01

77

Mutation induction in human lymphoid cells by energetic heavy ions  

NASA Astrophysics Data System (ADS)

One of the concerns for extended space flight outside the magnetosphere is exposure to galactic cosmic radiation. In the series of studies presented herein, the mutagenic effectiveness of high energy heavy ions is examined using human B-lymphoblastoid cells across an LET range from 32keV/?m to 190 keV/?m. Mutations were scored for an autosomal locus, thymidine kinase (tk), and for an X-linked locus, hypoxanthine phosphoribosyltransferase (hprt). For each of the radiations studied, the autosomal locus is more sensitive to mutation induction than is the X-linked locus. When mutational yields are expressed in terms of particle fluence, the two loci respond quite differently across the range of LET. The action cross section for mutation induction peaks at 61 keV/?m for the tk locus and then declines for particles of higher LET, including Fe ions. For the hprt locus, the action cross section for mutation is maximal at 95 keV/?m but is relatively constant across the range from 61 keV/?m to 190 keV/gmm. The yields of hprt-deficient mutants obtained after HZE exposure to TK6 lymphoblasts may be compared directly with published data on the induction of hprt-deficient mutants in human neonatal fibroblasts exposed to similar ions. The action cross section for induction of hprt-deficient mutants by energetic Fe ions is more than 10-fold lower for lymphoblastoid cells than for fibroblasts.

Kronenberg, A.

1994-10-01

78

Intrastriatal injection of hypoxanthine reduces striatal serotonin content and impairs spatial memory performance in rats  

Microsoft Academic Search

The aim of this study was to investigate the effects of intrastriatal injection of hypoxanthine, a metabolite accumulated\\u000a in Lesch-Nyhan disease, on rats’ performance in the Morris water maze tasks, along with the monoamine content in striatum\\u000a of rats. Male adult Wistar rats were divided in two groups: (1) saline-injected and (2) hypoxanthine-injected group. Seven\\u000a days after solutions infusion, animals

Caren Serra Bavaresco; Fabria Chiarani; Eduardo Duringon; Marcelo Machado Ferro; Cláudio Da Cunha; Carlos Alexandre Netto; Angela Terezinha de Souza Wyse

2007-01-01

79

Rapid method for the diagnosis of partial adenine phosphoribosyltransferase deficiencies causing 2,8-dihydroxyadenine urolithiasis  

Microsoft Academic Search

More than half of the Japanese patients with 2,8-dihydroxyadenine urolithiasis only partially lack adenine phosphoribosyltransferase (APRT), while all the Caucasian patients with the same disease completely lack the enzyme. APRT activities in healthy heterozygotes for the complete APRT deficiencies were at the same levels as the Japanese patients, and simple enzyme assay does not distinguish between these two conditions. We

F. Takeuchi; K. Matsuta; T. Miyamoto; S. Enomoto; S. Fujimori; I. Akaoka; N. Kamatani; K. Nishioka

1985-01-01

80

In vitro Methylation of the Hamster Adenine Phosphoribosyltransferase Gene Inhibits Its Expression in Mouse L Cells  

Microsoft Academic Search

The effect of DNA methylation on the expression of the hamster adenine phosphoribosyltransferase (aprt) gene in mouse cells has been examined. This gene was methylated in vitro at all of its C-C-G-G sites by using Hpa II methylase and was inserted into mouse Ltk- aprt- L cells by cotransformation, with the herpes virus thymidine kinase gene as a selectable vector.

R. Stein; A. Razin; H. Cedar

1982-01-01

81

Nicotinamide Phosphoribosyltransferase/Visfatin Does Not Catalyze Nicotinamide Mononucleotide Formation in Blood Plasma  

PubMed Central

Nicotinamide (Nam) phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme in mammalian NAD synthesis, catalyzing nicotinamide mononucleotide (NMN) formation from Nam and 5-phosphoribosyl 1-pyrophosphate (PRPP). NAMPT has also been described as an adipocytokine visfatin with a variety of actions, although physiological significance of this protein remains unclear. It has been proposed that possible actions of visfatin are mediated through the extracellular formation of NMN. However, we did not detect NMN in mouse blood plasma, even with a highly specific and sensitive liquid chromatography/tandem mass spectrometry. Furthermore, there is no or little ATP, the activator of NAMPT, in extracellular spaces. We thus questioned whether visfatin catalyzes the in situ formation of NMN under such extracellular milieus. To address this question, we here determined Km values for the substrates Nam and PRPP in the NAMPT reaction without or with ATP using a recombinant human enzyme and found that 1 mM ATP dramatically decreases Km values for the substrates, in particular PRPP to its intracellular concentration. Consistent with the kinetic data, only when ATP is present at millimolar levels, NAMPT efficiently catalyzed the NMN formation at the intracellular concentrations of the substrates. Much lower concentrations of Nam and almost the absence of PRPP and ATP in the blood plasma suggest that NAMPT should not efficiently catalyze its reaction under the extracellular milieu. Indeed, NAMPT did not form NMN in the blood plasma. From these kinetic analyses of the enzyme and quantitative determination of its substrates, activator, and product, we conclude that visfatin does not participate in NMN formation under the extracellular milieus. Together with the absence of NMN in the blood plasma, our conclusion does not support the concept of “NAMPT-mediated systemic NAD biosynthesis.” Our study would advance current understanding of visfatin physiology.

Hara, Nobumasa; Yamada, Kazuo; Shibata, Tomoko; Osago, Harumi; Tsuchiya, Mikako

2011-01-01

82

Pyrimidin-2(1H)-ones based inhibitors of Mycobacterium tuberculosis orotate phosphoribosyltransferase.  

PubMed

Tuberculosis (TB) is an ancient human chronic infectious disease caused mainly by Mycobacterium tuberculosis. The emergence of strains resistant to first and second line anti-TB drugs, associated with the increasing number of TB cases among HIV positive subjects, and the large number of individuals infected with latent bacilli have urged the development of new strategies to treat TB. Enzymes of nucleotide metabolism pathways provide promising molecular targets for the development of drugs, aiming at both active and latent TB. The orotate phosphoribosyltransferase (OPRT) enzyme catalyzes the synthesis of orotidine 5'-monophosphate from 5'-phospho-?-d-ribose 1'-diphosphate and orotic acid, in the de novo pyrimidine synthesis pathway. Based on the kinetic mechanism and molecular properties, here we describe the design, selection and synthesis of substrate analogs with inhibitory activity of M. tuberculosis OPRT (MtOPRT) enzyme. Steady-state kinetic measurements were employed to determine the mode of inhibition of commercially available and chemically derived compounds. The 6-Hydroxy-2-oxo-1,2-dihydropyridine-4-carboxylic acid (6) chemical compound and its derivative, 3-Benzylidene-2,6-dioxo-1,2,3,6-tetrahydropyridine-4-carboxylic acid (13), showed enzyme inhibition constants in the submicromolar range. Isothermal titration calorimetry data indicated that binding of both compounds to MtOPRT have negative enthalpy and favorable Gibbs free energy probably due to their high complementarity to the enzyme's binding pocket. Improvement of compound 13 hydrophobic character by addition of an aromatic ring substituent resulted in entropic optimization, reflected on a thermodynamic discrimination profile characteristic of high affinity ligands. These inhibitors represent lead compounds for further development of MtOPRT inhibitors with increased potency, which may be tested as anti-TB agents. PMID:22608674

Breda, Ardala; Machado, Pablo; Rosado, Leonardo Astolfi; Souto, André Arigony; Santos, Diógenes Santiago; Basso, Luiz Augusto

2012-08-01

83

Ground-state destabilization in orotate phosphoribosyltransferases by binding isotope effects.  

PubMed

Orotate phosphoribosyltransferases (OPRTs) form and break the N-ribosidic bond to pyrimidines by way of ribocation-like transition states (TSs) and therefore exhibit large ?-secondary 1'-(3)H k(cat)/K(m) kinetic isotope effects (KIEs) [Zhang, Y., and Schramm, V. L. (2010) J. Am. Chem. Soc. 132, 8787-8794]. Substrate binding isotope effects (BIEs) with OPRTs report on the degree of ground-state destabilization for these complexes and permit resolution of binding and transition-state effects from the k(cat)/K(m) KIEs. The BIEs for interactions of [1'-(3)H]orotidine 5'-monophosphate (OMP) with the catalytic sites of Plasmodium falciparum and human OPRTs are 1.104 and 1.108, respectively. These large BIEs establish altered sp(3) bond hybridization of C1' toward the sp(2) geometry of the transition states upon OMP binding. Thus, the complexes of these OPRTs distort OMP part of the way toward the transition state. As the [1'-(3)H]OMP k(cat)/K(m) KIEs are approximately 1.20, half of the intrinsic k(cat)/K(m) KIEs originate from BIEs. Orotidine, a slow substrate for these enzymes, binds to the catalytic site with no significant [1'-(3)H]orotidine BIEs. Thus, OPRTs are unable to initiate ground-state destabilization of orotidine by altered C1' hybridization because of the missing 5'-phosphate. However the k(cat)/K(m) KIEs for [1'-(3)H]orotidine are also approximately 1.20. The C1' distortion for OMP happens in two steps, half upon binding and half on going from the Michaelis complex to the TS. With orotidine as the substrate, there is no ground-state destabilization in the Michaelis complexes, but the C1' distortion at the TS is equal to that of OMP. The large single barrier for TS formation with orotidine slows the rate of barrier crossing. PMID:21526795

Zhang, Yong; Schramm, Vern L

2011-05-31

84

Cadmium down-regulates human OGG1 through suppression of Sp1 activity.  

PubMed

Cadmium is a well known human and animal carcinogen and is a ubiquitous contaminant in the environment. Although the carcinogenic mechanism of cadmium is a multifactorial process, oxidative DNA damage is believed to be of prime importance. In particular, cadmium suppresses the capacity of cells to repair oxidative DNA damage. In this study, cadmium treatment led to a significant increase in gamma-ray-induced 8-oxoguanine (8-oxoG) formation. Western blotting and semiquantitative reverse transcription-PCR revealed that cadmium treatment caused a decrease in the expression level of human OGG1 (8-oxoguanine-DNA glycosylase-1; hOGG1) in human fibroblast GM00637 and HeLa S3 cells. In addition, the cadmium-mediated decrease in hOGG1 transcription was the result of decreased binding of the transcription factor Sp1 to the hOGG1 promoter. Finally, we show that an increase in the functional hOGG1 expression level could inhibit the cadmium-mediated increase in gamma-ray-induced 8-oxoG accumulation as well as in gamma-radiation-induced mutation frequency at the HPRT (hypoxanthine-guanine phosphoribosyltransferase) gene locus. These results suggest that cadmium attenuates removal of gamma-ray-induced 8-oxoG adducts, which in turn increases the mutation frequency, and that this effect might, at least in part, result from suppression of hOGG1 transcription via inactivation of Sp1 as a result of cadmium treatment. PMID:15760895

Youn, Cha-Kyung; Kim, Soo-Hyun; Lee, Do Young; Song, Seung Hee; Chang, In-Youb; Hyun, Jin-Won; Chung, Myung-Hee; You, Ho Jin

2005-07-01

85

The kinetics of hypoxanthine transport across the perfused choroid plexus of the sheep.  

PubMed

The uptake of principal salvageable nucleobase hypoxanthine was investigated across the basolateral membrane of the sheep choroid plexus (CP) perfused in situ. The results suggest that hypoxanthine uptake was Na+-independent, which means that transport system on the basolateral membrane can mediate the transport in both directions. Although the unlabelled nucleosides adenosine and inosine markedly reduce the transport it seems that this inhibition was due to nucleoside degradation into nucleobases in the cells, since non-metabolised nucleoside analogue NBTI did not inhibit the transport. The presence of adenine also inhibits hypoxanthine uptake while the addition of the pyrimidines does not show any effect, so it seems that the transport of purine nucleobases through basolateral membrane is mediated via a common transporter which is different from the nucleoside transporters. The inclusion of allopurinol in the perfusion fluid did not change the value and general shape of the curve for the uptake which suggest that degradation of hypoxanthine into xanthine and uric acid does not occur in the CP. The capacity of the CP basolateral membrane to transport hypoxanthine is high (90.63+/-3.79 nM/min/g) and close to the values obtained for some essential amino acids by the CP and blood-brain barrier, while the free diffusion is negligible. The derived value of Km (20.72+/-2.42 microM) is higher than the concentration of hypoxanthine in the sheep plasma (15.61+/-2.28 microM) but less than a half of the concentration in the CSF, which indicates that the transport system at basolateral membrane mostly mediates the efflux of hypoxanthine from the cerebrospinal fluid in vivo. PMID:11792365

Redzic, Zoran B; Gasic, Jovana M; Segal, Malcolm B; Markovic, Ivanka D; Isakovic, Aleksandra J; Rakic, Miodrag Lj; Thomas, Sarah A; Rakic, Ljubisa M

2002-01-25

86

Selective determination of inosine in the presence of uric acid and hypoxanthine using modified electrode.  

PubMed

This article describes the selective determination of inosine (INO) in the presence of important physiological interferents, uric acid (UA) and hypoxanthine (HXN), by differential pulse voltammetry at physiological pH (7.2) using the electropolymerized film of 3-amino-5-mercapto-1,2,4-triazole (p-AMTa) modified glassy carbon (GC) electrode. The electropolymerization of AMTa was carried out by the potentiodynamic method in 0.1M H(2)SO(4). An atomic force microscopy image shows that the p-AMTa film contains a spherical-like structure. Bare GC electrode fails to resolve the voltammetric signal of INO in the presence of UA and HXN due to the surface fouling caused by the oxidized products of UA and HXN. However, p-AMTa film modified GC electrode (p-AMTa electrode) not only separates the voltammetric signals of UA, HXN, and INO, with potential differences of 730 mV between UA and HXN and 310 mV between HXN and INO, but also shows enhanced oxidation current for them. The selective determination of INO in the presence of UA and HXN at physiological pH was achieved for the first time. Using the amperometric method, we achieved the lowest detection of 50 nM for INO. The practical application of the current modified electrode was demonstrated by determining the concentration of INO in human blood serum and urine samples. PMID:22080039

Revin, S Brillians; John, S Abraham

2012-02-01

87

Analysis of the structural integrity of YACs comprising human immunoglobulin genes in yeast and in embryonic stem cells  

SciTech Connect

With the goal of creating a strain of mice capable of producing human antibodies, we are cloning and reconstructing the human immunoglobulin germline repertoire in yeast artificial chromosomes (YACs). We describe the identification of YACs containing variable and constant region sequences from the human heavy chain (IgH) and kappa light chain (IgK) loci and the characterization of their integrity in yeast and in mouse embryonic stem (ES) cells. The IgH locus-derived YAC contains five variable (V{sub H}) genes, the major diversity (D) gene cluster, the joining (J{sub H}) genes, the intronic enhancer (E{sub H}), and the constant region genes, mu (C{mu}) and delta (C{delta}). Two IgK locus-derived YACs each contain three variable (V{kappa}) genes, the joining (J{kappa}) region, the intronic enhancer (E{kappa}), the constant gene (C{kappa}), and the kappa deleting element (kde). The IgH YAC was unstable in yeast, generating a variety of deletion derivatives, whereas both IgK YACs were stable. YACs encoding heavy chain and kappa light chain, retrofitted with the mammalian selectable marker, hypoxanthine phosphoribosyltransferase (HPRT), were each introduced into HPRT-deficient mouse ES cells. Analysis of YAC integrity in ES cell lines revealed that the majority of DNA inserts were integrated in substantially intact form. 78 refs., 7 figs.

Mendez, M.J.; Abderrahim, H.; Noguchi, M. [Cell Genesys, Inc., Foster City, CA (United States)] [and others] [Cell Genesys, Inc., Foster City, CA (United States); and others

1995-03-20

88

Acyclic nucleoside phosphonates containing a second phosphonate group are potent inhibitors of 6-oxopurine phosphoribosyltransferases and have antimalarial activity.  

PubMed

Acyclic nucleoside phosphonates (ANPs) that contain a 6-oxopurine base are good inhibitors of the Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) 6-oxopurine phosphoribosyltransferases (PRTs). Chemical modifications based on the crystal structure of 2-(phosphonoethoxy)ethylguanine (PEEG) in complex with human HGPRT have led to the design of new ANPs. These novel compounds contain a second phosphonate group attached to the ANP scaffold. {[(2-[(Guanine-9H-yl)methyl]propane-1,3-diyl)bis(oxy)]bis(methylene)}diphosphonic acid (compound 17) exhibited a Ki value of 30 nM for human HGPRT and 70 nM for Pf HGXPRT. The crystal structure of this compound in complex with human HGPRT shows that it fills or partially fills three critical locations in the active site: the binding sites of the purine base, the 5'-phosphate group, and pyrophosphate. This is the first HG(X)PRT inhibitor that has been able to achieve this result. Prodrugs have been synthesized resulting in IC50 values as low as 3.8 ?M for Pf grown in cell culture, up to 25-fold lower compared to the parent compounds. PMID:23448281

Keough, Dianne T; Špa?ek, Petr; Hocková, Dana; Tichý, Tomáš; Vrbková, Silvie; Slav?tínská, Lenka; Janeba, Zlatko; Naesens, Lieve; Edstein, Michael D; Chavchich, Marina; Wang, Tzu-Hsuan; de Jersey, John; Guddat, Luke W

2013-03-28

89

The Small Molecule GMX1778 Is a Potent Inhibitor of NAD+ Biosynthesis: Strategy for Enhanced Therapy in Nicotinic Acid Phosphoribosyltransferase 1-Deficient Tumors?  

PubMed Central

GMX1777 is a prodrug of the small molecule GMX1778, currently in phase I clinical trials for the treatment of cancer. We describe findings indicating that GMX1778 is a potent and specific inhibitor of the NAD+ biosynthesis enzyme nicotinamide phosphoribosyltransferase (NAMPT). Cancer cells have a very high rate of NAD+ turnover, which makes NAD+ modulation an attractive target for anticancer therapy. Selective inhibition by GMX1778 of NAMPT blocks the production of NAD+ and results in tumor cell death. Furthermore, GMX1778 is phosphoribosylated by NAMPT, which increases its cellular retention. The cytotoxicity of GMX1778 can be bypassed with exogenous nicotinic acid (NA), which permits NAD+ repletion via NA phosphoribosyltransferase 1 (NAPRT1). The cytotoxicity of GMX1778 in cells with NAPRT1 deficiency, however, cannot be rescued by NA. Analyses of NAPRT1 mRNA and protein levels in cell lines and primary tumor tissue indicate that high frequencies of glioblastomas, neuroblastomas, and sarcomas are deficient in NAPRT1 and not susceptible to rescue with NA. As a result, the therapeutic index of GMX1777 can be widended in the treatment animals bearing NAPRT1-deficient tumors by coadministration with NA. This provides the rationale for a novel therapeutic approach for the use of GMX1777 in the treatment of human cancers.

Watson, Mark; Roulston, Anne; Belec, Laurent; Billot, Xavier; Marcellus, Richard; Bedard, Dominique; Bernier, Cynthia; Branchaud, Stephane; Chan, Helen; Dairi, Kenza; Gilbert, Karine; Goulet, Daniel; Gratton, Michel-Olivier; Isakau, Henady; Jang, Anne; Khadir, Abdelkrim; Koch, Elizabeth; Lavoie, Manon; Lawless, Michael; Nguyen, Mai; Paquette, Denis; Turcotte, Emilie; Berger, Alvin; Mitchell, Matthew; Shore, Gordon C.; Beauparlant, Pierre

2009-01-01

90

Plasmodium falciparum: assessment of in vitro growth by (/sup 3/H)hypoxanthine incorporation  

SciTech Connect

To evaluate rapidly Plasmodium falciparum growth in Vitro, (/sup 3/H)hypoxanthine was added to parasite microcultures and radioisotope incorporation was measured. When culture parameters were carefully controlled, (/sup 3/H)hypoxanthine incorporation was proportional to the number of parasitized erythrocytes present. Factors affecting (/sup 3/H)hypoxanthine incorporation included initial parasitemia, duration of culture, duration of radioisotope pulse, parasite stage, concentration of uninfected erythrocytes, the use of serum or plasma to supplement growth, and the concentration of a variety of purines in the culture medium. The method described can be used to measure inhibition of P. falciparum growth by immune serum and has previously been used to study antimalarial drug activity in vitro.

Chulay, J.D.; Haynes, J.D.; Diggs, C.L.

1983-02-01

91

Assignment of the gene for adenine phosphoribosyltransferase on the genetic map of mouse chromosome 8  

Microsoft Academic Search

Two electrophoretic variants of adenine phosphoribosyltransferase (APRT) were identified in a population of wild mice (Mus musculus bactrianus). Breeding tests demonstrated that the APRT variants are under the control of two alleles at an autosomal locus designatedAprt. We have examined the linkage relationships betweenAprt and the markers of chromosome 8 including esterase-1 and the centromere. The recombination distance between the

T. B. Nesterova; P. M. Borodin; S. M. Zakian; O. L. Serov

1987-01-01

92

Validation of adequate endogenous reference genes for the normalisation of qPCR gene expression data in human post mortem tissue.  

PubMed

Gene expression analyses based on messenger RNA (mRNA) profiling require accurate data normalisation. When using endogenous reference genes, these have to be validated carefully. Therefore, we examined the transcript stability of 10 potential reference genes using quantitative real-time polymerase chain reaction: beta actin, 18S rRNA, glyceraldehyde-3-phosphate dehydrogenase, TATA box-binding protein, hypoxanthine phosphoribosyl-transferase I, beta-2-microglobulin, hydroxymethylbilane synthase, succinate dehydrogenase complex, subunit A, cyclophilin A and ubiquitin C. The aim of the current study was to assess which reference genes show stable mRNA levels in human post mortem cardiac muscle, skeletal muscle and brain tissue. Considering cardiac muscle tissue, CYCA and TBP were identified as the most stable while in skeletal muscle tissue, SDHA and TBP, and in brain tissue, SDHA and HMBS turned out to be the most stable. Furthermore, we recommend a minimum of four carefully validated endogenous control genes for reliable data normalisation in human post mortem tissue. Parameters influencing the stability of transcript amounts were found to be mainly the post mortem interval in cardiac muscle and skeletal muscle tissue and the donor's cause of death in skeletal muscle and brain samples. Further parameters like gender, age at death and body mass index were found to influence mRNA quantities in skeletal muscle only. The set of stable control genes identified in this study may be used in further studies if the composition of the samples is similar to the one used here. PMID:20300940

Koppelkamm, Antje; Vennemann, Benedikt; Fracasso, Tony; Lutz-Bonengel, Sabine; Schmidt, Ulrike; Heinrich, Marielle

2010-09-01

93

Guanine analog-induced differentiation of human promyelocytic leukemia cells and changes in queuine modification of tRNA.  

PubMed Central

Treatment of hypoxanthine-guanine phosphoribosyltransferase (HGPRT)-deficient human promyelocytic leukemia (HL-60) cells with 6-thioguanine results in growth inhibition and cell differentiation. 6-Thioguanine is a substrate for the tRNA modification enzyme tRNA-guanine ribosyltransferase, which normally catalyzes the exchange of queuine for guanine in position 1 of the anticodon of tRNAs for asparagine, aspartic acid, histidine, and tyrosine. During the early stages of HGPRT-deficient HL-60 cell differentiation induced by 6-thioguanine, there was a transient decrease in the queuine content of tRNA, and changes in the isoacceptor profiles of tRNA(His) indicate that 6-thioguanine was incorporated into the tRNA in place of queuine. Reversing this structural change in the tRNA anticodon by addition of excess exogenous queuine reversed the 6-thioguanine-induced growth inhibition and differentiation. Similar results were obtained when 8-azaguanine (another inhibitor of queuine modification of tRNA that can be incorporated into the anticodon) replaced 6-thioguanine as the inducing agent. The data suggest a primary role for the change in queuine modification of tRNA in mediating the differentiation of HGPRT-deficient HL-60 cells induced by guanine analogs.

Kretz, K A; Katze, J R; Trewyn, R W

1987-01-01

94

Validation of Reference Genes for Normalization Gene Expression in Reverse Transcription Quantitative PCR in Human Normal Thyroid and Goiter Tissue  

PubMed Central

Reverse transcription quantitative polymerase chain reaction (RT-qPCR) has been recognized as the most accurate method for quantifying mRNA transcripts, but normalization of samples is a prerequisite for correct data interpretation. So, this study aimed to evaluate the most stable reference gene for RT-qPCR in human normal thyroid and goiter tissues. Beta-actin (ACTB); glyceraldehyde-3-phosphate dehydrogenase (GAPDH); succinate dehydrogenase, subunit A, flavoprotein (Fp) (SDHA); hypoxanthine phosphoribosyltransferase I (HPRTI); tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide (YWHAZ); and beta-2-microglobulin (B2M) were evaluated in 14 thyroid tissue samples (7 normal and 7 goiter tissues) by RT-qPCR. The mean Cq and the maximum fold change (MFC) and NormFinder software were used to assess the stability of the genes. As a result, ACTB gene was more stable than GAPDH, SDHA, HPRTI, YWHAZ, and B2M. In conclusion, ACTB could be used to normalize RT-qPCR data in normal thyroid and goiter tissues.

Bertoni, Ana Paula Santin; Bessestil, Laura Walter; Brasil, Beatriz Maria de Azevedo Assis; Brum, llma Simoni; Furlanetto, Tania Weber

2014-01-01

95

Adenine phosphoribosyltransferase: a simple spectrophotometric assay and the incidence of mutation in the normal population.  

PubMed

The significance of partial deficiency of erythrocyte adenine phosphoribosyltransferase (APRT), reported in a number of subjects with gout, has been investigated by studying its incidence in 700 normal blood donors. Three clearly deficient subjects were found, an incidence not significantly different from that in patients with abnormalities of urate metabolism. A new assay method for APRT is described in which an erythrocyte lysate is incubated with adenine and phosphoribosylpyrophosphate (PRPP) for a given time; both hemoglobin and adenine nucleotide (AMP) are then precipitated with lanthanum phosphate; the change in absorbance of adenine at 260 nm reflects the extent of its conversion to AMP by APRT. PMID:869896

Johnson, L A; Gordon, R B; Emmerson, B T

1977-04-01

96

Thirdhand smoke causes DNA damage in human cells  

PubMed Central

Exposure to thirdhand smoke (THS) is a newly described health risk. Evidence supports its widespread presence in indoor environments. However, its genotoxic potential, a critical aspect in risk assessment, is virtually untested. An important characteristic of THS is its ability to undergo chemical transformations during aging periods, as demonstrated in a recent study showing that sorbed nicotine reacts with the indoor pollutant nitrous acid (HONO) to form tobacco-specific nitrosamines (TSNAs) such as 4-(methylnitrosamino)-4-(3-pyridyl)butanal (NNA) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). The goal of this study was to assess the genotoxicity of THS in human cell lines using two in vitro assays. THS was generated in laboratory systems that simulated short (acute)- and long (chronic)-term exposures. Analysis by liquid chromatography–tandem mass spectrometry quantified TSNAs and common tobacco alkaloids in extracts of THS that had sorbed onto cellulose substrates. Exposure of human HepG2 cells to either acute or chronic THS for 24h resulted in significant increases in DNA strand breaks in the alkaline Comet assay. Cell cultures exposed to NNA alone showed significantly higher levels of DNA damage in the same assay. NNA is absent in freshly emitted secondhand smoke, but it is the main TSNA formed in THS when nicotine reacts with HONO long after smoking takes place. The long amplicon–quantitative PCR assay quantified significantly higher levels of oxidative DNA damage in hypoxanthine phosphoribosyltransferase 1 (HPRT) and polymerase ? (POLB) genes of cultured human cells exposed to chronic THS for 24h compared with untreated cells, suggesting that THS exposure is related to increased oxidative stress and could be an important contributing factor in THS-mediated toxicity. The findings of this study demonstrate for the first time that exposure to THS is genotoxic in human cell lines.

Hang, Bo

2013-01-01

97

Thirdhand smoke causes DNA damage in human cells.  

PubMed

Exposure to thirdhand smoke (THS) is a newly described health risk. Evidence supports its widespread presence in indoor environments. However, its genotoxic potential, a critical aspect in risk assessment, is virtually untested. An important characteristic of THS is its ability to undergo chemical transformations during aging periods, as demonstrated in a recent study showing that sorbed nicotine reacts with the indoor pollutant nitrous acid (HONO) to form tobacco-specific nitrosamines (TSNAs) such as 4-(methylnitrosamino)-4-(3-pyridyl)butanal (NNA) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). The goal of this study was to assess the genotoxicity of THS in human cell lines using two in vitro assays. THS was generated in laboratory systems that simulated short (acute)- and long (chronic)-term exposures. Analysis by liquid chromatography-tandem mass spectrometry quantified TSNAs and common tobacco alkaloids in extracts of THS that had sorbed onto cellulose substrates. Exposure of human HepG2 cells to either acute or chronic THS for 24h resulted in significant increases in DNA strand breaks in the alkaline Comet assay. Cell cultures exposed to NNA alone showed significantly higher levels of DNA damage in the same assay. NNA is absent in freshly emitted secondhand smoke, but it is the main TSNA formed in THS when nicotine reacts with HONO long after smoking takes place. The long amplicon-quantitative PCR assay quantified significantly higher levels of oxidative DNA damage in hypoxanthine phosphoribosyltransferase 1 (HPRT) and polymerase ? (POLB) genes of cultured human cells exposed to chronic THS for 24h compared with untreated cells, suggesting that THS exposure is related to increased oxidative stress and could be an important contributing factor in THS-mediated toxicity. The findings of this study demonstrate for the first time that exposure to THS is genotoxic in human cell lines. PMID:23462851

Hang, Bo; Sarker, Altaf H; Havel, Christopher; Saha, Saikat; Hazra, Tapas K; Schick, Suzaynn; Jacob, Peyton; Rehan, Virender K; Chenna, Ahmed; Sharan, Divya; Sleiman, Mohamad; Destaillats, Hugo; Gundel, Lara A

2013-07-01

98

Partial hypoxanthine-guanine phosphoribosyl transferase deficiency with full expression of the Lesch-Nyhan syndrome  

Microsoft Academic Search

A patient with the full clinical expression of the classical Lesch-Nyhan syndrome is presented with a residual hypoxanthine-guanine phosphoribosyl transferase (HGPRT) activity of 5–10% in erythrocyte lysate and about 30% in fibroblast lysate. The activities of other erythrocyte enzymes of purine metabolism were typical for a classical Lesch-Nyhan patient. The effects of allopurinol therapy on the excretion of urinary purine

Gert Rijksen; Gerard E. J. Staal; Margreet J. M. van der Vlist; Frits A. Beemer; Jaap Troost; Wolf Gutensohn; Jan P. R. M. van Laarhoven; Chris H. M. M. de Bruyn

1981-01-01

99

Biocompatible phosphonic acid-functionalized silica nanoparticles for sensitive detection of hypoxanthine in real samples.  

PubMed

A novel hypoxanthine biosensor fabricated by immobilizing the xanthine oxidase (XOD) onto the phosphonic acid-functionalized silica (SiO2-P) film on the surface of glassy carbon electrode (GCE) was designed and constructed in this work. A biomimetic platform was designed with the phosphonic acid-functionalized silica nanoparticles (SiO2-P NPs) synthesized by the method of reverse microemulsion and electrostatic binding. In such a platform, XOD was selected as model protein to fabricate hypoxanthine biosensor based on SiO2-P NPs. The nanocomposite was characterized with transmission electron microscopy (TEM), energy dispersive X-ray spectrometer (EDS) and electrochemical impedance spectroscopy (EIS). Based on the advantageous functions of SiO2-P NPs, the entrapped XOD could preserve its bioactivity and exhibited an excellent electrochemical behavior with a formal potential of -0.37 V in phosphate buffer solution (PBS, pH=7). Response studies to hypoxanthine were carried out using current-time response curve. The biosensor exhibited a wide linear response ranging from 1.00×10(-6) to 2.61×10(-4) M. The detection limit of 2.33×10(-7) M at a signal-to-noise ratio of 3 was lower than that most reported previously. In addition, the electrode modified with XOD/(SiO2-P NPs) film also had a strong anti-interference ability in the presence of uric acid (UA) and ascorbic acid (AA). The assay results of hypoxanthine in fish samples were in a good agreement with the reference values. PMID:24209378

Liu, Min; Chen, Shanshan; Zhao, Xianzheng; Ye, Yuhang; Li, Juan; Zhu, Qinshu; Zhao, Bo; Zhao, Wenbo; Huang, Xiaohua; Shen, Jian

2013-12-15

100

Pulse radiolytic investigation of the hypoxanthine-xanthine-uric acid system: evidence for transient species  

SciTech Connect

The oxidation in aqueous solutions of hypoxanthine into xanthine and xanthine into uric acid by OH radicals has been investigated using pulse radiolysis and fast kinetic absorption spectrophotometry. After hypoxanthine irradiations the spectrum of transient R/sub 1/ has been characterized. This radical is formed with a rate constant k/sub (Hyx+OH) = 6.5 x 10/sup 9/ M/sup -1/ sec/sup -1/ and disappears by disproportionation leading to xanthine and hypoxanthine with a rate constant 2K/sub (R/sub 1/+ r/sub 1// = 1.3 x 10/sup 8/ M/sup -1/ sec/sup -//sub 1/. After xanthine irradiations a radical intermediate R/sub 2/ is formed with a rate constant k/sub(X+ OH)/= 5.2 x 10/sup 8/ M/sup -1/ sec/sup -1/ and disappears through a second-order reaction 2K/sub (R/sub 2/+ R/sub 2/)/ = 2.0 x 10/sup 8/ M/sup -1/ sec/sup -1/. Finally, after aeration only uric acid and xanthine are measured.

Santamaria, J.; Pasquier, C.; Ferradini, C.; Pucheault, J.

1984-03-01

101

Hypoxanthine induces oxidative stress in kidney of rats: protective effect of vitamins E plus C and allopurinol.  

PubMed

In the present study, we investigated the in vitro effect of hypoxanthine on the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase, as well as on thiobarbituric-acid-reactive substances (TBA-RS), in the renal cortex and medulla of rats. Results showed that hypoxanthine, at a concentration of 10.0??M, enhanced the activities of CAT and SOD in the renal cortex of 15-, 30- and 60-day-old rats, enhanced SOD activity in the renal medulla of 60-day-old rats and enhanced TBA-RS levels in the renal medulla of 30-day-old rats, as compared with controls. Furthermore, we also verified the influence of allopurinol (an inhibitor of xanthine oxidase), as well as of the antioxidants, trolox and ascorbic acid on the effects elicited by hypoxanthine on the parameters tested. Allopurinol and/or administration of antioxidants prevented most alterations caused by hypoxanthine in the oxidative stress parameters evaluated. Data suggest that hypoxanthine alters antioxidant defences and induces lipid peroxidation in the kidney of rats; however, in the presence of allopurinol and antioxidants, some of these alterations in oxidative stress were prevented. Our findings lend support to a potential therapeutic strategy for this condition, which may include the use of appropriate antioxidants for ameliorating the damage caused by hypoxanthine. PMID:24578313

Rodrigues, André F; Roecker, Roberto; Junges, Gustavo M; de Lima, Daniela Delwing; da Cruz, José G P; Wyse, Angela T S; Dal Magro, Débora Delwing

2014-06-01

102

Virtual Screening of Combinatorial Libraries across a Gene Family: in Search of Inhibitors of Giardia lamblia Guanine Phosphoribosyltransferase  

Microsoft Academic Search

Parasitic protozoa lack the ability to synthesize purine nucleotides de novo, relying instead on purine salvage enzymes for their survival. Guanine phosphoribosyltransferase (GPRT) from the protozoan parasite Giardia lamblia is a potential target for rational antiparasitic drug design, based on the experimental evidence, which indicates the lack of interconversion between adenine and guanine nucleotide pools. The present study is a

ALEX M. ARONOV; NARSIMHA R. MUNAGALA; IRWIN D. KUNTZ; CHING C. WANG

2001-01-01

103

Mutagenesis in human cells with accelerated H and Fe ions  

NASA Technical Reports Server (NTRS)

The overall goals of this research were to determine the risks of mutation induction and the spectra of mutations induced by energetic protons and iron ions at two loci in human lymphoid cells. During the three year grant period the research has focused in three major areas: (1) the acquisition of sufficient statistics for human TK6 cell mutation experiments using Fe ions (400 MeV/amu), Fe ions (600 MeV/amu) and protons (250 MeV/amu); (2) collection of thymidine kinase- deficient (tk) mutants or hypoxanthine phosphoribosyltransferase deficient (hprt) mutants induced by either Fe 400 MeV/amu, Fe 600 MeV/amu, or H 250 MeV/amu for subsequent molecular analysis; and (3) molecular characterization of mutants isolated after exposure to Fe ions (600 MeV/amu). As a result of the shutdown of the BEVALAC heavy ion accelerator in December 1992, efforts were rearranged somewhat in time to complete our dose-response studies and to complete mutant collections in particular for the Fe ion beams prior to the shutdown. These goals have been achieved. A major effort was placed on collection, re-screening, and archiving of 3 different series of mutants for the various particle beam exposures: tk-ng mutants, tk-sg mutants, and hprt-deficient mutants. Where possible, groups of mutants were isolated for several particle fluences. Comparative analysis of mutation spectra has occured with characterization of the mutation spectrum for hprt-deficient mutants obtained after exposure of TK6 cells to Fe ions (600 MeV/amu) and a series of spontaneous mutants.

Kronenberg, Amy

1994-01-01

104

Genetic Regulation of Charged Particle Mutagenesis in Human Cells  

NASA Technical Reports Server (NTRS)

Our studies use a series of syngeneic, and where possible, isogenic human B-lymphoblastoid cell lines to assess the genetic factors that modulate susceptibility apoptosis and their impact on the mutagenic risks of low fluence exposures to 1 GeV Fe ions and 55 MeV protons. These ions are representative of the types of charged particle radiation that are of particular significance for human health in the space radiation environment. The model system employs cell lines derived from the male donor WIL-2. These cells have a single X chromosome and they are hemizygous for one mutation marker, hypoxanthine phosphoribosyltransferase (HPRT). TK6 and WTK1 cells were each derived from descendants of WIL-2 and were each selected as heterozygotes for a second mutation marker, the thymidine kinase (TK) gene located on chromosome 17q. The HPRT and TK loci can detect many different types of mutations, from single basepair substitutions up to large scale loss of heterozygosity (LOH). The single expressing copy of TK in the TK6 and WTKI cell lines is found on the same copy of chromosome 17, and this allele can be identified by a restriction fragment length polymorphism (RFLP) identified when high molecular weight DNA is digested by the SacI restriction endonuclease and hybridized against the cDNA probe for TK. A large series of polymorphic linked markers has been identified that span more than 60 cM of DNA (approx. 60 megabasepairs) and distinguish the copy of chromosome 17 bearing the initially active TK allele from the copy of chromosome 17 bearing the silent TK allele in both TK6 and WTKI cells. TK6 cells express normal p53 protein while WTKI cells express homozygous mutant p53. Expression of mutant p53 can increase susceptibility to x-ray-induced mutations. It's been suggested that the increased mutagenesis in p53 mutant cells might be due to reduced apoptosis.

Kronenberg, Amy; Gauny, S.; Cherbonnel-Lasserre, C.; Liu, W.; Wiese, C.

1999-01-01

105

Discovery of potent and efficacious cyanoguanidine-containing nicotinamide phosphoribosyltransferase (Nampt) inhibitors.  

PubMed

A co-crystal structure of amide-containing compound (4) in complex with the nicotinamide phosphoribosyltransferase (Nampt) protein and molecular modeling were utilized to design and discover a potent novel cyanoguanidine-containing inhibitor bearing a sulfone moiety (5, Nampt Biochemical IC50=2.5nM, A2780 cell proliferation IC50=9.7nM). Further SAR exploration identified several additional cyanoguanidine-containing compounds with high potency and good microsomal stability. Among these, compound 15 was selected for in vivo profiling and demonstrated good oral exposure in mice. It also exhibited excellent in vivo antitumor efficacy when dosed orally in an A2780 ovarian tumor xenograft model. The co-crystal structure of this compound in complex with the NAMPT protein was also determined. PMID:24279990

Zheng, Xiaozhang; Baumeister, Timm; Buckmelter, Alexandre J; Caligiuri, Maureen; Clodfelter, Karl H; Han, Bingsong; Ho, Yen-Ching; Kley, Nikolai; Lin, Jian; Reynolds, Dominic J; Sharma, Geeta; Smith, Chase C; Wang, Zhongguo; Dragovich, Peter S; Oh, Angela; Wang, Weiru; Zak, Mark; Wang, Yunli; Yuen, Po-Wai; Bair, Kenneth W

2014-01-01

106

Purine Phosphoribosyl Transferases in Human Hair Roots  

Microsoft Academic Search

A method is presented for the simultaneous measurement of the two enzymes involved in purine salvage in human hair roots. Km values of hypoxanthine-guanine phosphoribosyl transferase (HG-PRT) for hypoxanthine and 5?-phosphoribosyl-1-pyrophosphate (PRPP) and of adenine phosphoribosyl transferase (A-PRT) for adenine and PRPP in human hair roots were similar to values reported for human erythrocytes. No differences were observed between hair

C. H. M. M. de Bruyn; T. L. Oei

1974-01-01

107

Somatic cell gene mutations in humans: biomarkers for genotoxicity.  

PubMed Central

Somatic cell gene mutations arising in vivo in humans provide biomarkers for genotoxicity. Four assays, each measuring changes in a different "recorder" gene, are available for detecting mutations of the hemoglobin (Hb) and glycophorin A (gpa) genes in red blood cells and the hypoxanthine-guanine phosphoribosyltransferase (hprt) and HLA genes in T-lymphocytes. Mean adult background mutant frequencies have been established; i.e., approximately 4 x 10(-8) (Hb), 5-10 x 10(-6) (hprt), 10-20 x 10(-6) (gpa) and 30 x 10(-6) (HLA). All the assays have now been used in studies of individuals exposed to physical and/or chemical genotoxic agents, and all have shown elevated values following exposures; examples are presented. In addition to quantitation, the lymphocyte assays allow molecular analyses of in vivo mutations, the definition of background and induced mutational spectra, and the search for unique changes for characterizing specific mutagens. The HPRT system currently has the largest database in this regard. Approximately 15% of adult background hprt mutations are due to gross structural alterations (primarily deletions) having random breakpoints; 85% result from "point" changes detected only by sequencing. In contrast, a specific intragenic deletion due to DNA cleavage at specific sites characterizes fetal hprt mutations, implicating a developmental mistake in their genesis. (This kind of developmental mistake in other genes is frequently observed in lymphoid malignancies.) Mutational spectra are just beginning to be defined for induced hprt mutations, e.g., ionizing radiation produces large deletions.(ABSTRACT TRUNCATED AT 250 WORDS)

Albertini, R J; Nicklas, J A; O'Neill, J P

1993-01-01

108

Functional characterization of a gene encoding a dual domain for uridine kinase and uracil phosphoribosyltransferase in Arabidopsis thaliana  

Microsoft Academic Search

Uridine kinase (UK) and uracil phosphoribosyltransferase (UPRT) are enzymes catalyzing the formation of uridine 5?-monophosphate\\u000a (UMP) from uridine and adenine 5?-triphosphate (ATP) and from uracil and phosphoribosyl-?-1-pyrophosphate (PRPP), respectively, in the pyrimidine salvage pathway. Here, we report the characterization and functional\\u000a analysis of a gene AtUK\\/UPRT1 from Arabidopsis thaliana. Sequencing of an expressed sequence tag clone of this gene revealed

M. Rafiqul Islam; Hoyeun Kim; Shin-Wook Kang; Jung-Sup Kim; Young-Min Jeong; Hyun-Ju Hwang; So-Young Lee; Je-Chang Woo; Sang-Gu Kim

2007-01-01

109

Interallelic complementation at the pyrF locus and the homodimeric nature of orotate phosphoribosyltransferase (OPRTase) in Mucor circinelloides  

Microsoft Academic Search

Using 5-fluoroorotic acid (5-FOA) as a positive selection system we isolated mutants of Mucor circinelloides altered in the pyrimidine biosynthetic pathway. These mutants were found to be deficient either in orotidine-5?-monophosphate\\u000a decarboxylase (OMPdecase), or in orotate phosphoribosyltransferase (OPRTase) activity. Complementation tests among mutants\\u000a lacking OPRTase activity classified them into three groups, thus suggesting the possibility of interallelic complementation.\\u000a To investigate

A. Velayos; M. I. Alvarez; A. P. Eslava; E. A. Iturriaga

1998-01-01

110

Validation of adequate endogenous reference genes for the normalisation of qPCR gene expression data in human post mortem tissue  

Microsoft Academic Search

Gene expression analyses based on messenger RNA (mRNA) profiling require accurate data normalisation. When using endogenous\\u000a reference genes, these have to be validated carefully. Therefore, we examined the transcript stability of 10 potential reference\\u000a genes using quantitative real-time polymerase chain reaction: beta actin, 18S rRNA, glyceraldehyde-3-phosphate dehydrogenase,\\u000a TATA box-binding protein, hypoxanthine phosphoribosyl-transferase I, beta-2-microglobulin, hydroxymethylbilane synthase, succinate\\u000a dehydrogenase complex, subunit

Antje Koppelkamm; Benedikt Vennemann; Tony Fracasso; Sabine Lutz-Bonengel; Ulrike Schmidt; Marielle Heinrich

2010-01-01

111

Structure-based discovery of novel amide-containing nicotinamide phosphoribosyltransferase (nampt) inhibitors.  

