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1.
Rev Med Liege ; 77(5-6): 289-294, 2022 May.
Artigo em Francês | MEDLINE | ID: mdl-35657185

RESUMO

Asthma is a chronic inflammatory disease of the airways. Classification of asthma in different phenotypes has therapeutic implications and may lead to personalized medicine. Induced sputum is the gold standard for asthma phenotyping but is complex, time-consuming and not widely available. The combination of different biomarkers such as exhaled nitric oxide, blood eosinophils and total serum IgE levels allows the prediction of inflammatory phenotype in 58% of asthmatic patients when sputum is not available. We recently demonstrated the interest of measuring volatile organic compounds in exhaled breath to phenotype asthma. These compounds could play an important role in the future to predict the response to expensive biologicals available in severe asthma to reduce exacerbations and the use of systemic corticosteroids.


: L'asthme est une pathologie inflammatoire chronique des voies respiratoires. Classer l'asthme en différents phénotypes inflammatoires a des implications thérapeutiques importantes et peut conduire à un traitement personnalisé. Le gold standard pour l'établissement du phénotype inflammatoire est l'analyse de l'expectoration induite qui est une technique complexe, difficilement accessible en routine. La combinaison de plusieurs biomarqueurs d'intérêt tels le monoxyde d'azote dans l'air exhalé, l'éosinophilie systémique et le taux d'IgE sérique permet de prédire correctement le phénotype inflammatoire dans 58% des cas. Récemment, nous avons également mis en évidence l'intérêt de la détection de molécules dans l'haleine. Ces composés organiques volatiles pourraient représenter des biomarqueurs futurs de la réponse au traitement, spécialement dans l'asthme sévère, pour lequel des traitements ciblés coûteux sont actuellement disponibles en vue de réduire les exacerbations et le recours aux corticostéroïdes oraux.


Assuntos
Asma , Medicina de Precisão , Asma/diagnóstico , Asma/tratamento farmacológico , Biomarcadores , Eosinófilos , Humanos , Fenótipo , Escarro
2.
Respir Res ; 22(1): 15, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33441106

RESUMO

BACKGROUND: Elderly asthmatics represent an important group that is often excluded from clinical studies. In this study we wanted to present characteristics of asthmatics older than 70 years old as compared to younger patients. METHODS: We conducted a retrospective analysis on a series of 758 asthmatics subdivided in three groups: lower than 40, between 40 and 70 and older than 70. All the patients who had a successful sputum induction were included in the study. RESULTS: Older patients had a higher Body Mass Index, had less active smokers and were more often treated with Long Acting anti-Muscarinic Agents. We found a significant increase in sputum neutrophil counts with ageing. There was no significant difference in blood inflammatory cell counts whatever the age group. Forced expiratory volume in one second (FEV1) and FEV1/FVC values were significantly lower in elderly who had lower bronchial hyperresponsiveness and signs of air trapping. We found a lower occurrence of the allergic component in advanced ages. Asthmatics older than 70 years old had later onset of the disease and a significant longer disease duration. CONCLUSION: Our study highlights that asthmatics older than 70 years old have higher bronchial neutrophilic inflammation, a poorer lung function, signs of air trapping and lower airway variability. The role of immunosenescence inducing chronic low-grade inflammation in this asthma subtype remains to be elucidated.


Assuntos
Asma/metabolismo , Volume Expiratório Forçado/fisiologia , Mediadores da Inflamação/metabolismo , Neutrófilos/metabolismo , Testes de Função Respiratória/métodos , Escarro/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Asma/diagnóstico , Asma/imunologia , Feminino , Humanos , Mediadores da Inflamação/imunologia , Masculino , Pessoa de Meia-Idade , Neutrófilos/imunologia , Estudos Retrospectivos , Escarro/imunologia
3.
Respir Med Res ; 79: 100797, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33383519

