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Li M, Subedi BP, Fitzpatrick PF, Emerson JP. Thermodynamics of iron, tetrahydrobiopterin, and phenylalanine binding to phenylalanine hydroxylase from Chromobacterium violaceum. Arch Biochem Biophys 2022; 729:109378. [PMID: 35995215 PMCID: PMC10184773 DOI: 10.1016/j.abb.2022.109378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/13/2022] [Accepted: 08/16/2022] [Indexed: 11/02/2022]
Abstract
Phenylalanine hydroxylase (PheH) is a pterin-dependent, mononuclear nonheme iron(II) oxygenase that uses the oxidative power of O2 to hydroxylate phenylalanine to form tyrosine. PheH is a member of a superfamily of O2-activating enzymes that utilizes a common metal binding motif: the 2-His-1-carboxylate facial triad. Like most members of this superfamily, binding of substrates to PheH results in a reorganization of its active site to allow O2 activation. Exploring the energetics of each step before O2 activation can provide mechanistic insight into the initial steps that support the highly specific O2 activation pathway carried out by this metalloenzyme. Here the thermal stability of PheH and its substrate complexes were investigated under an anaerobic environment by using differential scanning calorimetry. In context with known binding constants for PheH, a thermodynamic cycle associated with iron(II), tetrahydrobiopterin (BH4), and phenylalanine binding to the active site was generated, showing a distinctive cooperativity between the binding of BH4 and Phe. The addition of phenylalanine and BH4 to PheH·Fe increased the stability of this enzyme (ΔTm of 8.5 (±0.7) °C with an associated δΔH of 43.0 (±2.9) kcal/mol). The thermodynamic data presented here gives insight into the complicated interactions between metal center, cofactor, and substrate, and how this interplay sets the stage for highly specific, oxidative C-H activation in this enzyme.
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Affiliation(s)
- Mingjie Li
- Department of Chemistry, Mississippi State University, Mississippi State, MS, 39762, USA
| | - Bishnu P Subedi
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Paul F Fitzpatrick
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX, 78229, USA.
| | - Joseph P Emerson
- Department of Chemistry, Mississippi State University, Mississippi State, MS, 39762, USA.
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Zhang Y, Siu KL, Li Q, Howard-Quijano K, Scovotti J, Mahajan A, Cai H. Diagnostic and predictive values of circulating tetrahydrobiopterin levels as a novel biomarker in patients with thoracic and abdominal aortic aneurysms. Redox Biol 2022; 56:102444. [PMID: 36116158 PMCID: PMC9486112 DOI: 10.1016/j.redox.2022.102444] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/03/2022] [Accepted: 08/11/2022] [Indexed: 11/25/2022] Open
Abstract
We have previously shown that circulating levels of tetrahydrobiopterin (H4B) function as a robust biomarker for aortic aneurysms in several independent animal models. In the present study, we examined diagnostic and predictive values of circulating H4B levels in human patients of thoracic aortic aneurysm (TAA) and abdominal aortic aneurysm (AAA) for the first time, while clinically applicable biomarkers for aortic aneurysms have never been previously available. Ninety-five patients scheduled for TAA repair surgeries and 53 control subjects were recruited at University of California Los Angeles (UCLA) Ronald Regan Medical Center, while 44 control subjects and 29 AAA patients were recruited through National Institute of Health (NIH) National Disease Research Interchange (NDRI) program. We had intriguing observations that circulating H4B levels were substantially lower in TAA and AAA patients, linearly correlated with aortic H4B levels (blood: R = 0.8071, p < 0.0001, n = 75; plasma: R = 0.7983, p < 0.0001, n = 75), and associated with incidence of TAA (blood: adjusted OR 0.495; 95% CI 0.379-0.647; p < 0.001; plasma: adjusted OR 0.501; 95% CI 0.385-0.652; p < 0.001) or AAA (blood: adjusted OR 0.329; 95% CI 0.125-0.868; p = 0.025) after adjustment for other factors. Blood or plasma H4B levels below 0.2 pmol/μg serve as an important threshold for prediction of aortic aneurysms independent of age and gender (for TAA risk - blood: adjusted OR 419.67; 95% CI 59.191-2975.540; p < 0.001; plasma: adjusted OR 206.11; 95% CI 40.956-1037.279; p < 0.001). This threshold was also significantly associated with incidence of AAA (p < 0.001 by Chi-square analysis). In addition, we observed previously unrecognized inverse association of Statin use with TAA, and an association of AAA with arrhythmia. Taken together, our data strongly demonstrate for the first time that circulating H4B levels can serve as a first-in-class, sensitive, robust and independent biomarker for clinical diagnosis and prediction of TAA and AAA in human patients, which can be rapidly translated to bedside to fundamentally improve clinical management of the devastating human disease of aortic aneurysms.
