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1.
Mod Rheumatol ; 2024 May 30.
Article in English | MEDLINE | ID: mdl-38814660

ABSTRACT

OBJECTIVES: To update evidence on the efficacy and safety of disease-modifying antirheumatic drugs (DMARDs) and provide information to the taskforce for the 2024 update of the Japan College of Rheumatology (JCR) clinical practice guidelines (CPG) for the management of rheumatoid arthritis (RA). METHODS: We searched various databases for randomised controlled trials on RA published until June 2022, with no language restriction. For each of the 15 clinical questions, 2 independent reviewers screened the articles, evaluated the core outcomes, and performed meta-analyses. RESULTS: Subcutaneous injection of methotrexate (MTX) showed similar efficacy to oral MTX in MTX-naïve RA patients. Ozoralizumab combined with MTX improved drug efficacy compared to the placebo in RA patients with inadequate response (IR) to csDMARD. Rituximab with and without concomitant csDMARDs showed similar efficacy to other bDMARDs in bDMARD-IR RA patients. Combined Janus kinase inhibitors and MTX achieved similar clinical responses and equal safety during a 4-year period compared to tumour necrosis factor inhibitors in MTX-IR RA patients. Biosimilars showed efficacy equivalent to that of the original bDMARDs in csDMARD-IR and bDMARD-IR RA patients. CONCLUSION: This systematic review provides latest evidence for the 2024 update of the JCR CPG for RA management.

2.
Clin Exp Med ; 24(1): 97, 2024 May 10.
Article in English | MEDLINE | ID: mdl-38727756

ABSTRACT

Data on the safety of Janus kinase inhibitors (JAKis) in patients with renal impairment are lacking. This study aimed to investigate the safety of JAKis compared to biological (b) DMARDs in patients with rheumatoid arthritis (RA) and renal impairment. We used a multi-centre observational registry of patients with RA in Japan (the ANSWER cohort). We assessed the drug retention rates of b/targeted synthetic DMARDs with different modes of action (tumour necrosis factor inhibitors (TNFis), immunoglobulins fused with cytotoxic T-lymphocyte antigen (CTLA-4-Ig), interleukin-6 receptor inhibitors (IL-6Ris), and JAKis) in patients with RA stratified by pre-treatment estimated glomerular filtration rate (eGFR) levels. The time to discontinuation of bDMARDs or JAKis was analysed using a multivariate Cox proportional hazards model This study included 3775 patients, who were classified into three groups (the normal group (eGFR ≥ 60 mL/min/1.73 m2): 2893 patients; CKDa group (eGFR 45-60 mL/min/1.73 m2): 551; and CKDb group (eGFR < 45 mL/min/1.73 m2): 331). In the CKDb group, the 12-month drug retention rate due to adverse events (AE) was the lowest in patients treated with JAKi (TNFi: 93.1%; IL-6Ri: 94.1%; CTLA-4-Ig: 92.3%; JAKi: 75.1%). In the normal and CKDa groups, drug retention rates due to AE were similar among patients treated with bDMARDs and JAKi. In contrast, drug retention rates due to inefficacy were similar between bDMARDs and JAKis in all groups. In the Cox-proportional model, in the CKDb group, TNFi, IL-6Ri, and CTLA-4-Ig showed lower incidence of drug discontinuation due to AE than JAKis (TNFi: hazard ratio = 0.23 (95% confidence interval 0.09-0.61), IL-6Ri: 0.34 (0.14-0.81), CTLA-4-Ig: 0.36 (0.15-0.89)). JAKis showed the lowest drug retention due to AE in patients with moderate-to-severe and severe renal impairment (eGFR < 45 mL/min/1.73 m2). Physicians should pay more attention to renal function when using JAKis than when using bDMARDs.