PubMed

Crystal structures of several urea- and thiourea-derived compounds in complex with the nicotinamide phosphoribosyltransferase (Nampt) protein were utilized to design a potent amide-containing inhibitor bearing an aza-indole moiety (7, Nampt BC IC50 = 9.0 nM, A2780 cell proliferation IC50 = 10 nM). The Nampt-7 cocrystal structure was subsequently obtained and enabled the design of additional amide-containing inhibitors which incorporated various other fused 6,5-heterocyclic moieties and biaryl sulfone or sulfonamide motifs. Additional modifications of these molecules afforded many potent biaryl sulfone-containing Nampt inhibitors which also exhibited favorable in vitro ADME properties (microsomal and hepatocyte stability, MDCK permeability, plasma protein binding). An optimized compound (58) was a potent inhibitor of multiple cancer cell lines (IC50 <10 nM vs U251, HT1080, PC3, MiaPaCa2, and HCT116 lines), displayed acceptable mouse PK properties (F = 41%, CL = 52.4 mL/min/kg), and exhibited robust efficacy in a U251 mouse xenograft model. PMID:23859118

Zheng, Xiaozhang; Bauer, Paul; Baumeister, Timm; Buckmelter, Alexandre J; Caligiuri, Maureen; Clodfelter, Karl H; Han, Bingsong; Ho, Yen-Ching; Kley, Nikolai; Lin, Jian; Reynolds, Dominic J; Sharma, Geeta; Smith, Chase C; Wang, Zhongguo; Dragovich, Peter S; Gunzner-Toste, Janet; Liederer, Bianca M; Ly, Justin; O'Brien, Thomas; Oh, Angela; Wang, Leslie; Wang, Weiru; Xiao, Yang; Zak, Mark; Zhao, Guiling; Yuen, Po-Wai; Bair, Kenneth W

2013-08-22

112

Intrauterine exposure to cocaine increased plasma ANP (atrial natriuretic peptide) but did not alter hypoxanthine concentrations in the sheep fetus  

Microsoft Academic Search

To assess the effects of cocaine, administered to the ewe, on the secretion of atrial natriuretic peptide (ANP), Plasma Renin Activity (PRA) and hypoxanthine in the fetus we studied 6 chronically cannulated sheep fetuses late in gestation. The ewe was given an intravenous injection of cocaine (2 mg\\/kg). Maternal and fetal arterial blood samples were withdrawn prior to the injection

Barbara Hargrave; Manford C. Castle

1995-01-01

113

Determination of Xanthine in the Presence of Hypoxanthine by Adsorptive Stripping Voltammetry at the Mercury Film Electrode  

PubMed Central

A stripping method for the determination of xanthine in the presence of hypoxanthine at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10?3 mol L?1 NaOH solution as supporting electrolyte, an accumulation potential of 0.00 V for xanthine and ?0.50 V for hypoxanthine–copper, and a linear scan rate of 200 mV second?1. The response of xanthine is linear over the concentration ranges of 20–140 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 36 ppt (2.3 × 10?10 mol L?1). Adequate conditions for measuring the xanthine in the presence of hypoxanthine, copper and other metals, uric acid, and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of xanthine associated with hypoxanthine, uric acid, nitrogenated bases, ATP, and ssDNA.

Farias, Percio Augusto Mardini; Castro, Arnaldo Aguiar

2014-01-01

114

Regional gene assignment of human porphobilinogen deaminase and esterase A4 to chromosome 11q23 leads to 11qter.  

PubMed Central

The regional gene assignments for human porphobilinogen deaminase (PBGD; EC 4.3.1.8) and esterase A4 (ESA4; EC3.1.1.1) chromosome 11 have been determined with somatic cell hybridization and immunologic, electrophoretic, and cytogenetic techniques. Dimethyl sulfoxide-induced erythroid differentiation of hybrid clones derived from the fusion of tetraploid Friend murine erythroleukemia (2S MEL) cells deficient in thymidine kinase and human Lesch--Nyhan fibroblasts (HLN) deficient in hypoxanthine phosphoribosyltransferase (HPRT-; EC 2.4.2.8) were examined for expression of human PBGD, ESA4, and lactate dehydrogenase A (LDHA; EC 1.1.1.27). Human PBGD was detected by rocket immunoelectrophoresis with rabbit anti-human PBGD IgG and by isoelectric focusing. The human chromosome complement of each clone was determined by cytogenetic and enzyme marker analyses. Of the five primary 2S MEL--HLN clones examined, three were positive for human PBGD. These were subcloned to yield a total of 10 secondary, tertiary, or quaternary clones. Analyses of these subclones permitted the regional assignment of human PBGD and ESA4 to the long arm of chromosome 11. Finer regional assignment of the loci for human PBGD and ESA4 was facilitated when two 2S MEL (HPRT-)--human fibroblast (HX/11) hybrids, each containing the X chromosome--autosome translocation (der11), t(X;11)(q25-26;q23) as the only human chromosome, were examined for expression of human PBGD, ESA4, and LDHA. One clone, HX/11-2, contained the intact X/11 translocated chromosome; in the other, HX/11-3, 11p was deleted, and the human X/11 derivative was translocated onto a mouse chromosome. HX/11-2 expressed human LDHA, but HX/11-3 did not, verifying that the latter human 11/X derivative did not include 11pter leads to 11p12; PBGD and ESA4 were not detected in either hybrid. These results confirm the location of the gene for human PBGD on chromosome 11 and establish the assignment of the loci for PBGD and ESA4 in the region 11q23 leads to 11qter. Images

Wang, A L; Arredondo-Vega, F X; Giampietro, P F; Smith, M; Anderson, W F; Desnick, R J

1981-01-01

115

Adenine phosphoribosyltransferase deficiency: its inheritance and occurrence in a female with gout and renal disease.  

PubMed

A deficiency of adenine phosphoribosyltransferase (APRT) enzyme activity to approximately 40% of normal has been found in erythrocytes from a young woman aged 24 years, who had suffered from recurrent gouty arthritis since 11 years of age. She also demonstrated considerable, although asymptomatic, renal impairment with a creatinine clearance of one-third normal. Her father had suffered from gouty arthritis but had a normal APRT activity; he was obese, had a high purine intake and was a regular beer drinker. The patient's mother was asymptomatic with a normal serum urate concentration, but demonstrated a similar reduction in APRT activity to that of her daughter. Eleven other asymptomatic members of the family also demonstrated a similar reduction in APRT activity in erythrocyte lysates. The pattern of inheritance was consistent with autosomal transmission. Concentrations of phosphoribosylpyrophospate (PRPP) in erythrocytes were within normal limits both in the subjects with deficient, and in those with normal, APRT activity. Partial purification of APRT enzyme from erythrocytes of the index case did not reveal any difference from the normal enzyme as far as Michaelis constants, heat stability, or mobility in polyacrylamide gel was concerned. No primary abnormality of lipoprotein metabolism was demonstrated either in the propositus or in other members of her family. Study of urate metabolism in the propositus indicated that, although urate production was within the normal range in absolute terms, there was increased incorporation of glycine into produced urate, usually taken as one index of de novo urate production. Impaired renal excretion of urate was also shown. Although detailed study of urate metabolism has not been undertaken in other family members with APRT deficiency, no conclusive relationship has yet been demonstrated between APRT deficiency and disordered urate metabolism. PMID:1061547

Emmerson, B T; Gordon, R B; Thompson, L

1975-10-01

116

Nicotinamide phosphoribosyltransferase inhibition reduces intraplaque CXCL1 production and associated neutrophil infiltration in atherosclerotic mice.  

PubMed

Pharmacological treatments targeting CXC chemokines and the associated neutrophil activation and recruitment into atherosclerotic plaques hold promise for treating cardiovascular disorders. Therefore, we investigated whether FK866, a nicotinamide phosphoribosyltransferase (NAMPT) inhibitor with anti-inflammatory properties that we recently found to reduce neutrophil recruitment into the ischaemic myocardium, would exert beneficial effects in a mouse atherosclerosis model. Atherosclerotic plaque formation was induced by carotid cast implantation in ApoE-/- mice that were fed with a Western-type diet. FK866 or vehicle were administrated intraperitoneally from week 8 until week 11 of the diet. Treatment with FK866 reduced neutrophil infiltration and MMP-9 content and increased collagen levels in atherosclerotic plaques compared to vehicle. No effect on other histological parameters, including intraplaque lipids or macrophages, was observed. These findings were associated with a reduction in both systemic and intraplaque CXCL1 levels in FK866-treated mice. In vitro, FK866 did not affect MMP-9 release by neutrophils, but it strongly reduced CXCL1 production by endothelial cells which, in the in vivo model, were identified as a main CXCL1 source at the plaque level. CXCL1 synthesis inhibition by FK866 appears to reflect interference with nuclear factor-?B signalling as shown by reduced p65 nuclear levels in endothelial cells pre-treated with FK866. In conclusion, pharmacological inhibition of NAMPT activity mitigates inflammation in atherosclerotic plaques by reducing CXCL1-mediated activities on neutrophils. These results support further assessments of NAMPT inhibitors for the potential prevention of plaque vulnerability. PMID:24196571

Nencioni, Alessio; da Silva, Rafaela F; Fraga-Silva, Rodrigo A; Steffens, Sabine; Fabre, Mathias; Bauer, Inga; Caffa, Irene; Magnone, Mirko; Sociali, Giovanna; Quercioli, Alessandra; Pelli, Graziano; Lenglet, Sébastien; Galan, Katia; Burger, Fabienne; Vázquez Calvo, Sara; Bertolotto, Maria; Bruzzone, Santina; Ballestrero, Alberto; Patrone, Franco; Dallegri, Franco; Santos, Robson A; Stergiopulos, Nikolaos; Mach, François; Vuilleumier, Nicolas; Montecucco, Fabrizio

2014-02-01

117

Leaving group activation and pyrophosphate ionic state at the catalytic site of Plasmodium falciparum orotate phosphoribosyltransferase.  

PubMed

Plasmodium falciparum orotate phosphoribosyltransferase (PfOPRT) catalyzes the reversible pyrophosphorolysis of orotidine 5'-monophosphate (OMP). Transition-state analysis from kinetic isotope effects supports a dianionic orotic acid (OA) leaving group. Isotope-edited Fourier transform infrared (FTIR) spectrometry complemented by homology modeling and quantum chemical calculations were used to characterize the orotate hydrogen-bond network for PfOPRT. Bond stretch frequencies for C(2)?O and C(4)?O of OMP were established from (13)C-edited FTIR difference spectra. Both frequencies were shifted downward by 20 cm(-1) upon formation of the Michaelis complex. Hydrogen-bond interactions to the orotate moiety induce strong leaving group polarization by ground-state destabilization. The C(2)?O bond is 2.7 Å from two conserved water molecules, and the C(4)?O bond is within 2.4 Å of the NH(2)(?) of Arg241 and the peptide NH of Phe97. Relative to free OMP, the N1 atom of PfOPRT-bound OMP indicates a ?pK(a) of -4.6. The decreased basicity of N1 supports leaving group activation through a hydrogen-bond network at the PfOPRT active site. PfOPRT in complex with (18)O-PPi and a proposed transition-state analogue revealed a trianionic PPi nucleophile with no significant P··O bond polarization, supporting a mechanism proceeding through the migration of the ribocation toward the PPi. These results along with previous PfOPRT transition-state analyses provide reaction coordinate information for the PfOPRT-catalyzed OMP pyrophosphorolysis reaction. PMID:21067187

Zhang, Yong; Deng, Hua; Schramm, Vern L

2010-12-01

118

Identification of Suitable Reference Genes for Real-Time PCR Analysis of Statin-Treated Human Umbilical Vein Endothelial Cells  

PubMed Central

Proper data normalization in quantitative real-time reverse-transcription polymerase chain reaction (RT-qPCR) is of critical importance for reliable mRNA expression analysis. Due to a diversity in putative reference genes expression stability in different in vitro models, a validation of an internal control gene should be made for each particular tissue or cell type and every specific experimental design. A few approaches have been proposed for reference gene selection, including pair-wise comparison approach and model-based approach. In this article we have assessed the expression stability of eight putative reference genes: ACTB, B2M, GADD45A, GAPDH, HPRT1, PES1, PSMC4, YWHAZ, in human umbilical vein endothelial cells (HUVEC) treated with different statins and with TNF-?. The analysis was performed with three reference gene validation programs: geNorm, NormFinder and BestKeeper. We have shown that hypoxanthine phosphoribosyltransferase 1 gene (HPRT1) and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide gene (YWHAZ) are the most stably expressed genes among the analyzed ones. Furthermore, our results show that ?-actin gene (ACTB) is downregulated by statins and thus should not be used as a normalizing gene in a discussed experimental setup. A ranking of candidate reference genes stability values is provided and might serve as a valuable guide for future gene expression studies in endothelial cells. This is the first report on reference gene selection for RT-qPCR applications in statin-treated HUVEC model.

Zyzynska-Granica, Barbara; Koziak, Katarzyna

2012-01-01

119

Virtual screening of combinatorial libraries across a gene family: in search of inhibitors of Giardia lamblia guanine phosphoribosyltransferase.  

PubMed

Parasitic protozoa lack the ability to synthesize purine nucleotides de novo, relying instead on purine salvage enzymes for their survival. Guanine phosphoribosyltransferase (GPRT) from the protozoan parasite Giardia lamblia is a potential target for rational antiparasitic drug design, based on the experimental evidence, which indicates the lack of interconversion between adenine and guanine nucleotide pools. The present study is a continuation of our efforts to use three-dimensional structures of parasitic phosphoribosyltransferases (PRTs) to design novel antiparasitic agents. Two micromolar phthalimide-based GPRT inhibitors were identified by screening the in-house phthalimide library. A combination of structure-based scaffold selection using virtual library screening across the PRT gene family and solid phase library synthesis led to identification of smaller (molecular weight, <300) ligands with moderate to low specificity for GPRT; the best inhibitors, GP3 and GP5, had K(i) values in the 23 to 25 microM range. These results represent significant progress toward the goal of designing potent inhibitors of purine salvage in Giardia parasites. As a second step in this process, altering the phthalimide moiety to optimize interactions in the guanine-binding pocket of GPRT is expected to lead to compounds with promising activity against G. lamblia PRT. PMID:11502531

Aronov, A M; Munagala, N R; Kuntz, I D; Wang, C C

2001-09-01

120

Substrate Orientation and Catalytic Specificity in the Action of Xanthine Oxidase: The Sequential Hydroxylation of Hypoxanthine to Uric Acid  

SciTech Connect

Xanthine oxidase is a molybdenum-containing enzyme catalyzing the hydroxylation of a sp{sup 2}-hybridized carbon in a broad range of aromatic heterocycles and aldehydes. Crystal structures of the bovine enzyme in complex with the physiological substrate hypoxanthine at 1.8 {angstrom} resolution and the chemotherapeutic agent 6-mercaptopurine at 2.6 {angstrom} resolution have been determined, showing in each case two alternate orientations of substrate in the two active sites of the crystallographic asymmetric unit. One orientation is such that it is expected to yield hydroxylation at C-2 of substrate, yielding xanthine. The other suggests hydroxylation at C-8 to give 6,8-dihydroxypurine, a putative product not previously thought to be generated by the enzyme. Kinetic experiments demonstrate that >98% of hypoxanthine is hydroxylated at C-2 rather than C-8, indicating that the second crystallographically observed orientation is significantly less catalytically effective than the former. Theoretical calculations suggest that enzyme selectivity for the C-2 over C-8 of hypoxanthine is largely due to differences in the intrinsic reactivity of the two sites. For the orientation of hypoxanthine with C-2 proximal to the molybdenum center, the disposition of substrate in the active site is such that Arg880 and Glu802, previous shown to be catalytically important for the conversion of xanthine to uric acid, play similar roles in hydroxylation at C-2 as at C-8. Contrary to the literature, we find that 6,8-dihydroxypurine is effectively converted to uric acid by xanthine oxidase.

Cao, Hongnan; Pauff, James M.; Hille, Russ (UCR)

2010-11-29

121

Analysis of Kinetics of Dihydroethidium Fluorescence with Superoxide Using Xanthine Oxidase and Hypoxanthine Assay  

PubMed Central

Superoxide (O2?) is an important reactive oxygen species (ROS), and has an essential role in physiology and pathophysiology. An accurate detection of O2? is needed to better understand numerous vascular pathologies. In this study, we performed a mechanistic study by using the xanthine oxidase (XOD)/hypoxanthine (HX) assay for O2? generation and a O2? sensitive fluorescent dye dihydroethidium (DHE) for O2? measurement. To quantify O2? and DHE interactions, we measured fluorescence using a microplate reader. We conducted a detailed reaction kinetic analysis for DHE–O2? interaction to understand the effect of O2? self-dismutation and to quantify DHE–O2? reaction rate. Fluorescence of DHE and 2-hydroethidium (EOH), a product of DHE and O2? interaction, were dependent on reaction conditions. Kinetic analysis resulted in a reaction rate constant of 2.169±0.059×103 M?1s?1 for DHE-O2? reaction that is ~ 100× slower than the reported value of 2.6±0.6×105 M?1s?1. In addition, the O2? self-dismutation has significant effect on DHE-O2? interaction. A slower reaction rate of DHE with O2? is more reasonable for O2? measurements. In this manner, the DHE is not competing with superoxide dismutase and NO for O2?. Results suggest that an accurate measurement of O2? production rate may be difficult due to competitive interference for many factors; however O2? concentration may be quantified.

Chen, Juan; Rogers, Steven C.; Kavdia, Mahendra

2012-01-01

122

Effect of excision repair by diploid human fibroblasts on the kinds and locations of mutations induced by (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene in the coding region of the HPRT gene.  

PubMed Central

(+/-)-7 beta,8 alpha-Dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (BPDE) is a direct-acting carcinogen that forms DNA adducts only with purines, predominantly (greater than 95%) with guanine. To investigate the effect of nucleotide excision repair on the kinds and locations (spectra) of mutations induced in diploid human fibroblasts by BPDE, we synchronized cells and exposed them to BPDE either at the beginning of S phase just when the target gene hypoxanthine (guanine) phosphoribosyltransferase (HPRT) is replicated or 12 hr prior to the beginning of S phase (early G1 phase). Clones resistant to 6-thioguanine were isolated, and the mRNA in lysates of 100-500 cells from each mutant clone was used to synthesize cDNA. HPRT cDNA was amplified 10(11)-fold by the polymerase chain reaction and then sequenced directly. The mutants derived from the two populations did not differ in the kinds of mutations; 19/20 of the base substitutions in cells taken from S phase and 19/19 of those from G1 phase involved G.C base pairs, predominantly G.C----T.A. However, they differed significantly in the distribution of the mutations in the coding region of the gene. In the cells from G1 phase, 29% of the mutations were clustered within a unique run of six guanine bases; in the S-phase cells, only 4% were located there. Assuming that the premutagenic BPDE-induced lesions involved purines, in the cells treated at the beginning of S phase, 24% of these lesions were located in the transcribed strand, whereas in the G1-treated cells, none were. This suggests that in the HPRT gene of diploid human cells excision repair of BPDE adducts occurs preferentially on the transcribed strand.

Chen, R H; Maher, V M; McCormick, J J

1990-01-01

123

Partial and complete adenine phosphoribosyltransferase deficiency associated with 2,8-dihydroxyadenine urolithiasis: kinetic and immunochemical properties of APRT.  

PubMed

We have studied adenine phosphoribosyltransferase (APRT) in the hemolysates from the families of 2,8-dihydroxyadenine urolithiasis associated with partial deficiency of APRT (the Japanese type) and complete deficiency of APRT (the null type). The APRT in the control subjects was found to be heat-stable at the physiological concentration of phosphoribosylpyrophosphate (PRPP), which was close to the value of its Km for PRPP. The APRT in the Japanese type showed 10 times higher Km values for PRPP and needed a comparably increased level of PRPP for stability in vitro. No change in red cell PRPP was found in the Japanese type of APRT deficiency. The content of APRT enzyme protein was decreased in the hemolysates of the Japanese type, probably due to its lability at the level of PRPP present in the cells. The heterozygote of the null type also had labile enzyme molecules at the physiological PRPP concentration. PMID:2440671

Abe, S; Hayasaka, K; Narisawa, K; Tada, K; Okada, G; Koyama, H; Kurosu, S; Kudoh, M; Matsushita, K

1987-01-01

124

Simultaneous determination of uric acid, xanthine and hypoxanthine at poly(pyrocatechol violet)/functionalized multi-walled carbon nanotubes composite film modified electrode.  

PubMed

A sensitive and selective electrochemical method was developed for simultaneous determination of uric acid (UA), xanthine (XA) and hypoxanthine (HX) based on a poly (pyrocatechol violet)/carboxyl functionalized multi-walled carbon nanotubes composite film modified electrode. The preparation and basic electrochemical performance of the novel composite film modified glassy carbon electrode were investigated in details. The electrochemical behaviors of UA, XA and HX at the modified electrode were studied by cyclic voltammetry. The results showed that this new electrochemical sensor exhibited excellent electrocatalytic activity towards the oxidation of the three analytes. The mechanism of catalysis was discussed. The anodic peaks of the three species were well defined with lowered oxidation potential and enhanced oxidation peak currents, so the modified electrode was used for simultaneous voltammetric measurement of UA, XA and HX by differential pulse voltammetry. Under the optimum conditions, the detection limits were 0.16 ?mol L(-1) for UA, 0.05 ?mol L(-1) for XA and 0.20 ?mol L(-1) for HX, respectively (S/N of 3). The proposed method has been successfully applied to simultaneous determination of UA, XA and HX in human serum samples. PMID:21856133

Wang, Yan

2011-12-01

125

Functional characterization of a gene encoding a dual domain for uridine kinase and uracil phosphoribosyltransferase in Arabidopsis thaliana.  

PubMed

Uridine kinase (UK) and uracil phosphoribosyltransferase (UPRT) are enzymes catalyzing the formation of uridine 5'-monophosphate (UMP) from uridine and adenine 5'-triphosphate (ATP) and from uracil and phosphoribosyl-alpha-l-pyrophosphate (PRPP), respectively, in the pyrimidine salvage pathway. Here, we report the characterization and functional analysis of a gene AtUK/UPRT1 from Arabidopsis thaliana. Sequencing of an expressed sequence tag clone of this gene revealed that it contains a full-length open reading frame of 1461 nucleotides and encodes a protein with a molecular mass of approximately 53 kDa. The sequence analysis revealed that the N-terminal region of AtUK/UPRT1 contains a UK domain and the C-terminal region consists of a UPRT domain. Expression of AtUK/UPRT1 in upp and upp-udk mutants of Escherichia coli supplied with 5-fluorouracil (5-FU) and 5-fluorouridine (5-FD) led to growth inhibition. Identical results were obtained with 5-FD and 5-FU treatments when the UK and UPRT domains were separated by the introduction of translation initiation and stop codons prior to complementation into the upp-udk and upp mutants. These results suggest that the AtUK/UPRT1 product can use uracil and uridine as substrates for the production of UMP. We also investigated the function of AtUK/UPRT1 in an Arabidopsis mutant. The wild-type Arabidopsis plants showed drastic growth retardation when they were treated with 5-FU and 5-FD while the growth of atuk/uprtl mutant plants was not significantly affected. These findings confirm that AtUK/UPRT1 has a dual role in coding for both uridine kinase and uracil phosphoribosyltransferase that form UMP through the pyrimidine salvage pathway in Arabidopsis. PMID:17143579

Islam, M Rafiqul; Kim, Hoyeun; Kang, Shin-Wook; Kim, Jung-Sup; Jeong, Young-Min; Hwang, Hyun-Ju; Lee, So-Young; Woo, Je-Chang; Kim, Sang-Gu

2007-03-01

126

Analysis of abnormalities in purine metabolism leading to gout and to neurological dysfunctions in man.  

PubMed Central

A modelling approach is used to analyse diseases associated with purine metabolism in man. The specific focus is on deficiencies in two enzymes, hypoxanthine:guanine phosphoribosyltransferase and adenylosuccinate lyase. These deficiencies can lead to a number of symptoms, including neurological dysfunctions and mental retardation. Although the biochemical mechanisms of dysfunctions associated with adenylosuccinate lyase deficiency are not completely understood, there is at least general agreement in the literature about possible causes. Simulations with our model confirm that accumulation of the two substrates of the enzyme can lead to significant biochemical imbalance. In hypoxanthine:guanine phosphoribosyltransferase deficiency the biochemical mechanisms associated with neurological dysfunctions are less clear. Model analyses support some old hypotheses but also suggest new indicators for possible causes of neurological dysfunctions associated with this deficiency. Hypoxanthine:guanine phosphoribosyltransferase deficiency is known to cause hyperuricaemia and gout. We compare the relative importance of this deficiency with other known causes of gout in humans. The analysis suggests that defects in the excretion of uric acid are more consequential than defects in uric acid synthesis such as hypoxanthine:guanine phosphoribosyltransferase deficiency.

Curto, R; Voit, E O; Cascante, M

1998-01-01

127

[Effect of intraventricular injection of somatostatin on pain threshold, and contents of the monoamines, xanthine, hypoxanthine in rats brain].  

PubMed

Using HPLC with electrochemical detection, we found that icv somatostatin (Som) 5 or 10 micrograms increased rat's pain threshold and contents of 5-HT and 5-HIAA in hippocampus, hypothalamus and brainstem, except the 5-HIAA content of brainstem in Som 5 micrograms group. However, the changes of NE among above three areas of brain were different, the NE contents of hypothalamus and brainstem significantly increased while that of hippocampus markedly decreased. After icv Som 20 micrograms, hypoxanthine and xanthine in hippocampus and hypothalamus decreased significantly, but encephaledema occurred. Som 40 micrograms icv caused necrotic changes of neurons in brain. PMID:1688090

Li, X C; Li, H D; Zhao, B Y; Huan, H Z

1991-11-01

128

Highly sensitive electrocatalytic biosensing of hypoxanthine based on functionalization of graphene sheets with water-soluble conducting graft copolymer.  

PubMed

A novel electrocatalytic biosensing platform was designed by the functionalization of reduced graphene oxide sheets (RGO) with conducting polypyrrole graft copolymer, poly(styrenesulfonic acid-g-pyrrole) (PSSA-g-PPY), via ?-? noncovalent interaction. The resulting nanocomposite could well disperse in water for at least 2 months with a solubility of 3.0 mg mL(-1). The nanocomposite was characterized with atomic force microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible absorption, contact angle measurement, and electrochemical impedance spectroscopy. Based on the advantageous functions of PSSA-g-PPY and RGO, the functional nanocomposite modified platinum electrode showed high electrocatalytic activity toward the oxidation of hydrogen peroxide and uric acid in neutral media. Further, a hypoxanthine biosensor was constructed by combining the modified electrode with the enzymatic reaction of xanthine oxidase. The biosensor exhibited a wide linear response ranging from 3.0×10(-8) to 2.8×10(-5) M with a high sensitivity of 673±4 ?A M(-1) cm(-2). The detection limit of 10nM at a signal-to-noise ratio of 3 was one order of magnitude lower than that reported previously. The assay results of hypoxanthine in fish samples were in a good agreement with the reference values. The water-soluble conducting copolymer could serve as an efficient species for functionalization and solubilization of graphene sheets in biosensing and biocatalytic applications. PMID:20729055

Zhang, Jing; Lei, Jianping; Pan, Rong; Xue, Yadong; Ju, Huangxian

2010-10-15

129

Addition of hypoxanthine to culture media allows in vitro cultivation of Babesia bovis and B. bigemina at reduced serum concentrations.  

PubMed

The microaerophilous stationary phase system (MASP) was introduced in 1980 and successfully used as a standard technique for Babesia bovis and B. bigemina in vitro culture. The percentage of serum in the medium and the dependence on specific serum donors have been recognized as important constraints both for immunochemical studies and for the logistics of culture routine. In the present study the supplementation of RPMI 1640 with hypoxanthine at a concentration between 50 and 200 microM has enabled patterns of growth of B. bovis and B. bigemina to be achieved comparable to the standard technique with a simultaneous reduction of serum concentration from 40% to 5%. With hypoxanthine-supplemented medium it was possible to either replace the bovine serum from a specific donor with horse serum or use commercial adult bovine serum or foetal calf serum at 10%. When the serum replacement media Albumax II and GF21 were used, the growth of both B. bovis and B. bigemina markedly decreased after 3 x 72 h cycles. However, when these species were cultivated in culture flasks previously coated with cells from a murine peritoneal lavage, continuous parasite growth was achieved. PMID:11676367

Neves, L; Cross, H F; Loureiro, L; Akça, A; Hommel, M; Trees, A J

2001-10-01

130

[Properties of hypoxanthineguanine-phosphoribosyltransferase (HGPRTase) in a gout patient with partial deficiency of this enzyme (author's transl)].  

PubMed

Some physicochemical properties of HGPRTase were studied in hemolysates and fibroblasts of a gout patient with partial deficiency of this enzyme. In comparison to normal HGPRTase the mutant enzyme from erythrocytes was found to have an elevated apparent Km-value for hypoxanthine and guanine and a lower Km-value for PRPP. The patient's enzyme from erythrocytes is more stable at +4 degrees C and +80 degrees C, the enzyme from fibroblasts more labile than that of controls. The inhibition of the mutant enzyme by some purine nucleosides and -nucleotides differed from that found in controls. No evidence was shown for an inhibitor of the patient's HGPRTase from erythrocytes. Ultracentrifugation of hemolysate in a saccharose gradient revealed no difference in the sedimentation coefficient. PMID:762946

Gröbner, W; Zöllner, N

1979-01-15

131

Alternative substrates reveal catalytic cycle and key binding events in the reaction catalysed by anthranilate phosphoribosyltransferase from Mycobacterium tuberculosis.  

PubMed

AnPRT (anthranilate phosphoribosyltransferase), required for the biosynthesis of tryptophan, is essential for the virulence of Mycobacterium tuberculosis (Mtb). AnPRT catalyses the Mg2+-dependent transfer of a phosphoribosyl group from PRPP (5'-phosphoribosyl-1'-pyrophosphate) to anthranilate to form PRA (5'-phosphoribosyl anthranilate). Mtb-AnPRT was shown to catalyse a sequential reaction and significant substrate inhibition by anthranilate was observed. Antimycobacterial fluoroanthranilates and methyl-substituted analogues were shown to act as alternative substrates for Mtb-AnPRT, producing the corresponding substituted PRA products. Structures of the enzyme complexed with anthranilate analogues reveal two distinct binding sites for anthranilate. One site is located over 8 Å (1 Å=0.1 nm) from PRPP at the entrance to a tunnel leading to the active site, whereas in the second, inner, site anthranilate is adjacent to PRPP, in a catalytically relevant position. Soaking the analogues for variable periods of time provides evidence for anthranilate located at transient positions during transfer from the outer site to the inner catalytic site. PRPP and Mg2+ binding have been shown to be associated with the rearrangement of two flexible loops, which is required to complete the inner anthranilate-binding site. It is proposed that anthranilate first binds to the outer site, providing an unusual mechanism for substrate capture and efficient transfer to the catalytic site following the binding of PRPP. PMID:24712732

Cookson, Tammie V M; Castell, Alina; Bulloch, Esther M M; Evans, Genevieve L; Short, Francesca L; Baker, Edward N; Lott, J Shaun; Parker, Emily J

2014-07-01

132

The crystal structure of the orotate phosphoribosyltransferase complexed with orotate and alpha-D-5-phosphoribosyl-1-pyrophosphate.  

PubMed

The three-dimensional structure of Salmonella typhimurium orotate phosphoribosyltransferase (OPRTase) in complex with the ribose 5-phosphate donor alpha-D-5--phosphoribosyl-1-pyrophosphate (PRPP) and the nitrogenous base orotic acid has been solved and refined with X-ray diffraction data extending to 2.3 A resolution to a crystallographic R-factor of 18.7%. The complex was generated by carrying out catalysis in the crystal. Comparison of this structure with the previously reported structure of the orotidine 5'-monophosphate (OMP) complex [Scapin, G., Grubmeyer, C., and Sacchettini, J. C. (1994) Biochemistry 33, 1287-1294] revealed that the enzyme backbone undergoes only small movements. The most significant differences occur near the active site, at Ala71-Gly74, with the largest difference involving the side chains of Lys73, Val127-Ala133, the 5'-phosphate binding loop, and a long, solvent-exposed loop at the dimer interface. The position of the ribose moiety is, on the other hand, very different in the OMP and PRPP.orotate complexes, with its anomeric carbon moving approximately 7 A across the binding cavity. In the PRPP.orotate complex the highly conserved acidic side chain of Asp124 interacts with the ribose of PRPP, whereas there are no interactions of this aspartate with the substrate in the OMP complex. PMID:7545004

Scapin, G; Ozturk, D H; Grubmeyer, C; Sacchettini, J C

1995-08-29

133

Deficiency of UMP synthase in dairy cattle: a model for hereditary orotic aciduria.  

PubMed

Deficiency of uridine-5'-monophosphate (UMP) synthase in dairy cattle, a condition analogous to human hereditary orotic aciduria, is reviewed with consideration of similarities and differences between the enzyme deficiency in humans and cattle. New findings regarding the bovine condition are reported including presence of the enzyme deficiency in numerous tissues and absence of substantial effects on other aspects of nucleotide metabolism. Specifically, erythrocyte concentration of phosphoribosylpyrophosphate (PRPP) and activities of PRPP synthetase, adenine phosphoribosyltransferase, and hypoxanthine-guanine phosphoribosyltransferase appear to be normal in cattle heterozygous for UMP synthase deficiency. PMID:2448544

Harden, K K; Robinson, J L

1987-01-01

134

Transport of [14C]hypoxanthine by sheep choroid plexus epithelium as a monolayer in primary culture: Na+-dependent and Na+-independent uptake by the apical membrane and rapid intracellular metabolic conversion to nucleotides.  

PubMed

Hypoxanthine is the main product of purine metabolic degradation and previous studies have revealed that it is present in the sheep CSF and plasma in micromolar concentrations. The aim of this study was to elucidate the transport of this molecule across the sheep choroid plexus epithelium (CPE) as a monolayer in primary culture, to explore the mechanism of uptake by the apical side of the CPE and investigate the metabolic changes inside the cell. The estimated permeability of the CPE monolayer for [14C]hypoxanthine, [14C]adenine and [14C]guanine was low and comparable to the permeability towards the extracellular space markers. The study of [14C]hypoxanthine uptake by the CPE revealed two components: Na+-dependent and Na+-independent, the latter being partially mediated by the equilibrative nucleoside transporter 2. HPLC with simultaneous detection of radioactivity revealed that the majority of [14C]hypoxanthine inside the CPE is metabolised into [14C]nucleotides and [14C]inosine. The remaining intact [14C]hypoxanthine was transported across the opposite, basolateral side of CPE and appeared in the lower chamber buffer together with [14C]inosine. These findings indicate two possible roles of hypoxanthine uptake from the CSF by the CP epithelium in vivo: to provide material for nucleotide synthesis through the salvage pathways in the CPE, as well as to transfer excess hypoxanthine from CSF to blood. PMID:18164814

Isakovic, Aleksandra J; Dencic, Sonja Misirlic; Segal, Malcolm B; Redzic, Zoran B

2008-01-31

135

Interactions at the 2 and 5 positions of 5-phosphoribosyl pyrophosphate are essential in Salmonella typhimurium quinolinate phosphoribosyltransferase  

PubMed Central

Quinolinate phosphoribosyltransferase (QAPRTase, EC 2.4.2.19) catalyzes an unusual phosphoribosyl transfer that is linked to a decarboxylation reaction to form the NAD precursor nicotinate mononucleotide, carbon dioxide, and pyrophosphate from quinolinic acid (QA) and 5-phosphoribosyl 1-pyrophosphate (PRPP). Structural studies and sequence similarities with other PRTases have implicated Glu214, Asp235, Lys153 and Lys284 in contributing to catalysis through direct interaction with PRPP. The four residues were substituted by site-directed mutagenesis. A nadC deletant form of BL21DE3 was created to eliminate trace contamination by chromosomal QAPRTase. The mutant enzymes were readily purified and retained their dimeric aggregation state on gel filtration. Substitution of Lys153 with Ala resulted in an inactive enzyme, indicating its essential nature. Mutation of Glu214 to Ala or Asp caused at least a 4000-fold reduction in kcat, with 10-fold increases in Km and KD values for PRPP. However, mutation of Glu214 to Gln had only modest effects on ligand binding and catalysis. pH profiles indicated that the deprotonated form of a residue with pKa of 6.9 is essential for catalysis. The WT-like pH-profile of the E214Q mutant indicated that Glu214 is not that residue. Mutation of Asp235 to Ala did not affect ligand binding or catalysis. Mutation of Lys284 to Ala decreased kcat by 30-fold and increased Km and KD values for PRPP by 80-fold and at least 20-fold, respectively. The study suggests that Lys153 is necessary for catalysis and important for PRPP binding, Glu214 provides a hydrogen bond necessary for catalysis but does not act as a base or electrostatically to stabilize the transition state, Lys284 is involved in PRPP binding and Asp235 is not essential.

Bello, Zainab; Stitt, Barbara; Grubmeyer, Charles

2010-01-01

136

Biochemical Characterization of Quinolinic Acid Phosphoribosyltransferase from Mycobacterium tuberculosis H37Rv and Inhibition of Its Activity by Pyrazinamide  

PubMed Central

Quinolinic acid phosphoribosyltransferase (QAPRTase, EC 2.4.2.19) is a key enzyme in the de novo pathway of nicotinamide adenine dinucleotide (NAD) biosynthesis and a target for the development of new anti-tuberculosis drugs. QAPRTase catalyzes the synthesis of nicotinic acid mononucleotide from quinolinic acid (QA) and 5-phosphoribosyl-1-pyrophosphate (PRPP) through a phosphoribosyl transfer reaction followed by decarboxylation. The crystal structure of QAPRTase from Mycobacterium tuberculosis H37Rv (MtQAPRTase) has been determined; however, a detailed functional analysis of MtQAPRTase has not been published. Here, we analyzed the enzymatic activities of MtQAPRTase and determined the effect on catalysis of the anti-tuberculosis drug pyrazinamide (PZA). The optimum temperature and pH for MtQAPRTase activity were 60°C and pH 9.2. MtQAPRTase required bivalent metal ions and its activity was highest in the presence of Mg2+. Kinetic analyses revealed that the Km values for QA and PRPP were 0.08 and 0.39 mM, respectively, and the kcat values for QA and PRPP were 0.12 and 0.14 [s-1], respectively. When the amino acid residues of MtQAPRTase, which may interact with QA, were substituted with alanine residues, catalytic activity was undetectable. Further, PZA, which is an anti-tuberculosis drug and a structural analog of QA, markedly inhibited the catalytic activity of MtQAPRTase. The structure of PZA may provide the basis for the design of new inhibitors of MtQAPRTase. These findings provide new insights into the catalytic properties of MtQAPRTase.

Kim, Hyun; Shibayama, Keigo; Rimbara, Emiko; Mori, Shigetarou

2014-01-01

137

Nicotinamide phosphoribosyltransferase is required for the calorie restriction-mediated improvements in oxidative stress, mitochondrial biogenesis, and metabolic adaptation.  

PubMed

Calorie restriction (CR) is one of the most reproducible treatments for weight loss and slowing aging. However, how CR induces these metabolic alterations is not fully understood. In this work, we studied whether nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme for nicotinamide adenine dinucleotide biosynthesis, plays a role in CR-induced beneficial metabolic effects using a specific inhibitor of NAMPT (FK866). CR upregulated NAMPT mRNA and protein levels in rat skeletal muscle and white adipose tissue. Inhibition of NAMPT activity by FK866 in rats did not affect the SIRT1 upregulation by CR but suppressed the CR-induced SIRT1 activity and deacetylation of Forkhead box protein O1/peroxisome proliferator-activated receptor ? coactivator-1?. Inhibition of NAMPT activity by FK866 also attenuated the CR-induced SIRT3 activity, evidenced by deacetylation of superoxide dismutase-2. Furthermore, FK866 not only weakened the CR-induced decrease of oxidative stress (dichlorofluorescin signal, superoxide , and malondialdehyde levels), but also greatly attenuated the CR-induced improvements of antioxidative activity (total superoxide dismutase, glutathione, and glutathione/oxidized glutathione ratio) and mitochondrial biogenesis (mRNA levels of nuclear respiratory factor 1, cytochrome c oxidase IV, peroxisome proliferator-activated receptor-? coactivator-1?, and transcription factor A, mitochondrial and citrate synthase activity). At last, FK866 blocked the CR-induced insulin sensitizing, Akt signaling activation, and endothelial nitric oxide synthase phosphorylation. Collectively, our data provide the first evidence that the CR-induced beneficial effects in oxidative stress, mitochondrial biogenesis, and metabolic adaptation require NAMPT. PMID:23946338

Song, Jie; Ke, Sen-Fang; Zhou, Can-Can; Zhang, Sai-Long; Guan, Yun-Feng; Xu, Tian-Ying; Sheng, Chun-Quan; Wang, Pei; Miao, Chao-Yu

2014-01-01

138

The pyrimidine biosynthesis operon of the thermophile Bacillus caldolyticus includes genes for uracil phosphoribosyltransferase and uracil permease.  