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Affiliation(s)
- Yixuan Zhang
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, California, 90095, USA
| | - Kin Lung Siu
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, California, 90095, USA
| | - Qiang Li
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, California, 90095, USA
| | - Kimberly Howard-Quijano
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pennsylvania, 15260, USA
| | - Jennifer Scovotti
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, California, 90095, USA
| | - Aman Mahajan
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pennsylvania, 15260, USA
| | - Hua Cai
- Division of Molecular Medicine, Department of Anesthesiology and Perioperative Medicine, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, California, 90095, USA.
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Evers RAF, van Wegberg AMJ, MacDonald A, Huijbregts SCJ, Leuzzi V, van Spronsen FJ. Dietary Liberalization in Tetrahydrobiopterin-Treated PKU Patients: Does It Improve Outcomes? Nutrients 2022; 14:nu14183874. [PMID: 36145250 PMCID: PMC9504284 DOI: 10.3390/nu14183874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose: this systematic review aimed to assess the effects of dietary liberalization following tetrahydrobiopterin (BH4) treatment on anthropometric measurements, nutritional biomarkers, quality of life, bone density, mental health and psychosocial functioning, and burden of care in PKU patients. Methods: the PubMed, Cochrane, and Embase databases were searched on 7 April 2022. We included studies that reported on the aforementioned domains before and after dietary liberalization as a result of BH4 treatment in PKU patients. Exclusion criteria were: studies written in a language other than English; studies that only included data of a BH4 loading test; insufficient data for the parameters of interest; and wrong publication type. Both within-subject and between-subject analyses were assessed, and meta-analyses were performed if possible. Results: twelve studies containing 14 cohorts and 228 patients were included. Single studies reported few significant differences. Two out of fifteen primary meta-analyses were significant; BMI was higher in BH4-treated patients versus controls (p = 0.02; standardized mean difference (SMD) (95% confidence interval (CI)) = −0.37 (−0.67, −0.06)), and blood cholesterol concentrations increased after starting BH4 treatment (p = 0.01; SMD (CI) = −0.70 (−1.26, −0.15)). Conclusion: there is no clear evidence that dietary liberalization after BH4 treatment has a positive effect on anthropometric measurements, nutritional biomarkers, or quality of life. No studies could be included for bone density, mental health and psychosocial functioning, and burden of care.
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Affiliation(s)
- Roeland A. F. Evers
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, 9700 RB Groningen, The Netherlands
| | - Annemiek M. J. van Wegberg
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, 9700 RB Groningen, The Netherlands
| | - Anita MacDonald
- Dietetic Department, Birmingham Children’s Hospital, Birmingham B4 6NH, UK
| | - Stephan C. J. Huijbregts
- Department of Clinical Child and Adolescent Studies-Neurodevelopmental Disorders, Faculty of Social Sciences, Leiden University, 2300 RB Leiden, The Netherlands
| | - Vincenzo Leuzzi
- Unit of Child Neurology and Psychiatry, Department of Human Neuroscience, Sapienza University of Rome, 00185 Rome, Italy
| | - Francjan J. van Spronsen
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, 9700 RB Groningen, The Netherlands
- Correspondence: ; Tel.: +31-(0)50-3614147
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Degrush E, Shazeeb MS, Drachman D, Vardar Z, Lindsay C, Gounis MJ, Henninger N. Cumulative effect of simvastatin, L-arginine, and tetrahydrobiopterin on cerebral blood flow and cognitive function in Alzheimer's disease. Alzheimers Res Ther 2022; 14:134. [PMID: 36115980 PMCID: PMC9482313 DOI: 10.1186/s13195-022-01076-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 08/24/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVES Vascular disease is a known risk factor for Alzheimer's disease (AD). Endothelial dysfunction has been linked to reduced cerebral blood flow. Endothelial nitric oxide synthase pathway (eNOS) upregulation is known to support endothelial health. This single-center, proof-of-concept study tested whether the use of three medications known to augment the eNOS pathway activity improves cognition and cerebral blood flow (CBF). METHODS Subjects with mild AD or mild cognitive impairment (MCI) were sequentially treated with the HMG-CoA reductase synthesis inhibitor simvastatin (weeks 0-16), L-arginine (weeks 4-16), and tetrahydrobiopterin (weeks 8-16). The primary outcome of interest was the change in CBF as measured by MRI from baseline to week 16. Secondary outcomes included standard assessments of cognition. RESULTS A total of 11 subjects were deemed eligible and enrolled. One subject withdrew from the study after enrollment, leaving 10 subjects for data analysis. There was a significant increase in CBF from baseline to week 8 by ~13% in the limbic and ~15% in the cerebral cortex. Secondary outcomes indicated a modest but significant increase in the MMSE from baseline (24.2±3.2) to week 16 (26.0±2.7). Exploratory analysis indicated that subjects with cognitive improvement (reduction of the ADAS-cog 13) had a significant increase in their respective limbic and cortical CBF. CONCLUSIONS Treatment of mild AD/MCI subjects with medications shown to augment the eNOS pathway was well tolerated and associated with modestly increased cerebral blood flow and cognitive improvement. TRIAL REGISTRATION This study is registered in https://www. CLINICALTRIALS gov ; registration identifier: NCT01439555; date of registration submitted to registry: 09/23/2011; date of first subject enrollment: 11/2011.