Subject(s)
Antirheumatic Agents , Arthritis, Rheumatoid , Janus Kinase Inhibitors , Humans , Arthritis, Rheumatoid/drug therapy , Female , Male , Middle Aged , Janus Kinase Inhibitors/therapeutic use , Janus Kinase Inhibitors/adverse effects , Aged , Antirheumatic Agents/therapeutic use , Antirheumatic Agents/adverse effects , Japan , Glomerular Filtration Rate , Renal Insufficiency/chemically induced , Adult , Cohort Studies , Biological Products/therapeutic use , Biological Products/adverse effects
3.
Mod Rheumatol ; 34(3): 523-529, 2024 Mar 28.
Article in English | MEDLINE | ID: mdl-37300805

ABSTRACT

OBJECTIVES: Decreased sialylation of IgG-Fc glycans has been reported in autoimmune diseases, but its role in systemic lupus erythematosus (SLE) is not fully understood. In this study, we examined the pathogenicity of IgG desialylation and its association with Th17 in SLE using an animal model. METHODS: B6SKG mice, which develop lupus-like systemic autoimmunity due to the ZAP70 mutation, were used to investigate the pathogenicity of IgG desialylation. The proportion of sialylated IgG was compared between B6SKG and wild-type mice with or without ß-glucan treatment-induced Th17 expansion. Anti-interleukin (IL)-23 and anti-IL-17 antibodies were used to examine the role of Th17 cells in IgG glycosylation. Activation-induced cytidine deaminase-specific St6gal1 conditionally knockout (cKO) mice were generated to examine the direct effect of IgG desialylation. RESULTS: The proportions of sialylated IgG were similar between B6SKG and wild-type mice in the steady state. However, IgG desialylation was observed after ß-glucan-induced Th17 expansion, and nephropathy also worsened in B6SKG mice. Anti-IL-23/17 treatment suppressed IgG desialylation and nephropathy. Glomerular atrophy was observed in the cKO mice, suggesting that IgG desialylation is directly involved in disease exacerbation. CONCLUSIONS: IgG desialylation contributes to the progression of nephropathy, which is ameliorated by blocking IL-17A or IL-23 in an SLE mouse model.


Subject(s)
Lupus Erythematosus, Systemic , beta-Glucans , Mice , Animals , Th17 Cells , Virulence , Lupus Erythematosus, Systemic/genetics , Disease Models, Animal , Immunoglobulin G
4.
Rheumatology (Oxford) ; 63(2): 349-357, 2024 Feb 01.
Article in English | MEDLINE | ID: mdl-37354495

ABSTRACT

OBJECTIVES: Anaemia, a common comorbidity of RA, is related to high disease activity and poor prognosis. It is unknown which biologic/targeted synthetic (b/ts)-DMARDs are optimal for patients with anaemia and RA in regulating anaemia and controlling disease activity. METHODS: We investigated the change in haemoglobin (Hb) levels, drug retention rates and disease activities after the administration of b/ts-DMARDs with different modes of action [TNF inhibitors (TNFis), immunoglobulin fused with cytotoxic T-lymphocyte antigen (CTLA-4-Ig), IL-6 receptor inhibitors (IL-6Ris) and Janus kinase inhibitors (JAKis)] in patients with RA stratified by baseline Hb levels using the multicentre observational registry for patients with RA in Japan (ANSWER cohort). RESULTS: A total of 2093 patients with RA were classified into three groups based on tertiles of the baseline Hb levels (Hblow, anaemic; Hbint, intermediate; Hbhigh, non-anaemic). IL-6Ri increased Hb levels in all groups (the mean change at 12 months in Hblow was +1.5 g/dl, Hbint +0.7 g/dl and Hbhigh +0.1 g/dl). JAKis increased the Hb level in patients with anaemia and RA and retained or decreased the Hb level in non-anaemic patients (the mean change at 12 months in Hblow was +0.6 g/dl, Hbint 0 g/dl and Hbhigh -0.3 g/dl). In patients with anaemia and RA, overall adjusted 3-year drug retention rates were higher in JAKi followed by IL-6Ri, CTLA4-Ig and TNFi (78.6%, 67.9%, 61.8% and 50.8%, respectively). Change of disease activity at 12 months was not different among different b/ts-DMARDs treatments. CONCLUSION: IL-6Ri and JAKi can effectively treat patients with anaemia and RA in a real-world setting.