RESUMO

BACKGROUND: Eosinophilic inflammation has long been associated with asthma. Looking at systemic and airway eosinophilia, we have recently identified a group of patients exhibiting diffuse eosinophilic inflammation. Among the mechanisms governing eosinophilic inflammation, IgE-mediated mast cell activation is a key event leading to eosinophilia in atopic asthmatics. METHODS: We conducted a retrospective study on our asthma clinic database containing more than 1500 patients and identified 205 asthmatics with successful sputum induction and concordant eosinophilic phenotype. This phenotype was defined as a sputum eosinophil count≥3% and a blood eosinophils concentration≥400cells/mm3. IgE-high atopic phenotype was characterized by the presence of at least one positive specific IgE (>0.35kU/L) to common aeroallergens and a raised total serum IgE (≥113kU/L). RESULTS: The largest group of asthmatics displaying concordant eosinophilic phenotype had a raised total serum IgE and atopy (45%). IgE-low non-atopic concordant eosinophilic asthma was a predominantly late onset disease, exhibited a more intense airway eosinophilic inflammation (P<0.05), required more often maintenance treatment with oral corticosteroids (P<0.05) but, surprisingly, had a reduced level of bronchial hyperresponsiveness to methacholine (P<0.05) despite similar baseline airway calibre impairment. CONCLUSION: The more severe airway eosinophilic inflammation in IgE-low non-atopic asthmatics despite similar treatment with ICS and a higher burden of OCS points to a certain corticosteroid resistance in this asthma phenotype.


Assuntos
Asma , Eosinofilia Pulmonar , Eosinófilos , Humanos , Imunoglobulina E , Estudos Retrospectivos
4.
Rev Med Liege ; 75(5-6): 350-355, 2020 May.
Artigo em Francês | MEDLINE | ID: mdl-32496678

RESUMO

Asthma is a chronic heterogeneous airway disease. There are different asthma inflammatory phenotypes with various responses to treatment and different disease severities. When asthma requires chronic systemic corticosteroids or hospitalizations despite maximal inhaled therapies in asthmatic patients in whom comorbidities have been managed and who are considered as compliant, the pulmonologist may propose biological treatment to reduce exacerbations and the dose of systemic corticosteroids. During the last ten years, the number of biologics for the management of type-2 severe asthma has increased. Anti-IgE monoclonal antibodies (omalizumab) are available for more than ten years and recommended in severe allergic asthma. New biologics are now available to block IL-5 (mepolizumab, reslizumab) or its receptor (benralizumab). These treatments allow a reduction of exacerbations and of the dose of systemic corticosteroids, an improvement in asthma control, in asthma quality of life and for some of them, an increase in lung function. New biologics will soon be available in Belgium for the management of severe asthma. In addition to the improvement of asthma control in severe asthma, biological treatments have improved the understanding of the mechanisms leading to severe asthma.


L'asthme est une maladie hétérogène chronique des voies aériennes. Il existe, en effet, différents phénotypes inflammatoires d'asthme induisant une réponse variable aux traitements et différents degrés de sévérité. Lorsque l'asthme est sévère et requiert le recours aux corticostéroïdes systémiques ou à des hospitalisations malgré un traitement de fond maximal chez un patient asthmatique bon observant dont les comorbidités ont été prises en charge, le pneumologue peut proposer un traitement biologique en vue de réduire les exacerbations et la dose de corticostéroïdes systémiques. Au cours des dix dernières années, les traitements biologiques dans la prise en charge de l'asthme sévère de type 2 se sont étoffés. A côté du traitement par anti-IgE (omalizumab), disponible depuis plus de 10 ans et recommandé dans l'asthme sévère extrinsèque, d'autres traitements bloquant l'IL-5 (mépolizumab, reslizumab) ou son récepteur (benralizumab) ont vu le jour. Ces traitements permettent une réduction des exacerbations et de la dose de corticostéroïdes systémiques, une amélioration du contrôle, des paramètres de qualité de vie et, pour certains d'entre eux, de la fonction respiratoire. D'autres traitements ciblés prometteurs seront bientôt disponibles en Belgique. En plus d'améliorer le contrôle symptomatique des patients asthmatiques sévères, les traitements biologiques ont permis de mieux comprendre les mécanismes conduisant au développement d'un asthme sévère.