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Affiliation(s)
- Elizabeth Degrush
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA.
- Department of Psychiatry, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA.
| | - Mohammed Salman Shazeeb
- Image Processing and Analysis Core (iPAC), Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- New England Center for Stroke Research, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - David Drachman
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
| | - Zeynep Vardar
- Image Processing and Analysis Core (iPAC), Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- New England Center for Stroke Research, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Clifford Lindsay
- Image Processing and Analysis Core (iPAC), Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Matthew J Gounis
- Image Processing and Analysis Core (iPAC), Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- New England Center for Stroke Research, Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Nils Henninger
- Department of Neurology, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
- Department of Psychiatry, University of Massachusetts Chan Medical School, 55 Lake Ave, North, Worcester, MA, 01655, USA
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Hesthammer R, Dahle S, Storesund JP, Eide T, Djurhuus R, Svardal AM, Thorsen E. Nitric oxide in exhaled gas and tetrahydrobiopterin in plasma after exposure to hyperoxia. Undersea Hyperb Med 2020; 47:197-202. [PMID: 32574435 DOI: 10.22462/04.06.2020.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The fraction of nitric oxide in exhaled gas (FENO) is decreased after exposure to hyperoxia in vivo, although the mechanisms for this decrease is not clear. A key co-factor for nitric oxide synthase (NOS), tetrahydrobiopterin (BH4), has been shown to be oxidized in vitro when exposed to hyperoxia. We hypothesized that the decrease of FENO is due to decreased enzymatic generation of NO due to oxidation of BH4. The present study was performed to investigate the relationship between levels of FENO and plasma BH4 following hyperoxic exposure in humans. Two groups of healthy subjects were exposed to 100% oxygen for 90 minutes. FENO was measured before and 10 minutes (n = 13) or 60 minutes (n = 14) after the exposure. Blood samples were collected at the same time points for quantification of biopterin levels (BH4, BH2 and B) using LC-MS/MS. Each subject was his or her own control, breathing air for 90 minutes on a separate day. Hyperoxia resulted in a 28.6 % decrease in FENO 10 minutes after exposure (p < 0.001), confirming previous findings. Moreover, hyperoxia also caused a 14.2% decrease in plasma BH4 (p = 0.012). No significant differences were observed in the group measured 60 minutes after exposure. No significant correlation was found between the changes in FENO and BH4 after the hyperoxic exposure (r = 0.052, p = 0.795), this might be due to the recovery of BH4 being faster than the recovery of FENO.
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Affiliation(s)
- Ronja Hesthammer
- Norwegian Centre for Maritime and Diving Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Norway
| | - Stian Dahle
- Department of Clinical Science, University of Bergen, Norway
| | | | - Torunn Eide
- Department of Clinical Science, University of Bergen, Norway
| | - Rune Djurhuus
- Norwegian Centre for Maritime and Diving Medicine, Haukeland University Hospital, Bergen, Norway
| | | | - Einar Thorsen
- Norwegian Centre for Maritime and Diving Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Norway
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Chidley C, Haruki H, Pedersen MG, Muller E, Johnsson K. A yeast-based screen reveals that sulfasalazine inhibits tetrahydrobiopterin biosynthesis. Nat Chem Biol 2011. [PMID: 21499265 DOI: 10.1038/nphys1987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We introduce an approach for detection of drug-protein interactions that combines a new yeast three-hybrid screening for identification of interactions with affinity chromatography for their unambiguous validation. We applied the methodology to the profiling of clinically approved drugs, resulting in the identification of previously known and unknown drug-protein interactions. In particular, we were able to identify off-targets for erlotinib and atorvastatin, as well as an enzyme target for the anti-inflammatory drug sulfasalazine. We demonstrate that sulfasalazine and its metabolites, sulfapyridine and mesalamine, are inhibitors of the enzyme catalyzing the final step in the biosynthesis of the cofactor tetrahydrobiopterin. The interference with tetrahydrobiopterin metabolism provides an explanation for some of the beneficial and deleterious properties of sulfasalazine and furthermore suggests new and improved therapies for the drug. This work thus establishes a powerful approach for drug profiling and provides new insights in the mechanism of action of clinically approved drugs.