PubMed Central

A 3-kb DNA segment of the Bacillus caldolyticus genome including the 5' end end of the pyr cluster has been cloned and sequenced. The sequence revealed the presence of two open reading frames, pyrR and pyrP, located immediately upstream of the previously sequenced pyrB gene encoding the pyrimidine biosynthesis enzyme aspartate transcarbamoylase. The pyrR and pyrP genes encoded polypeptides with calculated molecular masses of 19.9 and 45.2 kDa, respectively. Expression of these ORFs was confirmed by analysis of plasmid-encoded polypeptides in minicells. Sequence alignment and complementation analyses identified the pyrR gene product as a uracil phosphoribosyltransferase and the pyrP gene product as a membrane-bound uracil permease. By using promoter expression vectors, a 650-bp EcoRI-HincII fragment, including the 5' end of pyrR and its upstream region, was found to contain the pyr operon promoter. The transcriptional start point was located by primer extension at a position 153 bp upstream of the pyrR translation initiation codon, 7 bp 3' of a sequence resembling a sigma A-dependent Bacillus subtilis promoter. This established the following organization of the ten cistrons within the pyr operon: promoter-pyrR-pyrP-pyrB-pyrC-pyrAa-pyrA b-orf2-pyrD-pyrF-pyrE. The nucleotide sequences of the region upstream of pyrR and of the pyrR-pyrP and pyrP-pyrB intercistronic regions indicated that the transcript may form two mutually exclusive secondary structures within each of these regions. One of these structures resembled a rho-independent transcriptional terminator. The possible implication of these structures for pyrimidine regulation of the operon is discussed. Images

Ghim, S Y; Neuhard, J

1994-01-01

139

Chromatin remodeling occurs independent of transcription factor binding during 5-azacytidine reactivation of the human HPRT gene  

SciTech Connect

A novel system of differential gene expression in mammals is established during normal female embryogenesis by X chromosome inactivation. Studies of 5-aza-2{prime}-deoxycytidine (5aCdr)-induced reactivation of genes on the inactive human X chromosome strongly implicate DNA methylation in maintaining the transcriptional repression of discrete loci on the inactive X. During the process of 5aCdr-induced reactivation of the human hypoxanthine phosphoribosyltransferase (HPRT) gene on the inactive X chromosome, changes in nuclease sensitivity of chromatin in the 5{prime} region of the HPRT gene and HPRT mRNA levels have been analyzed from 0-72 hrs. after 5aCdr exposure. Increased nuclease sensitivity is first detectable at 6 hrs. and reaches a maximum at 24 hrs. after initial exposure to 5aCdr, while the appearance of HPRT mRNA levels is first detectable by RT-PCR at 24 hrs. and reaches a maximum of 48 hrs. after 5aCdr exposure. Thus, the change in chromatin structure of the 5{prime} region as a result of 5aCdr treatment appears to occur prior to active transcription of the gene. However, it is unclear if the remodeling of chromatin requires the binding of transcription factors to the 5{prime} region, or if the binding of transcription factors is only required for transcription of the HPRT gene. We now have assayed the binding of transcription factors to the 5{prime} region of the HPRT gene on the inactive X chromosome during 5aCdr reactivation. We find that the change in chromatin structure as a result of 5aCdr treatment occurs independent of transcription factor binding, and that the binding of factors is correlated with active transcription of the gene rather than remodeling of chromatin structure. These data suggest that the differential binding of transcriptional activators (and differential expression of the HPRT gene) to the active and inactive HPRT genes is modulated by the accessibility of their binding sites due to chromatin structure.

Hornstra, L.K.; Litt, M.D.; Yang, T.P. [Univ. of Florida College of Medicine, Gainesville, FL (United States)] [and others

1994-09-01

140

Long-range ferromagnetic ordering in a 3D Cu(II)-tetracarboxylate framework assisted by an unprecedented bidentate ?2-O1,N4 hypoxanthine nucleobase.  

PubMed

The first hypoxanthine (hypH)-assisted 3D Cu(II)-tetracarboxylate framework, {[Cu(2)(hypH)(0.5)(H(2)O)(0.5)(btec)]·1.5H(2)O}(n) (btec = 1,2,4,5-benzenetetracarboxylate), was synthesized and exhibits long-range ferromagnetic ordering below 4.5 K, which opens a new window for the applications of nucleobase-based MOFs as magnetic materials. PMID:20820623

Yang, En-Cui; Liu, Zheng-Yu; Liu, Zhong-Yi; Zhao, Li-Na; Zhao, Xiao-Jun

2010-10-14

141

Xanthine oxidase inhibits growth of Plasmodium falciparum in human erythrocytes in vitro.  

PubMed Central

Malaria parasites, unable to synthesize purine de novo, use host-derived hypoxanthine preferentially as purine source. In a previous study (1990. J. Biol. Chem. 265:6562-6568), we noted that xanthine oxidase rapidly and completely depleted hypoxanthine in human erythrocytes, not by crossing the erythrocyte membrane, but rather by creating a concentration gradient which facilitated hypoxanthine efflux. We therefore investigated the ability of xanthine oxidase to inhibit growth of FCR-3, a chloroquine-resistant strain of Plasmodium falciparum in human erythrocytes in vitro. Parasites were cultured in human group O+ erythrocytes in medium supplemented, as required, with xanthine oxidase or chloroquine. Parasite viability was assessed by uptake of radiolabeled glycine and adenosine triphosphate-derived purine into protein and nucleic acid, respectively, by nucleic acid accumulation, by L-lactate production, and by microscopic appearance. On average, a 90% inhibition of growth was observed after 72 h of incubation in 20 mU/ml xanthine oxidase. Inhibition was notably greater than that exerted by 10(-7) M chloroquine (less than 10%) over a comparable period. The IC50 for xanthine oxidase was estimated at 0.2 mU/ml, compared to 1.5 x 10(-7) M for chloroquine. Inhibition was completely reversed by excess hypoxanthine, but was unaffected by oxygen radical scavengers, including superoxide dismutase and catalase. The data confirms that a supply of host-derived hypoxanthine is critical for nucleic acid synthesis in P. falciparum, and that depletion of erythrocyte hypoxanthine pools of chloroquine-resistant malaria infection in humans. of chloroquine-resistant malaria infection in humans. Images

Berman, P A; Human, L; Freese, J A

1991-01-01

142

De novo Synthesis of Purine Nucleotides in Human Blood Platelets  

Microsoft Academic Search

Human blood platelets were found to carry the complete pathway of de novo purine nucleotide synthesis. The rate of purine synthesis was gauged by the rate of incorporation of precursor (14C)formate into purines. The effect on formate incorporation of several compounds known to inhibit purine synthesis de novo was studied. Adenine, orotic acid and azaserine inhibited purine synthesis, but hypoxanthine

Z. Jerushalmy; M. Patya; P. Boer; O. Sperling

1980-01-01

143

Simultaneous assay of glucose, lactate, L-glutamate and hypoxanthine levels in a rat striatum using enzyme electrodes based on neutral red-doped silica nanoparticles.  

PubMed

An electrochemical method suitable for the simultaneous measurement of cerebral glucose, lactate, L-glutamate and hypoxanthine concentrations from in vivo microdialysis sampling has been successfully performed for the first time using a neutral red-doped silica (NRDS) nanoparticle-derived enzyme sensor system. These uniform NRDS nanoparticles (about 50 +/- 3 nm) were prepared by a water-in-oil (W/O) microemulsion method, and characterized by a TEM technique. The neutral red-doped interior maintained its high electron-activity, while the exterior nano-silica surface prevented the mediator from leaching out into the aqueous solution, and showed high biocompability. These nanoparticles were then mixing with the glucose oxidase (GOD), lactate oxidase (LOD), L-glutamate oxidase (L-GLOD) or xanthine oxidase (XOD), and immobilized on four glassy carbon electrodes, respectively. A thin Nafion film was coated on the enzyme layer to prevent interference from molecules such as ascorbic acid and uric acid in the dialysate. The high sensitivity of the NRDS modified enzyme electrode system enables the simultaneous monitoring of trace levels of glucose, L-glutamate, lactate and hypoxanthine in diluted dialysate samples from a rat striatum. PMID:15517210

Zhang, Fen-Fen; Wan, Qiao; Li, Chen-Xin; Wang, Xiao-Li; Zhu, Zi-Qiang; Xian, Yue-Zhong; Jin, Li-Tong; Yamamoto, Katsunobu

2004-10-01

144

Genetic Assay for Aneuploidy: Quantitation of Chromosome Loss Using a Mouse/Human Monochromosomal Hybrid Cell Line (Journal Version).  

National Technical Information Service (NTIS)

A genetic assay is described in which a mouse/human hybrid cell line R3-5 containing a single human chromosome (a monochromosomal hybrid) is used to detect chemically induced aneuploidy. The hybrid cells are deficient in hypoxanthine guanine phosphoribosy...

S. S. Sandhu, R. Gudi, R. S. Athwal

1988-01-01

145

Detection of an amino acid substitution in the mutant enzyme for a special type of adenine phosphoribosyltransferase (APRT) deficiency by sequence-specific protein cleavage.  

PubMed Central

Generally, if mutant and normal proteins have similar molecular weights and electric charges, they cannot easily be distinguished from one another. We have developed a unique method by which a mutant enzyme of adenine phosphoribosyltransferase (APRT) can easily be distinguished from normal enzyme with nearly identical molecular weight and electric charge. DNA sequencing data have suggested that in this special type of disease (Japanese-type APRT deficiency) there is an amino acid substitution from Met to Thr at position 136 of APRT. Since normal APRT has only one Met residue, the Japanese-type mutant APRT should be a methionine-free protein. Using both an amino acid sequence-specific antiserum against APRT, and specific cleavage of peptide at the methionine residue with BrCN, we could distinguish between normal and mutant proteins. Thus, normal but not mutant APRT was cleaved with BrCN, indicating that the mutant APRT is a methionine-free protein. All tested patients with the Japanese-type APRT deficiency were found to synthesize exclusively methionine-free APRT. Usefulness of this method is not restricted to a single family, as 79% of all the patients with this disease among Japanese, and more than half of all the patients with this disease reported in the world, are likely to have this unique mutation. Thus, not only sequence-specific cleavage of DNA with restriction endonucleases but also that of protein with a chemical agent has been shown to be sometimes useful for the diagnosis and analysis of a genetic disease by careful examination of normal and mutant amino acid sequences. Images Figure 2 Figure 3 Figure 4

Kamatani, N; Kuroshima, S; Terai, C; Hidaka, Y; Palella, T D; Nishioka, K

1989-01-01

146

Establishment and Characterization of Human T Hybrid Cells Secreting Immunoregulatory Molecules  

Microsoft Academic Search

Hybridization of human T cells with an azaguanine-resistant human T cell line gave rise to T hybrid cell lines secreting several immunoregulatory molecules. Analyses of karyotypes, HLA phenotypes, and other surface phenotypes, such as T-cell-specific antigens or receptors for sheep erythrocytes and the patterns of mitogen responsiveness confirmed that the hypoxanthine\\/aminopterin\\/thymidine-resistant cell lines were human T-T hybridomas. One of the

Masaji Okada; Norio Yoshimura; Takeji Kaieda; Yuichi Yamamura; Tadamitsu Kishimoto

1981-01-01

147

Reinvestigation of the molecular influence of hypoxanthine on the DNA cleavage efficiency of restriction endonucleases BglII, EcoRI and BamHI.  

PubMed

Hypoxanthine (Hyp), a deaminated base of adenine (Ade), can be employed as a good probe molecule to reveal the significance of the minor groove of guanine (Gua) in biomolecular interactions because Hyp possesses a similar structure to Gua lacking its 2-amino group. In this study, we examined cleavage efficiencies of restriction endonuclease enzymes on DNA substrates with Hyp in their recognition sequences. As a substrate for BglII, EcoRI and BamHI, 24-mer DNA oligomer with Hyp (in place of Gua) was prepared together with its complementary sequences with cytosine (Cyt) or thymine (Thy) as the counter base. At 37 degrees C incubation for 1 h, BglII and EcoRI showed higher DNA cleavage reactivity on Hyp-containing DNA substrates than on normal ones, whereas BamHI showed lower values on Hyp-containing substrates. Such high cleavage performance of BglII and EcoRI on Hyp-containing DNA substrates is in contrast to the results obtained 20 years ago, in which short DNA substrates (8- or 10-mer) and low reaction temperatures (15-20 degrees C) were employed. These new results suggest that the lack of the exocyclic 2-amino group of Gua could contribute to enhanced recognition access of BglII and EcoRI to DNA substrates. PMID:19364803

Doi, Akihiro; Pack, Seung Pil; Kodaki, Tsutomu; Makino, Keisuke

2009-08-01

148

Photosensitized Oxidation of Hypoxanthine and Xanthine by Aluminum Phthalocyanine Tetrasulfonate. Role of the Alkylating Quinone 2,5-Dichloro-diaziridinyl-1,4-benzoquinone  

PubMed Central

Photoirradiation of nitrogen-saturated aqueous solutions containing aluminum phthalocyanine tetrasulfonate (AlPcS4) at 675 nm in the presence of 2,5-dichloro-diaziridinyl-1,4-benzoquinone (AZDClQ) and hypoxanthine (HX) produces the oxidized HX derivatives, xanthine (X) and uric acid (UA). Concentrations of the AZDClQ semiquinone, X and UA increase at the expense of HX with an increase in irradiation time. Almost negligible decomposition of HX, as well as very low amounts of X, are detected if photolysis occurs under identical conditions but in the absence of AZDClQ. Addition of calf-thymus DNA produces quinone-DNA covalent adducts after photolysis of anaerobic samples containing quinone, DNA and AlPcS4, in the presence or absence of HX and at pH 5.5. However, larger amounts of quinone-DNA adducts are detected if HX is present. The results presented here could have applications in the photodynamic treatment of hypoxic tissues such as solid tumors, under conditions of high HX concentration, where Type-I pathways could be more important than singlet oxygen generation.

Alegria, Antonio E.; Inostroza, Yaritza; Kumar, Ajay

2009-01-01

149

Use of a selectable marker regulated by alpha interferon to obtain mutations in the signaling pathway.  

PubMed Central

We have selected mutations in genes encoding components of the signaling pathway for alpha interferon (IFN-alpha) by using a specially constructed cell line. The upstream region of the IFN-regulated human gene 6-16 was fused to the Escherichia coli guanine phosphoribosyltransferase (gpt) gene and transfected into hypoxanthine-guanine phosphoribosyltransferase-negative human cells. These cells express gpt only in the presence of IFN-alpha. They grow in medium containing hypoxanthine, aminopterin, and thymidine plus IFN and are killed by 6-thioguanine plus IFN. Two different types of mutants were obtained after treating the cells with mutagens. A recessive mutant, selected in 6-thioguanine plus IFN, was completely resistant to IFN-alpha but responded normally to IFN-gamma and, unexpectedly, partially to IFN-beta. A constitutive mutant, selected in hypoxanthine-aminopterin-thymidine alone, was abnormal in expressing endogenous genes in the absence of IFN. Both types revert infrequently, allowing selection for complementation of the defects by transfection. Images

Pellegrini, S; John, J; Shearer, M; Kerr, I M; Stark, G R

1989-01-01

150

The radioprotector WR1065 reduces radiation-induced mutations at the hypoxanthine-guanine phosphoribosyl transferase locus in V79 cells.  

PubMed

N-(2-mercaptoethyl)-1,3-diaminopropane (WR1065) protects against radiation-induced cell killing and mutagenesis at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus in V79 Chinese hamster lung fibroblast cells. At a concentration of 4 mM, WR1065 was found to be effective in protecting against radiation-induced cell lethality only if present during irradiation, e.g., a dose modification factor (DMF) of 1.9. No protective effect was observed if the protector was added within 5 min after irradiation or 3 h later, e.g., DMFs of 1.0 and 1.1, respectively. The effect of WR1065 on radiation-induced mutation, expressed as resistance to the cytotoxic purine analogue 6-thioguanine (HGPRT), was also investigated. In contrast to the treatment-schedule dependence for protection by WR1065 against cell killing, this agent was effective in reducing radiation-induced mutations regardless of when it was administered. Following a dose of 10 Gy of 60Co gamma-rays, the mutation frequencies observed per 10(6) survivors were 77 +/- 8, 27 +/- 6, 42 +/- 7, and 42 +/- 7 for radiation only, and WR1065 present during, immediately after, or 3 h after irradiation. These data suggest that although a segment of radiation-induced damage leading to reproductive death cannot be modulated through the postirradiation action of WR1065, processes leading to the fixation of gross genetic damage and mutation induction in surviving cells can be effectively altered and interfered with leading to a marked reduction in mutation frequency. PMID:4006082

Grdina, D J; Nagy, B; Hill, C K; Wells, R L; Peraino, C

1985-06-01

151

A simple and sensitive method for estimating the concentration and synthesis of 5-phosphoribosyl 1-pyrophosphate in red blood cells.  

PubMed

A method is presented for the determination of 5-phosphoribosyl 1-pyrophosphate (PRPP), which is based on the release of 14CO2 from [carboxyl-14C]-orotic acid by the consecutive action of orotate phosphoribosyltransferase and orotidine-5'-monophosphate decarboxylase. The assay is simpler and less time-consuming than most methods currently employed and is equally sensitive. The method proved to be suitable for measuring low concentrations of PRPP such as found in human erythrocytes and fibroblasts. An increased PRPP concentration was observed in erythrocytes from patients with partial or complete deficiency of hypoxanthine-guanine phospho-ribosyltransferase. frp, sp,e (but not all) gouty patients and from a patient with deficiency of purine nucleoside phosphorylase. PRPP synthetase activity was measured with a method similar to the assay for PRPP. In erythrocytes with an increased PRPP concentration, PRPP synthetase activity was found to be normal at both optimal and suboptimal substrate concentrations. PMID:195752

Tax, W J; Veerkamp, J H

1977-07-15

152

Oxidative stress to human lymphocytes by xanthine oxidoreductase activity.  

PubMed

The in vitro toxicity of the reactive oxygen species generating enzyme xanthine oxidoreductase (XOR) to human peripheral blood lymphocytes was studied after stimulation with phytohaemoagglutinin or anti-CD3/CD28 antibodies. Apoptosis and necrosis were induced by the XOR/hypoxanthine system in a time- and concentration-dependent manner. CD8+ lymphocytes showed a higher sensitivity than CD4+ cells to the XOR/hypoxanthine system. The occurrence of apoptosis was demonstrated by annexin-V binding to injured cell membrane, which was the most precocious alteration observed, followed by the increment of transglutaminase activity, which was significant at the lowest XOR concentration used. Nuclear damage was assessed by the increased hypodiploid nuclei and by DNA migration on gel electrophoresis, which turned to an apoptotic pattern before the occurrence of cell membrane necrotic lesions. Apoptosis was induced by XOR activity proportionally to substrate concentration and was prevented by the competitive enzyme inhibitor, allopurinol. The hydrogen peroxide scavenging enzyme, catalase, gave a higher protection than superoxide dismutase from the toxicity caused by the XOR/hypoxanthine system. Necrosis occurs in a variable percentage indicating that reactive oxygen species may trigger both apoptosis and necrosis in proliferating human lymphocytes, mostly depending on XOR concentration. PMID:11811520

Battelli, M G; Musiani, S; Tazzari, P L; Stirpe, F

2001-12-01

153

Pharmacology, tolerance, and antiviral activity of vidarabine monophosphate in humans.  

PubMed

Vidarabine (adenine arabinoside) is a purine nucleoside useful in humans for therapy of herpes simplex virus encephalitis and herpes zoster virus infections in immunocompromised patients. However, the potential usefulness of vidaribine is limited by its poor solubility, which requires continuous infusion in relatively large volumes of intravenous fluid. Vidarabine 5'-monophosphate is highly soluble and has the advantage that it can be administered intermittently intramuscularly or intravenously. In a clinical, pharmacokinetic study, plasma levels and urinary excretion of vidarabine 5'-monophosphate were determined after intravenous and intramuscular administration in 29 immunosuppressed patients with herpes simplex or zoster virus infections at dosages of 15 to 30 mg/kg per day administered for 5 days. As determined by high-pressure liquid chromatography, vidarabine 5'-monophosphate was metabolized in a fashion comparable to the metabolism of vidarabine and its major metabolite in plasma was arabinosyl hypoxanthine. After administration, 40 to 50% of the vidarabine 5'-monophosphate was recovered from the urine as arabinosyl hypoxanthine, and 3 to 4% was recovered as vidarabine. Determinations of areas under the curve for arabinosyl hypoxanthine were not statistically different by dosage for intramuscular or intravenous routes of administration. At all dosages studied, viral clearance appeared to occur with therapy. The advantage of increased solubility will lead to controlled clinical investigations in which vidarabine 5'-monophosphate is administered by intramuscular or intravenous routes against targeted human herpesvirus infections. PMID:6160811

Whitley, R J; Tucker, B C; Kinkel, A W; Barton, N H; Pass, R F; Whelchel, J D; Cobbs, C G; Diethelm, A G; Buchanan, R A

1980-11-01

154

[A new form of the Lesch-Nyhan syndrome. A study of hypoxanthine-guanine-phosphoribosyl-transferase in fibroblasts. The in vitro and in vivo effect of adenine on enzyme activity].  

PubMed

A new, clinically and biochemically atypical case of Lesch-Nyhan syndrome is presented. There is mild neurological involvement, the APRTase activity is normal, despite a raised PRPP concentration and HGPRTase activity is low. The optimal pH and temperature of fibroblast HGPRTase activity differ markedly from control values. The Km for hypoxanthine and PRPP are minimally changed. Erythrocyte HGPRTase activity does not vary following adenine ingestion in either the adult patient or the control. Fibroblast HGPRTase activity is not affected by the addition of adenine to cultures of fibroblasts. However, in the child suffering from classical Lesch-Nyhan syndrome, erythrocyte HGPRTase activity decreases following adenine ingestion. PMID:6186166

Warter, S; Bieth, R

1982-01-01

155

Epstein-Barr Virus and Human Chromosomes: Close Association of the Resident Viral Genome and the Expression of the Virus-Determined Nuclear Antigen (EBNA) with the Presence of Chromosome 14 in Human-Mouse Hybrid Cel  

Microsoft Academic Search

Fourteen hybrid clones derived from the fused cultures of human lymphoblastoid FV5 cells and 5-bromodeoxyuridine-resistant mouse fibroblastic MCB2 cells grown in hypoxanthine\\/aminopterin\\/thymidine selective medium were examined for the presence of Epstein-Barr virus (EBV) DNA, the expression of the virus-determined nuclear antigen (EBNA), and the presence of human chromosomes, in the course of serial passage in vitro. Among the hybrid clones

K. Yamamoto; F. Mizuno; T. Matsuo; A. Tanaka; M. Nonoyama; T. Osato

1978-01-01

156

Quantitative assay for mutation in diploid human lymphoblasts using microtiter plates  

SciTech Connect

A microtiter plating technique which eliminates the need for soft agar and fibroblast feeder layers to determine the colony-forming ability of diploid human lymphoblast lines was described. The calculation of cloning efficiency is based on the Poisson distribution, and a statistical method for calculating confidence intervals is presented. This technique has been applied to the comcomitant examination of induced mutation at the putative loci for hypoxanthine guanine phosphoribosyl transferase, thymidine, kinase, and Na/sup +//K/sup +/ adenosine triphosphatase.

Furth, E.A.; Thilly, W.G.; Penman, B.W.; Liber, H.L.; Rand, W.M.

1981-01-01

157

A spectrophotometric method for the determination of 5-phosphoribosyl-1-pyrophosphate.  

PubMed

A new, sensitive, specific and simple spectrophotometric method for the determination of 5-phosphoribosyl-l-pyrophosphate (PRPP) is presented. PRPP is reacted with excess hypoxanthine in the presence of hypoxanthine-guanine phosphoribosyltransferase. At the end of the reaction, PRPP concentration is measured from the extent of conversion of hypoxanthine to inositate. The concentration of the purine base is determined spectrophotometrically in the presence of xanthine oxidase. PMID:477861

Salerno, C; Giacomello, A; Messina, E

1979-08-15

158

Functional identification of the hypoxanthine/guanine transporters YjcD and YgfQ and the adenine transporters PurP and YicO of Escherichia coli K-12.  

PubMed

The evolutionarily broad family nucleobase-cation symporter-2 (NCS2) encompasses transporters that are conserved in binding site architecture but diverse in substrate selectivity. Putative purine transporters of this family fall into one of two homology clusters: COG2233, represented by well studied xanthine and/or uric acid permeases, and COG2252, consisting of transporters for adenine, guanine, and/or hypoxanthine that remain unknown with respect to structure-function relationships. We analyzed the COG2252 genes of Escherichia coli K-12 with homology modeling, functional overexpression, and mutagenesis and showed that they encode high affinity permeases for the uptake of adenine (PurP and YicO) or guanine and hypoxanthine (YjcD and YgfQ). The two pairs of paralogs differ clearly in their substrate and ligand preferences. Of 25 putative inhibitors tested, PurP and YicO recognize with low micromolar affinity N(6)-benzoyladenine, 2,6-diaminopurine, and purine, whereas YjcD and YgfQ recognize 1-methylguanine, 8-azaguanine, 6-thioguanine, and 6-mercaptopurine and do not recognize any of the PurP ligands. Furthermore, the permeases PurP and YjcD were subjected to site-directed mutagenesis at highly conserved sites of transmembrane segments 1, 3, 8, 9, and 10, which have been studied also in COG2233 homologs. Residues irreplaceable for uptake activity or crucial for substrate selectivity were found at positions occupied by similar role amino acids in the Escherichia coli xanthine- and uric acid-transporting homologs (XanQ and UacT, respectively) and predicted to be at or around the binding site. Our results support the contention that the distantly related transporters of COG2233 and COG2252 use topologically similar side chain determinants to dictate their function and the distinct purine selectivity profiles. PMID:24214977

Papakostas, Konstantinos; Botou, Maria; Frillingos, Stathis

2013-12-27

159

IgA class switch in I alpha exon-deficient mice. Role of germline transcription in class switch recombination.  

PubMed Central

Studies have implicated defective Ig class switch in the pathogenesis of IgA deficiency. To understand better the molecular events that regulate IgA class switch, a 1.4-kb region of the IgA locus containing the I alpha exon was replaced with a human hypoxanthine phosphoribosyltransferase minigene by gene targeting in murine embryonic stem cells. The I alpha exon-deficient mice derived from these embryonic stem cells had normal IgA levels in serum and secretions and normal numbers of IgA B cells in Peyer's patches and spleen. Further, I alpha exon-deficient B cells efficiently underwent IgA class switch in vitro, despite the absence of I alpha exon-containing germline transcripts. Notably, I alpha exon-deficient B cells did not require TGF-beta for IgA class switch since stimulation with LPS alone led to IgA expression. Nonetheless, whereas I alpha exon-deficient B cells constitutively expressed human hypoxanthine phosphoribosyltransferase transcripts, they did not produce IgA in the absence of LPS stimulation. These results demonstrate that the I alpha exon or transcripts containing the I alpha exon are not required for IgA class switch. Further, the effects of TGF-beta on I alpha locus transcription can be supplanted by expression of a heterologous minigene at that locus, but a second signal is required for the induction of IgA class switch.

Harriman, G R; Bradley, A; Das, S; Rogers-Fani, P; Davis, A C

1996-01-01

160

A QM/MM MD insight into photodynamics of hypoxanthine: distinct nonadiabatic decay behaviors between keto-N7H and keto-N9H tautomers in aqueous solution.  

PubMed

Extensive ab initio surface-hopping dynamics simulations have been used to explore the excited-state nonadiabatic decay of two biologically relevant hypoxanthine keto-N7H and keto-N9H tautomers in aqueous solution. QM/MM calculations and QM/MM-based MD simulations predict different hydrogen bonding networks around these nucleobase analogues, which influence their photodynamical properties remarkably. Furthermore, different solvent effects on the conical intersection formation of keto-N7H and keto-N9H were found in excited-state MD simulations, which also change the lifetimes of the excited states. In comparison with the gas-phase situation, the S1? S0 nonradiative decay of keto-N7H is slightly faster, while this decay process of keto-N9H becomes much slower in water. The presence of ?-electron hydrogen bonds in the solvated keto-N7H is considered to facilitate the S1? S0 nonradiative decay process. PMID:24945346

Guo, Xugeng; Zhao, Yuan; Cao, Zexing

2014-08-01

161

Lesch-Nyhan syndrome presenting as acute renal failure secondary to obstructive uropathy.  

PubMed

Lesch-Nyhan syndrome is a rare genetic disorder characterized by mental retardation, self-mutilation, choreoathetosis, and hyperuricemia. The disease is caused by a mutation in the hypoxanthine-guanine phosphoribosyltransferase gene and is transmitted as a sex-linked recessive disorder. Since hyperuricemia is the primary metabolic problem caused by a hypoxanthine-guanine phosphoribosyltransferase mutation, urologic evaluation and treatment is often necessary for children with this disease. We report a 3-year-old boy who presented with anuric renal failure secondary to bilateral obstructing uric acid calculi. The evaluation of T lymphocytes revealed a hypoxanthine-guanine phosphoribosyltransferase mutation consistent with Lesch-Nyhan syndrome. The diagnosis and urologic management of this disorder is discussed. PMID:11113762

Ankem, M; Glazier, D B; Barone, J G

2000-12-20

162

Nucleobase Transport by Human Equilibrative Nucleoside Transporter 1 (hENT1)*  

PubMed Central

The human equilibrative nucleoside transporters hENT1 and hENT2 (each with 456 residues) are 40% identical in amino acid sequence and contain 11 putative transmembrane helices. Both transport purine and pyrimidine nucleosides and are distinguished functionally by a difference in sensitivity to inhibition by nanomolar concentrations of nitrobenzylmercaptopurine ribonucleoside (NBMPR), hENT1 being NBMPR-sensitive. Previously, we used heterologous expression in Xenopus oocytes to demonstrate that recombinant hENT2 and its rat ortholog rENT2 also transport purine and pyrimidine bases, h/rENT2 representing the first identified mammalian nucleobase transporter proteins (Yao, S. Y., Ng, A. M., Vickers, M. F., Sundaram, M., Cass, C. E., Baldwin, S. A., and Young, J. D. (2002) J. Biol. Chem. 277, 24938–24948). The same study also revealed lower, but significant, transport of hypoxanthine by h/rENT1. In the present investigation, we have used the enhanced Xenopus oocyte expression vector pGEMHE to demonstrate that hENT1 additionally transports thymine and adenine and, to a lesser extent, uracil and guanine. Fluxes of hypoxanthine, thymine, and adenine by hENT1 were saturable and inhibited by NBMPR. Ratios of Vmax (pmol/oocyte·min?1):Km (mm), a measure of transport efficiency, were 86, 177, and 120 for hypoxantine, thymine, and adenine, respectively, compared with 265 for uridine. Hypoxanthine influx was competitively inhibited by uridine, indicating common or overlapping nucleobase and nucleoside permeant binding pockets, and the anticancer nucleobase drugs 5-fluorouracil and 6-mercaptopurine were also transported. Nucleobase transport activity was absent from an engineered cysteine-less version hENT1 (hENT1C?) in which all 10 endogenous cysteine residues were mutated to serine. Site-directed mutagenesis identified Cys-414 in transmembrane helix 10 of hENT1 as the residue conferring nucleobase transport activity to the wild-type transporter.

Yao, Sylvia Y. M.; Ng, Amy M. L.; Cass, Carol E.; Baldwin, Stephen A.; Young, James D.

2011-01-01

163

Mutatect: a mouse tumour model for detecting radiation-induced mutations in vivo  

Microsoft Academic Search

A new mouse model (Mutatect) that permits detection of mutations at the hprt (hypoxanthine phosphoribosyltransferase) locus is described. It is highly sensitive to detection of mutants induced by clastogenic agents such as ionizing radiation. MN-11 cells are grown as a subcutaneous tumour in C57BL\\/6 mice for a period of 2 weeks, during which time they can be exposed to mutagenic

H. Chaim Birnboim; Diana Wilkinson; Jagdeep K Sandhu; Jack R McLean; William Ross

1999-01-01

164

Mutagenicity and cytotoxicity of reactive oxygen and nitrogen species in the MN11 murine tumor cell line  

Microsoft Academic Search

There is increasing evidence that endogenously generated reactive oxygen (ROS) and reactive nitrogen (RNS) species at sites of inflammation and in tumors may be genotoxic. We have developed a murine tumor model (MN-11) in which mutations at the hypoxanthine phosphoribosyltransferase (HPRT) locus, arising both in vitro and in vivo, can be detected. In the present report, we describe an in

Jagdeep K Sandhu; H. Chaim Birnboim

1997-01-01

165

Local bystander effect induces dormancy in human medullary thyroid carcinoma model in vivo.  

PubMed

The extent of local bystander effect induced by fusion yeast cytosine deaminase::uracil phosphoribosyltransferase (yCD) in combination with 5-fluorocytosine (5FC) was evaluated in xenogeneic model of human medullary thyroid carcinoma (MTC). This approach to gene-directed enzyme/prodrug therapy (GDEPT) induces strong bystander cytotoxicity. Effector yCD-TT mixed with target EGFP-TT cells in a ratio 2:9 could achieve significant tumor regression and 14-fold decrease in serum marker calcitonin upon 5FC administration. Histopathological analysis unraveled that antitumor effect resulted in tumor dormancy and proliferation arrest of remaining tumor cell clusters in vivo. yCD/5FC combination represents another GDEPT approach to achieve tumor growth control in MTC. PMID:23485727

Kucerova, Lucia; Feketeova, Lucia; Matuskova, Miroslava; Kozovska, Zuzana; Janega, Pavol; Babal, Pavel; Poturnajova, Martina

2013-07-28

166

Regional Localization of Loci for Human PGM1 and 6PGD on Human Chromosome One by Use of Hybrids of Chinese Hamster-Human Somatic Cells  

PubMed Central

The human gene loci phosphoglucomutase1 (PGM1, EC 2.7.5.1) and 6-phosphogluconate dehydrogenase (6PGD, EC 1.1.1.43), which are located on human chromosome one, have been assigned to a specific region of the short arm of that chromosome, by use of a hybrid cell line derived from a Chinese hamster cell line deficient in hypoxanthine phosphoribosyl transferase and a strain of human diploid fibroblasts. Cytogenetic analysis of a hybrid clone maintained for about 50 generations in vitro revealed two populations of cells, the first containing a human chromosome one with a break point at band 1p33, such that about 25% of the short arm of this chromosome was deleted. The second cell population contained a normal chromosome one. Biochemical analysis of subclones derived by cloning this mixed population revealed two phenotypic classes, one of which expressed all three chromosome-one markers, PGM1, 6PGD, and peptidase C (Pep C), while the other expressed only Pep C. Cytogenetic analysis showed that the subclones expressing all three markers carried the normal human chromosome one, while those expressing only Pep C carried the deleted chromosome. These data indicate that the human gene loci PGM1 and 6PGD are located on the short arm of chromosome one distal to the break point, while Pep C lies elsewhere on the chromosome. Images

Douglas, George R.; McAlpine, Phyllis J.; Hamerton, John L.

1973-01-01

167

Exaggerated triglyceride accretion in human preadipocyte-murine renal line hybrids composed of cells from massively obese subjects.  

PubMed Central

To learn about adipose differentiation of precursors from postnatal adipose tissue of lean and massively obese subjects, human omental adipocyte precursor-murine renal adenocarcinoma cell (RAG) hybrids were formed by fusion with polyethylene glycol, and cultured selectively with 50 microM ouabain in hypoxanthine aminopterin thymidine (HAT) medium. Under conditions in which the parent cells did not differentiate, a number of hybrids, which were cloned, revealed morphologic and biochemical evidence of differentiation. In addition to activation of human genes within the common nucleus of the hybrids, murine cytoplasmic activators are probably also involved because heterocaryons (fused cells with two interspecific nuclei) revealed the same phenomenon. Hybrids composed of precursors from massively obese subjects disclosed more frequent and prominent differentiation. Since these hybrids, in contrast to those from the lean, recapitulate this phenomenon in subcultures, they provide the potential system for mapping the human gene(s) responsible for adipose differentiation and its exaggeration in massive obesity. Images

Le Blanc, P E; Roncari, D A; Hoar, D I; Adachi, A M

1988-01-01

168

Metabolite target analysis of human urine combined with pattern recognition techniques for the study of symptomatic gout.  

PubMed

Recurrent attacks and irregularity are two important characteristics of gout disease. Uric acid as a single evaluation indicator for clinical diagnosis is insufficient considering the versatile properties of gout. The aim of this work is to identify several endogenous metabolites from urine samples for the elucidation and prediction of gout disease. Metabolite target analysis was established for human urine by high performance liquid chromatography-diode array detection (HPLC-DAD). The targeted metabolites selected included hippuric acid, uracil, phenylalanine, tryptophan, uric acid and creatinine as well as nine purine compounds. Useful information was extracted from multivariate data through Fisher Linear Discriminant Analysis (FDA) and Orthogonal Signal Correction Partial Least Squares Discriminant Analysis (OSC-PLS-DA). Uric acid, hypoxanthine, xanthosine, guanosine, inosine and tryptophan were identified as important metabolites among the acute and chronic gout and controls. Based on OSC-PLS-DA models, the regression equations obtained could discriminate gout from the controls as well as the acute from chronic. The recognition and prediction ability is respectively 100% and 85.0% for the gout, 100% and 83.3% for the acute, and 90.91% and 89.9% for the chronic. Metabolic dysfunction of tryptophan and excessive metabolism of xanthosine and hypoxanthine to xanthine were confirmed for gout disease. Metabolic dysfunction of tryptophan was also proven to be induced by allopurinol in case of Kunming mice with hyperuricemia. Potential biomarkers can be used not only to distinguish gout patients from healthy people, but also to evaluate the disease state. PMID:22932763

Liu, Yun; Yu, Pinhua; Sun, Xiaoming; Di, Duolong

2012-11-01

169

Gender- and age-dependent changes in nucleoside levels in the cerebral cortex and white matter of the human brain.  

PubMed

Nucleosides are neuromodulators that participate in various neuronal functions in the brain. In previous studies, we described regional differences in the concentrations of nucleosides and their derivatives in the human brain. To better understand the functions of nucleosides in the central nervous system, we investigated gender- and age-dependent changes in the levels of nucleosides and their metabolites. The concentrations of uridine, inosine, guanosine and adenosine as well as uracil, hypoxanthine and xanthine were measured in the frontal cortex and white matter of post-mortem brain tissue samples of middle-aged and old men as well as women. The average in vivo concentrations calculated from the 40 samples investigated (regardless of anatomical locations, gender or age; mean +/- S.E.M.) were as follows (pmol/mg wet tissue weight): 9.7 +/- 0.8 adenosine, 85.8 +/- 3.9 inosine, 14.3 +/- 0.9 guanosine, 37.3 +/- 1.8 uridine, 8.9 +/- 0.6 uracil, 63.3 +/- 2.1 hypoxanthine and 38.7 +/- 1.5 xanthine. We conclude that concentration differences between uridine, inosine, guanosine and adenosine in the frontal cortex and cerebral white matter suggest that nucleoside metabolism is altered with aging and regulated differently between men and women. PMID:19853023

Kovács, Zsolt; Juhász, Gábor; Dobolyi, Arpád; Bobest, Mátyás; Papp, Vilmos; Takáts, Lajos; Kékesi, Katalin A

2010-04-01

170

Mouse transgenes in human cells detect specific base substitutions  

SciTech Connect

The authors describe a system of transgenic human cell lines that detects and identifies specific point mutations at defined positions within a gene. The target transgenome is a mouse adenine phosphoribosyltransferase (APRT) gene rendered nonfunctional by introduction of a substitution at either of two bases that comprise a splice acceptor site. Reversion at a mutated site results in the expression of wild-type mouse APRT and consequent growth of APRT{sup +} transgenic cell colonies. Site-specific reversion to wild-type sequence is confirmed by regeneration of a previously destroyed diagnostic Pst I site. Two independent cell clones, each with mutant transgenomes bearing an A {yields} G transition, exhibited an up to 7,500-fold, dose-dependent induction of reversion following treatment with ethyl methanesulfonate. Treatment of these clones with 2-aminopurine resulted in no induction of revertants. In contrast, another transgenic cell clone, bearing a G {yields} A transition, reverted as a consequence of 2-aminopurine, but not ethyl methanesulfonate, treatment. These data confirm for human cells the proposed mechanisms of action of these mutagens and provide evidence for the utility of their site-specific reversion method for mutagenesis studies.

Schaff, D.A.; Ponniah, S.; Stockelman, M.; Stambrook, P.J. (Univ. of Cincinnati, OH (United States)); Jarrett, R.A.; Dlouhy, S.R.; Tischfield, J.A. (Indiana Univ., Indianapolis (United States))

1990-11-01

171

Determination of the mechanism of free radical generation in human aortic endothelial cells exposed to anoxia and reoxygenation.  

PubMed

Endothelial cell-derived oxygen free radicals are important mediators of postischemic injury; however, the mechanisms that trigger this radical generation are not known, and it is not known if this process can occur in human cells and tissues. The enzyme xanthine oxidase can be an important source of radical generation; however, it has been reported that this enzyme may not be present in human endothelium. To determine the presence and mechanisms of radical generation in human vascular endothelial cells subjected to anoxia and reoxygenation, electron paramagnetic resonance measurements were performed on cultured human aortic endothelial cells using the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO). These measurements were correlated with cellular injury, xanthine oxidase activity, and alterations in cellular nucleotides. Upon reoxygenation after 60 min of anoxia, large DMPO-OH (aN = aH = 14.9 G) and smaller DMPO-R (aN = 15.8 G, aH = 22.8 G) signals were seen. Superoxide dismutase totally quenched this radical generation. The ferric iron chelator deferoxamine prevented cell death and totally quenched the DMPO-R signal with a 40% decrease in the DMPO-OH signal. Xanthine oxidase was shown to be present in these cells and to be the primary source of free radicals. While the concentration of this enzyme did not change after anoxia, the concentration of its substrate, hypoxanthine, markedly increased, resulting in increased free radical generation upon reoxygenation. Thus, reoxygenated human vascular endothelial cells generate superoxide free radicals, which further react with iron to form the reactive hydroxyl radical, which in turn causes cell death. Xanthine oxidase was the primary source of radical generation with this process triggered by the breakdown of ATP to the substrate hypoxanthine during anoxia. PMID:7929072

Zweier, J L; Broderick, R; Kuppusamy, P; Thompson-Gorman, S; Lutty, G A

1994-09-30

172

Adenosine transport in peripheral blood lymphocytes from Lesch-Nyhan patients.  

PubMed Central

We postulated that adenosine function could be related to some of the neurological features of Lesch-Nyhan syndrome and therefore characterized adenosine transport in PBLs (peripheral blood lymphocytes) obtained from Lesch-Nyhan patients (PBL(LN)) and from controls (PBL(C)). Adenosine transport was significantly lower in PBL(LN) when compared with that in PBL(C) and a significantly lower number of high affinity sites for [(3)H]nitrobenzylthioinosine binding were quantified per cell ( B (max)) in PBL(LN) when compared with that in PBL(C). After incubation with 25 microM hypoxanthine, adenosine transport was significantly decreased in PBL(LN) with respect to PBL(C). Hypoxanthine incubation lowers [(3)H]nitrobenzylthioinosine binding in PBL(C), with respect to basal conditions, but does not affect it in PBL(LN). This indicates that hypoxanthine affects adenosine transport in control and hypoxanthine-guanine phosphoribosyltransferase-deficient cells by different mechanisms.

Torres, Rosa J; Deantonio, Isabel; Prior, Carmen; Puig, Juan G

2004-01-01

173

Sialidosis and galactosialidosis: chromosomal assignment of two genes associated with neuraminidase-deficiency disorders.  