Assuntos
Antiasmáticos , Asma , Terapia Biológica , Asma/terapia , Bélgica , Humanos , Qualidade de Vida
5.
Biochem Pharmacol ; 179: 113994, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32335139

RESUMO

INTRODUCTION: Asthma in obese subjects is poorly understood. According to GINA guidelines, pulmonologists increase ICS in case of poor asthma control but lung volume restriction may also worsen respiratory symptoms in obese asthmatics leading to overtreatment in this subpopulation. METHODS: We conducted a retrospective study on 1217 asthmatics recruited from University Hospital of Liege. 92 patients with a BMI ≥30 came at least two times at the asthma clinic (mean interval: 335 days). In this obese population, we identified predictors of good (decrease in ACQ ≥0.5) versus poor response (rise in ACQ ≥0.5) to ICS step-up therapy. RESULTS: Obese asthmatics had a poorer asthma control and quality of life as compared to non-obese and exhibited reduced FVC, higher levels of blood leucocytes and markers of systemic inflammation. The proportion of asthma inflammatory phenotypes was similar to that observed in a general population of asthmatics. Among uncontrolled obese asthmatics receiving ICS step-up therapy, 53% improved their asthma control while 31% had a worsening of their asthma. Uncontrolled obese asthmatics showing a good response to increase in ICS had higher ACQ, lower CRP levels, higher sputum eosinophil counts and higher FeNO levels at visit 1. Uncontrolled obese asthmatics that worsened after increasing the dose of ICS had lower FVC, lower sputum eosinophil counts and higher sputum neutrophil counts. CONCLUSION: We observed poorer asthma control in obese asthmatics despite similar bronchial inflammation. Managing obese asthmatics according to ACQ alone seems to underestimate asthma control and the contribution of restriction to dyspnea. Increasing the dose of ICS in the absence of sputum eosinophilic inflammation or in the presence of restriction or bronchial neutrophilia led to poorer asthma control. In those patients, management of obesity should be the first choice.


Assuntos
Corticosteroides/uso terapêutico , Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Obesidade/complicações , Administração por Inalação , Corticosteroides/administração & dosagem , Adulto , Antiasmáticos/administração & dosagem , Asma/etiologia , Eosinófilos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Óxido Nítrico/análise , Obesidade/fisiopatologia , Qualidade de Vida , Estudos Retrospectivos , Escarro/citologia , Resultado do Tratamento
6.
Biochem Pharmacol ; 179: 113981, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32305435

RESUMO

Demonstration of bronchial hyperresponsiveness is a key feature in asthma diagnosis. Methacholine challenge has proved to be a highly sensitive test to diagnose asthma in patients with chronic respiratory symptoms and preserved baseline lung function (FEV1 > 70% pred.) but is time consuming and may sometimes reveal unpleasant to the patient. We conducted a retrospective study on 270 patients recruited from the University Asthma Clinic of Liege. We have compared the values of several lung function indices and fractional exhaled nitric oxide (FeNO) in predicting a provocative methacholine concentration ≤16 mg/ml on a discovery cohort of 129 patients (57 already on ICS) and on a validation cohort of 141 patients (66 already on ICS). In the discovery study (n = 129), 85 patients (66%) had a positive methacholine challenge with PC20M ≤ 16 mg/ml. Those patients had lower baseline % predicted FEV1 (92% vs. 100%; p < 0.01), lower FEV1/FVC ratio (79% vs. 82%; p < 0.05), higher RV/TLC ratio (114% vs. 100%; p < 0,0001), lower SGaw (specific conductance) (0.76 vs. 0.95; p < 0,001) and higher FeNO (29 ppb vs. 19 ppb; p < 0,01). When performing ROC curve the RV/TLC ratio provided the greatest AUC (0.74, p < 0.001), sGAW had intermediate AUC of 0.69 (p < 0.001) while FeNO, FEV1 and FEV1/FVC ratio were modestly predictive (AUC of 0.65 (p < 0.05), 0,67 (p < 0.001) and 0,63 (p < 0.001). These results were confirmed in the validation study (n = 141). Based on a logistic regression analysis, significant variables associated with positive methacholine challenge were FeNO and RV/TLC (% Pred). A combined application of FeNO and RV/TLC (% Pred) for predicting the PC20M had a specificity of 85%, a sensitivity of 59% and an AUC of 0.79. In the validation study, three variables (RV/TLC, FeNO and FEV1) were independently associated with positive methacholine challenge and the combination of these three variables yielded a specificity of 77%, a sensitivity of 39% and an AUC of 0.77. The RV/TLC ratio combined to FeNO may be of interest to predict significant methacholine bronchial hyperresponsiveness.