Subject(s)
Anemia , Antirheumatic Agents , Arthritis, Rheumatoid , Janus Kinase Inhibitors , Humans , Janus Kinase Inhibitors/therapeutic use , Interleukin-6 Inhibitors , Cohort Studies , Anemia/drug therapy , Anemia/etiology , Arthritis, Rheumatoid/complications , Arthritis, Rheumatoid/drug therapy , Antirheumatic Agents/therapeutic use
5.
Sci Rep ; 13(1): 10150, 2023 06 22.
Article in English | MEDLINE | ID: mdl-37349495

ABSTRACT

Advanced systemic sclerosis-associated interstitial lung disease (SSc-ILD) can be treated with lung transplantation. There is limited data on lung transplantation outcomes in patients with SSc-ILD, in non-Western populations.We assessed survival data of patients with SSc-ILD, on the lung transplant (LT) waiting list, and evaluated post-transplant outcomes in patients from an Asian LT center. In this single-center retrospective study, 29 patients with SSc-ILD, registered for deceased LT at Kyoto University Hospital, between 2010 and 2022, were identified. We investigated post-transplant outcomes in recipients who underwent LT for SSc-ILD, between February 2002 and April 2022. Ten patients received deceased-donor LT (34%), two received living-donor LT (7%), seven died waiting for LT (24%), and ten survived on the waiting list (34%). Median duration from registration to deceased-donor LT was 28.9 months and that from registration to living-donor LT or death was 6.5 months. Analysis of 15 recipients showed improved forced vital capacity with a median of 55.1% at baseline, 65.8% at 6 months, and 80.3% at 12 months post-transplant. The 5-year survival rate for post-transplant patients with SSc-ILD was 86.2%. The higher post-transplant survival rate at our institute than previously reported suggests that lung transplantation is acceptable in Asian patients with SSc-ILD.


Subject(s)
Lung Diseases, Interstitial , Lung Transplantation , Scleroderma, Systemic , Humans , Retrospective Studies , Lung Diseases, Interstitial/surgery , Lung Diseases, Interstitial/complications , Waiting Lists , Scleroderma, Systemic/complications , Scleroderma, Systemic/surgery , Lung , Prognosis , Lung Transplantation/adverse effects
6.
Mod Rheumatol ; 33(5): 936-943, 2023 Aug 25.
Article in English | MEDLINE | ID: mdl-36190743

ABSTRACT

OBJECTIVES: Pulmonary nontuberculous mycobacterial disease (pNTM) is a common pulmonary complication of rheumatoid arthritis (RA), but their association has rarely been researched. We aimed to reveal the clinical characteristics of RA with pNTM. METHODS: Among all the RA patients who visited Tenri hospital from April 2017 to March 2018, we enrolled those fulfilling the 2007 ATS/IDSA diagnostic criteria of pNTM, and sex- and age- matched control group at a ratio of 1:5. Demographic characteristics were compared between the two groups. RESULTS: Among 865 RA patients, 35 (4.0%) patients were complicated with pNTM. RA patients with pNTM had significantly lower BMI and higher rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) positivity. Bronchiectasis was the most frequent lesion, followed by clusters of small nodules, patchy consolidation and cavity. Multivariable logistic regression analysis revealed bronchiectasis as a strong independent associated factor of pNTM. Treatment for pNTM was needed in 14 of the 35 (40%) RA patients with pNTM and sputum negative conversion was accomplished in 11 of the 14 cases (78.6%). CONCLUSIONS: RA patients with lower BMI, RF/ACPA positivity, and bronchiectasis were associated with pNTM. Treatment for pNTM may attain sputum negative conversion and radiological improvement in patients with RA.


Subject(s)
Arthritis, Rheumatoid , Bronchiectasis , Mycobacterium Infections, Nontuberculous , Humans , Mycobacterium Infections, Nontuberculous/complications , Mycobacterium Infections, Nontuberculous/diagnosis , Cross-Sectional Studies , Nontuberculous Mycobacteria , Arthritis, Rheumatoid/complications , Arthritis, Rheumatoid/diagnostic imaging , Rheumatoid Factor , Bronchiectasis/complications , Bronchiectasis/diagnostic imaging
7.
Mod Rheumatol Case Rep ; 6(2): 270-272, 2022 06 24.
Article in English | MEDLINE | ID: mdl-35388431