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Affiliation(s)
- Christopher Chidley
- Institute of Chemical Sciences and Engineering, Institute of Bioengineering, National Centre of Competence in Research Chemical Biology, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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Walter R, Kaufmann PA, Buck A, Berthold T, Wyss C, von Schulthess GK, Schaffner A, Schoedon G. Tetrahydrobiopterin increases myocardial blood flow in healthy volunteers: a double-blind, placebo-controlled study. Swiss Med Wkly 2001; 131:91-4. [PMID: 11416883 DOI: 2001/07/smw-06147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Tetrahydrobiopterin (BH4) is a regulatory cofactor for the activity of nitric oxide synthases. Vasodilating properties of BH4 have been reported in vitro and in vivo. The influence of BH4 on myocardial blood flow (MBF), however, is largely unknown. We therefore performed a double-blind, placebo-controlled study to investigate the effect of intravenous BH4 on MBF in healthy volunteers. METHODS AND RESULTS Resting MBF was assessed in 15 subjects receiving either intravenous BH4 (10 mg/kg) or placebo using positron emission tomography (PET) and [13N]ammonia. From a mean baseline MBF of 0.91 +/- 0.09 ml/min/g, MBF increased to 1.18 +/- 0.10 ml/min/g after BH4 (n = 10; p = 0.0042). In contrast, in the group receiving placebo mean MBF remained unchanged (non-significant decrease from 0.97 +/- 0.19 to 0.84 +/- 0.11 ml/min/g; n = 5; p = 0.36). Systemic haemodynamics and ECGs remained unaffected in both groups. BH4 was very well tolerated. CONCLUSION Systemically administered BH4 is safe and effectively increases resting MBF in healthy volunteers.
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Affiliation(s)
- R Walter
- Department of Medicine, Medical Clinic B Research Unit, University Hospital of Zürich, Switzerland
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Abstract
Tetrahydrobiopterin (BH(4)) cofactor is essential for various processes, and is present in probably every cell or tissue of higher organisms. BH(4) is required for various enzyme activities, and for less defined functions at the cellular level. The pathway for the de novo biosynthesis of BH(4) from GTP involves GTP cyclohydrolase I, 6-pyruvoyl-tetrahydropterin synthase and sepiapterin reductase. Cofactor regeneration requires pterin-4a-carbinolamine dehydratase and dihydropteridine reductase. Based on gene cloning, recombinant expression, mutagenesis studies, structural analysis of crystals and NMR studies, reaction mechanisms for the biosynthetic and recycling enzymes were proposed. With regard to the regulation of cofactor biosynthesis, the major controlling point is GTP cyclohydrolase I, the expression of which may be under the control of cytokine induction. In the liver at least, activity is inhibited by BH(4), but stimulated by phenylalanine through the GTP cyclohydrolase I feedback regulatory protein. The enzymes that depend on BH(4) are the phenylalanine, tyrosine and tryptophan hydroxylases, the latter two being the rate-limiting enzymes for catecholamine and 5-hydroxytryptamine (serotonin) biosynthesis, all NO synthase isoforms and the glyceryl-ether mono-oxygenase. On a cellular level, BH(4) has been found to be a growth or proliferation factor for Crithidia fasciculata, haemopoietic cells and various mammalian cell lines. In the nervous system, BH(4) is a self-protecting factor for NO, or a general neuroprotecting factor via the NO synthase pathway, and has neurotransmitter-releasing function. With regard to human disease, BH(4) deficiency due to autosomal recessive mutations in all enzymes (except sepiapterin reductase) have been described as a cause of hyperphenylalaninaemia. Furthermore, several neurological diseases, including Dopa-responsive dystonia, but also Alzheimer's disease, Parkinson's disease, autism and depression, have been suggested to be a consequence of restricted cofactor availability.
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Affiliation(s)
- B Thöny
- Division of Clinical Chemistry, University Children's Hospital, Steinwiesstrasse 75, 8032 Zurich, Switzerland
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Abstract
Concentrations of neopterin were measured in urine specimens from 35 patients with active and eight with inactive systemic lupus erythematosus (SLE). Compared with those of apparently healthy controls, neopterin concentrations were higher in patients with active disease (P less than 0.001) and with inactive disease (P less than 0.01), those in patients with active disease being significantly higher than those in patients with inactive disease (P less than 0.001). The correlation between the neopterin concentration and evidence of disease activity was good. All of the patients with clinically active SLE had increased neopterin, but for only 37.5% (three of eight) did the neopterin concentration exceed the upper normal limit during clinical remission. The increase in neopterin concentration did not correlate with clinical courses or severity of renal function. Moreover, serial determinations of neopterin in active SLE patients showed a rapid decrease of initially high concentration, paralleling a decline of clinical activity after initiation of medical therapy. Thus, urinary neopterin may be a useful marker for monitoring disease activity in SLE patients.
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Affiliation(s)
- L Leohirun
- Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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