Assuntos
Asma/fisiopatologia , Cloreto de Metacolina/farmacologia , Óxido Nítrico/análise , Testes de Função Respiratória/métodos , Corticosteroides/administração & dosagem , Corticosteroides/uso terapêutico , Adulto , Idoso , Antiasmáticos/administração & dosagem , Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Testes Respiratórios/métodos , Brônquios/efeitos dos fármacos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pletismografia Total , Reprodutibilidade dos Testes
7.
Biochem Pharmacol ; 179: 113944, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32240649

RESUMO

BACKGROUND: Omalizumab arose as a therapeutic option in patients suffering from moderate to severe refractory allergic asthma. It acts as a humanized monoclonal antibody neutralizing circulating IgE antibodies. Randomized clinical trials and real life clinical studies have already confirmed benefits, cost-effectiveness and applicability of the medication. METHOD: Our study retrospectively reports on the clinical outcomes and airway inflammation in 157 severe allergic asthmatics who were initiated with omalizumab between 2007 and 2019. RESULTS: After 4 months of therapy, 76% of the patients were judged to have benefited from omalizumab and were admitted to prolonged treatment. During follow-up, we observed an improvement in asthma control, quality of life and spirometric performance. There was also a sustained reduction in exacerbation rate over the years. As for T2 biomarkers, FeNO significantly decreased and, in a subgroup of patients who had repeated sputum inductions, there was also significant reduction in sputum eosinophils but no change in blood eosinophil count. Lastly, we found a correlation between high FeNO levels at baseline and reduction in ACQ scores at 1 year. CONCLUSION: We conclude that omalizumab shows effectiveness in severe allergic asthma in a real life setting, by reducing exacerbation rate, improving patient perspective outcomes and airway calibre, together with reducing type-2 airway inflammation.


Assuntos
Antialérgicos/uso terapêutico , Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Pulmão/efeitos dos fármacos , Omalizumab/uso terapêutico , Adulto , Asma/etiologia , Feminino , Humanos , Pulmão/fisiologia , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Estudos Retrospectivos , Resultado do Tratamento
8.
Rev Med Liege ; 74(2): 74-81, 2019 Feb.
Artigo em Francês | MEDLINE | ID: mdl-30793559

RESUMO

As treating severe forms of asthma represents a medical and economical challenge, research for new therapies in this area is extensive and expansive. Recently, bronchial thermoplasty (BT) - ie. bronchoscopic procedure delivering a thermic form of energy through radiofrequency to the bronchi, in order to interfere with the components of the smooth muscle layer - arose as a promising technique. Our study followed the path of 10 patients from CHU Liège (University Hospital), who underwent this procedure in a context of severe asthma. We compared clinical and spirometric and treatment data in patients at 0 - 6 and 12 months post-procedural intervals, in order to determine whether thermoplasty had been improving asthma. Overall, we observed a stabilization and possibly a clinical improvement while reducing the total amount of exacerbation rate, and the burden of maintenance oral corticoids.


En raison du défi médico-économique que représente le traitement des formes sévères d'asthme, les recherches concernant de nouvelles thérapies dans ce domaine sont multiples et variées. Récemment, la thermoplastie bronchique - correspondant à un acte bronchoscopique permettant de délivrer une énergie par radiofréquence au niveau des bronches, afin d'interférer avec les composants de la couche musculaire lisse - s'annonçait comme une procédure prometteuse. Nous avons étudié 10 patients, suivis au CHU de Liège dans un contexte d'asthme sévère, et ayant bénéficié de cette technique. Nous avons comparé des données cliniques, spirométriques et thérapeutiques aux intervalles de 6 et 12 mois après procédure, afin de de déterminer si celle-ci avait été bénéfique sur leur pathologie asthmatique. Globalement, nous observons une stabilisation, voire une amélioration clinique, avec, notamment, une diminution des exacerbations, tout en réduisant la charge en corticoïdes systémiques.


