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1.
BMC Endocr Disord ; 22(1): 166, 2022 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-35761280

RESUMEN

BACKGROUND: Differences in sexual development (DSD) are rare diseases, which affect the chromosomal, anatomical or gonadal sex differentiation. Although patient education is recommended as essential in a holistic care approach, standardised programmes are still lacking. The present protocol describes the aims, study design and methods of the Empower-DSD project, which developed an age-adapted multidisciplinary education programme to improve the diagnosis-specific knowledge, skills and empowerment of patients and their parents. METHODS: The new patient education programme was developed for children, adolescents and young adults with congenital adrenal hyperplasia, Turner syndrome, Klinefelter syndrome or XX-/or XY-DSD and their parents. The quantitative and qualitative evaluation methods include standardised questionnaires, semi-structured interviews, and participatory observation. The main outcomes (assessed three and six months after the end of the programme) are health-related quality of life, disease burden, coping, and diagnosis-specific knowledge. The qualitative evaluation examines individual expectations and perceptions of the programme. The results of the quantitative and qualitative evaluation will be triangulated. DISCUSSION: The study Empower-DSD was designed to reduce knowledge gaps regarding the feasibility, acceptance and effects of standardised patient education programmes for children and youth with DSD and their parents. A modular structured patient education programme with four generic and three diagnosis-specific modules based on the ModuS concept previously established for other chronic diseases was developed. The topics, learning objectives and recommended teaching methods are summarised in the structured curricula, one for each diagnosis and age group. At five study centres, 56 trainers were qualified for the implementation of the training programmes. A total of 336 subjects have been already enrolled in the study. The recruitment will go on until August 2022, the last follow-up survey is scheduled for February 2023. The results will help improve multidisciplinary and integrated care for children and youth with DSD and their families. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00023096 . Registered 8 October 2020 - Retrospectively registered.


Asunto(s)
Educación del Paciente como Asunto , Calidad de Vida , Adolescente , Niño , Humanos , Padres , Desarrollo Sexual , Encuestas y Cuestionarios , Adulto Joven
2.
Eur J Cancer Care (Engl) ; 29(5): e13279, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32567091

RESUMEN

OBJECTIVE: As adolescent cancer patients may suffer from infertility following treatment, fertility counselling is essential. Our aim was to explore the current situation in four European countries in terms of (I) education about the risk for infertility, (II) counselling on fertility preservation, (III) patients' knowledge on fertility, (IV) sufficiency of information and (V) uptake of cryopreservation. METHODS: In total, 113 patients (13-20 years) at 11 study centres completed a self-report questionnaire three and six months after cancer diagnosis. Multivariate logistic regression was used to estimate odds ratios (OR) with 95% confidence intervals (CI). RESULTS: As many as 80.2% of participants reported having received education about the risk for infertility prior to treatment, 73.2% recalled counselling on fertility preservation. Only 52.3% stated they felt sufficiently informed to make a decision. Inability to recall counselling on fertility preservation (OR = 0.03, CI: 0.00-0.47) and female gender (OR = 0.11, CI: 0.03-0.48) was associated with lower use of cryopreservation, whereas older age was associated with higher use. CONCLUSION: Fertility counselling was available to a relatively high proportion of patients, and it did influence the utilisation of cryopreservation. However, many patients did not feel sufficiently informed. Further improvement is needed to enable adolescent cancer patients to make an informed decision on fertility preservation.


Asunto(s)
Preservación de la Fertilidad , Infertilidad , Neoplasias , Adolescente , Anciano , Consejo , Europa (Continente) , Femenino , Humanos , Infertilidad/prevención & control , Neoplasias/terapia
3.
Cell Physiol Biochem ; 39(2): 565-72, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27395380