PubMed Central

The inherited human disorders sialidosis and galactosialidosis are the result of deficiencies of glycoprotein-specific alpha-neuraminidase (acylneuraminyl hydrolase, EC 3.2.1.18; sialidase) activity. Two genes were determined to be necessary for expression of neuraminidase by using human-mouse somatic cell hybrids segregating human chromosomes. A panel of mouse RAG-human hybrid cells demonstrated a single-gene requirement for human neuraminidase and allowed assignment of this gene to the (pter----q23) region of chromosome 10. A second panel of mouse thymidine kinase (TK)-deficient LM/TK- -human hybrid cells demonstrated that human neuraminidase activity required both chromosomes 10 and 20 to be present. Analysis of human neuraminidase expression in interspecific hybrid cells or polykaryocytes formed from fusion of mouse RAG (hypoxanthine/guanine phosphoribosyltransferase deficient) or LM/TK- cell lines with human sialidosis or galactosialidosis fibroblasts indicated that the RAG cell line complemented the galactosialidosis defect, but the LM/TK- cell line did not. This eliminates the requirement for this gene in RAG-human hybrid cells and explains the different chromosome requirements of these two hybrid panels. Fusion of LM/TK- cell hybrids lacking chromosome 10 or 20 (phenotype 10+,20- and 10-,20+) and neuraminidase-deficient fibroblasts confirmed by complementation analysis that the sialidosis disorder results from a mutation on chromosome 10, presumably encoding the neuraminidase structural gene. Galactosialidosis is caused by a mutation in a second gene required for neuraminidase expression located on chromosome 20.

Mueller, O T; Henry, W M; Haley, L L; Byers, M G; Eddy, R L; Shows, T B

1986-01-01

174

Clinical and biochemical manifestations and molecular characterization of the mutation HPRT Jerusalem.  

PubMed

A novel point mutation (I137T) was identified in the hypoxanthine-guanine phosphoribosyltransferase (HPRT) encoding gene, in a patient with partial deficiency of the enzyme. The mutation, ATT to ACT (substitution of isoleucine to threonine), occurred at codon 137, which is within the region encoding the binding site for 5-phosphoribosyl-1-pyrophosphate (PRPP). The mutation caused decreased affinity for PRPP, manifested clinically as a Lesch-Nyhan variant (excessive purine production and delayed acquisition of language skills). The partial HPRT deficiency could be detected only by measuring HPRT activity in intact fibroblasts (uptake of hypoxanthine into nucleotides). PMID:15571222

Zoref-Shani, E; Bromberg, Y; Hirsch, J; Feinstein, S; Frishberg, Y; Sperling, O

2004-10-01

175

Adenoviruses Encoding HPRT Correct Biochemical Abnormalities of HPRT-Deficient Cells and Allow Their Survival in Negative Selection Medium  

Microsoft Academic Search

The Lesch-Nyhan syndrome is an X-linked disorder caused by a virtually complete absence of the key enzyme of purine recycling, hypoxanthine-guanine phosphoribosyltransferase (HPRT). It is characterized by uric acid overproduction and severe neurological dysfunction. No treatment is yet available for the latter symptoms. A possible long-term solution is gene therapy, and recombinant adenoviruses have been proposed as vectors for gene

Thomas D. Southgate; Derek Bain; Lynette D. Fairbanks; Adrian E. Morelli; Adriana T. Larregina; H. Anne Simmonds; Maria G. Castro; Pedro R. Löwenstein

1999-01-01

176

Cotransfer and phenotypic stabilisation of syntenic and asyntenic mink genes into mouse cells by chromosome-mediated gene transfer  

Microsoft Academic Search

By means of metaphase chromosomes, the genes for mink thymidine kinase (TK) and hypoxanthine-phosphoribosyltransferase (HPRT) were transferred to mutant mouse cells, LMTK-, A9 (HPRT-) and teratocarcinoma cells, PCC4-aza 1 (HPRT-). Eighteen colonies were isolated from LMTK- (series A), 9 from A9 (series B) and none from PCC4-aza 1. The transformed clones contained mink TK or HPRT. Analysis of syntenic markers

M. A. Sukoyan; N. M. Matveeva; N. D. Belyaev; S. D. Pack; A. A. Gradov; A. G. Shilov; N. S. Zhdanova; O. L. Serov

1984-01-01

177

Molecular Structure of 6-Mercaptopurine  

NSDL National Science Digital Library

Gertrude B. Elion invented 6-mercaptopurine (6MP) in 1954 as a leukemia-fighting drug while she was working on antagonists of nucleic acid building blocks. 6MP is converted to thioinosinic acid by the enzyme hypoxanthine-guanine phosphoribosyltransferase, thus inhibiting RNA synthesis. Mercaptopurine is a drug that is used to treat certain types of cancer and leukemia. There are many side effects to this drug such as reduction of bone marrow, liver function, ulcers, and diarrhea.

2002-09-12

178

Mutation analysis and prenatal diagnosis in a Lesch-Nyhan family showing non-random X-inactivation interfering with carrier detection tests  

Microsoft Academic Search

A nonsense mutation at the CpG-site in the codon for Arg(169) in the gene for hypoxanthine phosphoribosyltransferase (hprt) was identified by genomic polymerase chain reaction (PCR) and DNA sequencing in cultured fibroblasts from two brothers with Lesch Nyhan's syndrome. The recurrence of mutation at this CpG-site in several unrelated Lesch-Nyhan families suggests that deamination of 5-methylcytosine is a possible mechanism

Suzanne Marcus; Ann-Marie Steen; Björn Andersson; Bo Lambert; Ulf Kristoffersson; Uta Francke

1992-01-01

179

Clusters of CpG dinucleotides implicated by nuclease hypersensitivity as control elements of housekeeping genes  

Microsoft Academic Search

DNA sequences of the X-chromosome-linked hypoxanthine phos-phoribosyltransferase (HPRT) and glucose 6-phosphate dehydrogenase (G6PD) genes have revealed the presence of clusters of CpG dinucleotides1-3, raising the possibility that such clusters are involved in the control of expression of these genes, which are expressed in all tissues. Although CpG clusters are not exclusive features of the X chromosome4-6, the analysis of X-linked

Stanley F. Wolf; Barbara R. Migeon

1985-01-01

180

Multipoint linkage mapping of the Xq25-q26 region in a family affected by the X-linked lymphoproliferative syndrome.  

PubMed

We have performed, in a large Swiss family, a study of linkage between various DNA markers in the Xq24-27 region and the locus for the X-linked lymphoproliferative syndrome (XLP). Our results indicated that the marker DXS37 in Xq25-q26 is genetically linked to the XLP syndrome. The multipoint linkage analysis showed that the disease locus is distal to DXS11, but proximal to the hypoxanthine phosphoribosyl-transferase gene (HPRT). PMID:2574086

Sylla, B S; Wang, Q; Hayoz, D; Lathrop, G M; Lenoir, G M

1989-12-01

181

The biochemical basis of the neurobehavioral abnormalities in the Lesch–Nyhan syndrome: a hypothesis  

Microsoft Academic Search

Lesch–Nyhan syndrome (LNS) is a rare X-recessive disorder that leads to virtually complete deficiency of the purine salvage enzyme hypoxanthine–guanine phosphoribosyltransferase (HPRT). Partial HPRT deficiency results in uric acid overproduction with subsequent hyperuricemia, nephrolithiasis, renal failure and gouty arthritis. In contrast, at complete HPRT deficiency, besides overproduction of uric acid neurological problems appear including spasticity, choreoathetosis, mental retardation, and compulsive

Vladimir Kostadinov Neychev; Vanyo Ivano Mitev

2004-01-01

182

Proinflammatory and Immunomodulatory Cytokine mRNA Time Course Profiles in Hamsters Infected with a Virulent Variant of Leptospira interrogans  

Microsoft Academic Search

In order to quantify in vivo the mRNAs of cytokines which play important roles in leptospirosis, we have developed quantitative real-time PCR assays for interleukin-2 (IL-2), IL-4, IL-10, IL-12p40, tumor necrosis factor alpha (TNF-), gamma interferon (IFN-), transforming growth factor , and two housekeeping genes (encoding -actin and hypoxanthine phosphoribosyltransferase). We used a lethal hamster model reflecting severe leptospirosis in

Frederique Vernel-Pauillac; Fabrice Merien

2006-01-01

183

68 FR 32232 - Oral Health Care Drug Products for Over-the-Counter Human Use; Antigingivitis/Antiplaque Drug...  

Federal Register 2010, 2011, 2012, 2013

...phosphoribosyltransferase (HGPRT) forward gene mutation assay and unscheduled...Carpenter, ``The RecA+ Gene Product is More Important...Embryonic Fibroblasts,'' Mutation Research, 172:245-253...Mammalian Cell Forward Gene Mutation Assay,''...

2003-05-29

184

Proteomic analysis of human macrophages exposed to hypochlorite-oxidized low-density lipoprotein.  

PubMed

The invasion of monocytes through the endothelial wall of arteries and their transformation from macrophage into form cells has been implicated as a critical initiating event in atherogenesis. Human THP-1 monocytic cells can be induced to differentiate into macrophages by phorbol myristate acetate (PMA) treatment, and can be converted into foam cells by exposure to oxidized low-density lipoprotein (oxLDL). To identify proteins potentially involved in atherosclerotic processes, we performed a proteomic analysis of THP-1 macrophages exposed to oxLDL generated by treatment with native LDL with hypochlorous acid/hypochlorite (HOCl/OCl(-)). We detected more than a thousand proteins, of which 104 differentially expressed proteins were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) and the NCBI database. The largest differences in expression were observed for bifunctional purine biosynthesis protein, vacuolar protein sorting 33A, breast carcinoma amplified sequence, adenine phosphoribosyltransferase, and tropomyosin alpha 3 chain. Interestingly, many apoptotic proteins such as lamin B1, poly (ADP-ribose) polymerase, Bcl-2 related protein A1 and vimentin were identified by MALDI-TOF analysis. Identities were confirmed by matching the sequence of several tryptic peptides using MALDI-TOF/TOF MS, Western blot analyses and immunofluorescent microscopy. The data described here will contribute to establishing a functional profile of the human macrophage proteome. Furthermore, the proteins identified in this study are attractive candidates for further biomarkers involved in the pathogenesis of atherosclerosis. PMID:19103313

Kang, Jeong Han; Ryu, Hyun Su; Kim, Hyun Tae; Lee, Su Jin; Choi, Ung-Kyu; Park, Yong Bok; Huh, Tae-Lin; Choi, Myung-Sook; Kang, Tae-Cheon; Choi, Soo Young; Kwon, Oh-Shin

2009-03-01

185

Isolation and characterization of a new mutant human cell line unresponsive to alpha and beta interferons.  

PubMed Central

Previously we described human cell line 2fTGH, in which expression of guanine phosphoribosyltransferase is tightly controlled by the upstream region of interferon (IFN)-stimulated human gene 6-16. After mutagenesis of 2fTGH and selection with 6-thioguanine and IFN-alpha, we isolated 11.1, a recessive mutant that does not respond to IFN-alpha. We now describe U2, a second recessive mutant, selected similarly, that complements 11.1. U2 had no response to IFN-alpha or IFN-beta, and its response to IFN-gamma was partially defective. Although many genes did respond to IFN-gamma in U2, the 9-27 gene did not and the antiviral response of U2 cells to IFN-gamma was greatly reduced. Band shift assays showed that none of the transcription factors normally induced in 2fTGH cells by IFN-alpha (E and M) or IFN-gamma (G) were induced in U2. However, extracts of untreated U2 cells gave rise to a novel band that was increased by treatment with IFN-gamma but not IFN-alpha. Band shift complementation assays revealed that untreated and IFN-gamma-treated U2 cells lack the functional E gamma subunit of transcription factor E and that IFN-alpha-treated U2 cells do contain the functional E alpha subunit. Images

John, J; McKendry, R; Pellegrini, S; Flavell, D; Kerr, I M; Stark, G R

1991-01-01

186

Skeletal muscle NAMPT is induced by exercise in humans.  

PubMed

In mammals, nicotinamide phosphoribosyltransferase (NAMPT) is responsible for the first and rate-limiting step in the conversion of nicotinamide to nicotinamide adenine dinucleotide (NAD+). NAD+ is an obligate cosubstrate for mammalian sirtuin-1 (SIRT1), a deacetylase that activates peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), which in turn can activate mitochondrial biogenesis. Given that mitochondrial biogenesis is activated by exercise, we hypothesized that exercise would increase NAMPT expression, as a potential mechanism leading to increased mitochondrial content in muscle. A cross-sectional analysis of human subjects showed that athletes had about a twofold higher skeletal muscle NAMPT protein expression compared with sedentary obese, nonobese, and type 2 diabetic subjects (P < 0.05). NAMPT protein correlated with mitochondrial content as estimated by complex III protein content (R(2) = 0.28, P < 0.01), MRS-measured maximal ATP synthesis (R(2) = 0.37, P = 0.002), and Vo(2max) (R(2) = 0.63, P < 0.0001). In an exercise intervention study, NAMPT protein increased by 127% in sedentary nonobese subjects after 3 wk of exercise training (P < 0.01). Treatment of primary human myotubes with forskolin, a cAMP signaling pathway activator, resulted in an approximately 2.5-fold increase in NAMPT protein expression, whereas treatment with ionomycin had no effect. Activation of AMPK via AICAR resulted in an approximately 3.4-fold increase in NAMPT mRNA (P < 0.05) as well as modest increases in NAMPT protein (P < 0.05) and mitochondrial content (P < 0.05). These results demonstrate that exercise increases skeletal muscle NAMPT expression and that NAMPT correlates with mitochondrial content. Further studies are necessary to elucidate the pathways regulating NAMPT as well as its downstream effects. PMID:19887595

Costford, Sheila R; Bajpeyi, Sudip; Pasarica, Magdalena; Albarado, Diana C; Thomas, Shantele C; Xie, Hui; Church, Timothy S; Jubrias, Sharon A; Conley, Kevin E; Smith, Steven R

2010-01-01

187

Xenobiotic metabolism and mutation in a human lymphoblastoid cell line.  

PubMed

Aryl hydrocarbon hydroxylase-1 (AHH-1) cells are a human lymphoblastoid cell line competent in some aspects of xenobiotic metabolism. This cell line contains stable mixed function oxidase activity which is inducible by polycyclic aromatic hydrocarbons (PAHs) but not by phenobarbital or Arochlor 1254. Two substrates for the cellular mixed function oxidase activity, benzo[a]pyrene (B[a]P) and 7-ethoxyresorufin, have been examined. The basal and induced activities have different kinetic parameters toward these two substrates. In contrast, basal and induced activities had similar sensitivities to two cytochrome P-450 suicide substrates. B[a]P metabolism and mutagenicity were studied in this cell line. AHH-1 cells were found to produce predominantly B[a]P phenols and quinones. The major phenol metabolite cochromatographed with authentic 9-hydroxy B[a]P. AHH-1 cells were capable of forming glucuronic acid conjugates of B[a]P phenols; the major product after hydrolysis cochromatographed with 3-hydroxy B[a]P standard. AHH-1 cells did not contain detectable epoxide hydrolase activity using B[a]P-4,5-oxide as substrate. This observation is consistent with the absence of trans-dihydrodiol B[a]P metabolites in the metabolic profile. B[a]P-induced mutagenicity at the hypoxanthine guanine phosphoribosyl transferase (hgprt) locus in AHH-1 cells was found to be linearly related to phenol production during treatment and inhibited by alpha-naphthoflavone (ANF). PMID:4006009

Crespi, C L; Altman, J D; Marletta, M A

1985-05-01

188

Characterization of a human antigen specific helper factor  

SciTech Connect

While antigen (Ag) specific helper factors have been characterized in mice, similar molecules have not been identified in humans. To characterize human antigen specific helper molecules, an IL-2 dependent tetanus toxoid (T.T.) reactive T cell line was fused with a 6-thioguanine resistant CEM line, and hybrids selected in medium containing hypoxanthine and azaserine. Hybrids were screened by culturing the cells with /sup 35/S-Met then reacting the supernatants with T.T. or hepatitis vaccine immobilized on nitrocellulose. One hybrid, TT6BA-O, was identified which secreted a Met-containing molecule which bound T.T. but not hepatitis vaccine. Supernatants from TT6BA-O, but not the parent CEM line, when added to autologous peripheral blood mononuclear cells (PBMC's) stimulated secretion of T.T. specific antibodies (Abs). Specificity controls demonstrated that TT6BA-O supernatant did not induce antibodies to diphtheria toxoid, hepatitis vaccine or pneumococcal polysaccharide, and total immunoglobulin (lg) synthesis was minimally increased. In contrast, pokeweed mitogen stimulated significant lg synthesis as well as Ab's to pneumococcal polysaccharide and T.T. TT6BA-O supernatant induced anti-T.T.Ab's in autologous PBMC's but not PBMC's from 3 unrelated donors, suggesting that the activity of the helper factor is restricted, possibly by the MHC. The molecular weight of the helper factor was estimated at 100,000-150,000 by Sephacryl S-300 chromatography. Finally, the helper factor could be demonstrated to bind and elute from sephorose-immobilized T.T. and anti-DR antisera, but not anti-lg antisera or the T40/25 monoclonal antibody, which binds a nonpolymorphic determinant on the human T cell receptor. These results demonstrate that human Ag specific helper factors exist, bind antigen and bear class II MHC determinants.

Richardson, B.

1986-03-01

189

Efficient delivery of RNA interference oligonucleotides to polarized airway epithelia in vitro.  

PubMed

Polarized and pseudostratified primary airway epithelia present barriers that significantly reduce their transfection efficiency and the efficacy of RNA interference oligonucleotides. This creates an impediment in studies of the airway epithelium, diminishing the utility of loss-of-function as a research tool. Here we outline methods to introduce RNAi oligonucleotides into primary human and porcine airway epithelia grown at an air-liquid interface and difficult-to-transfect transformed epithelial cell lines grown on plastic. At the time of plating, we reverse transfect small-interfering RNA (siRNA), Dicer-substrate siRNA, or microRNA oligonucleotides into cells by use of lipid or peptide transfection reagents. Using this approach we achieve significant knockdown in vitro of hypoxanthine-guanine phosphoribosyltransferase, IL-8, and CFTR expression at the mRNA and protein levels in 1-3 days. We also attain significant reduction of secreted IL-8 in polarized primary pig airway epithelia 3 days posttransfection and inhibition of CFTR-mediated Cl? conductance in polarized air-liquid interface cultures of human airway epithelia 2 wk posttransfection. These results highlight an efficient means to deliver RNA interference reagents to airway epithelial cells and achieve significant knockdown of target gene expression and function. The ability to reliably conduct loss-of-function assays in polarized primary airway epithelia offers benefits to research in studies of epithelial cell homeostasis, candidate gene function, gene-based therapeutics, microRNA biology, and targeting the replication of respiratory viruses. PMID:23624792

Ramachandran, Shyam; Krishnamurthy, Sateesh; Jacobi, Ashley M; Wohlford-Lenane, Christine; Behlke, Mark A; Davidson, Beverly L; McCray, Paul B

2013-07-01

190

Characterization of human hybridomas secreting antibody to tetanus toxoid.  

PubMed Central

We have selected a thioguanine-resistant lymphoblastoid cell line (LTR228) that forms human-human hybrids with high efficiency. Fusions with peripheral B cells consistently yield one colony per 10(5) cells plated. To produce antitetanus monoclonal antibodies, we withdrew blood from persons who had recently received booster injections of tetanus toxoid. T cells were separated from peripheral mononuclear cells by 2-aminoethylisothiouronium bromide-induced rosette formation, given 1,500 rads (1 rad = 0.01 gray), and cultured in a 1:1 ratio with nonrosetting cells. After 3 days of pokeweed mitogen stimulation, heterokaryons were produced by a plate-fusion technique and cultured in Iscove's Dulbecco's minimal essential medium for 24 hr prior to hybrid selection. Colonies appeared after 10-14 days in hypoxanthine/azaserine supplemented medium. A direct binding enzyme-linked immunosorbent assay with specific tetanus toxoid inhibition identified positive wells. The hybridomas were cloned twice in soft agarose and by limiting dilution. The subcloned hybridomas double every 26 hr (vs. every 16 hr for LTR228) and produce 1-5 micrograms of specific IgG, kappa antibody per 10(6) cells per ml per 24 hr. All subclones (almost 200) continue to secrete antibody after 11 months of continuous culture. Twelve representative subclones have near tetraploid amounts of DNA. From hybridomas grown in 5-liter spinner flasks, milligram quantities of the IgG, kappa antibody were purified by staphylococcus protein A affinity chromatography. Specific antibody from hybridoma cultures protected mice injected with 1,000 times the LD50 of tetanus toxin. Our cell line and associated techniques should permit the production of therapeutically important human monoclonal antibodies. Images

Larrick, J W; Truitt, K E; Raubitschek, A A; Senyk, G; Wang, J C

1983-01-01

191

The human T-cell cloning assay: identifying genotypes susceptible to drug toxicity and somatic mutation.  

PubMed

Humans exhibit marked genetic polymorphisms in drug metabolism that contribute to high incidence of adverse effects in susceptible individuals due to altered balance between metabolic activation and detoxification. The T-cell cloning assay, which detects mutations in the gene for hypoxanthine-guanine phosphoribosyl transferase (HPRT), is the most well-developed reporter system for studying specific locus mutation in human somatic cells. The assay is based on a mitogen- and growth factor-dependent clonal expansion of peripheral T-lymphocytes in which the 6-thioguanine-resistant HPRT mutants can be selected, enumerated, and collected for molecular analysis of the mutational nature. The assay provides a unique tool for studying in vivo and in vitro mutagenesis, for investigating the functional impact of common polymorphism in metabolism and repair genes, and for identifying risk genotypes for drug-induced toxicity and mutagenicity. This chapter presents a simple and reliable method for the enumeration of HPRT mutant frequency induced in vitro without using any source of recombinant interleukin-2. The other main feature is that only truly induced and unique mutants are collected for further analysis. PMID:24623236

Hou, Sai-Mei

2014-01-01

192

Metabolism and Selective Toxicity of 6-Nitrobenzylthioinosine in Toxoplasma gondii  

PubMed Central

The purine nucleoside analogue NBMPR {nitrobenzylthioinosine or 6-[(4-nitrobenzyl)thio]-9-?-d-ribofuranosylpurine} was selectively phosphorylated to its nucleoside 5?-monophosphate by Toxoplasma gondii but not mammalian adenosine kinase (EC 2.7.1.20). NBMPR was also cleaved in toxoplasma to its nucleobase, nitrobenzylmercaptopurine. However, nitrobenzylmercaptopurine was not a substrate for either adenosine kinase or hypoxanthine-guanine-xanthine phosphoribosyltransferase (EC 2.4.2.8). Because of this unique and previously unknown metabolism of NBMPR by the parasite, the effect of NBMPR as an antitoxoplasmic agent was tested. NBMPR killed T. gondii grown in human fibroblasts in a dose-dependent manner, with a 50% inhibitory concentration of approximately 10 ?M and without apparent toxicity to host cells. Doses of up to 100 ?M had no significant toxic effect on uninfected host cells. The promising antitoxoplasmic effect of NBMPR led to the testing of other 6-substituted 9-?-d-ribofuranosylpurines, which were shown to be good ligands of the parasite adenosine kinase (M. H. Iltzsch, S. S. Uber, K. O. Tankersley, and M. H. el Kouni, Biochem. Pharmacol. 49:1501–1512, 1995), as antitoxoplasmic agents. Among the analogues tested, 6-benzylthioinosine, p-nitrobenzyl-6-selenopurine riboside, N6-(p-azidobenzyl)adenosine, and N6-(p-nitrobenzyl)adenosine, like NBMPR, were selectively toxic to parasite-infected cells. Thus, it appears that the unique characteristics of purine metabolism in T. gondii render certain 6-substituted 9-?-d-ribofuranosylpurines promising antitoxoplasmic drugs.

el Kouni, Mahmoud H.; Guarcello, Vincenzo; Al Safarjalani, Omar N.; Naguib, Fardos N. M.

1999-01-01

193

A cDNA cloning vector that permits expression of cDNA inserts in mammalian cells.  

PubMed Central

This paper describes a plasmid vector for cloning cDNAs in Escherichia coli; the same vector also promotes expression of the cDNA segment in mammalian cells. Simian virus 40 (SV40)-derived DNA segments are arrayed in the pcD vector to permit transcription, splicing, and polyadenylation of the cloned cDNA segment. A DNA fragment containing both the SV40 early region promoter and two introns normally used to splice the virus 16S and 19S late mRNAs is placed upstream of the cDNA cloning site to ensure transcription and splicing of the cDNA transcripts. An SV40 late region polyadenylation sequence occurs downstream of the cDNA cloning site, so that the cDNA transcript acquires a polyadenylated 3' end. By using pcD-alpha-globin cDNA as a model, we confirmed that the alpha-globin transcript produced in transfected cells is initiated correctly, spliced at either of the two introns, and polyadenylated either at the site coded in the cDNA segment or at the distal SV40 polyadenylation signal. A cDNA clone library constructed with mRNA from SV40-transformed human fibroblasts and this vector (about 1.4 X 10(6) clones) yielded full-length cDNA clones that express hypoxanthine-guanine phosphoribosyltransferase (Jolly et al., Proc. Natl. Acad. Sci. U.S.A., in press). Images

Okayama, H; Berg, P

1983-01-01

194

Expression of reference genes and T helper 17 associated cytokine genes in the equine intestinal tract.  

PubMed

There is accumulating evidence for the involvement of pro-inflammatory cytokines associated with a T helper 17 response in intestinal disorders such as inflammatory bowel disease (IBD) in humans. The involvement of interleukin (IL)-17 or IL-23 in equine IBD has not been studied and most gene expression studies in the equine intestine have been limited to the use of a single non-validated reference gene. In this study, expression of the reference gene candidates ?2 microglobulin (?2M), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), histone H2A type 1, hypoxanthine-guanine phosphoribosyltransferase (HPRT), 60S ribosomal protein L32 (RPL32), succinate dehydrogenase complex subunit A (SDHA) and transferrin receptor 1 protein coding (TFRC)in the equine intestine was evaluated by quantitative PCR. Three to four reference genes were adequate for normalisation of gene expression in the healthy duodenum, mid-jejunum, colon and rectum, although each segment required a unique combination of reference genes. No combination of the evaluated genes was optimal for the caecum and ileum. Another combination of reference genes (GAPDH, HPRT, RPL32 and SDHA) was optimal for normalisation of rectal samples from healthy and IBD-affected horses, indicating that reference genes should be re-evaluated if material from diseased specimens is analysed. Basal expression of IL-12p40, IL-17A and IL-23p19 was detected in each segment, which will enable gene expression studies of these cytokines by relative quantification. PMID:23810185

Hjertner, Bernt; Olofsson, Karin M; Lindberg, Ronny; Fuxler, Lisbeth; Fossum, Caroline

2013-09-01

195

Influence of DNA Repair on Nonlinear Dose-Responses for Mutation  

PubMed Central

Recent evidence has challenged the default assumption that all DNA-reactive alkylating agents exhibit a linear dose-response. Emerging evidence suggests that the model alkylating agents methyl- and ethylmethanesulfonate and methylnitrosourea (MNU) and ethylnitrosourea observe a nonlinear dose-response with a no observed genotoxic effect level (NOGEL). Follow-up mechanistic studies are essential to understand the mechanism of cellular tolerance and biological relevance of such NOGELs. MNU is one of the most mutagenic simple alkylators. Therefore, understanding the mechanism of mutation induction, following low-dose MNU treatment, sets precedence for weaker mutagenic alkylating agents. Here, we tested MNU at 10-fold lower concentrations than a previous study and report a NOGEL of 0.0075 µg/ml (72.8nM) in human lymphoblastoid cells, quantified through the hypoxanthine (guanine) phosphoribosyltransferase assay (OECD 476). Mechanistic studies reveal that the NOGEL is dependent upon repair of O6-methylguanine (O6MeG) by the suicide enzyme O6MeG-DNA methyltransferase (MGMT). Inactivation of MGMT sensitizes cells to MNU-induced mutagenesis and shifts the NOGEL to the left on the dose axis.

Johnson, George E.

2013-01-01

196

Sry-negative XX sex reversal in the American cocker spaniel dog.  

PubMed

The Sry gene product serves an important function in male sex determination through testis induction. However, testicular development has been reported in SRY-negative XX sex reversed humans. XX sex reversal of the American cocker spaniel, inherited as an autosomal recessive trait, may be a homolog of this disorder. The purpose of this study was to determine whether the Sry high mobility group (HMG) box is present in genomic DNA of affected dogs. Conserved Sry HMG box and hypoxanthine phosphoribosyltransferase (HPRT) sequences were used as primers in polymerase chain reactions. A 167 bp Y-specific canine Sry HMG box sequence was cloned from genomic DNA of normal male dogs. Internal primers generated a 104 bp Sry HMG box product from normal males, but not from females or XX sex reversed dogs. Parallel reactions generated an HPRT product from all dogs. Results indicate that the Sry HMG box is absent in genomic DNA of XX sex reversed dogs. We speculate that activation of the testis differentiation cascade in the absence of Sry in this model is due to a mutant autosomal gene. PMID:8588928

Meyers-Wallen, V N; Palmer, V L; Acland, G M; Hershfield, B

1995-07-01

197

The Human Homolog of Escherichia coli Endonuclease V Is a Nucleolar Protein with Affinity for Branched DNA Structures  

PubMed Central

Loss of amino groups from adenines in DNA results in the formation of hypoxanthine (Hx) bases with miscoding properties. The primary enzyme in Escherichia coli for DNA repair initiation at deaminated adenine is endonuclease V (endoV), encoded by the nfi gene, which cleaves the second phosphodiester bond 3? of an Hx lesion. Endonuclease V orthologs are widespread in nature and belong to a family of highly conserved proteins. Whereas prokaryotic endoV enzymes are well characterized, the function of the eukaryotic homologs remains obscure. Here we describe the human endoV ortholog and show with bioinformatics and experimental analysis that a large number of transcript variants exist for the human endonuclease V gene (ENDOV), many of which are unlikely to be translated into functional protein. Full-length ENDOV is encoded by 8 evolutionary conserved exons covering the core region of the enzyme, in addition to one or more 3?-exons encoding an unstructured and poorly conserved C-terminus. In contrast to the E. coli enzyme, we find recombinant ENDOV neither to incise nor bind Hx-containing DNA. While both enzymes have strong affinity for several branched DNA substrates, cleavage is observed only with E. coli endoV. We find that ENDOV is localized in the cytoplasm and nucleoli of human cells. As nucleoli harbor the rRNA genes, this may suggest a role for the protein in rRNA gene transactions such as DNA replication or RNA transcription.

Laerdahl, Jon K.; Gran Neurauter, Christine; Heggelund, Julie E.; Thorgaard, Eirik; Str?m-Andersen, Pernille; Bj?ras, Magnar; Dalhus, Bj?rn; Alseth, Ingrun

2012-01-01

198

Development and characterization of a mouse cell line expressing the human V2 vasopressin receptor gene.  

PubMed

Human genomic DNA and the HSV tk gene were cotransfected into mouse Ltk- cells and assayed for the acquisition of a Gs-coupled receptor to obtain cell lines expressing human receptors that are so far unavailable. The transfected cells were distributed into 96-well microtitration plates at a density such that after HAT (100 microM hypoxanthine, 1 microM aminopterin, and 10 microM thymidine) selection each well contained, on the average, two to three tk+ cell clones. After replication, half of them were tested for expression of a new phenotype: an adenylyl cyclase stimulatory receptor not normally expressed in the Ltk- recipient cell. The screen yielded a positive result on testing cells arising from the third transfection, the newly expressed receptor is that for arginine vasopressin, commonly referred to as type 2 or V2. DNA from primary transformants (HTB-1 cells) served to obtain secondary transformants by the same technique (HTB-2 cells). Pharmacological properties confirmed that this new receptor, which stimulates adenylyl cyclase activity 7- to 10-fold, is the human V2 receptor and not the activated homologous murine gene. The new cell line provides a permanent accessible source to study the human receptor, by-passing the need for human kidneys. The V2 receptor was susceptible to homologous down-regulation in the HTB-2 cell, but no down-regulation of the cell authentic prostaglandin E1 receptor was observed. The vasopressin receptor did not modify phospholipase-C activity in these cells as expected from V2 receptors. Thus, we successfully applied genomic DNA-mediated gene transfer and were able to develop a cell line expressing a Gs-coupled human receptor of low abundance and poor accessibility. PMID:2139494

Birnbaumer, M; Hinrichs, V; Themmen, A P; Themen, A P

1990-02-01

199

Development and application of human cell lines engineered to metabolically activate structurally diverse environmental mutagens  

NASA Astrophysics Data System (ADS)

Cytochromes P450 are responsible for the mutagenic/carcinogenic activation of many environmental promutagens/procarcinogens. These enzymes are present at highest concentrations in liver in vivo but are markedly absent in tester organisms for most in vitro mutagenicity test systems. Two approaches have been used to supply needed metabolic activation, incorporation of an extracellular activating system, usually derived from a rodent liver and introduction of activating enzymes into the target cell. The latter approach appears to result in a more sensitive testing system because of the close proximity of the activating enzymes and the target DNA. Human cell lines have been developed which stably express human cytochromes P450 and other cDNAs which have been introduced individually or in combination. The resulting cell lines are exquisitely sensitive to exposure to promutagens and procarcinogens. Mutagenicity is measured at the hypoxanthine phosphoribosyl transferase (hprt) and thymidine kinase (tk) gene loci. The most versatile cell line, designated MCL-5, stably express five cDNAs encoding all of the human hepatic P450s known to be principally responsible for known human procarcinogen activation. The induction of mutation is observed in MCL-5 cells upon exposure to ng/ml levels of model compounds such as nitrosamines, aflatoxin B1 and benzo(a)pyrene. A lower volume mutagenicity assay has been developed for use with samples available in limited amounts. Human lymphoblast mutation assays have been used to screen for mutagenic activity sediment samples from a polluted watershed. Two sediment samples were found to have mutagenic activity to human lymphoblasts.

Crespi, C. I.; Langenbach, Robert; Gonzalez, Frank J.; Gelboin, Harry V.; Penman, B. W.

1993-03-01

200

Method for the production of human T-T cell hybrids and production suppressor factor by human T-T cell hybrids  

SciTech Connect

This patent describes a method for production of human T-T cell hybrids which produce Suppressor Factor wherein cells of lymphoid origin are fused with comprises: (a) mixing cells from a first parent cell line comprising a non-mutagenized Jurkat lymoblastoid T cell line, wherein the Jurkat lymphoblastoid cells are not sensitive and cannot be killed by hypoxanthine-aminopterin-thymidine medium, with a second parent cell comprising mitogen or alloantigen activated peripheral blood leukocyte T cells or purified T-cells, (b) allowing the first and second parent cells to fuse in the presence of polyethylene glycol for about 10-20 minutes with gentle agitation to generate hybrids in the cell mixture, (c) incubating the cell mixture containing the hybrids and the first and second parent cells, after removal of the polyethylene glycol, for periods of between one to sixty days at 37{sup 0} in 5% CO/sub 2/, (d) selecting for the hybrids by separating the hybrids from the first parent Jurkat lymphoblastoid cells by coloning in agar medium wherein the hybrids form colonies, (e) recovering the hybrids that form colonies in agar medium and expanding them in culture, and (f) determining the presence of Suppressor Factor in the culture and recovering the T-T cell hybrids which produce suppressor factor.

Platsoucas, C.

1989-06-27

201

Oral glycotoxins are a modifiable cause of dementia and the metabolic syndrome in mice and humans.  

PubMed

Age-associated dementia and Alzheimer's disease (AD) are currently epidemic. Neither their cause nor connection to the metabolic syndrome (MS) is clear. Suppression of deacetylase survival factor sirtuin 1 (SIRT1), a key host defense, is a central feature of AD. Age-related MS and diabetes are also causally associated with suppressed SIRT1 partly due to oxidant glycotoxins [advanced glycation end products (AGEs)]. Changes in the modern diet include excessive nutrient-bound AGEs, such as neurotoxic methyl-glyoxal derivatives (MG). To determine whether dietary AGEs promote AD, we evaluated WT mice pair-fed three diets throughout life: low-AGE (MG(-)), MG-supplemented low-AGE (MG(+)), and regular (Reg) chow. Older MG(+)-fed mice, similar to old Reg controls, developed MS, increased brain amyloid-?42, deposits of AGEs, gliosis, and cognitive deficits, accompanied by suppressed SIRT1, nicotinamide phosphoribosyltransferase, AGE receptor 1, and PPAR?. These changes were not due to aging or caloric intake, as neither these changes nor the MS were present in age-matched, pair-fed MG(-) mice. The mouse data were enhanced by significant temporal correlations between high circulating AGEs and impaired cognition, as well as insulin sensitivity in older humans, in whom dietary and serum MG levels strongly and inversely associated with SIRT1 gene expression. The data identify a specific AGE (MG) as a modifiable risk factor for AD and MS, possibly acting via suppressed SIRT1 and other host defenses, to promote chronic oxidant stress and inflammation. Because SIRT1 deficiency in humans is both preventable and reversible by AGE reduction, a therapeutic strategy that includes AGE reduction may offer a new strategy to combat the epidemics of AD and MS. PMID:24567379

Cai, Weijing; Uribarri, Jaime; Zhu, Li; Chen, Xue; Swamy, Shobha; Zhao, Zhengshan; Grosjean, Fabrizio; Simonaro, Calogera; Kuchel, George A; Schnaider-Beeri, Michal; Woodward, Mark; Striker, Gary E; Vlassara, Helen

2014-04-01

202

Proteomics analysis of differential expression of cellular proteins in response to avian H9N2 virus infection in human cells.  

PubMed

We present the first proteomic analysis on the cellular responses to avian influenza virus (H9N2) infection in a human cell line in different time courses in order to search for target proteins for viral pathogenesis/adaptation studies. By using 2-DE coupled with MALDI-TOF MS and nano-ESI-MS/MS, we identified a set of differentially expressed cellular proteins, including cytoplasmic actin, cytokeratin, prohibitin, enoyl-CoA hydratase, peptide-prolyl cis-trans isomerase A (PPIase A), chloride intracellular channel protein 1, pyruvate dehydrogenase E1 component subunit beta, adenine phosphoribosyltransferase, guanine nucleotide-binding protein subunit beta, nucleoside diphosphate kinase A, elongation factor 1-beta and splicing factor, arginine/serine rich 1. The most significant changes in different time courses were found in cytoplasmic actin and cytokeratin, both of which constituted the major components of cytoskeleton network in the cells. The obtained data suggested a possible role of the cytoskeleton during avian influenza virus infection of mammalian cells, which might help for better understanding of the dynamics of avian influenza virus and host interaction in mammalian cell setting. PMID:18398875

Liu, Ning; Song, Wenjun; Wang, Pui; Lee, Kimchung; Chan, Wan; Chen, Honglin; Cai, Zongwei

2008-05-01

203

Development and maintenance of bovine cytotoxic lymphocytes with recombinant human interleukin-2.  

PubMed Central

Long-term bovine lymphocyte cultures were initiated by stimulation with alloantigens and maintained in continuous culture using medium containing recombinant human interleukin-2 (rh IL-2). The development of specific and lectin-dependent killing was monitored following primary alloantigen challenge. Cytolytic activity was barely detectable after 7 days of culture, but gradually increased with peak activity occurring after 21 days of culture. A panel of monoclonal antibodies (MoAb) was used to determine whether a shift in the antigen phenotype of the cell population occurred during culture. The primary cell type that grew in culture was of the T-cell lineage with minimal or no expression of class II antigens. The activities of adenosine deaminase (ADA), purine nucleotide phosphorylase (PNP), adenosine kinase (AK), deoxyadenosine kinase (dAK), deoxycytidine kinase (dCK), 5'-nucleotidase (5'-N), AMP deaminase, hypoxanthine-guanine phosphoribosyl transferase (HGPRT or HPRT), and adenine phosphoribosyl transferase (APRT) were measured by microassay in resting peripheral blood lymphocytes (PBL) and in cells from long-term cultures. Large increases in the activities of PNP and HPRT with a decrease in the activity of ADA were observed. The data show that long-term cultures of lymphocytes can be readily generated, and that sequential changes in antigenic phenotype and function can be monitored and correlated with quantitative changes in enzyme activity. Images Figure 1

Carter, J; Magnuson, N S; Davis, W C; Mason, P H; Magnuson, J A; Talmadge, J E; Barr, P J

1986-01-01

204

Age-associated modifications of Base Excision Repair activities in human skin fibroblast extracts.  

PubMed

Base Excision Repair (BER) is the predominant repair pathway responsible for removal of so-called small DNA lesions such as abasic sites (AP site), uracil (U), 8-oxo-7,8-dihydroguanine (8oxoG), thymine glycol (Tg). In this study, we investigated effect of aging on excision efficacy of several endogenous base lesions and AP sites using an in vitro multiplexed fluorescent approach on support (parallelized oligonucleotide cleavage assay). Human fibroblasts nuclear extracts from 29 donors of different ages were characterized in their ability to simultaneously excise the different lesions. Clearly, three different groups of lesions emerged according to the efficiency of their cleavage: one exhibited very high cleavage efficiency (AP sites and U paired with G), one showed intermediate cleavage efficiency (U paired with A and Tg). The third group included 8oxoG, A paired with 8oxoG, T at CpG site and hypoxanthine (Hx) and displayed poor repair. Aging was significantly associated with modification of excision efficiency for AP sites, uracil, Tg and 8oxoG. Repair rate decreased for the first three lesions and the most drastic effects were observed for repair of U:A. Surprisingly, excision of 8oxoG increased with aging suggesting a completely different regulation or adaptation for the initiation step of this related specific repair pathway. PMID:20854835

Pons, Bénédicte; Belmont, Anne-Sophie; Masson-Genteuil, Gwénaëlle; Chapuis, Violaine; Oddos, Thierry; Sauvaigo, Sylvie

2010-01-01

205

NAD+ Levels Control Ca2+ Store Replenishment and Mitogen-induced Increase of Cytosolic Ca2+ by Cyclic ADP-ribose-dependent TRPM2 Channel Gating in Human T Lymphocytes*  

PubMed Central

Intracellular NAD+ levels ([NAD+]i) are important in regulating human T lymphocyte survival, cytokine secretion, and the capacity to respond to antigenic stimuli. NAD+-derived Ca2+-mobilizing second messengers, produced by CD38, play a pivotal role in T cell activation. Here we demonstrate that [NAD+]i modifications in T lymphocytes affect intracellular Ca2+ homeostasis both in terms of mitogen-induced [Ca2+]i increase and of endoplasmic reticulum Ca2+ store replenishment. Lowering [NAD+]i by FK866-mediated nicotinamide phosphoribosyltransferase inhibition decreased the mitogen-induced [Ca2+]i rise in Jurkat cells and in activated T lymphocytes. Accordingly, the Ca2+ content of thapsigargin-sensitive Ca2+ stores was greatly reduced in these cells in the presence of FK866. When NAD+ levels were increased by supplementing peripheral blood lymphocytes with the NAD+ precursors nicotinamide, nicotinic acid, or nicotinamide mononucleotide, the Ca2+ content of thapsigargin-sensitive Ca2+ stores as well as cell responsiveness to mitogens in terms of [Ca2+]i elevation were up-regulated. The use of specific siRNA showed that the changes of Ca2+ homeostasis induced by NAD+ precursors are mediated by CD38 and the consequent ADPR-mediated TRPM2 gating. Finally, the presence of NAD+ precursors up-regulated important T cell functions, such as proliferation and IL-2 release in response to mitogens.