Assuntos
Asma , Termoplastia Brônquica , Asma/terapia , Brônquios , Broncoscopia , Humanos , Estudos Retrospectivos
9.
Clin Exp Allergy ; 48(5): 525-535, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29383782

RESUMO

BACKGROUND: While non-eosinophilic asthmatics are usually considered poorly responsive to inhaled corticosteroids (ICSs), studies assessing a step-down of ICS in this specific population are currently lacking. OBJECTIVES: To assess the proportion of non-eosinophilic asthmatics in whom ICS may be withdrawn without any clinical degradation and to determine the predictive markers of a failure to stop treatment with ICS. METHODS: This prospective study was completed by 36 non-eosinophilic asthmatics, defined by sputum eosinophils <3% and blood eosinophils <400/µL. In these patients, whichever the baseline asthma control level, the dose of ICS was gradually reduced every 3 months until they met the failure criteria or successfully discontinued ICS for 6 months. The failure criteria were an ACQ score ≥1.5 with an increase from baseline >0.5 or a number of severe exacerbations during the study which was greater than the number during the year prior to the baseline visit. Receiver-operating characteristic (ROC) curves were constructed to assess predictors of a failure to stop ICS. This study is registered with ClinicalTrials.gov, number NCT02169323. RESULTS: In 14 patients (39%), ICSs were completely withdrawn, and in 10 further patients (28%), ICS were stepped-down to a reduced ICS dose without any deterioration of asthma control and exacerbation rate. Baseline predictors of a failure to stop ICS were a greater age (area under ROC curve [ROC AUC] and [95% CI]: 0.77 [0.62-0.93]) and elevated blood eosinophils (ROC AUC [95% CI]: 0.77 [0.61-0.93]). After the first step-down of ICS, the best predictor was an elevated blood eosinophil count (ROC AUC [95% CI]: 0.85 [0.72-0.99]). CONCLUSIONS & CLINICAL RELEVANCE: Withdrawing or reducing the dose of ICS is feasible in two-thirds of non-eosinophilic asthmatics irrespective of baseline asthma control. An elevated blood eosinophil count may predict the failure to stop ICS.


Assuntos
Corticosteroides/administração & dosagem , Antiasmáticos/administração & dosagem , Asma/tratamento farmacológico , Administração por Inalação , Idoso , Asma/imunologia , Eosinófilos/imunologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
10.
Breast Cancer Res Treat ; 165(2): 321-327, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28608029

RESUMO

INTRODUCTION: Lymphedema can be a debilitating condition, causing a great decrease in a person's quality of life (QoL). Treatment with lymphaticovenular anastomosis (LVA), in which an anastomosis is created between the lymphatic and venous system, may attenuate lymphedema symptoms and reduce swelling. In this study, we share the results using LVA to treat breast cancer-related lymphedema (BCRL) at our institution. MATERIALS AND METHODS: Patients were eligible for inclusion if they suffered from unilateral BCRL, if functional lymphatics were available, if compression therapy was used for at least 6 months, and if the follow-up was 12 months at minimum. Lymph vessel functionality was assessed preoperatively using indocyanine green (ICG). During surgery, 1-3 anastomoses were created and shunt patency was confirmed using ICG. Arm volumes were measured before surgery and at 6- and 12-month follow-up. QoL was measured before surgery and at 6-month follow-up. Arm volume differences between the healthy arm and affected arm were compared between the time points. RESULTS: Twenty-nine consecutive female patients with unilateral BCRL were included. The preoperative mean difference in arm volumes was 701 ± 435 ml (36.9%). This was reduced to 496 ± 302 ml (24.7%) at 6-month follow-up (p = 0.00). At 12-month follow-up, the mean difference in arm volume was 467 ± 303 ml (23.5%) (p = 0.02). The overall perceived QoL was increased from 5.8 ± 1.1 to 7.4 ± 0.7 (p = 0.00). The functionality score decreased from 2.2 to 1.8 (p = 0.00), the appearance score decreased from 2.6 to 1.9 (p = 0.00), the symptoms score decreased from 2.8 to 1.8 (p = 0.00), and the mood score decreased from 2.7 to 1.5 (p = 0.00). Fifteen patients (53.6%) were able to discontinue the use of compression garment. CONCLUSION: Treatment with LVAs is effective in reducing arm volume difference in patients suffering from BCRL. Although no complete reduction of the edema was achieved at 12-month follow-up, the procedure significantly increased the patients' QoL.