RESUMEN

BACKGROUND/AIMS: Several recent clinical studies revealed an accumulation of ceramide in bronchial epithelial cells of patients with cystic fibrosis (CF). Degradation of ceramide concentrations in lungs of CF patients employing the functional acid sphingomyelinase inhibitor amitriptyline revealed a benefit in lung function, weight and exacerbation rates. METHODS: To test for a beneficial effect of amitriptyline in vivo, we performed two phase II randomised, double-blind, placebo-controlled studies. CF patients were treated with 25 mg amitriptyline twice daily, i.e. a total dose of 50 mg/d. After those two studies part of the patients used amitriptyline in an off-lable-use for routine treatment. These patients were observed after one, two and three years after continuous use of amitriptyline and were matched with those patients who were not treated. These patients were used as a control group. RESULTS: After one year of treatment, forced expiratory volume in 1 sec predicted (FEV1) increased significantly by 7.6±7.0%, p=<0.001, and weight increased by 2.1±2.3kg, p=<0.001 in the amitriptyline population (n=20), whereas FEV1 decreased significantly in the control group by 1.8±3.3%, p=0.010, and weight increased by 1.1±2.7kg, p=0.010 (n=14). After two years of treatment, FEV1 increased significantly by 5.6±10.3%, p=0.009, and weight increased by 3.6±2.9kg, p=<0.001 in the amitriptyline population (n=12). In contrast, FEV1 decreased in the control group by 2.1±3.7%, p=0.051 and weight increased by only 0.4±2.9kg, p=0.31 (n=10). After three years of treatment, FEV1 increased significantly by 7.7±8%, p=0.050, and weight increased by 7.3±3.8kg, p=0.016, in the amitriptyline population (n=5), whereas FEV1 decreased in the control group by 1.0±1.3%, p=0.075 and weight increased by 0.4±1.5kg, p=0.29 (n=5). CONCLUSION: Amitriptyline significantly increases FEV1, reduces ceramide in lung cells and increases weight of CF patients.


Asunto(s)
Amitriptilina/uso terapéutico , Ceramidas/metabolismo , Fibrosis Quística/tratamiento farmacológico , Volumen Espiratorio Forzado/efectos de los fármacos , Pulmón/efectos de los fármacos , Adulto , Antidepresivos Tricíclicos/uso terapéutico , Peso Corporal/efectos de los fármacos , Ensayos Clínicos Fase II como Asunto , Fibrosis Quística/metabolismo , Fibrosis Quística/fisiopatología , Método Doble Ciego , Femenino , Estudios de Seguimiento , Humanos , Pulmón/metabolismo , Pulmón/fisiopatología , Masculino , Estudios Multicéntricos como Asunto , Evaluación de Resultado en la Atención de Salud/métodos , Evaluación de Resultado en la Atención de Salud/estadística & datos numéricos , Ensayos Clínicos Controlados Aleatorios como Asunto , Factores de Tiempo , Adulto Joven
4.
Cell Physiol Biochem ; 39(3): 1141-51, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27576543

RESUMEN

BACKGROUND/AIMS: In cystic fibrosis (CF), chronic microbial lung infections are difficult to treat and cause morbidity and increased mortality. METHODS: In a multicentre, open-label, exploratory, non-interventional study, inhaled tobramycin (300 mg twice daily) and colistin (1 million I.U. twice daily) were sequentially combined with the aim to investigate the effect on 41 CF patients with chronic P. aeruginosa infections for six months (mean age 24 ± 10.8y). RESULTS: Six patients had adverse events that were assessed as being related to treatment. Mucus production and coughing both decreased in 39%, whereas FEV1 absolute and relative to baseline increased by 4.9% and 9.1%, respectively (p = 0.004) in 29 patients, who were definitely treated sequentially. Efficacy of the therapy was rated 'excellent' or 'good' by the physicians in 80.5% of the patients. CONCLUSIONS: The results indicate that treatment with inhaled antibiotics, sequentially combined, was very well tolerated by most patients and may have a beneficial effect, even if transitory on lung function and respiratory symptoms.


Asunto(s)
Antibacterianos/uso terapéutico , Colistina/uso terapéutico , Fibrosis Quística/tratamiento farmacológico , Infecciones por Pseudomonas/tratamiento farmacológico , Tobramicina/uso terapéutico , Administración por Inhalación , Adolescente , Adulto , Enfermedad Crónica , Fibrosis Quística/microbiología , Fibrosis Quística/patología , Esquema de Medicación , Combinación de Medicamentos , Femenino , Volumen Espiratorio Forzado/efectos de los fármacos , Humanos , Masculino , Estudios Prospectivos , Infecciones por Pseudomonas/microbiología , Infecciones por Pseudomonas/patología , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/crecimiento & desarrollo , Resultado del Tratamiento
5.
Infection ; 44(4): 513-20, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26861246