ABSTRACT

Intestinal amoebiasis is caused by Entamoeba histolytica (E. histolytica) and is characterised by cecal lesions, multiple lesions, aphthae, and multiple exudative erosions. Intestinal Behçet's disease (BD) is a chronic inflammatory disorder that is characterised by multiple ulcers. Although the aetiologies of these two bowel diseases are unrelated, they are difficult to distinguish because they present similarly with inflammation and ulcers, especially if evidence of specific pathogens is not detected. Herein, we report a case of intestinal amoebiasis in a patient with BD. The patient underwent colonoscopy four times before intestinal amoebiasis was diagnosed. As intestinal BD was initially suspected, she received high-dose glucocorticoid therapy, which exacerbated her condition. Following exacerbation, she underwent colonoscopy, and E. histolytica was revealed. Deliberate care should be taken to distinguish between intestinal amoebiasis and intestinal BD, as the appropriate treatments for these diseases are entirely different.


Subject(s)
Behcet Syndrome , Dysentery, Amebic , Intestinal Diseases , Behcet Syndrome/complications , Behcet Syndrome/diagnosis , Colonoscopy/adverse effects , Dysentery, Amebic/complications , Dysentery, Amebic/diagnosis , Female , Humans , Intestinal Diseases/etiology , Ulcer
8.
Rheumatol Int ; 42(7): 1227-1234, 2022 07.
Article in English | MEDLINE | ID: mdl-35266034

ABSTRACT

Rheumatoid factor (RF) binds to the fragment crystallizable (Fc) portion of immunoglobulin. It could bind to the Fc portion of anti-TNF inhibitors (TNFi) and attenuate the clinical efficacy. We tried to determine whether the therapeutic efficacy of TNFi with Fc might be lower than that of TNFi without Fc in rheumatoid arthritis (RA) patients with high titres of RF. The Kansai Consortium for Well-being of Rheumatic Disease Patients (ANSWER) cohort is an observational multi-center registry of patients with RA in the Kansai district of Japan. RA patients treated with TNFi were included and divided into two groups based on the structural characteristics between TNFi with Fc (infliximab, adalimumab, golimumab, and etanercept) and TNFi without Fc (certolizumab pegol). Patients were classified into 4 groups according to RF titre quartiles. The sequential disease activity score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR) was compared by Mann-Whitney U test between TNFi with and without Fc in each RF titre group. Multiple linear regression analysis was used to analyze the effect of TNFi without Fc for the change of DAS28-ESR adjusted after potential confounders. A total of 705 RA patients were classified into four groups (RF1; RF 0-15.0 IU/mL, RF2; 15.0-55.0, RF3; 55.0-166, RF4; 166-7555). In RF4, RA patients treated with TNFi without Fc had a significantly lower DAS28-ESR than those treated with TNFi with Fc [3.2 (2.3-4.2) vs. 2.7 (2.0-3.0)] after 12 months. This effect of TNFi without Fc for the change of DAS28-ESR after 12 months treatment retained in multivariate analysis in RF4. TNFi without Fc may be more efficacious than TNFi with Fc in RA patients with high RF titres.


Subject(s)
Antirheumatic Agents , Arthritis, Rheumatoid , Adalimumab/therapeutic use , Antirheumatic Agents/therapeutic use , Arthritis, Rheumatoid/diagnosis , Arthritis, Rheumatoid/drug therapy , Cohort Studies , Etanercept/therapeutic use , Humans , Infliximab/therapeutic use , Rheumatoid Factor , Tumor Necrosis Factor Inhibitors , Tumor Necrosis Factor-alpha
10.
Mod Rheumatol Case Rep ; 4(1): 16-20, 2020 01.
Article in English | MEDLINE | ID: mdl-33086965

ABSTRACT

An 18-year-old female was diagnosed with subclinical Cushing's syndrome (CS) due to a left adrenal adenoma. When she was 20 years old, she developed lupus nephritis. She was treated with high-dose prednisolone (PSL) and soon developed the symptoms of CS. When she was 25 years old, we evaluated her serum glucocorticoid level while she continued to take oral PSL. The result suggested her CS was affected by both the oral PSL and the endogenous cortisol secreted by the adrenocortical adenoma, which was therefore resected. Seven months after the operation, the patient's body weight was decreasing, and her SLE remained in clinical remission. CS complicated by SLE is rare, and the decision to surgically remove an adrenal tumor in such a case is even more rare.