Assuntos
Anastomose Cirúrgica/métodos , Veia Axilar/cirurgia , Neoplasias da Mama/complicações , Vasos Linfáticos/cirurgia , Linfedema/etiologia , Linfedema/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Braço/patologia , Feminino , Humanos , Linfedema/diagnóstico , Linfografia , Pessoa de Meia-Idade , Qualidade de Vida , Resultado do Tratamento
11.
Biomed Res Int ; 2016: 5184595, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28070510

RESUMO

Introduction. Pelvic organ prolapse (POP) and urinary incontinence (UI) have increasing prevalence in the elderly population. The aim of this study was to compare the comorbidities of these procedures between <70 y/o and ≥70 y/o patients. Materials and Methods. In our retrospective study over a period of 2.5 years, 407 patients had received an urogynecological procedure. All patients with POP were treated by reconstructive surgery. Complications were reported using the standardized classification of Clavien-Dindo (CD). The study can be assigned to stage 2b Exploration IDEAL (Idea, Development, Exploration, Assessment, Long-term study)-system of surgical innovation. Results. Operation time, blood loss, and intraoperative complications have not been more frequent in the elderly, whereas hospital stay was significantly longer in ≥70 y/o patients. Regarding postoperative complications, we noticed that ≥70 y/o patients had an almost threefold risk to develop mild early postoperative complications compared to younger patients (OR: 2.86; 95% CI: 1.76-4.66). On the contrary, major complications were not more frequent. No case of life-threatening complication or the need for blood transfusion was reported. Conclusion. After urogynecological procedures, septuagenarians and older patients are more likely to develop mild postoperative complications but not more intraoperative or severe postoperative complications compared to younger patients.


Assuntos
Procedimentos Cirúrgicos em Ginecologia/métodos , Laparoscopia/métodos , Complicações Pós-Operatórias/epidemiologia , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Pessoa de Meia-Idade , Prolapso de Órgão Pélvico/cirurgia , Procedimentos de Cirurgia Plástica/métodos , Estudos Retrospectivos , Telas Cirúrgicas , Incontinência Urinária/cirurgia , Prolapso Uterino/cirurgia , Vagina/cirurgia
14.
J Biol Chem ; 255(6): 2377-82, 1980 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-7358677

RESUMO

Hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) from beef brain has been purified 3100-fold to apparent homogeneity using a purification procedure based on GMP-Sepharose affinity chromatography. The native enzyme has a molecular weight of 84,000 as determined by gel filtration studies. A subunit molecular weight of 26,000 was obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting that the enzyme is a trimer. Two forms of the enzyme have been separated by nondenaturing polyacrylamide gel electrophoresis and isoelectric focusing. Basic pI values of 7.85 and 8.10 were obtained for the two forms. These values are much higher than have been observed with any other purified phosphoribosyltransferase. The amino acid composition of the enzyme is 18 Lys, 6 His, 9 Arg, 1 Trp, 6 Cys, 28 Asx, 12 Thr, 16 Ser, 19 Glx, 10 Pro, 23 Gly, 16 Ala, 17 Val, 5 Met, 11 Ile, 19 Leu, 9 Tyr, and 8 Phe. An unusual basic amino acid, yet to be identified, was also present. The enzyme exhibits Km values of 0.42 microM for guanine, 0.99 microM for hypoxanthine, 18.6 microM for P-Rib-PP in the presence of guanine, and 2.9 microM for P-Rib-PP in the presence of hypoxanthine.


Assuntos
Encéfalo/enzimologia , Hipoxantina Fosforribosiltransferase/isolamento & purificação , Aminoácidos/análise , Animais , Bovinos , Cromatografia de Afinidade , Concentração de Íons de Hidrogênio , Hipoxantina Fosforribosiltransferase/metabolismo , Cinética , Substâncias Macromoleculares , Peso Molecular
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