RESUMEN

BACKGROUND: Individuals with cystic fibrosis (CF) receive antibiotics continuously throughout their entire life which leads to drug resistant microbial lung infections which are difficult to treat. Nitric oxide (NO) gas possesses antimicrobial activity against a wide variety of microorganisms in vitro, in vivo in animal models and a phase I study in healthy adults showed administration of intermittent 160 ppm NO to be safe. METHODS: We assessed feasibility and safety of inhaled NO in eight CF patients who received 160 ppm NO for 30 min, three times daily for 2 periods of 5 days. RESULTS: The NO treatment was safe and in none of the patients were serious drug-related adverse events observed which caused termination of the study. The intention-to-treat analysis revealed a significant mean reduction of the colony forming units of all bacteria and all fungi, while mean forced expiratory volume 1 s % predicted (FEV1) relative to baseline increased 17.3 ± 8.9 % (P = 0.012). CONCLUSIONS: NO treatment may improve the therapy of chronic microbial lung infections in CF patients, particularly concerning pathogens with intrinsic or acquired resistance to antibiotics.


Asunto(s)
Antiinfecciosos/uso terapéutico , Fibrosis Quística/complicaciones , Óxido Nítrico/uso terapéutico , Infecciones del Sistema Respiratorio/complicaciones , Infecciones del Sistema Respiratorio/tratamiento farmacológico , Adulto , Antiinfecciosos/administración & dosificación , Antiinfecciosos/efectos adversos , Farmacorresistencia Bacteriana , Farmacorresistencia Fúngica , Estudios de Factibilidad , Femenino , Volumen Espiratorio Forzado , Humanos , Masculino , Óxido Nítrico/administración & dosificación , Óxido Nítrico/efectos adversos , Infecciones del Sistema Respiratorio/microbiología
6.
Proteins ; 82(9): 2041-53, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24623648

RESUMEN

Clostridium propionicum is the only organism known to ferment ß-alanine, a constituent of coenzyme A (CoA) and the phosphopantetheinyl prosthetic group of holo-acyl carrier protein. The first step in the fermentation is a CoA-transfer to ß-alanine. Subsequently, the resulting ß-alanyl-CoA is deaminated by the enzyme ß-alanyl-CoA:ammonia lyase (Acl) to reversibly form ammonia and acrylyl-CoA. We have determined the crystal structure of Acl in its apo-form at a resolution of 0.97 Å as well as in complex with CoA at a resolution of 1.59 Å. The structures reveal that the enyzme belongs to a superfamily of proteins exhibiting a so called "hot dog fold" which is characterized by a five-stranded antiparallel ß-sheet with a long α-helix packed against it. The functional unit of all "hot dog fold" proteins is a homodimer containing two equivalent substrate binding sites which are established by the dimer interface. In the case of Acl, three functional dimers combine to a homohexamer strongly resembling the homohexamer formed by YciA-like acyl-CoA thioesterases. Here, we propose an enzymatic mechanism based on the crystal structure of the Acl·CoA complex and molecular docking.


Asunto(s)
Amoníaco-Liasas/ultraestructura , Clostridium/enzimología , Pliegue de Proteína , Secuencia de Aminoácidos , Sitios de Unión , Coenzima A/metabolismo , Cristalografía por Rayos X , Fermentación/fisiología , Simulación del Acoplamiento Molecular , Datos de Secuencia Molecular , Complejos Multiproteicos , Estructura Cuaternaria de Proteína , Estructura Secundaria de Proteína , Alineación de Secuencia , beta-Alanina/metabolismo
7.
Cell Physiol Biochem ; 31(4-5): 505-12, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23572075

RESUMEN

BACKGROUND/AIMS: Several recent studies revealed an accumulation of ceramide in bronchial, tracheal and intestinal epithelial cells of mice and patients with cystic fibrosis (CF). Normalization of ceramide concentrations in lungs of CF mice employing the functional acid sphingomyelinase inhibitor amitriptyline also normalized mucociliary clearance, chronic inflammation and infection susceptibility to pulmonary P. aeruginosa in these mice. METHODS: To test for a beneficial effect of amitriptyline in vivo, we performed a phase IIb randomised, double-blind, placebo-controlled study. Twenty-one CF patients were treated with 25 mg/d amitriptyline twice daily for 28 days. The placebo consisted of 19 patients and was also treated twice per day. The primary endpoint was the change in lung function in the intention-to-treat (ITT) population. Secondary endpoints were ceramide levels in epithelial cells and safety. RESULTS: After treatment, forced expiratory volume in 1 sec predicted (FEV1) increased 6.3 ± 11.5% (p=0.08) in the ITT population (36 of 40 CF patients) and 8.5 ± 10% (p=0.013) in the per protocol (PP) population (29 of 40 patients). Ceramide levels decreased in nasal epithelial cells after amitriptyline treatment. Amitriptyline had no severe and only mild and mostly transient adverse effects, i.e. xerostomia and tiredness. CONCLUSION: Amitriptyline is safe in CF-patients, increases FEV1 and reduces ceramide in lung cells of CF patients.