Subject(s)
Cushing Syndrome/complications , Lupus Erythematosus, Systemic/complications , Lupus Erythematosus, Systemic/diagnosis , Adolescent , Adrenocortical Adenoma/diagnosis , Adrenocortical Adenoma/etiology , Adrenocortical Adenoma/surgery , Clinical Decision-Making , Cushing Syndrome/diagnosis , Disease Management , Female , Glucocorticoids/blood , Humans , Lupus Nephritis/diagnosis , Lupus Nephritis/drug therapy , Lupus Nephritis/etiology , Prednisolone/administration & dosage , Treatment Outcome
11.
JAMA Neurol ; 77(7): 872-877, 2020 07 01.
Article in English | MEDLINE | ID: mdl-32310254

ABSTRACT

Importance: Reports on dermatomyositis (DM) sine dermatitis (DMSD) are scarce, and the concept of the disease has not been widely accepted. Objective: To confirm the existence of DMSD, determine its prevalence, and characterize its serologic features. Design, Setting, and Participants: This is a cohort study that reviewed clinical information, laboratory data, and muscle pathology slides from January 2009 to August 2019. We further assessed the follow-up data of 14 patients with DMSD. The median (interquartile range) follow-up period was 34 (16-64) months. Muscle biopsy samples, along with clinical information and laboratory data, were sent to a referral center for muscle diseases in Japan for diagnosis. Of patients whose myopathologic diagnosis was made at the National Center of Neurology and Psychiatry between January 2009 and August 2019, 199 patients were eligible for inclusion. These patients underwent full investigation for DM-specific autoantibodies (against transcriptional intermediary factor γ, Mi-2, melanoma differentiation-associated gene 5, nuclear matrix protein 2 [NXP-2], and small ubiquitin-like modifier activating enzyme ); however, 17 patients were excluded because their muscle fibers did not express myxovirus resistance protein A, a sensitive and specific marker of DM muscle pathology. Main Outcomes and Measures: Diagnosis of DMSD was based on the absence of a skin rash at the time of muscle biopsy. Results: Of the 182 patients, 93 were women (51%) and 46 were children (25%) (<18 years). Fourteen patients (8%) had DMSD and none were clinically diagnosed with DM. Among the 14 patients with DMSD, 12 (86%) were positive for anti-NXP-2 autoantibodies, while the remaining 2 were positive for anti-transcriptional intermediary factor γ and anti-Mi-2 autoantibodies, respectively. Only 28% of patients (47 of 168) with a skin rash were positive for anti-NXP-2 autoantibodies, indicating a significant association between anti-NXP-2 autoantibodies and DMSD (86% [12 of 14] vs 28% [47 of 168]; P < .001). This association was also supported by multivariable models adjusted for disease duration (odds ratio, 126.47; 95% CI, 11.42-1400.64; P < .001). Conclusions and Relevance: Dermatomyositis sine dermatitis does exist and accounts for 8% of patients with DM confirmed with muscle biopsy. Dermatomyositis sine dermatitis is significantly associated with anti-NXP-2 autoantibodies, which contrasts with anti-MDA5 DM, which is typically clinically amyopathic in presentation. It is essential to distinguish DMSD from other types of myositis because DM-specific therapies that are currently under development, including Janus kinase inhibitors, may be effective for DMSD.