Magnone, Mirko; Bauer, Inga; Poggi, Alessandro; Mannino, Elena; Sturla, Laura; Brini, Marisa; Zocchi, Elena; De Flora, Antonio; Nencioni, Alessio; Bruzzone, Santina

2012-01-01

206

An improved method for the determination of 5-phosphoribosyl 1-pyrophosphate.  

PubMed

A spectrophotometric method for the determination of 5-phosphoribosyl 1-pyrophosphate (PRPP) is presented which shows several advantages in comparison to the radiochemical techniques, such as a relatively simple, rapid and less expensive procedure. This technique has been used to evaluate PRPP content in erythrocytes, leukocytes and lymphocytes of normal subjects and individuals with partial hypoxanthine guanine phosphoribosyltransferase (EC 2.4.2.8) deficiency. The results obtained proved to be completely reliable in both groups of subjects examined, with values of PRPP similar to those observed by radiochemical techniques. PMID:1183052

Micheli, V; Pompucci, G; Marcolongo, R

1975-12-01

207

Biochemical characterization of an exonuclease from Arabidopsis thaliana reveals similarities to the DNA exonuclease of the human Werner syndrome protein.  

PubMed

The human Werner syndrome protein (hWRN-p) possessing DNA helicase and exonuclease activities is essential for genome stability. Plants have no homologue of this bifunctional protein, but surprisingly the Arabidopsis genome contains a small open reading frame (ORF) (AtWRNexo) with homology to the exonuclease domain of hWRN-p. Expression of this ORF in Escherichia coli revealed an exonuclease activity for AtWRN-exo-p with similarities but also some significant differences to hWRN-p. The protein digests recessed strands of DNA duplexes in the 3' --> 5' direction but hardly single-stranded DNA or blunt-ended duplexes. In contrast to the Werner exonuclease, AtWRNexo-p is also able to digest 3'-protruding strands. DNA with recessed 3'-PO4 and 3'-OH termini is degraded to a similar extent. AtWRNexo-p hydrolyzes the 3'-recessed strand termini of duplexes containing mismatched bases. AtWRNexo-p needs the divalent cation Mg2+ for activity, which can be replaced by Mn2+. Apurinic sites, cholesterol adducts, and oxidative DNA damage (such as 8-oxoadenine and 8-oxoguanine) inhibit or block the enzyme. Other DNA modifications, including uracil, hypoxanthine and ethenoadenine, did not inhibit AtWRNexo-p. A mutation of a conserved residue within the exonuclease domain (E135A) completely abolished the exonucleolytic activity. Our results indicate that a type of WRN-like exonuclease activity seems to be a common feature of the DNA metabolism of animals and plants. PMID:12937173

Plchova, Helena; Hartung, Frank; Puchta, Holger

2003-11-01

208

Human bites  

MedlinePLUS

Bites - human ... Human bites that break the skin, like all puncture wounds, have a high risk of infection. They ... bite to express anger or other negative feelings. Human bites may be more dangerous than most animal ...

209

Modified phosphoribosylpyrophosphate (PRPP) radioenzymatic assay: increased sensitivity, technical simplification and new applications.  

PubMed

Phosphoribosylpyrophosphate in amounts as low as 25 pmol could be reliably and economically measured with a CO2-releasing radioenzymatic assay when appropriate technical modifications were introduced. The concentration of commercially available phosphoribosylpyrophosphate used for reference standards was ascertained by a method based on the utilization of phosphoribosylpyrophosphate by hypoxanthine catalyzed by hypoxanthine phosphoribosyltransferase from red blood cell lysates. The addition of inorganic phosphate increased intracellular phosphoribosylpyrophosphate levels in HL-60 cell lysates and can be used to amplify low levels of phosphoribosylpyrophosphate. This phosphoribosylpyrophosphate assay amplified by inorganic phosphate has been developed to assay perturbations in the purine biosynthetic nucleotide pathway in response to various chemotherapeutic agents, such as anti-folates, or as a result of folate deficiency. PMID:2439241

Ghitis, J; Waxman, S

1987-05-15

210

Human Development, Human Evolution.  

ERIC Educational Resources Information Center

One of the truly remarkable events in human evolution is the unprecedented increase in the size of the brain of "Homo" over a brief span of 2 million years. It would appear that some significant selective pressure or opportunity presented itself to this branch of the hominid line and caused a rapid increase in the brain, introducing a wholly new…

Smillie, David

211

Genotoxicity of 2,6- and 3,5-Dimethylaniline in Cultured Mammalian Cells: The Role of Reactive Oxygen Species  

PubMed Central

Several alkylanilines with structures more complex than toluidines have been associated epidemiologically with human cancer. Their mechanism of action remains largely undetermined, and there is no reported evidence that it replicates that of multicyclic aromatic amines even though the principal metabolic pathways of P450-mediated hydroxylation and phase II conjugation are very similar. As a means to elucidate their mechanisms of action, lethality and mutagenicity in the adenine phosphoribosyltransferase (aprt +/?) gene induced in several Chinese hamster ovary cell types by 2,6- and 3,5-dimethylaniline (2,6-DMA, 3,5-DMA) and their N- and ring-hydroxyl derivatives (N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, 3,5-DMAP) were assessed. Dose-response relationships were determined in the parental AA8 cell line, its repair-deficient UV5 subclone and other repair-deficient 5P3NAT2 or -proficient 5P3NAT2R9 subclones engineered to express mouse cytochrome P4501A2 (CYP1A2) and human N-acetyltransferase (NAT2), and also in AS52 cells harboring the bacterial guanine-hypoxanthine phosphoribosyltransferase (gpt) gene. Mutations in the gpt gene of AS52 cells were characterized and found to be dominated by G:C to A:T and A:T to G:C transitions. Separately, treatment of AS52 cells with N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, 3,5-DMAP, and 3,5-DMAP led to intracellular production of reactive oxygen species (ROS) for at least 24h after removal of the mutagens in every case. Using the comet assay, DNA strand breaks were observed in a dose-dependent manner in AS52 cells when treated with each of the four N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, and 3,5-DMAP derivatives. Comparative evaluation of the results indicates that the principal mechanism of mutagenic action is likely to be through redox cycling of intracellularly bound aminophenol/quinone imine structures to generate ROS rather than through formation of covalent DNA adducts.

Chao, Ming-Wei; Kim, Min Young; Wogan, Gerald N.

2012-01-01

212

Genotoxicity of 2,6- and 3,5-dimethylaniline in cultured mammalian cells: the role of reactive oxygen species.  

PubMed

Several alkylanilines with structures more complex than toluidines have been associated epidemiologically with human cancer. Their mechanism of action remains largely undetermined, and there is no reported evidence that it replicates that of multicyclic aromatic amines even though the principal metabolic pathways of P450-mediated hydroxylation and phase II conjugation are very similar. As a means to elucidate their mechanisms of action, lethality and mutagenicity in the adenine phosphoribosyltransferase (aprt (+/-)) gene induced in several Chinese hamster ovary cell types by 2,6- and 3,5-dimethylaniline (2,6-DMA, 3,5-DMA) and their N- and ring-hydroxyl derivatives (N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, 3,5-DMAP) were assessed. Dose-response relationships were determined in the parental AA8 cell line, its repair-deficient UV5 subclone and other repair-deficient 5P3NAT2 or -proficient 5P3NAT2R9 subclones engineered to express mouse cytochrome P4501A2 (CYP1A2) and human N-acetyltransferase (NAT2), and also in AS52 cells harboring the bacterial guanine-hypoxanthine phosphoribosyltransferase (gpt) gene. Mutations in the gpt gene of AS52 cells were characterized and found to be dominated by G:C to A:T and A:T to G:C transitions. Separately, treatment of AS52 cells with N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, 3,5-DMAP, and 3,5-DMAP led to intracellular production of reactive oxygen species (ROS) for at least 24h after removal of the mutagens in every case. Using the comet assay, DNA strand breaks were observed in a dose-dependent manner in AS52 cells when treated with each of the four N-OH-2,6-DMA, N-OH-3,5-DMA, 2,6-DMAP, and 3,5-DMAP derivatives. Comparative evaluation of the results indicates that the principal mechanism of mutagenic action is likely to be through redox cycling of intracellularly bound aminophenol/quinone imine structures to generate ROS rather than through formation of covalent DNA adducts. PMID:22831970

Chao, Ming-Wei; Kim, Min Young; Ye, Wenjie; Ge, Jing; Trudel, Laura J; Belanger, Crystal L; Skipper, Paul L; Engelward, Bevin P; Tannenbaum, Steven R; Wogan, Gerald N

2012-11-01

213

Transfer of nonselectable genes into mouse teratocarcinoma cells and transcription of the transferred human beta-globin gene.  

PubMed Central

Teratocarcinoma (TCC) stem cells can function as vehicles for the introduction of specific recombinant genes into mice. Because most genes do not code for a selectable marker, we investigated the transformation efficiency of vectors with a linked selectable gene. In one series, TCC cells first selected for thymidine kinase deficiency were treated with DNA from the plasmid vector PtkH beta 1 containing the human genomic beta-globin gene and the thymidine kinase gene of herpes simplex virus. A high transformation frequency was obtained after selection in hypoxanthine-aminopterin-thymidine medium. Hybridization tests revealed that the majority of transformants had intact copies of the human gene among three to six total copies per cell. These were associated with cellular DNA sequences as judged from the presence of additional new restriction fragments and from stability of the sequences in tumors produced by injecting the cells subcutaneously. Total polyadenylate-containing RNA from cell cultures of two out of four transformants examined showed hybridization to the human gene probe: one RNA species resembled mature human beta-globin mRNA transcripts; the others were of larger size. In differentiating tumors, various tissues, including hematopoietic cells of TCC provenance could be found. In a second model set of experiments, wild-type TCC cells were used to test a dominant-selection scheme with pSV-gpt vectors. Numerous transformants were isolated, and their transfected DNA was apparently stably integrated. Thus, any gene of choice can be transferred into TCC stem cells even without mutagenesis of the cells, and selected cell clones can be characterized. Cells of interest may then be introduced into early embryos to produce new mouse strains with predetermined genetic changes. Images

Wagner, E F; Mintz, B

1982-01-01

214

Loop Tryptophan Human PNP Reveals Submillisecond Protein Dynamics  

PubMed Central

Human PNP is a homotrimer, containing three non-conserved tryptophan residues at positions 16, 94 and 178, all remote from the catalytic site. The catalytic sites of PNP are located near the subunit-subunit interfaces where residue F159 is a catalytic site residue donated from an adjacent subunit. F159 covers the top (?) surface of the ribosyl group at the catalytic site. QM/MM calculations of human PNP have shown that F159 is the center of the most mobile region of the protein providing access to the substrate in the active site. F159 is also the key residue in a cluster of hydrophobic residues that shield catalytic site ligands from bulk solvent. Trp-free human PNP (Leuko-PNP) was previously engineered by replacing the three Trp residues of native PNP with Tyr. From this active construct, a single Trp residue was placed in the catalytic site loop (F159W-Leuko-PNP) as a reporter group for the ribosyl region of the catalytic site. The F159W-Leuko-PNP fluorescence is red shifted compared to native PNP suggesting a solvent-exposed Trp residue. Upon ligand binding (hypoxanthine), the 3-fold fluorescence quench confirms conformational packing of the catalytic site pocket hydrophobic-cluster. F159W-Leuko-PNP has an on-enzyme thermodynamic equilibrium constant (Keq) near unity in the temperature range between 20 and 30 °C and non-zero enthalpic components, making it suitable for laser induced T-jump analyses. T-jump relaxation kinetics of F159W-Leuko-PNP in equilibrium with substrates and/or products indicate the conformational equilibria of at least two ternary complex intermediates in the nano- to milli-second time scale (1000 to 10,000 s?1) that equilibrate prior to the slower chemical step (?200 s?1). F159W-Leuko-PNP provides a novel protein platform to investigate the protein conformational dynamics occurring prior to transition state formation.

Ghanem, Mahmoud; Zhadin, Nickolay; Callender, Robert; Schramm, Vern L.

2009-01-01

215

Pseudogenes as Weaknesses of ACTB (Actb) and GAPDH (Gapdh) Used as Reference Genes in Reverse Transcription and Polymerase Chain Reactions  

PubMed Central

The genes encoding ?-actin (ACTB in human or Actb in mouse) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH in human or Gapdh in mouse) are the two most commonly used references for sample normalization in determination of the mRNA level of interested genes by reverse transcription (RT) and ensuing polymerase chain reactions (PCR). In this study, bioinformatic analyses revealed that the ACTB, Actb, GAPDH and Gapdh had 64, 69, 67 and 197 pseudogenes (PGs), respectively, in the corresponding genome. Most of these PGs are intronless and similar in size to the authentic mRNA. Alignment of several PGs of these genes with the corresponding mRNA reveals that they are highly homologous. In contrast, the hypoxanthine phosphoribosyltransferase-1 gene (HPRT1 in human or Hprt in mouse) only had 3 or 1 PG, respectively, and the mRNA has unique regions for primer design. PCR with cDNA or genomic DNA (gDNA) as templates revealed that our HPRT1, Hprt and GAPDH primers were specific, whereas our ACTB and Actb primers were not specific enough both vertically (within the cDNA) and horizontally (compared cDNA with gDNA). No primers could be designed for the Gapdh that would not mis-prime PGs. Since most of the genome is transcribed, we suggest to peers to forgo ACTB (Actb) and GAPDH (Dapdh) as references in RT-PCR and, if there is no surrogate, to use our primers with extra caution. We also propose a standard operation procedure in which design of primers for RT-PCR starts from avoiding mis-priming PGs and all primers need be tested for specificity with both cDNA and gDNA.

Sun, Yuan; Li, Yan; Luo, Dianzhong; Liao, D. Joshua

2012-01-01

216

High-frequency mutagenesis of human cells and characterization of a mutant unresponsive to both alpha and gamma interferons.  

PubMed Central

2fTGH is a human cell line containing the selectable marker guanine phosphoribosyltransferase regulated by alpha interferon (IFN-alpha). Two IFN-alpha-unresponsive mutants were isolated previously at a low frequency (ca. 10(-8)) by selecting mutagenized 2fTGH cells in selective medium containing 6-thioguanine and IFN-alpha. By using five rounds of mutagenesis, mutants can be isolated at an appreciably higher frequency, greater than 3 x 10(-7). Five new mutants have been isolated, and all are recessive, as are the two mutants we described previously. The seven mutants are in four complementation groups (U1-U4). Since several different types of mutants unresponsive to IFN-alpha have been isolated with high frequency, related approaches may succeed with other cytokines or growth factors. Mutants in the two new complementation groups U3 and U4 are unresponsive to IFN-alpha and, surprisingly, also unresponsive to IFN-gamma. They are also partially defective in response to double-stranded RNA. These results indicate that the signaling pathways for the two types of IFN and double-stranded RNA share common components or that their function depends on common enzymes or transcription factors. IFN receptors are unaffected in mutants U3A and U4A. A major defect appears to be in the synthesis or activation of E, the transcription factor mediating the primary response to type I (alpha/beta) IFNs. Band-shift complementation assays show that U3A contains the E gamma subunit but does not contain an active E alpha subunit after treatment with IFN-alpha. Images

McKendry, R; John, J; Flavell, D; Muller, M; Kerr, I M; Stark, G R

1991-01-01

217

The Human Spark: Being Human  

NSDL National Science Digital Library

This lesson plan from PBS covers a variety of biology topics related to the human as an animal. Students will view and discuss segments from the PBS program The Human Spark. In the first learning activity, the class will explore how human thought differs from that of other species. In the second learning activity, students will examine different traits and abilities, how these abilities have evolved to help humans deal with their environment, and how they distinguish humans from other animals.

WNET (Television station : New York, N.Y.)

2010-07-05

218

Description and partial characterization of a nucleolar RNA-associated autoantigen defined by a human monoclonal antibody.  

PubMed

B lymphocytes from a patient with systemic lupus erythematosus (SLE) and several circulating autoantibodies (including antinucleolar antibodies) were immortalized by fusion with a hypoxanthine/guanine phosphoribosyl transferase (HGPRT)-deficient human B cell line. Multiple human monoclonal antibodies (mAb) were obtained which, in solid-phase enzyme immunoassay, were reactive with DNA. One mAb was of special interest because it reacted strongly with both single-stranded DNA and an extractable nuclear antigen found in rabbit thymus extract (RTE). In an immunofluorescent assay using fixed human cells, the latter mAb also bound predominantly to cell nucleoli. A combination of enzyme digestion and metabolic inhibitor studies of the target cells in this immunofluorescent assay suggested that the antigen(s) bound by the mAb was an RNA-associated protein or a ribonucleoprotein that is distinct from intact RNA polymerase I and not associated with the transcriptional units of the nucleolus. In other experiments, using fractions of RTE isolated by ion-exchange chromatography, the antigens bound by the mAb were shown to be highly negatively charged molecules. Immunoprecipitation and SDS-PAGE analyses of labeled cell extracts bound by the mAb revealed a doublet of 17 and 18 kD. Since the original patient's serum autoantibodies also bound to both an RNase-sensitive, acidic, extractable nuclear antigen and to nucleoli, and immunoprecipitated proteins of similar molecular masses in SDS-PAGE, it appears that the described mAb is a product of an immortalized autoantibody-producing B cell clone from the SLE patient's peripheral blood. This mAb probably defines a novel RNA-associated autoantigen residing predominantly in the nucleolus or, less likely, a variant of either RNA polymerase I or the ribosomal autoantigens (P proteins). PMID:2435834

Chiorazzi, N; Reeves, W H

1987-04-01

219

Molecular characterization of Borrelia persica, the agent of tick borne relapsing fever in Israel and the Palestinian Authority.  

PubMed

The identification of the Tick Borne Relapsing Fever (TBRF) agent in Israel and the Palestinian Authority relies on the morphology and the association of Borrelia persica with its vector Ornithodoros tholozani. Molecular based data on B. persica are very scarce as the organism is still non-cultivable. In this study, we were able to sequence three complete 16S rRNA genes, 12 partial flaB genes, 18 partial glpQ genes, 16 rrs-ileT intergenic spacers (IGS) from nine ticks and ten human blood samples originating from the West Bank and Israel. In one sample we sequenced 7231 contiguous base pairs that covered completely the region from the 5'end of the 16S rRNA gene to the 5'end of the 23S rRNA gene comprising the whole 16S rRNA (rrs), and the following genes: Ala tRNA (alaT), Ile tRNA (ileT), adenylosuccinate lyase (purB), adenylosuccinate synthetase (purA), methylpurine-DNA glycosylase (mag), hypoxanthine-guanine phosphoribosyltransferase (hpt), an hydrolase (HAD superfamily) and a 135 bp 5' fragment of the 23S rRNA (rrlA) genes. Phylogenic sequence analysis defined all the Borrelia isolates from O. tholozani and from human TBRF cases in Israel and the West Bank as B. persica that clustered between the African and the New World TBRF species. Gene organization of the intergenic spacer between the 16S rRNA and the 23S rRNA was similar to that of other TBRF Borrelia species and different from the Lyme disease Borrelia species. Variants of B. persica were found among the different genes of the different isolates even in the same sampling area. PMID:21124792

Safdie, Gracia; Farrah, Iba Y; Yahia, Reem; Marva, Esther; Wilamowski, Amos; Sawalha, Samer S; Wald, Naama; Schmiedel, Judith; Moter, Annette; Göbel, Ulf B; Bercovier, Herve; Abdeen, Ziad; Assous, Marc V; Fishman, Yolanta

2010-01-01

220

Proinflammatory and Immunomodulatory Cytokine mRNA Time Course Profiles in Hamsters Infected with a Virulent Variant of Leptospira interrogans  

PubMed Central

In order to quantify in vivo the mRNAs of cytokines which play important roles in leptospirosis, we have developed quantitative real-time PCR assays for interleukin-2 (IL-2), IL-4, IL-10, IL-12p40, tumor necrosis factor alpha (TNF-?), gamma interferon (IFN-?), transforming growth factor ?, and two housekeeping genes (encoding ?-actin and hypoxanthine phosphoribosyltransferase). We used a lethal hamster model reflecting severe leptospirosis in humans. The LightCycler system was used to quantify the gene expression levels with the SYBR green I detection format using external standard curves for each target. We compared the expression levels of cytokine mRNA in the peripheral blood mononuclear cells of both control (uninfected) hamsters and Leptospira interrogans-inoculated hamsters from 1 to 24 h and then 1 to 4 days postinfection. In this kinetic study, there was pronounced expression of Th1 cytokine mRNA (TNF-?, IFN-?, and IL-12), with transcripts being detected as early as 1 h postinfection. Expression of anti-inflammatory cytokines, such as IL-4 and IL-10, was prominent in delayed samples from 1 to 4 days postinfection in response to infection with Leptospira interrogans. Our data are the first to establish that pathogenic leptospires can stimulate in vivo the production of type 1 cytokines involved in cellular immunity by using this informative animal model. Measuring and assessing cytokine profiles may provide a useful method for accurate study of the mechanisms of anti-Leptospira immunity, indications of prognosis factors, and prospective evaluation of leptospirosis vaccine efficacy in humans.

Vernel-Pauillac, Frederique; Merien, Fabrice

2006-01-01

221

ALDH16A1 is a novel non-catalytic enzyme that may be involved in the etiology of gout via protein-protein interactions with HPRT1  

PubMed Central

Gout, a common form of inflammatory arthritis, is strongly associated with elevated uric acid concentrations in the blood (hyperuricemia). A recent study in Icelanders identified a rare missense single nucleotide polymorphism (SNP) in the ALDH16A1 gene, ALDH16A1*2, to be associated with gout and serum uric acid levels. ALDH16A1 is a novel and rather unique member of the ALDH superfamily in relation to its gene and protein structures. ALDH16 genes are present in fish, amphibians, protista, bacteria but absent from archaea, fungi and plants. In most mammalian species, two ALDH16A1 spliced variants (ALDH16A1, long form and ALDH16A1_v2, short form) have been identified and both are expressed in HepG-2, HK-2 and HK-293 human cell lines. The ALDH16 proteins contain two ALDH domains (as opposed to one in the other members of the superfamily), four transmembrane and one coiled-coil domains. The active site of ALDH16 proteins from bacterial, frog and lower animals contain the catalytically important cysteine residue (Cys-302); this residue is absent from the mammalian and fish orthologs. Molecular modeling predicts that both the short and long forms of human ALDH16A1 protein would lack catalytic activity but may interact with the hypoxanthine-guanine phosphoribosyltransferase (HPRT1) protein, a key enzyme involved in uric acid metabolism and gout. Interestingly, such protein-protein interactions with HPRT1 are predicted to be impaired for the long or short forms of ALDH16A1*2. These results lead to the intriguing possibility that association between ALDH16A1 and HPRT1 may be required for optimal HPRT activity with disruption of this interaction possibly contributing to the hyperuricemia seen in ALDH16A1*2 carriers.

Vasiliou, Vasilis; Sandoval, Monica; Backos, Donald S.; Jackson, Brian C.; Chen, Ying; Reigan, Philip; Lanaspa, Miguel A.; Johnson, Richard J.; Koppaka, Vindhya; Thompson, David C.

2013-01-01

222

ALDH16A1 is a novel non-catalytic enzyme that may be involved in the etiology of gout via protein-protein interactions with HPRT1.  

PubMed

Gout, a common form of inflammatory arthritis, is strongly associated with elevated uric acid concentrations in the blood (hyperuricemia). A recent study in Icelanders identified a rare missense single nucleotide polymorphism (SNP) in the ALDH16A1 gene, ALDH16A1*2, to be associated with gout and serum uric acid levels. ALDH16A1 is a novel and rather unique member of the ALDH superfamily in relation to its gene and protein structures. ALDH16 genes are present in fish, amphibians, protista, bacteria but absent from archaea, fungi and plants. In most mammalian species, two ALDH16A1 spliced variants (ALDH16A1, long form and ALDH16A1_v2, short form) have been identified and both are expressed in HepG-2, HK-2 and HK-293 human cell lines. The ALDH16 proteins contain two ALDH domains (as opposed to one in the other members of the superfamily), four transmembrane and one coiled-coil domains. The active site of ALDH16 proteins from bacterial, frog and lower animals contain the catalytically important cysteine residue (Cys-302); this residue is absent from the mammalian and fish orthologs. Molecular modeling predicts that both the short and long forms of human ALDH16A1 protein would lack catalytic activity but may interact with the hypoxanthine-guanine phosphoribosyltransferase (HPRT1) protein, a key enzyme involved in uric acid metabolism and gout. Interestingly, such protein-protein interactions with HPRT1 are predicted to be impaired for the long or short forms of ALDH16A1*2. These results lead to the intriguing possibility that association between ALDH16A1 and HPRT1 may be required for optimal HPRT activity with disruption of this interaction possibly contributing to the hyperuricemia seen in ALDH16A1*2 carriers. PMID:23348497

Vasiliou, Vasilis; Sandoval, Monica; Backos, Donald S; Jackson, Brian C; Chen, Ying; Reigan, Philip; Lanaspa, Miguel A; Johnson, Richard J; Koppaka, Vindhya; Thompson, David C

2013-02-25

223

Molecular Characterization of Borrelia persica, the Agent of Tick Borne Relapsing Fever in Israel and the Palestinian Authority  

PubMed Central

The identification of the Tick Borne Relapsing Fever (TBRF) agent in Israel and the Palestinian Authority relies on the morphology and the association of Borrelia persica with its vector Ornithodoros tholozani. Molecular based data on B. persica are very scarce as the organism is still non-cultivable. In this study, we were able to sequence three complete 16S rRNA genes, 12 partial flaB genes, 18 partial glpQ genes, 16 rrs-ileT intergenic spacers (IGS) from nine ticks and ten human blood samples originating from the West Bank and Israel. In one sample we sequenced 7231 contiguous base pairs that covered completely the region from the 5?end of the 16S rRNA gene to the 5?end of the 23S rRNA gene comprising the whole 16S rRNA (rrs), and the following genes: Ala tRNA (alaT), Ile tRNA (ileT), adenylosuccinate lyase (purB), adenylosuccinate synthetase (purA), methylpurine-DNA glycosylase (mag), hypoxanthine-guanine phosphoribosyltransferase (hpt), an hydrolase (HAD superfamily) and a 135 bp 5? fragment of the 23S rRNA (rrlA) genes. Phylogenic sequence analysis defined all the Borrelia isolates from O. tholozani and from human TBRF cases in Israel and the West Bank as B. persica that clustered between the African and the New World TBRF species. Gene organization of the intergenic spacer between the 16S rRNA and the 23S rRNA was similar to that of other TBRF Borrelia species and different from the Lyme disease Borrelia species. Variants of B. persica were found among the different genes of the different isolates even in the same sampling area.

Safdie, Gracia; Farrah, Iba Y.; Yahia, Reem; Marva, Esther; Wilamowski, Amos; Sawalha, Samer S.; Wald, Naama; Schmiedel, Judith; Moter, Annette; Gobel, Ulf B.; Bercovier, Herve; Abdeen, Ziad; Assous, Marc V.; Fishman, Yolanta

2010-01-01

224

Human Bites  

MedlinePLUS

Copyright 2013 American Academy of Orthopaedic Surgeons Human Bites A human bite that has broken the skin. Reproduced with permission from: Griffin LY (ed): Essentials of Musculoskeletal Care, 3rd Edition. Rosemont, ...

225

Effects of cell cycle position on ionizing radiation mutagenesis. I. Quantitative assays of two genetic loci in a human lymphoblastoid cell line.  

PubMed

Relatively little work has been done on the influence of the position of the cell in the cell cycle on ionizing radiation-induced mutagenesis. We synchronized WTK1 human lymphoblastoid cells with 200 microM lovastatin for 48 h; under these conditions more than 80% of the cells were arrested in G1 phase. Upon release, there was a 12-15-h lag followed by movement of a large fraction into S phase. We irradiated cells with either 1.5 Gy X rays at 1, 15, 18, 21 or 24 h or 1.5 Gy gamma rays at 1, 5, 10, 15 or 24 h after release from lovastatin. We showed that WTK1 cells were most sensitive to ionizing radiation-induced toxicity in G1 and into S phase, and more resistant in mid to late S and G2/M phase. Somewhat surprisingly, we found that the two different gene loci had different sensitivities to radiation-induced mutation through the cell cycle. Cells in late G1 through mid-S phase were most sensitive to radiation-induced mutations at the autosomal thymidine kinase (TK) locus, whereas G1 phase was the most sensitive phase at the X-linked hypoxanthine guanine phosphoribosyl transferase (HPRT) locus. PMID:8896575

Chuang, Y Y; Liber, H L

1996-11-01

226

Effects of cell cycle position on ionizing radiation mutagenesis. I. Quantitative assays of two genetic loci in a human lymphoblastoid cell line  

SciTech Connect

Relatively little work has been done on the influence of the position of the cell in the cell cycle on ionizing radiation-induced mutagenesis. We synchronized WTK1 human lymphoblastoid cells with 200 {mu}M lovastatin for 48 h; under these conditions more than 80% of the cells were arrested in G{sub 1} phase. Upon release, there was a 12-15-h lag followed by movement of a large fraction into S phase. We irradiated cells with either 1.5 Gy X rays at 1, 15, 18, 21 or 24 h or 1.5 Gy {gamma} rays at 1, 5, 10, 15 or 24 h after release from lovastatin. We showed that WTK1 cells were most sensitive to ionizing radiation-induced toxicity in G{sub 1} and into S phase, and more resistant in mid to late S and G{sub 2}/M phase. Somewhat surprisingly, we found that the two different gene loci had different sensitivities to radiation-induced mutation through the cell cycle. Cells in late G{sub 1} through mid-S phase were most sensitive to radiation-induced mutations at the autosomal thymidine kinase (TK) locus, whereas G{sub 1} phase was the most sensitive phase at the X-linked hypoxanthine guanine phosphoribosyl transferase (HPRT) locus. 29 refs., 6 figs., 1 tab.

Chuang, Yao-Yu; Liber, H.L. [Harvard School of Public Health, Boston, MA (United States)

1996-11-01

227

Human Anatomy  

NSDL National Science Digital Library

Please find links below: Human Anatomy Human Anatomy Online Human Body - Gray s Anatomy - Digestive Aparatus MEDtropolis - Virtual Body - can be viewed in English or Spanish. Contains tours of the Human Brain, Skeleton, Human Heart, and Digestive Tract. Respiratory System National Heart, Lung, and Blood Institute HealthTalk COPD (chronic obstructive pulmonary disease) American Lung Association - Disease Finder Association of Legal Aid Attorneys/UAW 2325 Canadian Lung Association Kids Health Family Living and Personal Living - Ms. Schultz added this link because on this page there is CDC, American ...

Schultz, Ms.

2007-11-09

228

Charged-particle mutagenesis 2. Mutagenic effects of high energy charged particles in normal human fibroblasts  

NASA Technical Reports Server (NTRS)

The biological effects of high Linear Energy Transfer (LET) charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 sq micrometer and 0.09 to 5.56 x 10(exp -3) sq micrometer respectively. The maximum values were obtained by Fe-56 with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(exp -5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

1994-01-01

229

Charged-particle mutagenesis II. Mutagenic effects of high energy charged particles in normal human fibroblasts  

NASA Technical Reports Server (NTRS)

The biological effects of high LET charged particles are a subject of great concern with regard to the prediction of radiation risk in space. In this report, mutagenic effects of high LET charged particles are quantitatively measured using primary cultures of human skin fibroblasts, and the spectrum of induced mutations are analyzed. The LET of the charged particles ranged from 25 KeV/micrometer to 975 KeV/micrometer with particle energy (on the cells) between 94-603 MeV/u. The X-chromosome linked hypoxanthine guanine phosphoribosyl transferase (hprt) locus was used as the target gene. Exposure to these high LET charged particles resulted in exponential survival curves; whereas, mutation induction was fitted by a linear model. The Relative Biological Effect (RBE) for cell-killing ranged from 3.73 to 1.25, while that for mutant induction ranged from 5.74 to 0.48. Maximum RBE values were obtained at the LET of 150 keV/micrometer. The inactivation cross-section (alpha i) and the action cross-section for mutant induction (alpha m) ranged from 2.2 to 92.0 micrometer2 and 0.09 to 5.56 x 10(-3) micrometer2, respectively. The maximum values were obtained by 56Fe with an LET of 200 keV/micrometer. The mutagenicity (alpha m/alpha i) ranged from 2.05 to 7.99 x 10(-5) with the maximum value at 150 keV/micrometer. Furthermore, molecular analysis of mutants induced by charged particles indicates that higher LET beams are more likely to cause larger deletions in the hprt locus.

Chen, D. J.; Tsuboi, K.; Nguyen, T.; Yang, T. C.

1994-01-01

230

Glyoxylate lowers metabolic ATP in human platelets without altering adenylate energy charge or aggregation.  

PubMed

Human blood platelets adhere to exposed collagen at the site of vascular injury, initiating a signaling cascade leading to fibrinogen activation, secretion of granules and aggregation, thus producing a stable thrombus. All these steps require metabolic ATP. In this study we have labeled the metabolic pool of ATP with nucleotides, treated platelets with various inhibitors and have monitored their ability to be activated. Incubating platelets with glyoxylate dramatically reduced the ATP level without a change in the adenylate energy charge (AEC). This reduction of ATP did not affect ADP-induced primary or secondary aggregation, whereas glyoxal, methyl glyoxal, or the combination of antimycin plus deoxyglucose reduced both ATP and AEC and inhibited aggregation. The reduction of ATP by glyoxylate was almost quantitatively matched by an increase in hypoxanthine without elevation of ADP. AMP, IMP or inosine, acetoacetate, aspartate, or glutamate had no effect on glyoxylate-induced breakdown of ATP, while pyruvate stopped the ATP reduction fast and efficiently. Glyoxylate also lowered the citrate content. The glyoxylate-induced breakdown of ATP coincided with an increase in fructose-1,6-bisphosphate, indicating that the phosphofructokinase reaction was the main ATP-consuming step. Glyoxylate was a substrate for lactate dehydrogenase although with a Km almost 100 times higher than pyruvate. We suggest that glyoxylate primarily competes with pyruvate in the pyruvate dehydrogenase reaction, thus lowering the citrate concentration, which in turn activates phosphofructokinase. Clearly, lowering of ATP in the cytosol by more than 50% does not affect platelet aggregation provided that the AEC is not reduced. PMID:23488475

Dangelmaier, Carol A; Holmsen, Holm

2014-01-01

231

Normal uricemia in lesch-nyhan syndrome and the association with pulmonary embolism in a young child-a case report and literature review.  

PubMed

Deficiency of hypoxanthine phosphoribosyltransferase activity is a rare inborn error of purine metabolism with subsequent uric acid overproduction and neurologic presentations. The diagnosis of Lesch-Nyhan syndrome (LNS) is frequently delayed until self-mutilation becomes evident. We report the case of a boy aged 1 year and 10 months who was diagnosed with profound global developmental delay, persistent chorea, and compulsive self-mutilation since the age of 1 year. Serial serum uric acid levels showed normal uric acid level, and the spot urine uric acid/creatinine ratio was >2. The hypoxanthine phosphoribosyltransferase cDNA showed the deletion of exon 6, and the boy was subsequently diagnosed to have LNS. He also had respiratory distress due to pulmonary embolism documented by chest computed tomography scan. This report highlights the need to determine the uric acid/creatinine ratio caused by increased renal clearance in LNS in young children. The presence of pulmonary embolism is unusual and may be the consequence of prolonged immobilization. PMID:23597535

Tsai, Jeng-Dau; Chen, Shan-Ming; Lin, Chien-Heng; Ku, Min-Sho; Tsao, Teng-Fu; Sheu, Ji-Nan

2014-08-01

232

Clonal expansions of 6-thioguanine resistant T lymphocytes in the blood and tumor of melanoma patients.  

PubMed

The identification of specific lymphocyte populations that mediate tumor immune responses is required for elucidating the mechanisms underlying these responses and facilitating therapeutic interventions in humans with cancer. To this end, mutant hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficient (HPRT-) T-cells were used as probes to detect T-cell clonal amplifications and trafficking in vivo in patients with advanced melanoma. Mutant T-cells from peripheral blood were obtained as clonal isolates or in mass cultures in the presence of 6-thioguanine (TG) selection and from tumor-bearing lymph nodes (LNs) or metastatic melanoma tissues by TG-selected mass cultures. Nonmutant (wild-type) cells were obtained from all sites by analogous means, but without TG selection. cDNA sequences of the T-cell receptor (TCR) beta chains (TCR-beta), determined directly (clonal isolates) or following insertion into plasmids (mass cultures), were used as unambiguous biomarkers of in vivo clonality of mature T-cell clones. Clonal amplifications, identified as repetitive TCR-beta V-region, complementarity determining region 3 (CDR3), and J-region gene sequences, were demonstrated at all sites studied, that is, peripheral blood, LNs, and metastatic tumors. Amplifications were significantly enriched among the mutant compared with the wild-type T-cell fractions. Importantly, T-cell trafficking was manifested by identical TCR-beta cDNA sequences, including the hypervariable CDR3 motifs, being found in both blood and tissues in individual patients. The findings described herein indicate that the mutant T-cell fractions from melanoma patients are enriched for proliferating T-cells that infiltrate the tumor, making them candidates for investigations of potentially protective immunological responses. PMID:18712786

Albertini, Mark R; Macklin, Michael D; Zuleger, Cindy L; Newton, Michael A; Judice, Stephen A; Albertini, Richard J

2008-12-01

233

Severe pyridine nucleotide depletion in fibroblasts from Lesch-Nyhan patients.  

PubMed Central

The relationship between a complete deficiency of the purine enzyme hypoxanthine-guanine phosphoribosyltransferase and the neurobehavioural abnormalities in Lesch-Nyhan disease remains an enigma. In vitro studies using lymphoblasts or fibroblasts have evaluated purine and pyrimidine metabolism with conflicting results. This study focused on pyridine nucleotide metabolism in control and Lesch-Nyhan fibroblasts using radiolabelled salvage precursors to couple the extent of uptake with endocellular nucleotide concentrations. The novel finding, highlighted by specific culture conditions, was a marked NAD depletion in Lesch-Nyhan fibroblasts. ATP and GTP were also 50% of the control, as reported in lymphoblasts. A 6-fold greater incorporation of [(14)C]nicotinic acid into nicotinic acid- adenine dinucleotide by Lesch-Nyhan fibroblasts, with no unmetabolized substrate (20% in controls), supported disturbed pyridine metabolism, NAD depletion being related to utilization by poly(ADP-ribose) polymerase in DNA repair. Although pyrimidine nucleotide concentrations were similar to controls, Lesch-Nyhan cells showed reduced [(14)C]cytidine/uridine salvage into UDP sugars. Incorporation of [(14)C]uridine into CTP by both was minimal, with more than 50% [(14)C]cytidine metabolized to UTP, indicating that fibroblasts, unlike lymphoblasts, lack active CTP synthetase, but possess cytidine deaminase. Restricted culture conditions may be neccesary to mimic the situation in human brain cells at an early developmental stage. Cell type may be equally important. NAD plus ATP depletion in developing brain could restrict DNA repair, leading to neuronal damage/loss by apoptosis, and, with GTP depletion, affect neurotransmitter synthesis and basal ganglia dopaminergic neuronal systems. Thus aberrant pyridine nucleotide metabolism could play a vital role in the pathophysiology of Lesch-Nyhan disease.

Fairbanks, Lynette D; Jacomelli, Gabriella; Micheli, Vanna; Slade, Tina; Simmonds, H Anne

2002-01-01

234

Alkyltransferase-mediated toxicity of bis-electrophiles in mammalian cells  

PubMed Central

The primary function of O6-alkylguanine-DNA alkyltransferase (AGT) is to maintain genomic integrity in the face of damage by both endogenous and exogenous alkylating agents. However, paradoxically, bacterial and mammalian AGTs have been shown to increase cytotoxicity and mutagenicity of dihaloalkanes and other bis-electrophiles when expressed in bacterial cells. We have extended these studies to mammalian cells using CHO cells that lack AGT expression and CHO cells stably transfected with a plasmid that expresses human AGT. The cytotoxicity of 1,2-dibromoethane, dibromomethane and epibromohydrin was significantly increased by the presence of AGT but cytotoxicity of butadiene diepoxide was not affected. Mutations caused by these agents were assessed using hypoxanthine-guanine phosphoribosyltransferase (HPRT) as a reporter gene. There was a small (c. 2–3-fold) but statistically significant AGT-mediated increase in mutations caused by 1,2-dibromoethane, dibromomethane and epibromohydrin. Analysis of the mutation spectrum induced by 1,2-dibromoethane showed that the presence of AGT also altered the types of mutations with an increase in total base substitution mutants due to a rise in transversions at both G:C and A:T sites. AGT expression also led to mutations arising from the transcribed strand, which were not seen in cells lacking AGT. Although the frequency of deletion mutations was decreased by AGT expression, the formation of large deletions (?3 exons) was increased. This work demonstrates that interaction of AGT with some bis-electrophiles can cause mutagenicity and diminished cell survival in mammalian cells. It is consistent with the hypothesis that DNA-AGT cross-links, which have been characterized in experiments with purified AGT protein and such bis-electrophiles, can be formed in mammalian cells.

Kalapila, Aley G.; Pegg, Anthony E.

2009-01-01

235

Pyridine nucleotide cycle of Salmonella typhimurium: regulation of nicotinic acid phosphoribosyltransferase and nicotinamide deamidase.  

PubMed Central

Nicotinic acid phosphoribosyl transferase (NAPRTase) and nicotinamide deamidase activities from Salmonella typhimurium were examined regarding their regulation by either feedback inhibition or repression mechanisms. The results indicate that neither enzyme is subject to feedback inhbition. Nicotinamide deamidase does not appear to be under repression control. NAPRTase, however, is repressed when cells are grown in minimal medium supplemented with various intermediates of the pyridine nucleotide cycle. The concentration of exogenously supplied pyridine nucleotide necessary to effect repression of NAPRTas was found to be that concentration which will result in a nadA mutant generation time of less than 60 min. Furthermore, the results presented indicate that nicotinamide adenine dinucleotide is the actual corepressor molecule. The analogs 6-aminonicotinic acid and 6-aminonicotinamide were also capable of repressing NAPRTase, but only when an intact pyridine nucleotide cycl permitted conversion to 6-aminonicotinamide adenine dinucleotide. The role of a repressible NAPRTase is discussed in relation to the overall functioning of the pyridine nucleotide cycle.

Foster, J W; Kinney, D M; Moat, A G

1979-01-01

236

Detection of deletion mutations in pSV2gpt-transformed cells.  

PubMed Central

We have developed a system to study mutations that affect xanthine-guanine phosphoribosyltransferase gene (gpt) expression in hypoxanthine-guanine phosphoribosyltransferase-deficient CHO cells that have been transformed by the plasmid vector pSV2gpt. One isolated transformant, designated AS52, carries a single copy of the Escherichia coli gpt gene stably integrated into the high-molecular-weight DNA and expresses the bacterial gene for the enzyme xanthine-guanine phosphoribosyltransferase. Mutants deficient in this enzyme can be induced in the AS52 cell line by a variety of mutagens, and spontaneous or induced mutants can be selected for resistance to 6-thioguanine (Tgr). Two Tgr clones derived from the AS52 line were analyzed by Southern blot hybridization and were found to contain deletions involving at least a portion of the gpt gene. Because of the small size and stability of the integrated pSV2gpt plasmid, and the well-defined selection protocol for mutant isolation, the AS52 line offers promise as a system suitable for the study of mutation at the molecular level in CHO cells. Images

Tindall, K R; Stankowski, L F; Machanoff, R; Hsie, A W

1984-01-01

237

Methotrexate inhibits the first committed step of purine biosynthesis in mitogen-stimulated human T-lymphocytes: a metabolic basis for efficacy in rheumatoid arthritis?  