Asunto(s)
Inhibidores de Captación Adrenérgica/uso terapéutico , Amitriptilina/uso terapéutico , Fibrosis Quística/tratamiento farmacológico , Adolescente , Adulto , Ceramidas/análisis , Estudios de Cohortes , Método Doble Ciego , Femenino , Volumen Espiratorio Forzado , Humanos , Masculino , Efecto Placebo , Resultado del Tratamiento , Adulto Joven
8.
World J Pediatr Surg ; 6(4): e000599, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37860275

RESUMEN

Background: Complications are frequently reported after hypospadias repair and there is a need to understand the factors that influence their occurrence. Methods: Data from boys with hypospadias born between 2000 and 2020 were obtained from the International Disorders of Sex Development (I-DSD) Registry. Logistic regressions, fisher's exact tests and spearman's correlation tests were performed on the data to assess associations between clinical factors and complication rates. Results: Of the 551 eligible boys, data were available on 160 (29%). Within the cohort, the median (range) External Masculinization Score (EMS) was 6 (2, 9). All presented with one or more additional genital malformation and 61 (38%) presented with additional extragenital malformations. Disorders of androgen action, androgen synthesis and gonadal development were diagnosed in 28 (18%), 22 (14%) and 9 (6%) boys, respectively. The remaining 101 (62%) patients were diagnosed as having non-specific 46,XY Disorders of Sex Development. Eighty (50%) boys had evidence of abnormal biochemistry, and gene variants were identified in 42 (26%). Median age at first hypospadias surgery was 2 years (0, 9), and median length of follow-up was 5 years (0, 17). Postsurgical complications were noted in 102 (64%) boys. There were no significant associations with postsurgical complications. Conclusions: Boys with proximal hypospadias in the I-DSD Registry have high rates of additional comorbidities and a high risk of postoperative complications. No clinical factors were significantly associated with complication rates. High complication rates with no observable cause suggest the involvement of other factors which need investigation.

9.
Horm Res Paediatr ; 95(2): 137-148, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34689140

RESUMEN

INTRODUCTION: Genetic obesity is rare and quite challenging for pediatricians in terms of early identification. Src-homology-2 (SH2) B adapter protein 1 (SH2B1) is an important component in the leptin-melanocortin pathway and is found to play an important role in leptin and insulin signaling and therefore in the pathogenesis of obesity and diabetes. Microdeletions in chromosome 16p11.2, encompassing the SH2B1 gene, are known to be associated with obesity, insulin resistance, hyperphagia, and developmental delay. The aim of our study is to report on a case series of young individuals with 16p11.2 microdeletions, including the SH2B1 gene, and provide detailed information on body mass index (BMI) development and obesity-associated comorbidities. In this way, we want to raise awareness of this syndromic form of obesity as a differential diagnosis of genetic obesity. METHODS: We describe the phenotype of 7 children (3 male; age range: 2.8-18.0 years) with 16p11.2 microdeletions, encompassing the SH2B1 gene, and present their BMI trajectories from birth onward. Screening for obesity-associated comorbidities was performed at the time of genetic diagnosis. RESULTS: All children presented with severe, early-onset obesity already at the age of 5 years combined with variable developmental delay. Five patients presented with elevated fasting insulin levels, 1 patient developed diabetes mellitus type 2, 4 patients had dyslipidemia, and 4 developed nonalcoholic fatty-liver disease. DISCUSSION/CONCLUSION: Chromosomal microdeletions in 16p11.2, including the SH2B1 gene, in children are associated with severe, early-onset obesity and comorbidities associated with insulin resistance. Early genetic testing in suspicious patients and early screening for comorbidities are recommended.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales , Obesidad Infantil , Proteínas Adaptadoras Transductoras de Señales/genética , Adolescente , Índice de Masa Corporal , Niño , Preescolar , Femenino , Eliminación de Gen , Humanos , Insulina/metabolismo , Resistencia a la Insulina/genética , Leptina/metabolismo , Masculino , Obesidad Infantil/diagnóstico , Obesidad Infantil/genética
10.
J Infect Dis ; 202(10): 1585-92, 2010 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-20942647