Subject(s)
Autoantibodies/immunology , Autoimmune Diseases/immunology , DNA-Binding Proteins/immunology , Dermatomyositis/immunology , Transcription Factors/immunology , Adolescent , Adult , Aged , Autoantigens/immunology , Autoimmune Diseases/pathology , Child , Cohort Studies , Dermatitis , Dermatomyositis/pathology , Female , Humans , Male , Middle Aged , Young Adult
14.
Acta Neurochir (Wien) ; 159(1): 15-18, 2017 01.
Article in English | MEDLINE | ID: mdl-27812816

ABSTRACT

Cerebral amyloid angiopathy (CAA), a cause of recurrent and multiple lobar hemorrhages, characteristically occurs in persons aged ≥55 years. We report a case of a 32-year-old male who had recurrent hemorrhage in the left multiple lobes, with a history of traumatic brain injury and hematoma evacuation at the age of 1 year. He underwent surgical treatment and was histopathologically diagnosed as having CAA. The literature review yielded six CAA cases, including ours, aged less than 55 years. All were male and four had histories of severe TBI, suggesting that male sex and TBI may be associated with CAA in young persons.


Subject(s)
Brain Injuries, Traumatic/complications , Cerebral Amyloid Angiopathy/etiology , Cerebral Hemorrhage/etiology , Adult , Cerebral Amyloid Angiopathy/complications , Humans , Male
16.
Artif Life ; 14(1): 29-48, 2008.
Article in English | MEDLINE | ID: mdl-18171129

ABSTRACT

The circadian clock of Drosophila is a model pathway for research in biological clock mechanisms, both with traditional experimental approaches and with emerging systems biology approaches utilizing mathematical modeling and in silico computer simulation. Dynamic diurnal oscillations are achieved by the complex interaction of components as a system, and mathematical reconstruction has proven to be an invaluable means of understanding such systematic behavior. In this study, we implemented eight published models of the Drosophila circadian clock in Systems Biology Markup Language (SBML) for comparative systems biology studies using E-Cell Simulation Environment version 3, to examine the system-level requirements for the clock mechanism to be robust, by calculating the period and amplitude sensitivity coefficients with simulation experiments. While all models were generally robust as determined by the network topology of the oscillatory feedback loop structure, existing models place relatively strong emphasis on transcription regulation, although this is a limitation on robustness. We suggest that more comprehensive modeling including protein phosphorylation, polymerization, and nuclear transport with regard to amplitude sensitivity will be necessary for understanding the light entrainment and temperature compensation of circadian clocks.


Subject(s)
Biological Clocks/physiology , Circadian Rhythm/physiology , Computer Simulation , Drosophila/physiology , Models, Biological , Animals , Drosophila Proteins/genetics , Drosophila Proteins/metabolism , Gene Expression Regulation , Reproducibility of Results , Sensitivity and Specificity , Software
17.
Chirality ; 20(3-4): 282-7, 2008 Mar.
Article in English | MEDLINE | ID: mdl-17597116

ABSTRACT

The partial resolution is described of a series of racemic trans-4-[5-(4-alkoxyphenyl)-2,5-dimethylpyrrolidine-1-oxyl-2-yl]benzoic acids (1), which are the key intermediates for the synthesis of chiral organic radical liquid crystalline compounds and are crystallized to give racemic compounds. Racemic acid 1 [(+/-)-1] with a long alkyl chain (C7 to C13) could be resolved by the conventional diastereomeric salt formation using (R)- or (S)-1-phenylethylamine (2) as the resolving agent, whereas resolution of (+/-)-1 with a short alkyl chain (C4 to C6) was unsuccessful. Use of six equiv of (R)- or (S)-2 for the initial diastereomeric salt formation of (+/-)-1 with a C7-C13 alkyl chain, followed by recrystallization of the resulting salts once or twice, gave 2S,5S- or 2R,5R-enriched 1, respectively, in an ee range of 75-92% and with an overall recovery of 11-27%, based on the original quantity of (+/-)-1.