PubMed Central

The immunosuppressive and anti-inflammatory effects of low-dose methotrexate (MTX) have been related directly to inhibition of folate-dependent enzymes by polyglutamated derivatives, or indirectly to adenosine release and/or apoptosis and clonal deletion of activated peripheral blood lymphocytes in S-phase. In this study of phytohaemagglutinin-stimulated primary human T-lymphocytes we show that MTX (20 nM to 20 microM) was cytostatic not cytotoxic, halting proliferation at G(1). This stasis of blastogenesis was associated with an inhibition of purine ribonucleotide synthesis but a stimulation of pyrimidine biosynthesis, the normal mitogen-induced expansion of ATP and GTP pools over 72 h being restricted to concentrations of unstimulated T-cells, whereas the increment in UTP pools exceeded that of controls. Decreased incorporation of H(14)CO(3) or [(14)C]glycine into purine ribonucleotides, with no radiolabel accumulation in any de novo synthetic intermediate but enhanced H(14)CO(3) incorporation into UTP, supported these MTX-related effects. Exaggerated [(14)C]hypoxanthine salvage (which normalized the purine and UTP pools) confirmed the increased availability of 5-phosphoribosyl-1-pyrophosphate (PP-ribose-P) as the molecular mechanism underlying these disparate changes. These results provide the first substantive evidence that the immunosuppressive effects of low-dose MTX in primary blasting human T-lymphocytes relate not to the inhibition of the two folate-dependent enzymes of purine biosynthesis but to inhibition of the first enzyme, amidophosphoribosyltransferase, thereby elevating PP-ribose-P and stimulating UTP synthesis. Varying cell types or incubation conditions employed by other workers, especially malignant/activated cells with high basal metabolic rates, might mask the effects noted in primary human T-lymphocytes. The findings imply the involvement of low-dose MTX in the inhibition of T-lymphocyte proliferation and proliferation-dependent processes in rheumatoid arthritis.

Fairbanks, L D; Ruckemann, K; Qiu, Y; Hawrylowicz, C M; Richards, D F; Swaminathan, R; Kirschbaum, B; Simmonds, H A

1999-01-01

238

Human Aggression.  

National Technical Information Service (NTIS)

The paper presents an approach to human aggression concerned with environmental stimuli. Details of recent studies and analysis of aversive stimuli and reinforcing stimuli are presented. The paper concludes by suggesting some possible generalizations from...

R. E. Ulrich J. E. Favell

1968-01-01

239

Human otoacariasis.  

PubMed

Accidental entry of foreign bodies into the ear canal is very common. Animate foreign bodies constitute upto 14% of cases, majority being the cockroaches. Not many cases of ticks entering into human ears are found in the scientific literature. Even the available reports are from South Africa, Nepal, Malaysia, Chile and Srilanka. This Indian study discusses the occurence, clinical features, the methods adopted in the removal and the complications of tick infestation of human ear. A total of 144 cases of ticks entering the human ears were studied over a period of two years from Jan 2004 to Dec 2005. This report represents one of the largest recorded series of human otoacariasis available in the Indian literature. PMID:23120441

Somayaji, K S Gangadhara; Rajeshwari, A

2007-09-01

240

Human Evolution  

NSDL National Science Digital Library

This resource from PBS focuses on human evolution in a format aimed at kids but easily adapted to a classroom of any kind. A classroom activity (available as Shockwave or text only formats) describes the steps in human evolution (physically and behaviorally) from Ardipithecus ramidus about 4.4 million years ago to our current state as modern Homo sapiens. There are also brief summaries of the importance of Lucy, fossilized footprints, and the "Taung child," the first Autralopithecus specimen found.

1969-12-31

241

Establishment of a rat cell line inducible for the expression of human cytomegalovirus immediate-early gene products by protein synthesis inhibition.  

PubMed Central

Upon transfection of Rat-2-TK- cells with plasmid pES, containing the cloned 7.0-kilobase (kb) EcoRI-SalI fragment (0.063 to 0.089 map units) of the human cytomegalovirus genome, major immediate-early antigen expression was obtained in 1 to 2% of the nuclei of the transfected cells, as determined by immunofluorescence with the E3 monoclonal antibody. Cotransfection of pES with the cloned herpes simplex virus type 1 thymidine kinase gene resulted in the establishment of a hypoxanthine-aminopterin-thymidine-resistant cell line which expressed a major immediate-early antigen in approximately 1% of the cells at early passages, with expression gradually declining to less than 0.1% upon subculturing. Southern blot analysis of DNA extracted from this cell line revealed the presence of multiple integration events of pES DNA sequences into cellular DNA, including a head-to-tail tandem array of approximately 10 copies of pES. The integration pattern was stable for at least 80 passages. Metaphase chromosomes prepared from this cell line showed, upon in situ hybridization, a strong hybridization signal in both sister chromatids of a large submetacentric chromosome which is considered to have harbored the tandemly integrated pES molecules. Whereas in most cells of the population, immediate-early expression seemed to be repressed, this repression could be overcome by protein synthesis inhibition, resulting in a massive induction of human-cytomegalovirus-specific transcripts of 2.1 and 1.9 kb and a minor species of 2.9 kb. After release from protein synthesis inhibition, approximately 20% of the cells showed nuclear fluorescence when the E3 monoclonal antibody was used. Images

Boom, R; Geelen, J L; Sol, C J; Raap, A K; Minnaar, R P; Klaver, B P; van der Noordaa, J

1986-01-01

242

Human monkeypox.  

PubMed

Human monkeypox is a zoonotic Orthopoxvirus with a presentation similar to smallpox. Clinical differentiation of the disease from smallpox and varicella is difficult. Laboratory diagnostics are principal components to identification and surveillance of disease, and new tests are needed for a more precise and rapid diagnosis. The majority of human infections occur in Central Africa, where surveillance in rural areas with poor infrastructure is difficult but can be accomplished with evidence-guided tools and educational materials to inform public health workers of important principles. Contemporary epidemiological studies are needed now that populations do not receive routine smallpox vaccination. New therapeutics and vaccines offer hope for the treatment and prevention of monkeypox; however, more research must be done before they are ready to be deployed in an endemic setting. There is a need for more research in the epidemiology, ecology, and biology of the virus in endemic areas to better understand and prevent human infections. PMID:24158414

McCollum, Andrea M; Damon, Inger K

2014-01-01

243

Human Anatomy  

NSDL National Science Digital Library

The EMuseum at the University of Minnesota-Mankato provides this educational site on human anatomy. Although some parts of the site are still under construction, the Introduction to the Skeletal System section offers a straightforward introduction to the topic, complete with black-and-white skeletal photographs. Topics in this section include skeletal functions, axial and appendicular divisions, types of bone, bone composition, and a brief list of anatomical terms. For educators of introductory human anatomy, this site should provide interesting supplemental information.

244

Digitizing humanity  

PubMed Central

The application of ex vivo synthetic DNA as a high capacity information storage medium is well documented. Herein, we consider the potential for synthetic DNA to be incorporated as part of the human genome; providing a definitive, accessible, in vivo database of patient history.

Sleator, Roy D.; O' Driscoll, Aisling

2013-01-01

245

Human Impact  

NSDL National Science Digital Library

Collection of nine classroom activities that focus on human impact on the environment. Topics include: oil spills; oil consumption; oil tanker size; greenhouse effect; salt water incursion; ozone hole and its affect on the food web; and zebra mussels. Each activity provides list of materials needed, background information, and procedure.

246

Human Cloning.  

National Technical Information Service (NTIS)

On December 27, 2002, a representative of Clonaid announced the overseas birth of the first cloned human to a 31-year old American woman. Although the company said genetic tests would show that the baby is a clone of the birth mother, tests results have n...

J. A. Johnson

2003-01-01

247

Humanizing Calculus  

ERIC Educational Resources Information Center

In this article, the author explores the history and the mathematics used by Newton and Leibniz in their invention of calculus. The exploration of this topic is intended to show students that mathematics is a human invention. Suggestions are made to help teachers incorporate the mathematics and the history into their own lessons. (Contains 3…

Cirillo, Michelle

2007-01-01

248

Human torso  

NSDL National Science Digital Library

The torso is the central area of the body that all the other body parts connect to. The ribcage contains the lungs and the heart. The intestines are located below them. The pelvic region contains the human reproductive parts and parts of the digestive and waste tracts.

William Cheselden (None;)

2000-04-02

249

Human Effect  

NSDL National Science Digital Library

In this lesson, students will investigate changes in air quality due to human interaction particularly burning of fossil fuels, and crop burning which increase levels of carbon monoxide. Students will evaluate changes in air quality over a 6 month time frame using Air Quality-Carbon Monoxide Data and draw conclusions based on observing color plot comparison graphs.

250

Human Trafficking  

ERIC Educational Resources Information Center

The shadowy, criminal nature of human trafficking makes evaluating its nature and scope difficult. The U.S. State Department and anti-trafficking groups estimate that worldwide some 27 million people are caught in a form of forced servitude today. Public awareness of modern-day slavery is gaining momentum thanks to new abolitionist efforts. Among…

Wilson, David McKay

2011-01-01

251

Human Capital, (Human) Capabilities and Higher Education  

ERIC Educational Resources Information Center

In this article I initiate a debate into the (de)merits of human capital theory and human capability theory and discuss implications of the debate for higher education. Human capital theory holds that economic growth depends on investment in education and that economic growth is the basis for improving the quality of human life. Human capable…

Le Grange, L.

2011-01-01

252

Poverty and Human Development.  

National Technical Information Service (NTIS)

Contents: Poverty, growth and human development; Human development issues and policies; Implementing human development programs: Some practical lessons; Priorities and progress in regional perspective; Summary and conclusions.

1980-01-01

253

Human Rights  

NSDL National Science Digital Library

The idea of "human rights" is a relatively new development in history, but as this website from Britain's National Archives notes in its discussion of the long trajectory of struggles for equality and so forth, "We could do worse than characterizing this history as the struggle for human rights." This visually compelling online exhibit uses original documents from The National Archives to take a long view of these struggles and movements. Visitors can start their journey through the site by picking a time period, and then reading an introductory essay on the period. Each time period includes a timeline and links to digitized version of relevant documents, such as The Poor Act of 1601 and a poster for a Staffordshire coal miners' union public meeting from 1831. The site is rounded out by a thorough glossary and a document index.

254

Human protothecosis.  

PubMed

Human protothecosis is a rare infection caused by members of the genus Prototheca. Prototheca species are generally considered to be achlorophyllic algae and are ubiquitous in nature. The occurrence of protothecosis can be local or disseminated and acute or chronic, with the latter being more common. Diseases have been classified as (i) cutaneous lesions, (ii) olecranon bursitis, or (iii) disseminated or systemic manifestations. Infections can occur in both immunocompetent and immunosuppressed patients, although more severe and disseminated infections tend to occur in immunocompromised individuals. Prototheca wickerhamii and Prototheca zopfii have been associated with human disease. Usually, treatment involves medical and surgical approaches; treatment failure is not uncommon. Antifungals such as ketoconazole, itraconazole, fluconazole, and amphotericin B are the most commonly used drugs to date. Among them, amphotericin B displays the best activity against Prototheca spp. Diagnosis is largely made upon detection of characteristic structures observed on histopathologic examination of tissue. PMID:17428884

Lass-Flörl, Cornelia; Mayr, Astrid

2007-04-01

255

Human Anatomy  

NSDL National Science Digital Library

This website, crafted by the State University of New York-Upstate Medical University, brings together key resources for students and others interested in human anatomy. These materials were designed with first year medical students in mind, but they will also be of use to individuals taking biology and other science-related courses. On the site, visitors can make their way through six sections ranging from extremities to the head and neck. Each area contains a variety of detailed anatomical charts, glossaries, and images. Radiology resources are also prominently featured within each section, providing students with a different perspective of the human body through x-rays, CT scans, and MRIs. Other helpful resources include fact sheets, quizzes, teaching materials, and other freely available course materials offered from other medical schools.

256

Human Protothecosis  

PubMed Central

Human protothecosis is a rare infection caused by members of the genus Prototheca. Prototheca species are generally considered to be achlorophyllic algae and are ubiquitous in nature. The occurrence of protothecosis can be local or disseminated and acute or chronic, with the latter being more common. Diseases have been classified as (i) cutaneous lesions, (ii) olecranon bursitis, or (iii) disseminated or systemic manifestations. Infections can occur in both immunocompetent and immunosuppressed patients, although more severe and disseminated infections tend to occur in immunocompromised individuals. Prototheca wickerhamii and Prototheca zopfii have been associated with human disease. Usually, treatment involves medical and surgical approaches; treatment failure is not uncommon. Antifungals such as ketoconazole, itraconazole, fluconazole, and amphotericin B are the most commonly used drugs to date. Among them, amphotericin B displays the best activity against Prototheca spp. Diagnosis is largely made upon detection of characteristic structures observed on histopathologic examination of tissue.

Lass-Florl, Cornelia; Mayr, Astrid

2007-01-01

257

Human Locomotion  

PubMed Central

The development of bipedal plantigrade progression is a purely human, and apparently learned, accomplishment. Experimental findings confirm the hypothesis that the human body will integrate the motion of various segments of the body and control the activity of muscles to minimize energy expenditure. Movements which are integrated for this purpose include vertical displacement of the body, horizontal rotation of the pelvis, mediolateral pelvic tilt, flexion of the knee, plantar flexion of the ankle and foot, lateral displacement of the torso and rotation of the shoulder girdle. Raising and lowering the body results in gains and losses of potential energy, and acceleration and deceleration result in gains and losses of kinetic energy. The motions are so co-ordinated that a transfer of energy back and forth from kinetic to potential occurs during walking, which tends to minimize total energy expenditure as well as muscle work. ImagesFig. 1

Inman, Verne T.

1966-01-01

258

Human Traits  

NSDL National Science Digital Library

In this activity, learners investigate variations in human traits. This allows learners' natural curiosity about their identity to draw them into the study of heredity. Learners can investigate traits such as earlobe attachment, tongue rolling, hair and eye color, and hair texture. Through these traits, learners get an introduction to different inheritance patterns such as simple and incomplete dominance. Activity is usually done over multiple days to give learners time to survey people about their traits.

Salter, Irene

2012-06-26

259

Human evolution.  

PubMed

The common ancestor of modern humans and the great apes is estimated to have lived between 5 and 8 Myrs ago, but the earliest evidence in the human, or hominid, fossil record is Ardipithecus ramidus, from a 4.5 Myr Ethiopian site. This genus was succeeded by Australopithecus, within which four species are presently recognised. All combine a relatively primitive postcranial skeleton, a dentition with expanded chewing teeth and a small brain. The most primitive species in our own genus, Homo habilis and Homo rudolfensis, are little advanced over the australopithecines and with hindsight their inclusion in Homo may not be appropriate. The first species to share a substantial number of features with later Homo is Homo ergaster, or 'early African Homo erectus', which appears in the fossil record around 2.0 Myr. Outside Africa, fossil hominids appear as Homo erectus-like hominids, in mainland Asia and in Indonesia close to 2 Myr ago; the earliest good evidence of 'archaic Homo' in Europe is dated at between 600-700 Kyr before the present. Anatomically modern human, or Homo sapiens, fossils are seen first in the fossil record in Africa around 150 Kyr ago. Taken together with molecular evidence on the extent of DNA variation, this suggests that the transition from 'archaic' to 'modern' Homo may have taken place in Africa. PMID:8976151

Wood, B

1996-12-01

260

Human Chromosomes  

NSDL National Science Digital Library

Representation of the 23 paired chromosomes of the human male. Chromosome: a very long DNA molecule and associated proteins, that carry portions of the hereditary information of an organism. a. Structure of a chromosome (Typical metaphase chromosome): A chromosome is formed from a single DNA molecule that contains many genes. A chromosomal DNA molecule contains three specific nucleotide sequences which are required for replication: a DNA replication origin; a centromere to attach the DNA to the mitotic spindle.; a telomere located at each end of the linear chromosome. The DNA molecule is highly condensed. The human DNA helix occupy too much space in the cell. Small proteins are responsible for packing the DNA into units called nucleosomes. b. Stained chromosomes: Chromosomes are stained with A-T (G bands) and G-C (R bands) base pair specific dyes. When they are stained, the mitotic chromosomes have a banded structure that unambiguously identifies each chromosome of a karyotype. Each band contains millions of DNA nucleotide pairs which do not correspond to any functional structure. Adapted from K.F. Jorgenson, J.H. van de Sande, and C.C. Lin, Chromosoma 68:287-302, 1978. c. Karyotype of a male: The human haploid genome contains 3,000,000,000 DNA nucleotide pairs, divided among twenty two (22) pairs of autosomes and one pair of sex chromosomes.

BEGIN:VCARD VERSION:2.1 FN:Access Excellence N:Excellence;Access REV:2005-03-12 END:VCARD

2005-03-12

261

Human Metapnemovirus (HMPV)  

MedlinePLUS

... Register for ENews Home > Lung Disease > Human Metapneumovirus Human Metapneumovirus Human metapneumovirus (hMPV) is a recently identified member of ... respiratory illnesses for at least 50 years worldwide. Human metapneumovirus can cause upper and lower respiratory tract ...

262

Obesity-Related Metabolomic Analysis of Human Subjects in Black Soybean Peptide Intervention Study by Ultraperformance Liquid Chromatography and Quadrupole-Time-of-Flight Mass Spectrometry  

PubMed Central

The present study aimed to identify key metabolites related to weight reduction in humans by studying the metabolic profiles of sera obtained from 34 participants who underwent dietary intervention with black soybean peptides (BSP) for 12 weeks. This research is a sequel to our previous work in which the effects of BSP on BMI and blood composition of lipid were investigated. Sera of the study were subjected to ultra performance liquid chromatography and quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS), and the data were analyzed using partial least-squares discriminate analysis (PLS-DA) score plots. Body mass index and percent body fat of the test group were reduced. Levels of betaine, benzoic acid, pyroglutamic acid, pipecolic acid, N-phenylacetamide, uric acid, l-aspartyl-l-phenylalanine, and lysophosphatidyl cholines (lysoPCs) (C18:1, C18:2, C20:1, and C20:4) showed significant increases. Levels of l-proline, valine, l-leucine/isoleucine, hypoxanthine, glutamine, l-methionine, phenylpyruvic acid, several carnitine derivatives, and lysoPCs (C14:0, PC16:0, C15:0, C16:0, C17:1, C18:0, and C22:0) were significantly decreased. In particular, lysoPC 16:0 with a VIP value of 12.02 is esteemed to be the most important metabolite for evaluating the differences between the 2 serum samples. Our result confirmed weight-lowering effects of BSP, accompanied by favorable changes in metabolites in the subjects' blood. Therefore, this research enables us to better understand obesity and increases the predictability of the obesity-related risk by studying metabolites present in the blood.

Kim, Min Jung; Yang, Hye Jeong; Kim, Jin Hee; Ahn, Chang-Won; Lee, Jong Ho; Kim, Kang Sung; Kwon, Dae Young

2013-01-01

263

Human Propulsion  

NSDL National Science Digital Library

This lesson points out that the motion of objects (velocity or acceleration) is almost never constant, and applies this idea to the motion of a person walking. The discussion covers the energy transfers involved in walking and in some other forms of human-powered transportation (crutches, bicycle, wheelchair), and the velocity and acceleration of an object that is moving in one dimension. The lesson includes an activity in which students use an accelerometer attached to a student volunteer to measure instantaneous acceleration in three dimensions, and calculate the total work which is done.

Pratte, John

264

Human schistosomiasis.  

PubMed

Human schistosomiasis--or bilharzia--is a parasitic disease caused by trematode flukes of the genus Schistosoma. By conservative estimates, at least 230 million people worldwide are infected with Schistosoma spp. Adult schistosome worms colonise human blood vessels for years, successfully evading the immune system while excreting hundreds to thousands of eggs daily, which must either leave the body in excreta or become trapped in nearby tissues. Trapped eggs induce a distinct immune-mediated granulomatous response that causes local and systemic pathological effects ranging from anaemia, growth stunting, impaired cognition, and decreased physical fitness, to organ-specific effects such as severe hepatosplenism, periportal fibrosis with portal hypertension, and urogenital inflammation and scarring. At present, preventive public health measures in endemic regions consist of treatment once every 1 or 2 years with the isoquinolinone drug, praziquantel, to suppress morbidity. In some locations, elimination of transmission is now the goal; however, more sensitive diagnostics are needed in both the field and clinics, and integrated environmental and health-care management will be needed to ensure elimination. PMID:24698483

Colley, Daniel G; Bustinduy, Amaya L; Secor, W Evan; King, Charles H

2014-06-28

265

Comparing Human-Human to Human-Computer Tutorial Dialogue.  

National Technical Information Service (NTIS)

Intelligent Tutoring Systems are often modeled after human tutors; however, the effectiveness of this strategy is yet to be determined. Research on media interactions suggests that behaviors with humans are similar to those with computers. Intelligent Tut...

G. E. Campbell K. M. Harrison L. S. Taylor M. O. Dzikovska N. B. Steinhauser

2010-01-01

266

Damage to Aspergillus fumigatus and Rhizopus oryzae Hyphae by Oxidative and Nonoxidative Microbicidal Products of Human Neutrophils In Vitro  

PubMed Central

Our previous studies established that human neutrophils could damage and probably kill hyphae of Aspergillus fumigatus and Rhizopus oryzae in vitro, primarily by oxygen-dependent mechanisms active at the cell surface. These studies were extended, again quantitating hyphal damage by reduction in uptake of 14C-labeled uracil or glutamine. Neither A. fumigatus nor R. oryzae hyphae were damaged by neutrophils from patients with chronic granulomatous disease, confirming the importance of oxidative mechanisms in damage to hyphae. In contrast, neutrophils from one patient with hereditary myeloperoxidase deficiency damaged R. oryzae but not A. fumigatus hyphae. Cell-free, in vitro systems were then used to help determine the relative importance of several potentially fungicidal products of neutrophils. Both A. fumigatus and R. oryzae hyphae were damaged by the myeloperoxidase-hydrogen peroxide-halide system either with reagent hydrogen peroxide or enzymatic systems for generating hydrogen peroxide (glucose oxidase with glucose, or xanthine oxidase with either hypoxanthine or acetaldehyde). Iodide with or without chloride supported the reaction, but damage was less with chloride alone as the halide cofactor. Hydrogen peroxide alone damaged hyphae only in concentrations ?1 mM, but 0.01 mM hypochlorous acid, a potential product of the myeloperoxidase system, significantly damaged R. oryzae hyphae (a 1 mM concentration was required for significant damage to A. fumigatus hyphae). Damage to hyphae by the myeloperoxidase system was inhibited by azide, cyanide, catalase, histidine, and tryptophan, but not by superoxide dismutase, dimethyl sulfoxide, or mannitol. Photoactivation of the dye rose bengal resulted in hyphal damage which was inhibited by histidine, tryptophan, and 1,4-diazobicyclo(2,2,2)octane. Lysates of neutrophils or separated neutrophil granules did not affect A. fumigatus hyphae, but did damage R. oryzae hyphae. Similarly, three preparations of cationic proteins purified from human neutrophil granules were more active in damaging R. oryzae than A. fumigatus hyphae. This damage, as with the separated granules and whole cell lysates, was inhibited by the polyanion heparin. Damage to R. oryzae hyphae by neutrophil cationic proteins was enhanced by activity of the complete myeloperoxidase system or by hydrogen peroxide alone in subinhibitory concentrations. These data support the importance of oxidative products in general and the myeloperoxidase system in particular in damage to hyphae by neutrophils. Cationic proteins may also contribute significantly to neutrophil-mediated damage to R. oryzae hyphae.

Diamond, Richard D.; Clark, Robert A.

1982-01-01

267

Human Factors in Human-Systems Integration  

NASA Technical Reports Server (NTRS)

Any large organization whose mission is to design and develop systems for humans, and train humans needs a well-developed integration and process plan to deal with the challenges that arise from managing multiple subsystems. Human capabilities, skills, and needs must be considered early in the design and development process, and must be continuously considered throughout the development lifecycle. This integration of human needs within system design is typically formalized through a Human-Systems Integration (HSI) program. By having an HSI program, an institution or organization can reduce lifecycle costs and increase the efficiency, usability, and quality of its products because human needs have been considered from the beginning.

Fitts, David J.; Sandor, Aniko; Litaker, Harry L., Jr.; Tillman, Barry

2008-01-01

268

Human Rhinoviruses  

PubMed Central

Human rhinoviruses (HRVs), first discovered in the 1950s, are responsible for more than one-half of cold-like illnesses and cost billions of dollars annually in medical visits and missed days of work. Advances in molecular methods have enhanced our understanding of the genomic structure of HRV and have led to the characterization of three genetically distinct HRV groups, designated groups A, B, and C, within the genus Enterovirus and the family Picornaviridae. HRVs are traditionally associated with upper respiratory tract infection, otitis media, and sinusitis. In recent years, the increasing implementation of PCR assays for respiratory virus detection in clinical laboratories has facilitated the recognition of HRV as a lower respiratory tract pathogen, particularly in patients with asthma, infants, elderly patients, and immunocompromised hosts. Cultured isolates of HRV remain important for studies of viral characteristics and disease pathogenesis. Indeed, whether the clinical manifestations of HRV are related directly to viral pathogenicity or secondary to the host immune response is the subject of ongoing research. There are currently no approved antiviral therapies for HRVs, and treatment remains primarily supportive. This review provides a comprehensive, up-to-date assessment of the basic virology, pathogenesis, clinical epidemiology, and laboratory features of and treatment and prevention strategies for HRVs.

Lamson, Daryl M.; St. George, Kirsten; Walsh, Thomas J.

2013-01-01

269

Human Papillomavirus (HPV)  

MedlinePLUS

... Preventable Diseases > Human Papillomavirus (HPV) Health Issues Listen Human Papillomavirus (HPV) Article Body According to the Centers ... Control and Prevention, there is an epidemic of human papillomavirus (HPV) in the United States. HPV is ...

270

Secular Humanism and Education.  

ERIC Educational Resources Information Center

Addresses allegations that public schools are unconstitutionally promoting secular humanism. Presents perspectives defining secular humanism and explores whether secular humanism is considered a religion under the establishment clause. Deals with charges by conservative parent groups. (164 references) (MLF)

McCarthy, Martha M.

1990-01-01

271

Human Genome Diversity Project.  

National Technical Information Service (NTIS)

The Human Genome Diversity Project (HGD Project) is an international anthropology project that seeks to study the genetic richness of the entire human species. This kind of genetic information can add a unique thread to the tapestry knowledge of humanity....

L. Cavalli-Sforza

1994-01-01

272

Humanized Mouse Models to Study Human Diseases  

PubMed Central

Purpose of review Update on humanized mouse models and their use in biomedical research. Recent findings The recent description of immunodeficient mice bearing a mutated IL-2 receptor gamma chain (IL2ry) facilitated greatly the engraftment and function of human hematolymphoid cells and other cells and tissues. These mice permit the development of human immune systems, including functional T and B cells, following engraftment of hematopoietic stem cells (HSC). The engrafted functional human immune systems are capable of T and B cell-dependent immune responses, antibody production, anti-viral responses, and allograft rejection. Immunodeficient IL2rynull mice also support heightened engraftment of primary human cancers and malignant progenitor cells, permitting in vivo investigation of pathogenesis and function. In addition, human-specific infectious agents for which animal models were previously unavailable can now be studied in vivo using these new generation humanized mice. Summary Immunodeficient mice bearing an IL2rynull mutated gene can be engrafted with functional human cells and tissues, including human immune systems, following engraftment with human hematolymphoid cells. These mice are now used as in vivo models to study human hematopoiesis, immunity, regeneration, stem cell function, cancer, and human-specific infectious agents without putting patients at risk.

Brehm, Michael A.; Shultz, Leonard D.; Greiner, Dale L.

2010-01-01

273

Engineered human vaccines  

SciTech Connect

The limitations of human vaccines in use at present and the design requirements for a new generation of human vaccines are discussed. The progress in engineering of human vaccines for bacteria, viruses, parasites, and cancer is reviewed, and the data from human studies with the engineered vaccines are discussed, especially for cancer and AIDS vaccines. The final section of the review deals with the possible future developments in the field of engineered human vaccines and the requirement for effective new human adjuvants.

Sandhu, J.S. (Mount Sinai Hospital, Toronto, Ontario (Canada). Div. of Immunology and Neurobiology)

1994-01-01

274

Human-machine interactions  

DOEpatents

Digital technology utilizing a cognitive model based on human naturalistic decision-making processes, including pattern recognition and episodic memory, can reduce the dependency of human-machine interactions on the abilities of a human user and can enable a machine to more closely emulate human-like responses. Such a cognitive model can enable digital technology to use cognitive capacities fundamental to human-like communication and cooperation to interact with humans.

Forsythe, J. Chris (Sandia Park, NM); Xavier, Patrick G. (Albuquerque, NM); Abbott, Robert G. (Albuquerque, NM); Brannon, Nathan G. (Albuquerque, NM); Bernard, Michael L. (Tijeras, NM); Speed, Ann E. (Albuquerque, NM)

2009-04-28

275

Normal activity of metabolic pathways involved in the formation and utilization of phosphoribosylpyrophosphate in erythrocytes of patients with primary metabolic gout.  

PubMed

The activity of metabolic pathways involved in the formation and utilization of phosphoribosylpyrophosphate (PRPP) was studied in. The erythrocytes of 34 patients with idiopathic metabolic gout. The activities of the oxidative pentose shunt, of the hypoxanthine-guanine and adenine phosphoribosyltransferases (HGPRT, APRT) and of PRPP synthetase, as well as the rates of PRPP generation and of adenine incorporation into nucleotides were found to be normal in the erythrocytes of all these patients. Four patients with metabolic gout due to enzymatic abnormalities, two relatives with partial deficiency of HGPRT and two relatives with mutant feedback-resistant PRPP synthetase, were studied for comparison. The significance of the results is discussed in relation to postulated mechanisms for purine overproduction in metabolic gout. PMID:172821

Sperling, O; Boer, P; Brosh, S; Elazar, E; Szeinberg, A; de Vries, A

1975-01-01

276

Lethal Accumulation of Guanylic Nucleotides in Saccharomyces cerevisiae HPT1-Deregulated Mutants  

PubMed Central

Guanylic nucleotide biosynthesis is a conserved and highly regulated process. Drugs reducing GMP synthesis affect the immunological response and mutations enabling guanylic-derivative recycling lead to severe mental retardation. While the effects of decreased GMP synthesis have been well documented, the consequences of GMP overproduction in eukaryotes are poorly understood. In this work, we selected and characterized several mutations making yeast hypoxanthine–guanine phosphoribosyltransferase insensitive to feedback inhibition by GMP. In these mutants, accumulation of guanylic nucleotides can be triggered by addition of extracellular guanine. We show that such an accumulation is highly toxic for yeast cells and results in arrest of proliferation and massive cell death. This growth defect could be partially suppressed by overexpression of Rfx1p, a transcriptional repressor of the DNA damage response pathway. Importantly, neither guanylic nucleotide toxicity nor its suppression by Rfx1p was associated with an alteration of forward mutation frequency.

Breton, Annick; Pinson, Benoit; Coulpier, Fanny; Giraud, Marie-France; Dautant, Alain; Daignan-Fornier, Bertrand

2008-01-01

277

Investigation of coelectroporation as a method for introducing small mutations into embryonic stem cells.  

PubMed

We have investigated coelectroporation as a method for introducing minor genetic changes into specific genes in embryonic stem cells. A selectable marker (neo) and a targeting replacement vector designed to insert a 4-bp insertion into exon 3 of the mouse hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene were coelectroporated into embryonic stem cells and selected in G418 and 6-thioguanine (6-TG). HPRT-negative clones were obtained at a frequency of approximately 1 per 520 G418r clones. Southern analysis and the polymerase chain reaction were used to demonstrate that 3 of 36 of the 6-TG-resistant clones had the desired 4-bp insertion without any other disruption of the HPRT locus. Initial studies indicated that the other 33 6-TG-resistant clones probably resulted from the targeted integration of a concatemer containing both the targeting construct and the selectable neo gene. PMID:1588968

Davis, A C; Wims, M; Bradley, A

1992-06-01

278

Investigation of coelectroporation as a method for introducing small mutations into embryonic stem cells.  

PubMed Central

We have investigated coelectroporation as a method for introducing minor genetic changes into specific genes in embryonic stem cells. A selectable marker (neo) and a targeting replacement vector designed to insert a 4-bp insertion into exon 3 of the mouse hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene were coelectroporated into embryonic stem cells and selected in G418 and 6-thioguanine (6-TG). HPRT-negative clones were obtained at a frequency of approximately 1 per 520 G418r clones. Southern analysis and the polymerase chain reaction were used to demonstrate that 3 of 36 of the 6-TG-resistant clones had the desired 4-bp insertion without any other disruption of the HPRT locus. Initial studies indicated that the other 33 6-TG-resistant clones probably resulted from the targeted integration of a concatemer containing both the targeting construct and the selectable neo gene. Images

Davis, A C; Wims, M; Bradley, A

1992-01-01

279

Homologies between T cell receptor junctional sequences unique to multiple sclerosis and T cells mediating experimental allergic encephalomyelitis.  

PubMed Central

The selection of T cell clones with mutations in the hypoxanthine guanine phosphoribosyltransferase (hprt) gene has been used to isolate T cells reactive to myelin basic protein (MBP) in patients with multiple sclerosis (MS). These T cell clones are activated in vivo, and are not found in healthy individuals. The third complementarity determining regions (CDR3) of the T cell receptor (TCR) alpha and beta chains are the putative contact sites for peptide fragments of MBP bound in the groove of the HLA molecule. The TCR V gene usage and CDR3s of these MBP-reactive hprt-T cell clones are homologous to TCRs from other T cells relevant to MS, including T cells causing experimental allergic encephalomyelitis (EAE) and T cells found in brain lesions and in the cerebrospinal fluid (CSF) of MS patients. In vivo activated MBP-reactive T cells in MS patients may be critical in the pathogenesis of MS.

Allegretta, M; Albertini, R J; Howell, M D; Smith, L R; Martin, R; McFarland, H F; Sriram, S; Brostoff, S; Steinman, L

1994-01-01

280

Adenine and adenosine salvage in Leishmania donovani.  

PubMed

6-aminopurine metabolism in Leishmania is unique among trypanosomatid pathogens since this genus expresses two distinct routes for adenine salvage: adenine phosphoribosyltransferase (APRT) and adenine deaminase (AAH). To evaluate the relative contributions of APRT and AAH, adenine salvage was evaluated in ?aprt, ?aah, and ?aprt/?aah null mutants of L. donovani. The data confirm that AAH plays the dominant role in adenine metabolism in L. donovani, although either enzyme alone is sufficient for salvage. Adenosine salvage was also evaluated in a cohort of null mutants. Adenosine is also primarily converted to hypoxanthine, either intracellularly or extracellularly, but can also be phosphorylated to the nucleotide level by adenosine kinase when the predominant pathways are genetically or pharmacologically blocked. These data provide genetic verification for the relative contributions of 6-aminopurine metabolizing pathways in L. donovani and demonstrate that all of the pathways can function under appropriate conditions of genetic or pharmacologic perturbation. PMID:23845934

Boitz, Jan M; Ullman, Buddy

2013-08-01

281

Thirteen years experience with selective screening for disorders in purine and pyrimidine metabolism.  

PubMed

Purine and pyrimidine disorders represent a heterogeneous group with variable clinical symptoms and low prevalence rate. In the last thirteen years, we have studied urine/plasma specimens from about 1600 patients and we have identified 35 patients: eight patients with adenylosuccinate lyase deficiency, eight patients with hypoxanthine-guanine phosphoribosyltransferase deficiency, one patient with purine nucleoside phosphorylase deficiency, ten patients with xanthine dehydrogenase deficiency, six patients with molybdenum cofactor deficiency and two patients with dihydropyrimidine dehydrogenase deficiency. Despite low incidence of these diseases, our findings highlight the importance of including the purine and pyrimidine analysis in the selective screening for inborn errors of metabolism in specialized laboratories, where amino acid and organic acid disorders are simultaneously investigated. PMID:24940674

Castro, M; Carrillo, R; García, F; Sanz, P; Ferrer, I; Ruiz-Sala, P; Vega, A I; Ruíz Desviat, L; Pérez, B; Pérez-Cerdá, C; Merinero, B; Ugarte, M

2014-04-01

282

Update on the Phenotypic Spectrum of Lesch-Nyhan Disease and its Attenuated Variants  

PubMed Central

Congenital deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT) results in a spectrum of clinical phenotypes. All of these phenotypes are associated with marked overproduction of uric acid and related problems such as hyperuricemia, urate nephrolithiasis, tophi, and gout. The mildest phenotypes include only problems related to overproduction of uric acid. The most severe phenotype is known as Lesch-Nyhan disease, in which the phenotype also includes severe motor handicap, intellectual disability, and self-injurious behavior. In between these two extremes is a continuous spectrum of phenotypes with varying degrees of motor and cognitive handicap but no self-injurious behavior. The pathogenesis of overproduction of uric acid in HPRT deficiency is well-understood, and treatments are available to control it. The pathogenesis of the neurobehavioral problems is less well-understood, and effective treatments for them are lacking.

Torres, Rosa J.; Puig, Juan G.; Jinnah, Hyder A.

2012-01-01

283

HPV (Human Papillomavirus)  

MedlinePLUS

... papillomavirus test for primary cervical cancer screening HPV (human papillomavirus) Print and Share (PDF 1105 KB ) En Español HPV (human papillomavirus) is a sexually transmitted virus. It is ...

284

Evaluation and validation of housekeeping genes in response to ionizing radiation and chemical exposure for normalizing RNA expression in real-time PCR.  

PubMed

Gene expression changes are used with increasing frequency to assess the effects of exposure to environmental agents. Housekeeping (Hk) genes are essential in these analyses as internal controls for normalizing expression levels evaluated with Real-Time PCR (RT-PCR). Ideal Hk genes are constitutively expressed, do not respond to external stimuli and exhibit little or no sample-to-sample or run-to-run variation. Previous studies indicate that some commonly used Hk genes including glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and beta-actin have differential expression in various cell lines. Here we examine the expression of 11 Hk genes in four normal human lymphoblastoid cell lines and one T-cell leukemia (Jurkat) cell line following exposure to graded doses of ionizing radiation or to varying ratio concentrations of phytohemagglutinin (PHA) and phorbol myristate acetate (PMA). PHA and PMA are known to have synergistic effects on the expression of some genes and have very different effects from those of radiation. There has been no systematic study performed to ascertain the best control genes for radiation and/or PHA/PMA exposures in lymphoblastoid cells. Using a two-step reverse-transcriptase RT-PCR protocol we show that following radiation doses ranging from 0 to 400 cGy, 18S rRNA, acidic ribosomal protein, beta-actin, cyclophilin, GAPDH, phosphoglycerokinase, beta-2 microglobulin (B2M), beta-glucuronidase, hypoxanthine phosphoribosyltransferase and transferrin receptor showed no significant variation in expression in normal lymphoblastoid cells. In contrast, only 18S rRNA levels were unchanged in Jurkat cells. After PHA/PMA treatment of the same normal cell lines, B2M showed no significant variation and 18S rRNA, GAPDH and transcription binding protein (TBP) were minimally responsive, whereas in Jurkat cells all these genes were unresponsive. While our results suggest that the utility of a particular Hk gene should be determined for each experimental condition, 18S rRNA and B2M appear to be excellent candidates for use as internal controls in RT-PCR in human lymphoblastoid cells because they have the most constant levels of expression across cell lines following exposure to ionizing radiation as well as to PHA/PMA. PMID:17904413

Banda, Malathi; Bommineni, Aryamani; Thomas, Robert A; Luckinbill, Leo S; Tucker, James D

2008-01-01

285

Human Research Program Opportunities  

NASA Technical Reports Server (NTRS)

The goal of HRP is to provide human health and performance countermeasures, knowledge, technologies, and tools to enable safe, reliable, and productive human space exploration. The Human Research Program was designed to meet the needs of human space exploration, and understand and reduce the risk to crew health and performance in exploration missions.

Kundrot, Craig E.

2014-01-01

286

Visualizing Humans by Computer.  

ERIC Educational Resources Information Center

Presents an overview of the problems and techniques involved in visualizing humans in a three-dimensional scene. Topics discussed include human shape modeling, including shape creation and deformation; human motion control, including facial animation and interaction with synthetic actors; and human rendering and clothing, including textures and…

Magnenat-Thalmann, Nadia

1992-01-01

287

Adenine metabolism in Plasmodium falciparum.  

PubMed

Plasmodium falciparum lacks the de novo purine biosynthesis pathway and relies entirely on the salvage pathway to meet its purine nucleotide requirements. The entire flux for purine nucleotide biosynthesis in the parasite is believed to be through hypoxanthine guanine phosphoribosyltransferase (HGPRT), with the enzymes, adenosine kinase and adenine phosphoribosyltransferase (APRT) being unannotated in the Plasmodium genome database. This manuscript reports on the studies carried out to explore bypass mechanisms, if any, for AMP synthesis in the intraerythrocyitc stages of the parasite life cycle. Uptake and subsequent incorporation of radiolabel adenine in the nucleotide pool of saponin released erythrocyte free parasites implicated the role of parasite encoded enzymes in adenine metabolism. To explore the route for AMP synthesis in the parasite, we have monitored adenine mediated supplementation of metabolic viability in saponin released hadacidin (N-formyl-N-hydroxyglycine) treated parasites. Our results implicate the role of an APRT like activity that enables parasite survival when the flux through the HGPRT pathway is blocked. PMID:20093117

Mehrotra, Sonali; Bopanna, Monnanda P; Bulusu, Vinay; Balaram, Hemalatha

2010-06-01

288

Preference for human eyes in human infants.  