RESUMEN

BACKGROUND: Antibiotic combination therapy might be more efficient than single antibiotics to combat Pseudomonas aeruginosa biofilms in the airways of patients with cystic fibrosis. We tested the ability of colistin sulphate-tobramycin combinations and single antibiotics to kill P. aeruginosa biofilms. METHODS: P. aeruginosa biofilms were generated in vitro and in rat lungs. In a pilot study, 5 patients with cystic fibrosis inhaled colistin and then tobramycin for 4 weeks. The changes in P. aeruginosa counts and lung function were assessed before and after therapy. RESULTS: Antibiotic combination therapy significantly reduced the number of P. aeruginosa cells in P. aeruginosa biofilm models in vitro. When rats were challenged with 1 x 10(7) cfu of P. aeruginosa, which was embedded in alginate beads, mortality rates, lung pathologic findings, and bacterial colony-forming unit counts were significantly lower after 7 days in animals receiving antibiotic combination than in animals receiving single antibiotics. In patients with cystic fibrosis, inhaled colistin-tobramycin was well tolerated and resulted in a mean decrease of 2.52 + /- 2.5 log(10) cfu of P. aeruginosa per milliliter of sputum (P = .027). Measurements of forced expiratory volume in 1 s, obtained both before and after the study, did not differ significantly. CONCLUSION: Colistin-tobramycin combinations are more efficient than respective single antibiotics for killing P. aeruginosa in biofilms in vitro, and they significantly reduced P. aeruginosa cell counts in a rat lung infection model and in patients with cystic fibrosis.


Asunto(s)
Antibacterianos/uso terapéutico , Biopelículas/efectos de los fármacos , Colistina/uso terapéutico , Fibrosis Quística/tratamiento farmacológico , Infecciones por Pseudomonas/tratamiento farmacológico , Pseudomonas aeruginosa/efectos de los fármacos , Tobramicina/uso terapéutico , Administración por Inhalación , Adulto , Animales , Antibacterianos/administración & dosificación , Colistina/administración & dosificación , Fibrosis Quística/microbiología , Quimioterapia Combinada , Femenino , Humanos , Pulmón/microbiología , Masculino , Pruebas de Sensibilidad Microbiana , Proyectos Piloto , Infecciones por Pseudomonas/microbiología , Pseudomonas aeruginosa/fisiología , Ratas , Ratas Endogámicas Lew , Tobramicina/administración & dosificación , Resultado del Tratamiento
11.
J Adolesc Young Adult Oncol ; 9(1): 55-62, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31621493

RESUMEN

Purpose: Within a multicenter European study, we explored fertility-related wishes, concerns, and decision-making of adolescent cancer patients and their parents. Patients and Methods: Patients and parents were each asked to complete a fertility-related questionnaire 3 months after initial diagnosis. In total, 113 of 142 (79.6%) eligible patients participated; 53.1% were male and the median age was 16 years (range 13-20 years). The questionnaire was completed by 111 parents. Univariate analyses were conducted using nonparametric methods with alpha = 5%. For multivariate analyses, binary logistic regression was conducted. Results: Both patients (86.1%) and parents (96.3%) indicated a strong desire for biological parenthood for themselves/their children. Female patients (odds ratio [OR] = 3.70; confidence interval [CI]: 1.43-9.50) and parents (OR = 2.70; CI: 1.21-6.00) were more likely to report a high fear of cancer recurrence. Patients who estimated their risk for fertility impairment being high were more likely to be concerned about their fertility (OR = 5.69; CI: 1.41-22.98). Parents who received fertility preservation information were more likely to recommend its use to their children (OR = 5.50; CI: 1.07-28.40), whereas parents of female patients were less likely to do so (OR = 0.13; CI: 0.03-0.61). Conclusions: The prospect of fertility following cancer treatment is important for adolescent cancer patients and their parents, yet it is associated with many concerns. Counseling regarding fertility preservation can be more effective when the individual needs of patients and their parents are taken into consideration.