18.
Theor Biol Med Model ; 4: 19, 2007 May 20.
Article in English | MEDLINE | ID: mdl-17511884

ABSTRACT

BACKGROUND: In the process of constructing a dynamic model of a metabolic pathway, a large number of parameters such as kinetic constants and initial metabolite concentrations are required. However, in many cases, experimental determination of these parameters is time-consuming. Therefore, for large-scale modelling, it is essential to develop a method that requires few experimental parameters. The hybrid dynamic/static (HDS) method is a combination of the conventional kinetic representation and metabolic flux analysis (MFA). Since no kinetic information is required in the static module, which consists of MFA, the HDS method may dramatically reduce the number of required parameters. However, no adequate method for developing a hybrid model from experimental data has been proposed. RESULTS: In this study, we develop a method for constructing hybrid models based on metabolome data. The method discriminates enzymes into static modules and dynamic modules using metabolite concentration time series data. Enzyme reaction rate time series were estimated from the metabolite concentration time series data and used to distinguish enzymes optimally for the dynamic and static modules. The method was applied to build hybrid models of two microbial central-carbon metabolism systems using simulation results from their dynamic models. CONCLUSION: A protocol to build a hybrid model using metabolome data and a minimal number of kinetic parameters has been developed. The proposed method was successfully applied to the strictly regulated central-carbon metabolism system, demonstrating the practical use of the HDS method, which is designed for computer modelling of metabolic systems.


Subject(s)
Enzymes/metabolism , Escherichia coli/enzymology , Metabolism , Saccharomyces cerevisiae/enzymology , Escherichia coli Proteins/metabolism , Kinetics , Models, Biological , Reproducibility of Results , Saccharomyces cerevisiae Proteins/metabolism
19.
FEBS J ; 274(6): 1449-58, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17489100

ABSTRACT

Methemoglobin (metHb), an oxidized form of hemoglobin, is unable to bind and carry oxygen. Erythrocytes are continuously subjected to oxidative stress and nitrite exposure, which results in the spontaneous formation of metHb. To avoid the accumulation of metHb, reductive pathways mediated by cytochrome b5 or flavin, coupled with NADH-dependent or NADPH-dependent metHb reductases, respectively, keep the level of metHb in erythrocytes at less than 1% of the total hemoglobin under normal conditions. In this work, a mathematical model has been developed to quantitatively assess the relative contributions of the two major metHb-reducing pathways, taking into consideration the supply of NADH and NADPH from central energy metabolism. The results of the simulation experiments suggest that these pathways have different roles in the reduction of metHb; one has a high response rate to hemoglobin oxidation with a limited reducing flux, and the other has a low response rate with a high capacity flux. On the basis of the results of our model, under normal oxidative conditions, the NADPH-dependent system, the physiological role of which to date has been unclear, is predicted to be responsible for most of the reduction of metHb. In contrast, the cytochrome b5-NADH pathway becomes dominant under conditions of excess metHb accumulation, only after the capacity of the flavin-NADPH pathway has reached its limit. We discuss the potential implications of a system designed with two metHb-reducing pathways in human erythrocytes.


Subject(s)
Adaptation, Physiological , Erythrocytes/metabolism , Methemoglobin/metabolism , Oxidative Stress , Humans , Oxidation-Reduction
20.
Science ; 316(5824): 593-7, 2007 Apr 27.
Article in English | MEDLINE | ID: mdl-17379776

ABSTRACT

Analysis of cellular components at multiple levels of biological information can provide valuable functional insights. We performed multiple high-throughput measurements to study the response of Escherichia coli cells to genetic and environmental perturbations. Analysis of metabolic enzyme gene disruptants revealed unexpectedly small changes in messenger RNA and proteins for most disruptants. Overall, metabolite levels were also stable, reflecting the rerouting of fluxes in the metabolic network. In contrast, E. coli actively regulated enzyme levels to maintain a stable metabolic state in response to changes in growth rate. E. coli thus seems to use complementary strategies that result in a metabolic network robust against perturbations.


Subject(s)
Escherichia coli Proteins/metabolism , Escherichia coli/genetics , Escherichia coli/metabolism , Genes, Bacterial , Metabolic Networks and Pathways , Systems Biology/methods , Chromatography, Liquid , Computational Biology , Electrophoresis, Capillary , Electrophoresis, Gel, Two-Dimensional , Enzyme Induction , Enzyme Repression , Enzymes/genetics , Enzymes/metabolism , Escherichia coli/enzymology , Escherichia coli/growth & development , Escherichia coli Proteins/genetics , Gene Expression , Mass Spectrometry , Metabolic Networks and Pathways/genetics , Mutation , Oligonucleotide Array Sequence Analysis , Proteome , RNA, Messenger/genetics , RNA, Messenger/metabolism , Transcription, Genetic
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