PubMed

Despite evidence supporting an early attraction to human faces, the nature of the face representation in neonates and its development during the first year after birth remain poorly understood. One suggestion is that an early preference for human faces reflects an attraction toward human eyes because human eyes are distinctive compared with other animals. In accord with this proposal, prior empirical studies have demonstrated the importance of the eye region in face processing in adults and infants. However, an attraction for the human eye has never been shown directly in infants. The current study aimed to investigate whether an attraction for human eyes would be present in newborns and older infants. With the use of a preferential looking time paradigm, newborns and 3-, 6-, 9-, and 12-month-olds were simultaneously presented with a pair of nonhuman primate faces (chimpanzees and Barbary macaques) that differed only by the eyes, thereby pairing a face with original nonhuman primate eyes with the same face in which the eyes were replaced by human eyes. Our results revealed that no preference was observed in newborns, but a preference for nonhuman primate faces with human eyes emerged from 3months of age and remained stable thereafter. The findings are discussed in terms of how a preference for human eyes may emerge during the first few months after birth. PMID:24581972

Dupierrix, Eve; de Boisferon, Anne Hillairet; Méary, David; Lee, Kang; Quinn, Paul C; Di Giorgio, Elisa; Simion, Francesca; Tomonaga, Masaki; Pascalis, Olivier

2014-07-01

289

MeIQx-induced DNA adduct formation and mutagenesis in DNA repair deficient CHO cells expressing human CYP1A1 and rapid or slow acetylator NAT2  

PubMed Central

2-Amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MeIQx) is one of the most potent and abundant mutagens in the western diet. Bioactivation includes N-hydroxylation catalyzed by cytochrome P450s followed by O-acetylation catalyzed by N-acetyltransferase 2 (NAT2). Nucleotide excision repair-deficient chinese hamster ovary (CHO) cells were constructed by stable transfection of human cytochrome P4501A1 (CYP1A1) and a single copy of either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles. CYP1A1 and NAT2 catalytic activities were undetectable in untransfected CHO cell lines. CYP1A1 activity did not differ significantly (p > 0.05) among the CYP1A1-transfected cell lines. Cells transfected with NAT2*4 had significantly higher levels of sulfamethazine N-acetyltransferase (p = 0.0001) and N-hydroxy-MeIQx O-acetyltransferase (p = 0.0093) catalytic activity than cells transfected with NAT2*5B. Only cells transfected with both CYP1A1 and NAT2*4 showed concentration-dependent cytotoxicity and hypoxanthine phosphoribosyl transferase (hprt) mutagenesis following MeIQx treatment. dG-C8-MeIQx was the primary DNA adduct formed and levels were dose-dependent in each cell line and in the order: untransfected < transfected with CYP1A1 < transfected with CYP1A1 & NAT2*5B < transfected with CYP1A1 & NAT2*4. MeIQx DNA adduct levels were significantly higher (p < 0.001) in CYP1A1/NAT2*4 than CYP1A1/NAT2*5B cells at all concentrations of MeIQx tested. MeIQx-induced DNA adduct levels correlated very highly (r2 = 0.88) with MeIQx-induced mutants. These results strongly support extrahepatic activation of MeIQx by CYP1A1 and a robust effect of human NAT2 genetic polymorphism on MeIQx –induced DNA adducts and mutagenesis. The results provide laboratory-based support for epidemiological studies reporting higher frequency of heterocyclic amine-related cancers in rapid NAT2 acetylators.

Bendaly, Jean; Zhao, Shuang; Neale, Jason R.; Metry, Kristin J.; Doll, Mark A.; States, J. Christopher; Pierce, William M.; Hein, David W.

2007-01-01

290

Human bites (image)  

MedlinePLUS

Human bites present a high risk of infection. Besides the bacteria which can cause infection, there is ... the wound extends below the skin. Anytime a human bite has broken the skin, seek medical attention.

291

Human Mycoplasma Infections.  

National Technical Information Service (NTIS)

The present evidence for the infectiousness of the mycoplasma as causative agents of human disease has been reviewed. Two decades of intensive investigation of primary atypical pneumonia have established the mycoplasma as true pathogens for human beings. ...

M. C. Shepard

1966-01-01

292

Human Parathyroid Hormone.  

National Technical Information Service (NTIS)

The patent application relates to the isolation and purification of human parathyroid hormone from human parathyroid adenomas. The primary sequence of the amino terminal 34 residues was determined and the peptide of the first 34 residues synthesized.

H. B. Brewer

1973-01-01

293

Human Model Report  

Microsoft Academic Search

12 pages\\u000aProvider Notes:This page contains the human model report.Last update 11\\/21\\/2005. In the order of importance, human needs oxygen, water and food for survival. Human produces energy, carbon dioxide, sweat, urine, and feces. These inputs and outputs contents and quantity are depended on human consumption and body structures such as gender, age, and body mass. Environment is a very

ALS-NSCORT

2005-01-01

294

Esprit: A Humanities Magazine.  

ERIC Educational Resources Information Center

In March 1984, the first issue of "Esprit," a semi-annual humanities magazine for the 56 two-year colleges in New York State, was published. The magazine seeks to confront the apparent decline of student interest in the humanities, community doubts about the relevance of the humanities, and the seeming indifference to the special truths inherent…

Parker, Donald G.; Capella, Barry John

295

The Humanities' Value  

ERIC Educational Resources Information Center

Why should society support the humanities when so many people are suffering from the effects of the economic crisis? What claim do the humanities, or scholarship generally, have on increasingly limited resources? Shouldn't such pursuits be considered luxuries at a time when people should be focusing on essentials? The alleviation of human

Harpham, Geoffrey Galt

2009-01-01

296

Dogs catch human yawns  

Microsoft Academic Search

Summary This study is the first to demonstrate that human yawns are possibly contagious to domestic dogs (Canis familiaris). Twenty-nine dogs observed a human yawning or making control mouth movements. Twenty-one dogs yawned when they observed a human yawning, but control mouth movements did not elicit yawning from any of them. The presence of contagious yawning in dogs suggests that

Ramiro M. Joly-Mascheroni; Atsushi Senju; Alex J. Shepherd

2008-01-01

297

Urban human ecology  

Microsoft Academic Search

Cities are human ecosystems. Eight primary concepts assist us in understanding human ecosystems in terms of variability, time, and complexity. These concepts include: systems thinking; language, culture, and technology; structure, function, and change; edges, boundaries, and ecotones; interaction, integration, and institution; diversity; adaptation; and holism. Hierarchy theory presents a framework for organizing these concepts. Human settlements can be viewed hierarchically,

Frederick Steiner

2004-01-01

298

HUMAN USE INDEX (FUTURE)  

EPA Science Inventory

Human land uses may have major impacts on ecosystems, affecting biodiversity, habitat, air and water quality. The human use index (also known as U-index) is the percentage of human land use in an area, including agriculture, urban and suburban development, and mining. Low values ...

299

HUMAN USE INDEX  

EPA Science Inventory

Human land uses may have major impacts on ecosystems, affecting biodiversity, habitat, air and water quality. The human use index (also known as U-index) is the percentage of human land use in an area, including agriculture, urban and suburban development, and mining. Low values ...

300

dGTP Starvation in Escherichia coli Provides New Insights into the Thymineless-Death Phenomenon  

PubMed Central

Starvation of cells for the DNA building block dTTP is strikingly lethal (thymineless death, TLD), and this effect is observed in all organisms. The phenomenon, discovered some 60 years ago, is widely used to kill cells in anticancer therapies, but many questions regarding the precise underlying mechanisms have remained. Here, we show for the first time that starvation for the DNA precursor dGTP can kill E. coli cells in a manner sharing many features with TLD. dGTP starvation is accomplished by combining up-regulation of a cellular dGTPase with a deficiency of the guanine salvage enzyme guanine-(hypoxanthine)-phosphoribosyltransferase. These cells, when grown in medium without an exogenous purine source like hypoxanthine or adenine, display a specific collapse of the dGTP pool, slow-down of chromosomal replication, the generation of multi-branched nucleoids, induction of the SOS system, and cell death. We conclude that starvation for a single DNA building block is sufficient to bring about cell death.

Itsko, Mark; Schaaper, Roel M.

2014-01-01

301

Purine metabolism in Toxoplasma gondii  

SciTech Connect

We have studied the incorporation and interconversion of purines into nucleotides by freshly isolated Toxoplasma gondii. They did not synthesize nucleotides from formate, glycine, or serine. The purine bases hypoxanthine, xanthine, guanine, and adenine were incorporated at 9.2, 6.2, 5.1, and 4.3 pmol/10(7) cells/h, respectively. The purine nucleosides adenosine, inosine, guanosine, and xanthosine were incorporated at 110, 9.0, 2.7, and 0.3 pmol/10(7) cells/h, respectively. Guanine, xanthine, and their respective nucleosides labeled only guanine nucleotides. Inosine, hypoxanthine, and adenine labeled both adenine and guanine nucleotide pools at nearly equal ratios. Adenosine kinase was greater than 10-fold more active than the next most active enzyme in vitro. This is consistent with the metabolic data in vivo. No other nucleoside kinase or phosphotransferase activities were found. Phosphorylase activities were detected for guanosine and inosine; no other cleavage activities were detected. Deaminases were found for adenine and guanine. Phosphoribosyltransferase activities were detected for all four purine nucleobases. Interconversion occurs only in the direction of adenine to guanine nucleotides.

Krug, E.C.; Marr, J.J.; Berens, R.L.

1989-06-25

302

Identification of hypoxanthine as a urine marker for non-Hodgkin lymphoma by low-mass-ion profiling  

Microsoft Academic Search

BACKGROUND: Non-Hodgkin lymphoma (NHL) is a hematologic malignancy for which good diagnostic markers are lacking. Despite continued improvement in our understanding of NHL, efforts to identify diagnostic markers have yielded dismal results. Here, we translated low-mass-ion information in urine samples from patients with NHL into a diagnostic marker. METHODS: To minimize experimental error, we tested variable parameters before MALDI-TOF analysis

Byong Chul Yoo; Sun-Young Kong; Sang-Geun Jang; Kyung-Hee Kim; Sun-A Ahn; Weon-Seo Park; Sohee Park; Tak Yun; Hyeon-Seok Eom

2010-01-01

303

Human milk and human milk fortifiers.  

PubMed

Human milk contains numerous immune-protective components that protect the premature infant from sepsis and necrotizing enterocolitis. Because of these protective effects, human milk is the feeding of choice for the premature infant. However, human milk does not provide adequate amounts of most nutrients for premature infants and must therefore be supplemented (fortified) with nutrients. Commercially available fortifiers provide energy and most nutrients in adequate amounts. The exception is protein, which is present in expressed milk in highly variable amounts and which is not provided in sufficient amounts by most fortifiers. Some liquid fortifiers are higher in protein content than powder fortifiers and provide adequate amounts of protein. PMID:24751632

Ziegler, Ekhard E

2014-01-01

304

Human-technology Integration  

NASA Astrophysics Data System (ADS)

Human-technology integration is the replacement of human parts and extension of human capabilities with engineered devices and substrates. Its result is hybrid biological-artificial systems. We discuss here four categories of products furthering human-technology integration: wearable computers, pervasive computing environments, engineered tissues and organs, and prosthetics, and introduce examples of currently realized systems in each category. We then note that realization of a completely artificial sytem via the path of human-technology integration presents the prospect of empirical confirmation of an aware artificially embodied system.

Mullen, Katharine M.

305

Human Infection with Newcastle Virus.  

National Technical Information Service (NTIS)

The Newcastle infection of humans shows all the characteristics of zoonosis. As yet the transmission from human to human or reverse transmission from human to fowl is acknowledged. It is also always concerned in dull ending ramifications from its infectio...

G. Schoop

1965-01-01

306

Biomarkers and human hepatocytes.  

PubMed

The accuracy of preclinical safety evaluation to predict human toxicity is hindered by species difference in drug metabolism and toxic mechanism between human and nonhuman animals. In vitro human-based experimental systems allowing the assessment of human-specific drug properties represent a logical and practical approach to provide human-specific information. An advantage of in vitro approaches is that they require only limited amounts of time and resources, and, most importantly, do not invoke harm to human patients. Human hepatocytes, with complete hepatic metabolizing enzymes, transporters and cofactors, represent a practical and useful experimental system to assess drug metabolism. The use of human hepatocytes to evaluate two major adverse drug properties, drug-drug interactions and hepatotoxicity, are reviewed. The application of human hepatocytes in metabolism-based drug-drug interactions includes metabolite profiling, pathway identification, CYP450 inhibition, CYP450 induction, and uptake and efflux transporter inhibition. The application of human hepatocytes in toxicity evaluation includes in vitro hepatotoxicity and metabolism-based drug toxicity determination. Correlation of drug toxicity with proteomics and genomics data may allow the discovery of clinical biomarkers for early detection of liver toxicity. PMID:24521013

Li, Albert P

2014-02-01

307

Human Rights and Peacebuilding  

Microsoft Academic Search

We begin this chapter by describing the principles of human rights and relating them to the promotion of a culture of peace.\\u000a After discussing how war interferes with human rights, we show how people were able to further human rights by creating a\\u000a space for peace in the midst of a war in the Philippines. We examine the history of

Ernesto Anasarias; Peter Berliner

308

Annotated Webliography Of Humanism  

NSDL National Science Digital Library

Created and maintained by Peter Derkx, a professor of history at the University for Humanist Studies, this Website offers a useful directory of annotated links on the subject of humanism from its inception in the Renaissance to its current struggles with Marxism and Postmodernism. The selections when addressing more contemporary topics often deal with humanism only indirectly -- a sign perhaps of the failing interest in humanism per se, rather than any lack of diligence on Dr. Derkx' part.

Derkx, Peter.

1998-01-01

309

Human Health Risk Assessment  

Microsoft Academic Search

\\u000a Exposure of humans to contaminated sites may result in many types of health damage ranging from relatively innocent symptoms\\u000a such as skin eruption or nausea, on up to cancer or even death. Human health protection is considered as a major protection\\u000a target, both by decision-makers as well as by the general public. The first step in Human Health Risk Assessment

Frank A. Swartjes; Christa Cornelis

310

Human reliability analysis  

SciTech Connect

The authors present a treatment of human reliability analysis incorporating an introduction to probabilistic risk assessment for nuclear power generating stations. They treat the subject according to the framework established for general systems theory. Draws upon reliability analysis, psychology, human factors engineering, and statistics, integrating elements of these fields within a systems framework. Provides a history of human reliability analysis, and includes examples of the application of the systems approach.

Dougherty, E.M.; Fragola, J.R.

1988-01-01

311

Automatic human body detector  

SciTech Connect

A method is devised for the automatic detection of a human body. The method utilizes the near-infrared reflection bands of the skin of the human body as the identifying signature. Illumination of the body is provided by a near-infrared light source and the detection of the reflection bands. When each of the three detectors simultaneously register a signal of the proper reflection values, a coincident trigger circuit enables an indicator device which signifies a human body is detected.

Hacskaylo, M.

1985-02-19

312

Climate and Human Migrations  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. About 14,600 years ago, humans first appeared in south central Chile. But the arid regions of the Atacama desert in northern Chile were not populated for another 2000 years, and human occupation of this region subsequently remained intermittent. In his Perspective, Dillehay highlights the report of Núñez et al., whose integrative archaeological and paleoecological study shows that climate was the key factor in these human migrations. The study illustrates the power of an integrative approach to understanding the relation between human societies and climate change.

Tom D. Dillehay (University of Kentucky;Department of Anthropology)

2002-10-25

313

Against human nature  

Microsoft Academic Search

Against human nature\\u000a \\u000a Tim Ingold12 \\u000a \\u000a \\u000a \\u000a (12) \\u000a Department of Anthropology, University of Aberdeen, Aberdeen, Scotland, UK\\u000a \\u000a \\u000a Abstract\\u000a Are cultural differences superimposed upon a universal human nature? The appeal to an essentialist concept of human nature\\u000a is a defensive reaction to the legacy of racist science left by Darwin’s argument in The Descent of Man. Humans are made to appear different in degree

Tim Ingold

314

Human Development Report 1997  

NSDL National Science Digital Library

The United Nations Development Programme's Human Development Report Office provides two useful selections from its Human Development Report 1997. Overview of HDR 1997 is a detailed summary of the contents of the report, discussing world poverty and a six point strategy for poverty reduction. HDR 1997 Rankings contain Human Development Index, Gender-Related Development Index and Gender Empowerment Measure rankings tables for 175 countries. More detailed information on the meaning of the HDI is contained in Analytical Tools for Human Development. Full text of the report is forthcoming, and ordering information is available at the site.

1997-01-01

315

Human Security Centre: Human Security Brief 2006  

NSDL National Science Digital Library

While the concept of human security is a relatively new one, there is a growing consensus that the subject is one that will continue to be of the utmost importance in the coming years. Generally, the term is used to describe "the complex of interrelated threats associated with civil war, genocide and the displacement of populations." Recently, the Human Security Centre (located at the University of British Columbia) published its annual Human Security Brief, and placed it online at this site. The report analyzes the findings of several datasets that track trends in such areas as organized violence against civilians and the conclusion of armed conflicts worldwide. While this ambitious work does have some positive findings to announce, there are a number of other troubling trends, such as the fact that four of the world's six regions have experienced increased numbers of conflicts since 2002.

316

Becoming Human: Paleoanthropology, Evolution, and Human Origins  

NSDL National Science Digital Library

A project involving Arizona State University's Institute for Human Origins (founded and directed by Donald C. Johanson, best-known for his discovery of "Lucy"), documentary filmmaker Lenora C. Johanson, and Terra Incognita, this site is designed to teach a general audience about human evolution and the search for early hominid life in the field. The key feature of the site is an extensive (and very professional) flash-driven, online documentary which includes a number of pop-up sub-exhibits that provide additional information and resources on various topics. Other sections of the site include News & Views, which offers recent paleo news stories and expert views, and Resources, which includes a glossary, related sites, and media references. A Learning Center with activities and lesson plans is scheduled to be added this summer. This site, probably the best online documentary seen by this reviewer, should appeal to anyone with an interest in human origins and is highly recommended.

2001-01-01

317

Human organ markets and inherent human dignity.  

PubMed

It has been suggested that human organs should be bought and sold on a regulated market as any other material property belongingto an individual. This would have the advantage of both addressing the grave shortage of organs available for transplantation and respecting the freedom of individuals to choose to do whatever they want with their body parts. The old arguments against such a market in human organs are, therefore, being brought back into question. The article examines the different arguments both in favour and against the sale of human organs. It concludes that the body and any of its elements is a full expression of the whole person. As such, they cannot have a price if the individual is to retain his or her full inherent dignity and if society is to retain and protect this very important concept. PMID:24979876

MacKellar, Calum

2014-01-01

318

HUMAN ACTION SENSING FOR PROACTIVE HUMAN INTERFACE: COMPUTER VISION APPROACH  

Microsoft Academic Search

In this paper, we discuss human action sensing for proac- tive human interface. Proactive human interface is an idea of advanced interface based on perceptual user interface, and provides easy and natural interaction between humans and systems based on observing human activity through many modalities including visual, audio, tactile information etc. \\

Rin-ichiro Taniguchi; Daisaku Arit; Seiichi Uchida; Ryo Kurazume; Tsutomu Hasegawa

319

Developing Human Resources through Actualizing Human Potential  

ERIC Educational Resources Information Center

The key to human resource development is in actualizing individual and collective thinking, feeling and choosing potentials related to our minds, hearts and wills respectively. These capacities and faculties must be balanced and regulated according to the standards of truth, love and justice for individual, community and institutional development,…

Clarken, Rodney H.

2012-01-01

320

Health and Humanity: Humanities 401 Syllabus.  

ERIC Educational Resources Information Center

A syllabus for the "Health and Humanities" interdisciplinary course at Northwestern State University, Louisiana, is presented. An introduction suggests that with the proliferation of technological advances in the field of health care, there is a need for reconsideration of many moral, ethical, legal, and humanistic questions. Information is…

Snowden, Fraser; Taylor, Maxine

321

HUMAN DIGNITY AND HUMAN REPRODUCTIVE CLONING  

Microsoft Academic Search

he complexities and arguments both for and against human reproductive cloning (HRC) seem to have been discussed in almost every sphere imaginable. The worlds of law, medicine, science, bioethics, philosophy, and religion have all laid claim to the forum or framework in which the issues should be discussed. While public debate and the responses of national gov- ernments have been

Steven Malby

2002-01-01

322

HUMAN CARCINOGENESIS BY ARSENIC  

EPA Science Inventory

Arsenic is one of the few human carcinogens for which there is not yet a reliable animal cancer model. s such, the classification of arsenic as a carcinogen is based upon data derived from human epidemiologic studies. Although the mechanisms of action of arsenic as a toxic agent ...

323

Human Granulocytic Anaplasmosis, Japan  

PubMed Central

We retrospectively confirmed 2 cases of human Anaplasma phagocytophilum infection. Patient blood samples contained unique p44/msp2 for the pathogen, and antibodies bound to A. phagocytophilum antigens propagated in THP-1 rather than HL60 cells. Unless both cell lines are used for serodiagnosis of rickettsiosis-like infections, cases of human granulocytic anaplasmosis could go undetected.

Gaowa; Wuritu; Kawamori, Fumihiko; Wu, Dongxing; Yoshikawa, Yuko; Chiya, Seizou; Fukunaga, Kazutoshi; Funato, Toyohiko; Shiojiri, Masaaki; Nakajima, Hideki; Hamauzu, Yoshiji; Takano, Ai; Kawabata, Hiroki; Ando, Shuji; Kishimoto, Toshio

2013-01-01

324

Human Super Intelligence  

Microsoft Academic Search

The manuscript will be interesting for scientists in any field, as it explains how human super intelligence can be implemented in the near future and enable people to successfully solve multi-factor tasks currently impossible for human intelligence. Indeed, all dependencies discovered in all sciences so far, with a rare exception (e.g., the third Kepler's law with Newton's correction), are described

Alexander A. Antonov

2011-01-01

325

Humanities in the Classroom.  

ERIC Educational Resources Information Center

One of eighteen in a series, this annotated bibliography includes 64 publications that deal with the humanities and humanizing formal instruction at all instructional levels. Citations include recent ERIC documents, journal articles, and books. Others in the series are: SO 002 222 and SO 002 224. (DJB)

Poli, Rosario, Comp.

326

Manipulation in Human Environments  

Microsoft Academic Search

Robots that work alongside us in our homes and workplaces could extend the time an elderly person can live at home, provide physical assistance to a worker on an assembly line, or help with household chores. In order to assist us in these ways, robots will need to successfully perform manipulation tasks within human environments. Human environments present special challenges

Aaron Edsinger; Charles C. Kemp

2006-01-01

327

Human Nature and Curricula.  

ERIC Educational Resources Information Center

This paper is concerned with the development of a coherent unified theory for a science of curriculum--specifically, the development of logical consistency and compatibility with related fields in the formation of theory. Learning as a common human activity is subject to principles germane to human activity in general, as well as to universal…

Hough, Herbert William

328

Humane Education Projects Handbook.  

ERIC Educational Resources Information Center

This handbook was developed to promote interest in humane education and to encourage the adoption of humane education projects. Although specifically designed to assist Junior Leagues in developing such projects, the content should prove valuable to animal welfare organizations, zoos, aquariums, nature centers, and other project-oriented groups…

Junior League of Ogden, UT.

329

Mapping the human genome.  

National Technical Information Service (NTIS)

The following pages aim to lay a foundation for understanding the excitement surrounding the ''human genome project,'' as well as to convey a flavor of the ongoing efforts and plans at the Human Genome Center at the Lawrence Berkeley Laboratory. Our own w...

1989-01-01

330

Autoantibodies against human insulin  

Microsoft Academic Search

Sera from 680 non-diabetic subjects with suspected autoimmune disease were screened for 13 different antibodies. Of the 582 sera found to contain these antibodies, nine bound insulin in an IgG specific enzyme linked immunosorbent assay (micro ELISA). Four of the sera bound human, porcine, and bovine insulins and five bound exclusively human insulin. \\

T J Wilkin; S Nicholson

1984-01-01

331

Aging and Human Performance  

Microsoft Academic Search

Objectives: I identify major theoretical and practical contributions to aging and human performance as reflected primarily in the pages of Human Factors.Background: Populations worldwide are aging. True experimental work on aging is not possible because age levels cannot be manipulated. Sophisticated theoretical frameworks and modeling techniques are required to reach valid inferences about age effects and age changes. Method: Citation

Neil Charness

2008-01-01

332

Healthline Human Body Maps  

NSDL National Science Digital Library

This website provides a 3-D animation of the human body. The animation allows visitors to view a variety of layers of the human body organized by both system and organs. In addition, health information, articles, and structures can be found with each layer. The website is also searchable by specific structure.

Healthline (Healthline Networks Inc)

2005-01-01

333

Evaluating the Humanities  

ERIC Educational Resources Information Center

How can one measure the value of teaching the humanities? The problem of assessment and accountability is prominent today, of course, in secondary and higher education. It is perhaps even more acute for those who teach the humanities in nontraditional settings, such as medical and other professional schools. The public assumes that academes can…

Brody, Howard

2013-01-01

334

Human Dignity Through History.  

ERIC Educational Resources Information Center

A major educational need, as assessed by a committee of teachers, students, and community members, is to recognize acceptance of human dignity as the ultimate value in decision making. This concept provides a basis for the elementary and secondary social studies program. Although the concept of human dignity was promoted with the signing of the…

Satterlie, Arthur L.

335

Assessment of Human Factors  

NASA Technical Reports Server (NTRS)

Human Factors Engineering, often referred to as Ergonomics, is a science that applies a detailed understanding of human characteristics, capabilities, and limitations to the design, evaluation, and operation of environments, tools, and systems for work and daily living. Human Factors is the investigation, design, and evaluation of equipment, techniques, procedures, facilities, and human interfaces, and encompasses all aspects of human activity from manual labor to mental processing and leisure time enjoyments. In spaceflight applications, human factors engineering seeks to: (1) ensure that a task can be accomplished, (2) maintain productivity during spaceflight, and (3) ensure the habitability of the pressurized living areas. DSO 904 served as a vehicle for the verification and elucidation of human factors principles and tools in the microgravity environment. Over six flights, twelve topics were investigated. This study documented the strengths and limitations of human operators in a complex, multifaceted, and unique environment. By focusing on the man-machine interface in space flight activities, it was determined which designs allow astronauts to be optimally productive during valuable and costly space flights. Among the most promising areas of inquiry were procedures, tools, habitat, environmental conditions, tasking, work load, flexibility, and individual control over work.

Mount, Frances; Foley, Tico

1999-01-01

336

Animation of Human Diving  

Microsoft Academic Search

The motion of a human platform diver was simulated using a dynamic model and a control system. Thedynamic model has 32 actuated degrees of freedom and dynamic parameters within the range of thosereported in the literature for humans. The control system uses algorithms for balance, jumping, andtwisting to initiate the dive, sequences of desired values for proportional--derivative servos to performthe

Wayne L. Wooten; Jessica K. Hodgins

1996-01-01

337

The Visible Human Project  

Microsoft Academic Search

The Visible Human Project data sets are designed to serve as a common reference point for the study of human anatomy, as a set of common public-domain data for testing medical imaging algorithms, and as a testbed and model for the construction of image libraries that can be accessed through networks. The data sets are being applied to a wide

MICHAEL J. ACKERMAN

1998-01-01

338

Quantification of human responses  

NASA Technical Reports Server (NTRS)

Human perception is a complex phenomenon which is difficult to quantify with instruments. For this reason, large panels of people are often used to elicit and aggregate subjective judgments. Print quality, taste, smell, sound quality of a stereo system, softness, and grading Olympic divers and skaters are some examples of situations where subjective measurements or judgments are paramount. We usually express what is in our mind through language as a medium but languages are limited in available choices of vocabularies, and as a result, our verbalizations are only approximate expressions of what we really have in mind. For lack of better methods to quantify subjective judgments, it is customary to set up a numerical scale such as 1, 2, 3, 4, 5 or 1, 2, 3, ..., 9, 10 for characterizing human responses and subjective judgments with no valid justification except that these scales are easy to understand and convenient to use. But these numerical scales are arbitrary simplifications of the complex human mind; the human mind is not restricted to such simple numerical variations. In fact, human responses and subjective judgments are psychophysical phenomena that are fuzzy entities and therefore difficult to handle by conventional mathematics and probability theory. The fuzzy mathematical approach provides a more realistic insight into understanding and quantifying human responses. This paper presents a method for quantifying human responses and subjective judgments without assuming a pattern of linear or numerical variation for human responses. In particular, quantification and evaluation of linguistic judgments was investigated.

Steinlage, R. C.; Gantner, T. E.; Lim, P. Y. W.

1992-01-01

339

Dimensions of Human Development  

Microsoft Academic Search

If human development is “multidimensional” then perhaps we need to discuss what we mean by multidimensional: what is a dimension, and what are the multiple dimensions of interest? This paper develops an account of dimensions of human development, and shows its usefulness and its limitations—both in general and in relation to Amartya Sen's capability approach. The second half of the

Sabina Alkire

2002-01-01

340

Humanism within Globalization  

ERIC Educational Resources Information Center

The complexity of adult learning connects it to almost all other facets of human endeavor. Consequently, the future of adult education depends, to a large extent on who participates and the quality of such participation. Quality participation, when teamed with environments committed to a concern for humanity, launches opportunities for varied…

Weber, Jennifer E.

2014-01-01

341

The great human expansion  

PubMed Central

Genetic and paleoanthropological evidence is in accord that today’s human population is the result of a great demic (demographic and geographic) expansion that began approximately 45,000 to 60,000 y ago in Africa and rapidly resulted in human occupation of almost all of the Earth’s habitable regions. Genomic data from contemporary humans suggest that this expansion was accompanied by a continuous loss of genetic diversity, a result of what is called the “serial founder effect.” In addition to genomic data, the serial founder effect model is now supported by the genetics of human parasites, morphology, and linguistics. This particular population history gave rise to the two defining features of genetic variation in humans: genomes from the substructured populations of Africa retain an exceptional number of unique variants, and there is a dramatic reduction in genetic diversity within populations living outside of Africa. These two patterns are relevant for medical genetic studies mapping genotypes to phenotypes and for inferring the power of natural selection in human history. It should be appreciated that the initial expansion and subsequent serial founder effect were determined by demographic and sociocultural factors associated with hunter-gatherer populations. How do we reconcile this major demic expansion with the population stability that followed for thousands years until the inventions of agriculture? We review advances in understanding the genetic diversity within Africa and the great human expansion out of Africa and offer hypotheses that can help to establish a more synthetic view of modern human evolution.

Henn, Brenna M.; Cavalli-Sforza, L. L.; Feldman, Marcus W.

2012-01-01

342

Human Water Cycle  

NSDL National Science Digital Library

Students learn about the human water cycle, or how humans impact the water cycle by settling down in civilizations. Specifically, they learn how people obtain, use and dispose of water. Students also learn about shortages of treated, clean and safe water and learn about ways that engineers address this issue through water conservation and graywater recycling.

Integrated Teaching And Learning Program

343

Implications for human health.  

PubMed Central

To analyze the implications for human health, the toxicologist requires four sets of data: the results of toxicity and other studies in animals; quantitative data on actual or potential human exposure; whatever information is available on effects of exposure in man; and the statistical extrapolations from the dose-response relationships in animals to the (usually) much lower levels of human exposure. Professional expertise in toxicology is essential to assess the nature and severity of the toxic effects observed in animals, including such characteristics as potential for progression, irreversibility and production of incapacity. Given sufficient data, an estimate can be arrived at of the likelihood that such effects will be elicited in human populations of differing susceptibilities. The criteria by which the overall implications for human health can be judged comprise both the direct effects on man, as well as the indirect consequences stemming from environmental impacts.

Golberg, L

1979-01-01

344

Human Space Flight  

NASA Technical Reports Server (NTRS)

The first human space flight, in the early 1960s, was aimed primarily at determining whether humans could indeed survive and function in micro-gravity. Would eating and sleeping be possible? What mental and physical tasks could be performed? Subsequent programs increased the complexity of the tasks the crew performed. Table 1 summarizes the history of U.S. space flight, showing the projects, their dates, crew sizes, and mission durations. With over forty years of experience with human space flight, the emphasis now is on how to design space vehicles, habitats, and missions to produce the greatest returns to human knowledge. What are the roles of the humans in space flight in low earth orbit, on the moon, and in exploring Mars?

Woolford, Barbara; Mount, Frances

2004-01-01

345

Helminths in human carcinogenesis.  

PubMed

This review examines the salient literature on selected helminths involved in carcinogenicity in humans and updates information in an earlier review on cancer and helminths by Mayer and Fried (2007, Advances in Parasitology 65, 239-296). The earlier review was concerned with various helminths, i.e., trematodes, cestodes, and nematodes, that are definitely implicated as being carcinogenic. This review examines only those helminths, all of which turn out to be trematodes, that are definitely implicated as being carcinogenic. These trematodes are the blood flukes Schistosoma haematobium, associated with inducing human carcinoma of the urinary bladder and the liver flukes Opisthorchis viverrini and Clonorchis sinensis, associated with inducing cancer of the bile duct (cholangiocarcinoma) and cancer of the liver (hepatocarcinoma) in humans. The review examines mainly the epidemiology and pathology of these helminthic infections in humans and considers what we know about the mechanisms associated with the carcinogenicity of these three trematodes in humans. PMID:20667649

Fried, Bernard; Reddy, Aditya; Mayer, David

2011-06-28

346

Human hepatocyte carcinogenesis  

PubMed Central

Hepatocellular carcinoma is the third most frequent cause of cancer-related death worldwide; and its incidence rate is increasing. Clinical and molecular medical analyses have revealed substantial information on hepatocarcinogenesis. Hepatocarcinogenesis is a stepwise process during which multiple genes are altered. Genetic changes and their biological consequences in human HCC can be divided into at least 4 groups: i) tumor suppressor genes (p53, retinoblastoma, phosphatase tensin homolog and runt-related transcription factor 3), ii) oncogenes (myc, K-ras, BRAF), iii) reactivation of developmental pathways (Wnt, hedgehog), and iv) growth factors and their receptors (transforming growth factor-?, insulin-like growth factor-2 receptor). An experimental model of human hepatocarcinogenesis such as in vitro neoplastic transformation of human hepatocytes has not been successfully achieved yet, but several immortalized human hepatocyte cell lines have been established. These immortalized human hepatocytes will become useful tools for the elucidation of hepatocarcinogenesis, especially for the initial step of multistep hepatocarcinogenesis.

SHIRAHA, HIDENORI; YAMAMOTO, KAZUHIDE; NAMBA, MASAYOSHI

2013-01-01

347

Beliefs about Human Extinction  

SciTech Connect

This paper presents the results of a web-based survey about futures issues. Among many questions, respondents were asked whether they believe humans will become extinct. Forty-five percent of the almost 600 respondents believe that humans will become extinct. Many of those holding this believe felt that humans could become extinct within 500-1000 years. Others estimated extinction 5000 or more years into the future. A logistic regression model was estimated to explore the bases for this belief. It was found that people who describe themselves a secular are more likely to hold this belief than people who describe themselves as being Protestant. Older respondents and those who believe that humans have little control over their future also hold this belief. In addition, people who are more apt to think about the future and are better able to imagine potential futures tend to also believe that humans will become extinct.

Tonn, Bruce Edward [ORNL

2009-11-01

348

Mars Human Exploration Objectives  

NASA Technical Reports Server (NTRS)

This paper reviews the objectives and other considerations of Human exploration of Mars. The objectives of human exploration of Mars are: (1) to learn how Mars is similar to, and different from, Earth; (2) to explore possible life, past and present; (3) to discover what Mars is like now from the perspective of Geoscience and geologic history; and (4) how did Mars form and how did its formation differ from Earth. Considerations of human Martian exploration involve: (1) having a capable base laboratory; (2) having long range transportation; (3) having operational autonomy of the crew, and the requirement of the crew to possess a range of new cognitive processes along with easy communications with terrestrial colleagues; and finally (4) creating the human habitat along with human factors which involve more than just survivability.

Briggs, Geoff

1998-01-01

349

Humanization of immunotoxins.  

PubMed Central

The construction and expression of a chimeric gene encoding a mouse/human antibody to the human transferrin receptor fused to the gene for angiogenin, a human homolog of pancreatic RNase, are described. F(ab')2-like antibody-enzyme fusions were prepared by linking the gene for human angiogenin to a chimeric anti-transferrin receptor heavy chain gene. The antibody-enzyme fusion gene was introduced into a transfectoma that secretes the chimeric light chain of the same antibody, and cell lines were cloned that synthesize and secrete the antibody-enzyme fusion protein of the expected size at a concentration of 1-5 ng/ml. Culture supernatants from clones secreting the fusion protein caused inhibition of growth and protein synthesis of K562 cells that express the human transferrin receptor but not toward a non-human-derived cell line that lacks this receptor. Whereas excess antibody to the same receptor did not itself inhibit protein synthesis, it was able to completely prevent the protein synthesis inhibition caused by the fusion protein. These results indicate that the cytotoxicity is due to a transferrin receptor-mediated mechanism involving the angiogenin portion of the fusion protein and demonstrate the feasibility of constructing recombinant antibody-RNase molecules capable of killing tumor cells bearing the transferrin receptor. The significance of the acquired cytotoxicity of a mouse/human chimeric antibody linked to a human protein may bear importantly in human therapeutic strategies that use mouse antibodies linked to toxins from plants or bacteria to target tumor cells. It is expected that the humanization of immunotoxins will lead to less toxicity and immunogenicity than currently available reagents. Images

Rybak, S M; Hoogenboom, H R; Meade, H M; Raus, J C; Schwartz, D; Youle, R J

1992-01-01

350

Human Health Countermeasures (HHC) Element Management Plan: Human Research Program.  

National Technical Information Service (NTIS)

NASA s Human Research Program (HRP) is an applied research and technology program within the Human Exploration and Operations Mission Directorate (HEOMD) that addresses human health and performance risk mitigation strategies in support of exploration miss...

D. Baumann P. Norsk

2012-01-01

351

Habitability and Human Factors Contributions to Human Space Flight  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the work of the Habitability and Human Factors Branch in support of human space flight in two main areas: Applied support to major space programs, and Space research. The field of Human Factors applies knowledge of human characteristics for the design of safer, more effective, and more efficient systems. This work is in several areas of the human space program: (1) Human-System Integration (HSI), (2) Orion Crew Exploration Vehicle, (3) Extravehicular Activity (EVA), (4) Lunar Surface Systems, (5) International Space Station (ISS), and (6) Human Research Program (HRP). After detailing the work done in these areas, the facilities that are available for human factors work are shown.

Sumaya, Jennifer Boyer

2011-01-01

352

Human Space Exploration  

NASA Technical Reports Server (NTRS)

The Mars probe, launched by India a few months ago, is on its way to Mars. At this juncture, it is appropriate to talk about the opportunities presented to us for the Human Exploration of Mars. I am planning to highlight some of the challenges to take humans to Mars, descend, land, stay, ascend and return home safely. The logistics of carrying the necessary accessories to stay at Mars will be delivered in multiple stages using robotic missions. The primary ingredients for human survival is air, water, food and shelter and the necessity to recycle the primary ingredients will be articulated. Humans have to travel beyond the van Allen radiation belt under microgravity condition during this inter-planetary travel for about 6 months minimum one way. The deconditioning of human system under microgravity conditions and protection of humans from Galactic cosmic radiation during the travel should be taken into consideration. The multi-disciplinary effort to keep the humans safe and functional during this journey will be addressed.

Jeevarajan, Antony

2014-01-01

353

Strategic Implications of Human Trafficking.  

National Technical Information Service (NTIS)

There is a problem known as human trafficking that could have a direct effect on America's national security. Human trafficking involves various forms of human enslavement for prostitution and other forms of exploitation, including false promises of jobs ...

D. D. Watkins

2005-01-01

354

Office for Human Research Protections  

MedlinePLUS

... OHRP Text Size: A A A Office for Human Research Protections (OHRP) The Office for Human Research Protections ( ... contemplating various ways to enhance the regulations overseeing research on human subjects. For more information, click on this button ...

355

Genetics of Human Growth  

PubMed Central

Genes involved in human growth consist of major growth genes and minor growth genes. Major growth genes have fundamental effects on human growth, and their mutations cause growth failure (or overgrowth) which are recognizable as single gene disorders. Minor growth genes exert relative minor additive effects on human growth, and their combination is involved in the development of short (or tall) stature as a multifactorial trait. This review summarizes the current knowledge about the major and the minor growth genes, and refers to the recent molecular approach of identification of the growth genes.

Ogata, Tsutomu

2006-01-01

356

Redrawing Humanity's Family Tree  

NSDL National Science Digital Library

This New York Times article details two skulls, one from central Africa and the other from the Black Sea republic of Georgia, that "have shaken the human family tree to its roots, sending scientists scrambling to see if their favorite theories are among the fallen fruit." The article discusses how the two skulls have caused scientists to rethink not only how we conceive of human evolution and its chain of events, but even the geography of evolution and migration patterns of very early humans.

Wilford, John N.

1969-12-31

357

Human resource management.  

PubMed

The occupational health physician can take advantage of the broad functions of human resource management to offer care and treatment in a very practical way in the day-to-day workplace. Understanding the capabilities and services of the human resource department can aid the occupational health practitioner in maintaining employee health and productivity. Thus, the individual is helped as well as the organization. This article describes the functions of the human resource department and delineates the close connection between it and the occupational health physician. PMID:11401792

Borst, D; Fallon, L F

2001-01-01

358

Aluminium in human sweat.  

PubMed

It is of burgeoning importance that the human body burden of aluminium is understood and is measured. There are surprisingly few data to describe human excretion of systemic aluminium and almost no reliable data which relate to aluminium in sweat. We have measured the aluminium content of sweat in 20 healthy volunteers following mild exercise. The concentration of aluminium ranged from 329 to 5329?g/L. These data equate to a daily excretion of between 234 and 7192?g aluminium and they strongly suggest that perspiration is the major route of excretion of systemic aluminium in humans. PMID:24239230

Minshall, Clare; Nadal, Jodie; Exley, Christopher

2014-01-01

359

Human Computer Interaction  

NASA Astrophysics Data System (ADS)

The paper basically deals with the study of HCI (Human computer interaction) or BCI(Brain-Computer-Interfaces) Technology that can be used for capturing brain signals and translating them into commands that allow humans to control (just by thinking) devices such as computers, robots, rehabilitation technology and virtual reality environments. The HCI is based as a direct communication pathway between the brain and an external device. BCIs are often aimed at assisting, augmenting, or repairing human cognitive or sensory-motor functions.The paper also deals with many advantages of BCI Technology along with some of its applications and some major drawbacks.

Bhagwani, Akhilesh; Sengar, Chitransh; Talwaniper, Jyotsna; Sharma, Shaan

2012-08-01

360

PSYCHOANALYTIC ACTIVISM: Finding the Human, Staying Human  

Microsoft Academic Search

Drawing on my work in human rights abuse, I reflect on the process of dehumanization in torture, and make the links between the life-negating denial of death in trauma victims and the ethical responsibility of society vis-à-vis these victims. In examining how my own past helps me enter into my patients' posttraumatic narrative, I seek to show that the psychoanalytic

Leanh Nguyen

2012-01-01

361

78 FR 74174 - Humanities Panel Advisory Committee  

Federal Register 2010, 2011, 2012, 2013

...NATIONAL FOUNDATION ON THE ARTS AND THE HUMANITIES Humanities Panel Advisory Committee AGENCY: National Endowment for the Humanities. ACTION: Notice of Charter Renewal for Humanities Panel Advisory...

2013-12-10

362

Introduction to the Human Body  

MedlinePLUS

... Citation Help Home » Cancer Registration & Surveillance Modules » Anatomy & Physiology » Intro to the Human Body Cancer Registration & Surveillance Modules Anatomy & Physiology Intro to the Human Body Body Functions & Life ...

363

Regulation of NAMPT in Human Gingival Fibroblasts and Biopsies  

PubMed Central

Adipokines, such as nicotinamide phosphoribosyltransferase (NAMPT), are molecules, which are produced in adipose tissue. Recent studies suggest that NAMPT might also be produced in the tooth-supporting tissues, that is, periodontium, which also includes the gingiva. The aim of this study was to examine if and under what conditions NAMPT is produced in gingival fibroblasts and biopsies from healthy and inflamed gingiva. Gingival fibroblasts produced constitutively NAMPT, and this synthesis was significantly increased by interleukin-1? and the oral bacteria P. gingivalis and F. nucleatum. Inhibition of the MEK1/2 and NF?B pathways abrogated the stimulatory effects of F. nucleatum on NAMPT. Furthermore, the expression and protein levels of NAMPT were significantly enhanced in gingival biopsies from patients with periodontitis, a chronic inflammatory infectious disease of the periodontium, as compared to gingiva from periodontally healthy individuals. In summary, the present study provides original evidence that gingival fibroblasts produce NAMPT and that this synthesis is increased under inflammatory and infectious conditions. Local synthesis of NAMPT in the inflamed gingiva may contribute to the enhanced gingival and serum levels of NAMPT, as observed in periodontitis patients. Moreover, local production of NAMPT by gingival fibroblasts may represent a possible mechanism whereby periodontitis may impact on systemic diseases.