Asunto(s)
Fertilidad/fisiología , Neoplasias/complicaciones , Adolescente , Adulto , Femenino , Humanos , Masculino , Neoplasias/psicología , Padres/psicología , Encuestas y Cuestionarios , Adulto Joven
12.
FEBS J ; 272(3): 813-21, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15670161

RESUMEN

The fermentation of beta-alanine by Clostridium propionicum proceeds via activation to the CoA-thiol ester, followed by deamination to acryloyl-CoA, which is also an intermediate in the fermentation of l-alanine. By shifting the organism from the carbon and energy source alpha-alanine to beta-alanine, the enzyme beta-alanyl-CoA:ammonia lyase is induced 300-fold (approximately 30% of the soluble protein). The low basal lyase activity is encoded by the acl1 gene, whereas the almost identical acl2 gene (six amino acid substitutions) is responsible for the high activity after growth on beta-alanine. The deduced beta-alanyl-CoA:ammonia lyase proteins are related to putative beta-aminobutyryl-CoA ammonia lyases involved in lysine fermentation and found in the genomes of several anaerobic bacteria. beta-Alanyl-CoA:ammonia lyase 2 was purified to homogeneity and characterized as a heteropentamer composed of 16 kDa subunits. The apparent K(m) value for acryloyl-CoA was measured as 23 +/- 4 microm, independent of the concentration of the second substrate ammonia; k(cat)/K(m) was calculated as 10(7) m(-1) x s(-1). The apparent K(m) for ammonia was much higher, 70 +/- 5 mm at 150 microm acryloyl-CoA with a much lower k(cat)/K(m) of 4 x 10(3) m(-1) x s(-1). In the reverse reaction, a K(m) of 210 +/- 30 microM was obtained for beta-alanyl-CoA. The elimination of ammonia was inhibited by 70% at 100 mm ammonium chloride. The content of beta-alanyl-CoA:ammonia lyase in beta-alanine grown cells is about 100 times higher than that required to sustain the growth rate of the organism. It is therefore suggested that the enzyme is needed to bind acryloyl-CoA, in order to keep the toxic free form at a very low level. A formula was derived for the calculation of isomerization equilibra between L-alanine/beta-alanine or D-lactate/3-hydroxypropionate.


Asunto(s)
Amoníaco-Liasas/metabolismo , Clostridium/enzimología , Amoníaco-Liasas/química , Amoníaco-Liasas/genética , Amoníaco-Liasas/aislamiento & purificación , Secuencia de Bases , Cromatografía Líquida de Alta Presión , Clostridium/genética , Cartilla de ADN , Electroforesis en Gel de Poliacrilamida , Genes Bacterianos , Cinética , Mapeo Peptídico , Especificidad por Sustrato
14.
J Mol Microbiol Biotechnol ; 10(2-4): 105-19, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-16645308

RESUMEN

Anaerobic bacteria ferment glutamate via two different pathways to ammonia, carbon dioxide, acetate, butyrate and molecular hydrogen. The coenzyme B12-dependent pathway in Clostridium tetanomorphum via 3-methylaspartate involves pyruvate:ferredoxin oxidoreductase and a novel enzyme, a membrane-bound NADH:ferredoxin oxidoreductase. The flavin- and iron-sulfur-containing enzyme probably uses the energy difference between reduced ferredoxin and NADH to generate an electrochemical Na+ gradient, which drives transport processes. The other pathway via 2-hydroxyglutarate in Acidaminococcus fermentans and Fusobacterium nucleatum involves glutaconyl-CoA decarboxylase, which uses the free energy of decarboxylation to generate also an electrochemical Na+ gradient. In the latter two organisms, similar membrane-bound NADH:ferredoxin oxidoreductases have been characterized. We propose that in the hydroxyglutarate pathway these oxidoreductases work in the reverse direction, whereby the reduction of ferredoxin by NADH is driven by the Na+ gradient. The reduced ferredoxin is required for hydrogen production and the activation of radical enzymes. Further examples show that reduced ferredoxin is an agent, whose reducing energy is about 1 ATP 'richer' than that of NADH.


Asunto(s)
Bacterias Anaerobias/enzimología , Glutamatos/metabolismo , Hidrógeno/metabolismo , Bombas Iónicas/metabolismo , Modelos Moleculares , Secuencia de Aminoácidos , Transporte Biológico Activo , Glutaratos/metabolismo , Bombas Iónicas/química , Datos de Secuencia Molecular , Homología de Secuencia de Aminoácido , Sodio/metabolismo
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