Damanaki, Anna; Nokhbehsaim, Marjan; Gotz, Werner; Winter, Jochen; Wahl, Gerhard; Jager, Andreas; Jepsen, S?ren

2014-01-01

364

Superantigens in Human Disease  

Microsoft Academic Search

Superantigens have been implicated in a wide variety of human diseases. Yet, solid evidence for their role in pathogenesis is available only for Toxic Shock Syndrome and a few other conditions. This evidence is critically reviewed herein.

Alejandro Bernal; Thomas Proft; John D. Fraser; David N. Posnett

1999-01-01

365

Human hand recognition system  

NASA Astrophysics Data System (ADS)

Human hand recognition is a practical problem in pattern recognition for restricted access environment. The methodology of shape analysis, a conventional method for object identification, has been studied in this paper for human hand recognition. The idea behind the chosen approach is to consider human hand as an object of definite rigid shape, extract its boundary and shape parameters as recognition features. Shape analysis requires the extraction of object features, often normalized and invariant to various geometric change such as translation, rotation and scale. In the human hand recognition system three different views at different orientations of the same hand were taken with the help of PULNIX CCD camera. The digital image of hand has been analyzed using Fourier descriptors and various moment invariants.

Sharma, Sunil; Prasad, M. S.

1997-07-01

366

Human Services Inventory: Definitions.  

National Technical Information Service (NTIS)

Definitions are presented of 24 categories of human services and of specific programs within the categories. The service categories defined are as follows: alcoholism, children and youth, community care, community groups/associations, consumer services, c...

M. Marks

1976-01-01

367

Human Biomass Consumption  

NASA Video Gallery

Humans are using an increasing amount of Earthâ??s annual production of plants. Research shows that, from 1995 to 2005, consumption rose from 20 to 25 percent of the planet's annual production. Wha...

368

Teaching about Human Geography.  

ERIC Educational Resources Information Center

Presents a sampling of items from the ERIC database concerning the teaching of human geography. Includes documents dealing with Africa, Asia, the United States, Canada, Antarctica, and geographic concepts. Explains how to obtain ERIC documents. (SG)

Schlene, Vickie J.

1991-01-01

369

Chemotaxis of Human Eosinophils.  

National Technical Information Service (NTIS)

Human eosinophils respond chemotactically to preparations that are also chemotactically active for neutrophils. These include soluble bacterial factors in culture filtrates, and rabbit serum treated with immune complexes or with a mixture of highly purifi...

P. A. Ward

1968-01-01

370

Human Health Effects Assays.  

National Technical Information Service (NTIS)

The use of assays to evaluate and assist in predicting potentially adverse human health effects associated with exposure to pollutants in water (that is, municipal wastewater, sewage sludge, ambient water, and drinking water) is the focus of the review.

L. Fradkin C. Sonich-Mullin M. Cerny C. Kruger F. Cavender

1989-01-01

371

Viruses and human cancer  

SciTech Connect

This book contains papers on the following topics: Immunology and Epidemiology, Biology and Pathogenesis, Models of Pathogenesis and Treatment, Simian and Bovine Retroviruses, Human Papilloma Viruses, EBV and Herpesvirus, and Hepatitis B Virus.

Gallo, R.C.; Haseltine, W.; Klein, G.; Zur Hausen, H.

1987-01-01

372

Human Pulmonary Dirofilariasis.  

National Technical Information Service (NTIS)

Eight cases of human pulmonary dirofilariasis are reported, bringing the total number of reported cases to 27. The lesions and the anatomic features of the worms are described and illustrated. (Author)

R. C. Neafie J. Piggott

1971-01-01

373

Human Papillomavirus (HPV) Screening  

MedlinePLUS

... visit this page: About CDC.gov . Human Papillomavirus (HPV) Share Compartir Screening Cervical cancer is the easiest ... and then every three years after that. The HPV test checks for the virus that can cause ...

374

Aerospace Human Factors  

NASA Technical Reports Server (NTRS)

The following contains the final report on the activities related to the Cooperative Agreement between the human factors research group at NASA Ames Research Center and the Psychology Department at San Jose State University. The participating NASA Ames division has been, as the organization has changed, the Aerospace Human Factors Research Division (ASHFRD and Code FL), the Flight Management and Human Factors Research Division (Code AF), and the Human Factors Research and Technology Division (Code IH). The inclusive dates for the report are November 1, 1984 to January 31, 1999. Throughout the years, approximately 170 persons worked on the cooperative agreements in one capacity or another. The Cooperative Agreement provided for research personnel to collaborate with senior scientists in ongoing NASA ARC research. Finally, many post-MA/MS and post-doctoral personnel contributed to the projects. It is worth noting that 10 former cooperative agreement personnel were hired into civil service positions directly from the agreements.

Jordan, Kevin

1999-01-01

375

Human Reliability Program Overview  

SciTech Connect

This presentation covers the high points of the Human Reliability Program, including certification/decertification, critical positions, due process, organizational structure, program components, personnel security, an overview of the US DOE reliability program, retirees and academia, and security program integration.

Bodin, Michael

2012-09-25

376

Human Assisted Assembly Processes  

SciTech Connect

Automatic assembly sequencing and visualization tools are valuable in determining the best assembly sequences, but without Human Factors and Figure Models (HFFMs) it is difficult to evaluate or visualize human interaction. In industry, accelerating technological advances and shorter market windows have forced companies to turn to an agile manufacturing paradigm. This trend has promoted computerized automation of product design and manufacturing processes, such as automated assembly planning. However, all automated assembly planning software tools assume that the individual components fly into their assembled configuration and generate what appear to be a perfectly valid operations, but in reality the operations cannot physically be carried out by a human. Similarly, human figure modeling algorithms may indicate that assembly operations are not feasible and consequently force design modifications; however, if they had the capability to quickly generate alternative assembly sequences, they might have identified a feasible solution. To solve this problem HFFMs must be integrated with automated assembly planning to allow engineers to verify that assembly operations are possible and to see ways to make the designs even better. Factories will very likely put humans and robots together in cooperative environments to meet the demands for customized products, for purposes including robotic and automated assembly. For robots to work harmoniously within an integrated environment with humans the robots must have cooperative operational skills. For example, in a human only environment, humans may tolerate collisions with one another if they did not cause much pain. This level of tolerance may or may not apply to robot-human environments. Humans expect that robots will be able to operate and navigate in their environments without collisions or interference. The ability to accomplish this is linked to the sensing capabilities available. Current work in the field of cooperative automation has shown the effectiveness of humans and machines directly interacting to perform tasks. To continue to advance this area of robotics, effective means need to be developed to allow natural ways for people to communicate and cooperate with robots just as they do with one another.

CALTON,TERRI L.; PETERS,RALPH R.

2000-01-01

377

Evolution and human sexuality.  

PubMed

The aim of this review is to put core features of human sexuality in an evolutionary light. Toward that end, I address five topics concerning the evolution of human sexuality. First, I address theoretical foundations, including recent critiques and developments. While much traces back to Darwin and his view of sexual selection, more recent work helps refine the theoretical bases to sex differences and life history allocations to mating effort. Second, I consider central models attempting to specify the phylogenetic details regarding how hominin sexuality might have changed, with most of those models honing in on transitions from a possible chimpanzee-like ancestor to the slightly polygynous and long-term bonded sociosexual partnerships observed among most recently studied hunter-gatherers. Third, I address recent genetic and physiological data contributing to a refined understanding of human sexuality. As examples, the availability of rapidly increasing genomic information aids comparative approaches to discern signals of selection in sexuality-related phenotypes, and neuroendocrine studies of human responses to sexual stimuli provide insight into homologous and derived mechanisms. Fourth, I consider some of the most recent, large, and rigorous studies of human sexuality. These provide insights into sexual behavior across other national samples and on the Internet. Fifth, I discuss the relevance of a life course perspective to understanding the evolution of human sexuality. Most research on the evolution of human sexuality focuses on young adults. Yet humans are sexual beings from gestation to death, albeit in different ways across the life course, and in ways that can be theoretically couched within life history theory. PMID:24151100

Gray, Peter B

2013-12-01

378

Geology and Human Health  

NSDL National Science Digital Library

This site contains a variety of educational and supporting materials for faculty teaching in the emerging field of geology and human health. You will find links to internet resources, books, teaching activities, and a group email list, as well as posters, presentations and discussions from the spring 2004 workshop on Geology and Human Health. These resources reflect the contributions of faculty members from across the country and the collections will continue to grow as materials are developed.

379

Human facial beauty  

Microsoft Academic Search

It is hypothesized that human faces judged to be attractive by people possess two features—averageness and symmetry—that promoted\\u000a adaptive mate selection in human evolutionary history by way of production of offspring with parasite resistance. Facial composites\\u000a made by combining individual faces are judged to be attractive, and more attractive than the majority of individual faces.\\u000a The composites possess both symmetry

Randy Thorrthill; Steven W. Gangestad

1993-01-01

380

Human endothelial dysfunction: EDCFs  

Microsoft Academic Search

Human studies, conducted in the presence of clinical conditions characterized by endothelial dysfunction, evidenced that endothelial\\u000a cells, in response to different agonists and physical stimuli, become a source of endothelium-derived contracting factors\\u000a (EDCFs), mainly cyclooxygenase (COX)-derived prostanoids. Their production has been documented in several human diseases,\\u000a mostly in essential hypertension and aging. The EDCF production was at first identified as

Agostino Virdis; Lorenzo Ghiadoni; Stefano Taddei

2010-01-01

381

Human cardiac stem cells  

PubMed Central

The identification of cardiac progenitor cells in mammals raises the possibility that the human heart contains a population of stem cells capable of generating cardiomyocytes and coronary vessels. The characterization of human cardiac stem cells (hCSCs) would have important clinical implications for the management of the failing heart. We have established the conditions for the isolation and expansion of c-kit-positive hCSCs from small samples of myocardium. Additionally, we have tested whether these cells have the ability to form functionally competent human myocardium after infarction in immunocompromised animals. Here, we report the identification in vitro of a class of human c-kit-positive cardiac cells that possess the fundamental properties of stem cells: they are self-renewing, clonogenic, and multipotent. hCSCs differentiate predominantly into cardiomyocytes and, to a lesser extent, into smooth muscle cells and endothelial cells. When locally injected in the infarcted myocardium of immunodeficient mice and immunosuppressed rats, hCSCs generate a chimeric heart, which contains human myocardium composed of myocytes, coronary resistance arterioles, and capillaries. The human myocardium is structurally and functionally integrated with the rodent myocardium and contributes to the performance of the infarcted heart. Differentiated human cardiac cells possess only one set of human sex chromosomes excluding cell fusion. The lack of cell fusion was confirmed by the Cre-lox strategy. Thus, hCSCs can be isolated and expanded in vitro for subsequent autologous regeneration of dead myocardium in patients affected by heart failure of ischemic and nonischemic origin.

Bearzi, Claudia; Rota, Marcello; Hosoda, Toru; Tillmanns, Jochen; Nascimbene, Angelo; De Angelis, Antonella; Yasuzawa-Amano, Saori; Trofimova, Irina; Siggins, Robert W.; LeCapitaine, Nicole; Cascapera, Stefano; Beltrami, Antonio P.; D'Alessandro, David A.; Zias, Elias; Quaini, Federico; Urbanek, Konrad; Michler, Robert E.; Bolli, Roberto; Kajstura, Jan; Leri, Annarosa; Anversa, Piero

2007-01-01

382

Human cardiac stem cells.  

PubMed

The identification of cardiac progenitor cells in mammals raises the possibility that the human heart contains a population of stem cells capable of generating cardiomyocytes and coronary vessels. The characterization of human cardiac stem cells (hCSCs) would have important clinical implications for the management of the failing heart. We have established the conditions for the isolation and expansion of c-kit-positive hCSCs from small samples of myocardium. Additionally, we have tested whether these cells have the ability to form functionally competent human myocardium after infarction in immunocompromised animals. Here, we report the identification in vitro of a class of human c-kit-positive cardiac cells that possess the fundamental properties of stem cells: they are self-renewing, clonogenic, and multipotent. hCSCs differentiate predominantly into cardiomyocytes and, to a lesser extent, into smooth muscle cells and endothelial cells. When locally injected in the infarcted myocardium of immunodeficient mice and immunosuppressed rats, hCSCs generate a chimeric heart, which contains human myocardium composed of myocytes, coronary resistance arterioles, and capillaries. The human myocardium is structurally and functionally integrated with the rodent myocardium and contributes to the performance of the infarcted heart. Differentiated human cardiac cells possess only one set of human sex chromosomes excluding cell fusion. The lack of cell fusion was confirmed by the Cre-lox strategy. Thus, hCSCs can be isolated and expanded in vitro for subsequent autologous regeneration of dead myocardium in patients affected by heart failure of ischemic and nonischemic origin. PMID:17709737

Bearzi, Claudia; Rota, Marcello; Hosoda, Toru; Tillmanns, Jochen; Nascimbene, Angelo; De Angelis, Antonella; Yasuzawa-Amano, Saori; Trofimova, Irina; Siggins, Robert W; Lecapitaine, Nicole; Cascapera, Stefano; Beltrami, Antonio P; D'Alessandro, David A; Zias, Elias; Quaini, Federico; Urbanek, Konrad; Michler, Robert E; Bolli, Roberto; Kajstura, Jan; Leri, Annarosa; Anversa, Piero

2007-08-28

383

Human neuronal nicotinic receptors  

Microsoft Academic Search

Nicotine is a very widely used drug of abuse, which exerts a number of neurovegetative, behavioural and psychological effects by interacting with neuronal nicotinic acetylcholine receptors (NAChRs). These receptors are distributed widely in human brain and ganglia, and form a family of ACh-gated ion channels of different subtypes, each of which has a specific pharmacology and physiology. As human NAChRs

C. Gotti; D. Fornasari; F. Clementi

1997-01-01

384

Human exploration mission studies  

NASA Technical Reports Server (NTRS)

This paper describes several case studies of human space exploration, considered by the NASA's Office of Exploration in 1988. Special attention is given to the mission scenarios, the critical technology required in these expeditions, and the extraterrestrial power requirements of significant system elements. The cases examined include a manned expedition to Phobos, the inner Martian moon; a human expedition to Mars; the Lunar Observatory; and a lunar outpost to early Mars evolution.

Cataldo, Robert L.

1990-01-01

385

[Demography and human ecology].  

PubMed

At the end of the 19th century the German biologist Ernest Haekel was the first scientist to use the term ecology, which was defined as the study of relationships of organisms or groups of organisms with the environment and indicated the interdependence of the living world, including plants, animals, and humans. This concept also indicates a continuous process of adaptation of organisms to their external environment. The basic concepts of scientific ecology, which developed at the end of the 19th century, can be attributed to Darwin: the relationships between living beings and the notion of the process of adaptation to their environment. The term human ecology appeared in the early 1920s. Human ecology embodies fundamental ideas: biotype, habitat, community, biocenosis, ecosystem, biomass, interchange and equilibrium, and circulation of energy. The accumulated knowledge about human ecology is broken down using the criteria of topography (ecology of humid forests, deserts, lakes, etc.); followed by the appearance of species; and the variants of classical division: auto ecology (influence of external factors on living beings) and sinecology (the study of groups of associated organisms, i.e., natural, animal, and vegetation communities). The species are considered on the basis of equality or sinecology (all of them have the same interests), while in human ecology a species is determined by its relation to a reference group--autoecology or anthropocentric ecology. In 1911, J. Thompson bridged the gap between biological knowledge and social sciences; in 1921, H. Barrows identified human ecology as a component of geography; in 1925, L. Bernard presented the classification of ecosystems; and in 1936, Ezra Park published his work, Human Ecology, followed in 1945 by the emergence of the Chicago school. Demography and human ecology are intimately connected because population is the result of natural and migratory movements, therefore the two sciences require a methodology that integrates the dynamics of biocultural interactions. PMID:12179860

Nazareth, J M

1993-01-01

386

Mapping the human genome  

SciTech Connect

This article is a review of the book Mapping the Human Genome: Using Law and Ethics as Guides, edited by George C. Annas and Sherman Elias. The book is a collection of essays on the subject of using ethics and laws as guides to justify human gene mapping. It addresses specific issues such problems related to eugenics, patents, insurance as well as broad issues such as the societal definitions of normality.

Annas, G.C.; Elias, S. (eds.)

1992-01-01

387

Proteomics of Human Bile  

Microsoft Academic Search

Bile is an important body fluid with crucial functions ranging from fat absorption to excretion of metabolic breakdown products.\\u000a Although the chemical composition of human bile is well understood, its protein constituents are beginning to be unravelled\\u000a only recently. Here, we provide an overview of the proteomics of human bile, both in health and in diseases such as cholangiocarcinoma.\\u000a A

Troels Zakarias Kristiansen; Anirban Maitra; Akhilesh Pandey

388

Human and Robot Sensors  

NSDL National Science Digital Library

Students are provided with a rigorous background in human "sensors" (including information on the main five senses, sensor anatomies, and nervous system process) and their engineering equivalents, setting the stage for three associated activities involving sound sensors on LEGO® robots. As they learn how robots receive input from sensors, transmit signals and make decisions about how to move, students reinforce their understanding of the human body's sensory process.

GK-12 Program, Computational Neurobiology Center,

389

Paperworks: The Human Touch  

Microsoft Academic Search

Paperworks: The Human Touch\\u000aan exhibition of works by the Western Reserve Calligraphers\\u000aSOUTH EUCLID, Ohio—8 August 2012—In conjunction with Octavofest, a celebration of the book and paper arts, and Watermarks 2012, Notre Dame College’s (NDC’s) Clara Fritzsche Library will host “Paperworks: The Human Touch,” a showing of works by the Western Reserve Calligraphers. An opening reception will be held

2012-01-01

390

The human loricrin gene.  

PubMed

Loricrin is the major protein component of the cornified cell envelope of terminally differentiated mammalian epidermal (stratum corneum) cells. Using a specific human cDNA clone, we have isolated and characterized the human loricrin gene. We show that it has a very simple structure of a single intron of 1188 base pairs (bp) in the 5'-untranslated region; there are no introns in coding sequences. By use of rodent-human somatic cell hybrids, followed by in situ hybridization with a biotin-labeled genomic DNA clone, the single-copy gene maps to chromosome location 1q21. Polymerase chain reaction analyses of genomic DNAs from different individuals show that human loricrin consists of two allelic size variants, due to sequence variations in its second glycine loop domain, and these variants segregate in the human population by normal Mendelian mechanisms. Furthermore, there are multiple sequence variants within these two size class alleles due to various deletions of 12 bp (4 amino acids) in the major loop of this glycine loop domain. By use of a specific loricrin antibody, we show by immunogold electron microscopy that loricrin initially appears in the granular layer of human epidermis and forms composite keratohyalin granules with profilaggrin, but localizes to the cell periphery (cell envelope) of fully differentiated stratum corneum cells. PMID:1355480

Yoneda, K; Hohl, D; McBride, O W; Wang, M; Cehrs, K U; Idler, W W; Steinert, P M

1992-09-01

391

Caloric Restriction in Humans  

PubMed Central

Studies on mice and rats have demonstrated that calorie restriction (CR) slows primary aging, has a protective effect against secondary aging, and markedly decreases the incidence of malignancies. However, the only way to determine whether CR “works” in humans is to conduct studies on people. Such studies are difficult to perform in free-living people. While research on CR in humans is still at an early stage, a modest amount of information has accumulated. Because it is not feasible to conduct studies of the effects of CR on longevity in humans, surrogate measures have to be used. Preliminary information obtained using this approach provides evidence that CR provides a powerful protective effect against secondary aging in humans. This evidence consists of the finding that risk factors for atherosclerosis and diabetes are markedly reduced in humans on CR. Humans on CR also show some of the same adaptations that are thought to be involved in slowing primary aging in rats and mice. These include a very low level of inflammation as evidenced by low circulatory levels of c-reactive protein and TNF?, serum triiodothyronine levels at the low end of the normal range, and a more elastic “younger” left ventricle (LV), as evaluated by echo-doppler measures of LV stiffness.

Holloszy, John O.; Fontana, Luigi

2007-01-01

392

Human Factors Review Plan  

SciTech Connect

''Human Factors'' is concerned with the incorporation of human user considerations into a system in order to maximize human reliability and reduce errors. This Review Plan is intended to assist in the assessment of human factors conditions in existing DOE facilities. In addition to specifying assessment methodologies, the plan describes techniques for improving conditions which are found to not adequately support reliable human performance. The following topics are addressed: (1) selection of areas for review describes techniques for needs assessment to assist in selecting and prioritizing areas for review; (2) human factors engineering review is concerned with optimizing the interfaces between people and equipment and people and their work environment; (3) procedures review evaluates completeness and accuracy of procedures, as well as their usability and management; (4) organizational interface review is concerned with communication and coordination between all levels of an organization; and (5) training review evaluates training program criteria such as those involving: trainee selection, qualification of training staff, content and conduct of training, requalification training, and program management.

Paramore, B.; Peterson, L.R. (eds.)

1985-12-01

393

Understanding the Social Relationship Between Humans and Virtual Humans  

Microsoft Academic Search

Our review surveys a range of human-human relationship models and research that might provide insights to understanding the social relationship between humans and virtual humans. This involves investigating several social constructs (expectations, communication, trust, etc.) that are identified as key variables that influence the relationship between people and how these variables should be implemented in the design for an effective

Sung Park; Richard Catrambone

2007-01-01

394

Analysis of human metapneumovirus and human bocavirus viral load.  

PubMed

Viral load (VL) of human metapneumovirus and human bocavirus in infants <12 months admitted for bronchiolitis was analyzed. VL correlated with length of hospital stay in both viruses, human metapneumovirus VL with the duration oxygen therapy and human bocavirus VL inversely with days of respiratory effort before admission. Infants coinfected by other viruses were younger, but no differences were seen regarding VL. PMID:23538515

Ricart, Silvia; Garcia-Garcia, Juan Jose; Anton, Andres; Pumarola, Tomas; Pons, Marti; Muñoz-Almagro, Carmen; Marcos, Maria Angeles

2013-09-01

395

Science and the humanities: the case for state humanities councils  

Microsoft Academic Search

Although joined together by their commitment to inquiry, in their pursuit of seemingly divergent goals science and the humanities sometimes appear to be in tension. This article suggests that the public humanities programs sponsored by state humanities councils, the independent nonprofit state affiliates of the National Endowment for the Humanities, serve as vehicles for reconciling the differing concerns of science

G. M. Leftwich

2002-01-01

396

Human behavior and human performance: Psychomotor demands  

NASA Technical Reports Server (NTRS)

The results of several experiments are presented in abstract form. These studies are critical for the interpretation and acceptance of flight based science to be conducted by the Behavior and Performance project. Some representative titles are as follow: External audio for IBM/PC compatible computers; A comparative assessment of psychomotor performance (target prediction by humans and macaques); Response path (a dependent measure for computer maze solving and other tasks); Behavioral asymmetries of psychomotor performance in Rhesus monkey (a dissociation between hand preference and skill); Testing primates with joystick based automated apparatus; and Environmental enrichment and performance assessment for ground or flight based research with primates;

1992-01-01

397

Activation of human complement by totally human monoclonal antibodies  

Microsoft Academic Search

A uniquely developed series of totally§§The term “totally” is used to distinguish these antibodies from humanized immunoglobulins or monoclonals produced from mouse\\/human heterohybridomas. human monoclonal antibodies (mAbs) were examined for their complement fixing properties in comparison to human myeloma preparations and to commercially available human polyclonal immunoglobulins. C3b and C4b deposition was measured using a kinetic ELISA technique. When the

Susanne L. Dillman; Anthony J. Strelkauskas; Helene R. Su; Robert J. Boackle

1995-01-01

398

Human-mouse cell hybrid with human multiple Y chromosomes  

Microsoft Academic Search

HUMAN-mouse cell hybrids usually exhibit preferential loss of human chromosomes1,2. After a time interval, which depends in part on the cell types used, most or sometimes all the human chromosomes segregate out from the hybrid cells3. In the course of investigation of the phenomenon of preferential loss of human chromosomes from hybrids between the mouse cell line RAG and human

Menashe Marcus; RAMANA TANTRAVAHI; VAITHILINGAM G. DEV; DOROTHY A. MILLER; ORLANDO J. MILLER

1976-01-01

399

The Exploration of Mars by Humans: Why Mars? Why Humans?  

NASA Technical Reports Server (NTRS)

As we commemorate the 50th anniversary of Yuri Gagarin's historic flight in 1961, the first flight of a human in space, plans are underway for another historic human mission. Plans are being developed for a human mission to Mars. Once we reach Mars, the human species will become the first two-planet species. Both the Bush Administration (in 2004) and the Obama Administration (in 2010) proposed a human mission to Mars as a national goal of the United States.

Levine, Joel S.

2011-01-01

400

Human Modeling for Ground Processing Human Factors Engineering Analysis  

NASA Technical Reports Server (NTRS)

There have been many advancements and accomplishments over the last few years using human modeling for human factors engineering analysis for design of spacecraft. The key methods used for this are motion capture and computer generated human models. The focus of this paper is to explain the human modeling currently used at Kennedy Space Center (KSC), and to explain the future plans for human modeling for future spacecraft designs

Stambolian, Damon B.; Lawrence, Brad A.; Stelges, Katrine S.; Steady, Marie-Jeanne O.; Ridgwell, Lora C.; Mills, Robert E.; Henderson, Gena; Tran, Donald; Barth, Tim

2011-01-01

401

Human Modeling For Ground Processing Human Factors Engineering Analysis  

NASA Technical Reports Server (NTRS)

There have been many advancements and accomplishments over that last few years using human modeling for human factors engineering analysis for design of spacecraft and launch vehicles. The key methods used for this are motion capture and computer generated human models. The focus of this paper is to explain the different types of human modeling used currently and in the past at Kennedy Space Center (KSC) currently, and to explain the future plans for human modeling for future spacecraft designs.

Tran, Donald; Stambolian, Damon; Henderson, Gena; Barth, Tim

2011-01-01

402

Spaceflight Human System Standards  

NASA Technical Reports Server (NTRS)

NASA created a new approach for human system integration and human performance standards. NASA created two documents a standard and a reference handbook. The standard is titled NASA Space Flight Human-System Standard (SFHSS) and consists of two-volumes: Volume 1- Crew Health This volume covers standards needed to support astronaut health (medical care, nutrition, sleep, exercise, etc.) Volume 2 Human Factors, Habitability and Environmental Health This volume covers the standards for system design that will maintain astronaut performance (ie., environmental factors, design of facilities, layout of workstations, and lighting requirements). It includes classic human factors requirements. The new standards document is written in terms so that it is applicable to a broad range of present and future NASA systems. The document states that all new programs prepare system-specific requirements that will meet the general standards. For example, the new standard does not specify a design should accommodate specific percentiles of a defined population. Rather, NASA-STD-3001, Volume 2 states that all programs shall prepare program-specific requirements that define the user population and their size ranges. The design shall then accommodate the full size range of those users. The companion reference handbook, Human Integration Design Handbook (HIDH), was developed to capture the design consideration information from NASA-STD-3000, and adds spaceflight lessons learned, gaps in knowledge, example solutions, and suggests research to further mature specific disciplines. The HIDH serves two major purposes: HIDH is the reference document for writing human factors requirements for specific systems. HIDH contains design guidance information that helps insure that designers create systems which safely and effectively accommodate the capabilities and limitations of space flight crews.

Holubec, Keith; Tillman, Barry; Connolly, Jan

2009-01-01

403

Making IBM's Computer, Watson, Human  

ERIC Educational Resources Information Center

This essay uses the recent victory of an IBM computer (Watson) in the TV game, "Jeopardy," to speculate on the abilities Watson would need, in addition to those it has, to be human. The essay's basic premise is that to be human is to behave as humans behave and to function in society as humans function. Alternatives to this premise are considered…

Rachlin, Howard

2012-01-01

404

Human Challenges in Exploration Missions  

NASA Technical Reports Server (NTRS)

This viewgraph presents an overview using pictures some of the history of human exploration of the new frontiers of Earth and then examines some of the challenges to human exploration of space. Particular attention is given to the environmental factors and to the social and human factors that effect humans in space environments.

Lloyd, Charles W.

2007-01-01

405

THE MIDAS HUMAN PERFORMANCE MODEL  

Microsoft Academic Search

A unique software tool for conducting human factors analyses of complex human-machine systems has been developed at NASA Ames Research Center. Called the Man-Machine Integration Design and Analysis System (MIDAS), this simulation system contains models of human performance that can be used to evaluate candidate procedures, controls, and displays prior to more expensive and time consuming hardware simulators and human

Sherman W. Tyler; Christian Neukom; Michael Logan; Jay Shively

406

Human Rights: The Essential Reference.  

ERIC Educational Resources Information Center

This reference work documents the history of human rights theory, explains each article of the Universal Declaration of Human Rights, explores the contemporary human rights movement, and examines the major human rights issues facing the world today. This book is the first to combine historical and contemporary perspectives on these critical…

Devine, Carol; Hansen, Carol Rae; Wilde, Ralph; Bronkhorst, Daan; Moritz, Frederic A.; Rolle, Baptiste; Sherman, Rebecca; Southard, Jo Lynn; Wilkinson, Robert; Poole, Hilary, Ed.

407

Archaic human genomics.  

PubMed

For much of the 20th century, the predominant view of human evolutionary history was derived from the fossil record. Homo erectus was seen arising in Africa from an earlier member of the genus and then spreading throughout the Old World and into the Oceania. A regional continuity model of anagenetic change from H. erectus via various intermediate archaic species into the modern humans in each of the regions inhabited by H. erectus was labeled the multiregional model of human evolution (MRE). A contrasting model positing a single origin, in Africa, of anatomically modern H. sapiens with some populations later migrating out of Africa and replacing the local archaic populations throughout the world with complete replacement became known as the recent African origin (RAO) model. Proponents of both models used different interpretations of the fossil record to bolster their views for decades. In the 1980s, molecular genetic techniques began providing evidence from modern human variation that allowed not only the different models of modern human origins to be tested but also the exploration demographic history and the types of selection that different regions of the genome and even specific traits had undergone. The majority of researchers interpreted these data as strongly supporting the RAO model, especially analyses of mitochondrial DNA (mtDNA). Extrapolating backward from modern patterns of variation and using various calibration points and substitution rates, a consensus arose that saw modern humans evolving from an African population around 200,000 years ago. Much later, around 50,000 years ago, a subset of this population migrated out of Africa replacing Neanderthals in Europe and western Asia as well as archaics in eastern Asia and Oceania. mtDNA sequences from more than two-dozen Neanderthals and early modern humans re-enforced this consensus. In 2010, however, the complete draft genomes of Neanderthals and of heretofore unknown hominins from Siberia, called Denisovans, demonstrated gene flow between these archaic human species and modern Eurasians but not sub-Saharan Africans. Although the levels of gene flow may be very limited, this unexpected finding does not fit well with either the RAO model or MRE model. More thorough sampling of modern human diversity, additional fossil discoveries, and the sequencing of additional hominin fossils are necessary to throw light onto our origins and our history. PMID:23124308

Disotell, Todd R

2012-01-01

408

Human herpesvirus 6.  

PubMed Central

Human herpesvirus 6 variant A (HHV-6A) and human herpesvirus 6 variant B (HHV-6B) are two closely related yet distinct viruses. These visuses belong to the Roseolovirus genus of the betaherpesvirus subfamily; they are most closely related to human herpesvirus 7 and then to human cytomegalovirus. Over 95% of people older than 2 years of age are seropositive for either or both HHV-6 variants, and current serologic methods are incapable of discriminating infection with one variant from infection with the other. HHV-6A has not been etiologically linked to any human disease, but such an association will probably be found soon. HHV-6B is the etiologic agent of the common childhood illness exanthem subitum (roseola infantum or sixth disease) and related febrile illnesses. These viruses are frequently active and associated with illness in immunocompromised patients and may play a role in the etiology of Hodgkin's disease and other malignancies. HHV-6 is a commensal inhabitant of brains; various neurologic manifestations, including convulsions and encephalitis, can occur during primary HHV-6 infection or in immunocompromised patients. HHV-6 and distribution in the central nervous system are altered in patients with multiple sclerosis; the significance of this is under investigation.

Braun, D K; Dominguez, G; Pellett, P E

1997-01-01

409

Human postural dynamics.  

PubMed

The study of posture dynamics is important not only to understand disorders of impaired equilibrium and protective reactions to unexpected displacements of the human body, but also to the design of prosthesis and functional neuromuscular stimulation as aids to patients with impaired postural stability and locomotion. Coordinated control of the body segments is a complex aspect of motor behavior, owing to the multiple degrees of freedom of the controlled system. Several interacting subsystems are involved in the dynamics of human posture and locomotion, including the skeletal, neuromuscular, and sensory systems. Human posture control is maintained by somatosensory, vestibular, and visual feedback, integrated within the locomotor and central nervous systems. Studies of posture dynamics and stability therefore entail the study of mechanical aspects of the human body, its sensory systems, and the principles governing coordination in motion control. In this paper is reviewed some of the research done in the field of human posture dynamics, including such topics as biomechanics, equilibrium, stability, motion coordination, neural feedback, neural control systems modeling, motion strategies, optimality of motion, and adaptation. We consider experimental approaches and theoretical models, as well as the gap between them. Principles for the experimental investigation of control systems are considered. PMID:1855384

Johansson, R; Magnusson, M

1991-01-01

410

Human Antibodies by Guided Selection  

Microsoft Academic Search

\\u000a Guided selection is a method for humanization of pre-existing non-human (for example, mouse) antibodies, based on chain shuffling\\u000a of V-genes by using phage display technology. Mouse VH and VL domains are used to guide the selection of a human antibody\\u000a partner and are replaced sequentially or in parallel with human VH and VL domains, respectively to derive human antibody.\\u000a The

Sang Jick Kim; Insoo Park; Hyo Jeong Hong

411

Uncovering the Human Methyltransferasome*  

PubMed Central

We present a comprehensive analysis of the human methyltransferasome. Primary sequences, predicted secondary structures, and solved crystal structures of known methyltransferases were analyzed by hidden Markov models, Fisher-based statistical matrices, and fold recognition prediction-based threading algorithms to create a model, or profile, of each methyltransferase superfamily. These profiles were used to scan the human proteome database and detect novel methyltransferases. 208 proteins in the human genome are now identified as known or putative methyltransferases, including 38 proteins that were not annotated previously. To date, 30% of these proteins have been linked to disease states. Possible substrates of methylation for all of the SET domain and SPOUT methyltransferases as well as 100 of the 131 seven-?-strand methyltransferases were surmised from sequence similarity clusters based on alignments of the substrate-specific domains.

Petrossian, Tanya C.; Clarke, Steven G.

2011-01-01

412

From mice to humans.  

PubMed

The genomes of many species have now been completely sequenced including human and mouse. Great progress has been made in understanding the complex genetics that underlie diabetes and obesity in human populations. One of the current challenges is the functional identification and characterization of the genes within loci that are being mapped. There are many approaches to this problem and this review outlines the valuable role that the mouse can play. We outline the mouse resources that are available to the research community, including knockouts with conditional potential for every gene, and the efforts of the International Mouse Phenotyping Consortium to attach phenotype information to these genes. We also briefly consider the potential of TALEN technology to tailor-make new mouse models of specific mutations discovered in humans. Finally, we consider the recent progress in characterizing the GWAS genes FTO, TCF7L2, CDKAL1, and SLC30A8 in engineered mouse models. PMID:22996130

McMurray, Fiona; Moir, Lee; Cox, Roger D

2012-12-01

413

Human-Robot Interaction  

NASA Technical Reports Server (NTRS)

Risk of Inadequate Design of Human and Automation/Robotic Integration (HARI) is a new Human Research Program (HRP) risk. HRI is a research area that seeks to understand the complex relationship among variables that affect the way humans and robots work together to accomplish goals. The DRP addresses three major HRI study areas that will provide appropriate information for navigation guidance to a teleoperator of a robot system, and contribute to the closure of currently identified HRP gaps: (1) Overlays -- Use of overlays for teleoperation to augment the information available on the video feed (2) Camera views -- Type and arrangement of camera views for better task performance and awareness of surroundings (3) Command modalities -- Development of gesture and voice command vocabularies

Rochlis-Zumbado, Jennifer; Sandor, Aniko; Ezer, Neta

2012-01-01

414

Humanities on the Road  

NSDL National Science Digital Library

The goal of the Pennsylvania Humanities Council is to encourage lifelong learning, and one way they accomplish this goal is by sponsoring the Humanities on the Road. The show is an "arts and culture-themed television series showcas[ing] humanities presentations at cultural sites across Pennsylvania." The accompanying website provides visitors access to the episodes of the series, along with text about the content of each show. Visitors should check out the episode "May I Have the Pleasure of This Dance?", which was filmed at the Scranton Cultural Center at the Masonic Temple. A couple dances their way through history through waltzes, tangos, ragtime, and more. The "Behind the Scenes" tab near the top of the page offers visitors a glimpse into the world of the crew of the show, including interviews with the host, the series producer, the production assistant, and others.

415

North Carolina Humanities Council  

NSDL National Science Digital Library

Created in 1972, the North Carolina Humanities Council is a statewide nonprofit and affiliate of the National Endowment for the Humanities that works to make the humanities "a cornerstone of public life." The Council's bright and well-designed website contains information about grant-making initiatives, upcoming events and talks, and publications as well as a gallery of images. First-time visitors may want to start by browsing through the latest issues of "North Carolina Conversations," found under Publications. One recent issue included a profile of downtown Greensboro, a short story by John York, and information on traveling folklife exhibits. The Programs area contains vibrant information on the Council's "Road Scholars" initiative, which brings speakers to audiences around the state. Also, this area contains the "Museum on Main Street," which provides information on the traveling exhibit jointly sponsored by the Council and the Smithsonian Institution Traveling Exhibition. The Publications area contains the Council's annual reports and its newsletter, "Crossroads"

416

Teleoperator human factors study  

NASA Technical Reports Server (NTRS)

An investigation of the spectrum of space teleoperation activities likely in the 1985 to 1995 decade focused on the resolution of critical human engineering issues and characterization of the technology effect on performance of remote human operators. The study began with the identification and documentation of a set of representative reference teleoperator tasks. For each task, technology, development, and design options, issues, and alternatives that bear on human operator performance were defined and categorized. A literature survey identified existing studies of man/machine issues. For each teleoperations category, an assessment was made of the state of knowledge on a scale from adequate to void. The tests, experiments, and analyses necessary to provide the missing elements of knowledge were then defined. A limited set of tests were actually performed, including operator selection, baseline task definition, control mode study, lighting study, camera study, and preliminary time delay study.

1986-01-01

417

Human Embryology Animations  

NSDL National Science Digital Library

For students of human development, the Human Embryology Animations site is a worthy resource. Created by Dr. Valerie O'Loughlin at Indiana University, the goal of this site is to help students "better understand the complex processes that must occur in embryologic development." The animations are divided into five thematic sections, including General Embryology, Development of the Limbs, and Urinary and Reproductive Embryology. Each animation lasts anywhere from 20 seconds to 8 minutes, and they cover heart tube folding, septum development, postnatal circulation, and 30 or so other processes. The site is designed for students and members of the general public with a basic understanding of human biology, and the animations are well-planned and worth a look. Additionally, they could be used for students reviewing materials for a course like AP Biology.

O'Loughlin, Valerie

2012-03-02

418

Preparing for Human Exploration  

NASA Technical Reports Server (NTRS)

NASA's Human Exploration and Development of Space (HEDS) Enterprise is defining architectures and requirements for human exploration that radically reduce the costs of such missions through the use of advanced technologies, commercial partnerships and innovative systems strategies. In addition, the HEDS Enterprise is collaborating with the Space Science Enterprise to acquire needed early knowledge about Mars and to demonstrate critical technologies via robotic missions. This paper provides an overview of the technological challenges facing NASA as it prepares for human exploration. Emphasis is placed on identifying the key technologies including those which will provide the most return in terms of reducing total mission cost and/or reducing potential risk to the mission crew. Top-level requirements are provided for those critical enabling technology options currently under consideration.

Drake, Bret G.; Joosten, B. Kent

1998-01-01

419

Journal of Digital Humanities  

NSDL National Science Digital Library

The Journal of Digital Humanities is a comprehensive, peer-reviewed, open access journal that features "the best scholarship, tools, and conversations produced by the digital humanities community." This endeavor was started by the Press Forward Project and its rigorous evaluation process ensures that interested parties will be exposed to a wide range of talent and subject matter. Arranged by trimester, recent issues of the journal have focused in on the ways digital humanities projects can be used to teach undergraduates about the world around them, while also highlighting the pedagogy involved with such endeavors. Visitors can search through the entire collection of back issues or they may also look through the list of contributors to get a sense of those involved with the project.

420

[Humanized antibodies as therapeutics].  

PubMed

Since 1997, nine humanized antibodies received the approval of the FDA to be used as drugs for the treatment of various diseases including transplant rejections, metastatic breast and colon cancers, leukaemia, non-Hodgkin lymphomas, allergic conditions or multiple sclerosis. This review describes techniques used to engineer these antibodies and presents the recent evolutions of these techniques : SDRs grafting or < abbreviated > CDRs grafting. Based on the illustrative examples of several antibodies, Mylotarg, Herceptin or Xolair, the therapeutic effectiveness of humanized antibodies are underlined and, with the example of Tysabri, the sometimes dramatic adverse effects associated with their clinical use is stressed. In a second part, this review presents some future and realistic avenues to improve the effectiveness of the humanized antibodies, to decrease their immunogenicity and to reduce their cost. PMID:16324646

Bellet, Dominique; Dangles-Marie, Virginie

2005-12-01

421

Similarities and differences between human–human and human–automation trust: an integrative review  

Microsoft Academic Search

The trust placed in diagnostic aids by the human operator is a critical psychological factor that influences operator reliance on automation. Studies examining the nature of human interaction with automation have revealed that users have a propensity to apply norms of human–human inter-personal interaction to their interaction with ‘intelligent machines’. Nevertheless, there exist subtle differences in the manner in which

P. Madhavan; D. A. Wiegmann

2007-01-01

422

Simulated human skin scales  

PubMed Central

Human skin scales which have been shed naturally bear a flora of microorganisms which is unknown until tested. To replace these scales in a study of the micro-environment of both the human body and of models a method has been devised of making synthetic scales which behave both physically and aerodynamically in a similar way to the natural material. The synthetic materials carry no natural flora and it is possible to include in them test markers of several kinds to assist in identification after dispersion. ImagesFig. 1Fig. 2

Lees, Julienne; Brighton, W. D.

1972-01-01

423

Human MSH2 protein  

DOEpatents

The human MSH2 gene, responsible for hereditary non-polyposis colorectal cancer, was identified by virtue of its homology to the MutS class of genes, which are involved in DNA mismatch repair. The sequence of cDNA clones of the human gene are provided, and the sequence of the gene can be used to demonstrate the existence of germ line mutations in hereditary non-polyposis colorectal cancer (HNPCC) kindreds, as well as in replication error.sup.+ (RER.sup.+) tumor cells.

de la Chapelle, Albert (Helsingfors, FI); Vogelstein, Bert (Baltimore, MD); Kinzler, Kenneth W. (Baltimore, MD)

1997-01-01