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1.
Br Dent J ; 228(6): 397, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32221423
2.
Breast Cancer Res Treat ; 136(2): 535-45, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23053659

RESUMEN

For women with breast cancer who undergo mastectomy, immediate breast reconstruction (IR) offers a cosmetic and psychological advantage. We evaluated the association between demographic, hospital, surgeon and insurance factors and receipt of IR. We conducted a retrospective hospital-based analysis with the Perspective database. Women who underwent a mastectomy for invasive breast cancer (IBC) and ductal carcinoma in situ (DCIS) from 2000 to 2010 were included. Logistic regression analysis was used to determine factors predictive of IR. Analyses were stratified by age (<50 vs. ≥ 50) and IBC versus DCIS. Of the 108,992 women with IBC who underwent mastectomy, 30,859 (28.3 %) underwent IR, as compared to 6,501 (44.2 %) of the 14,710 women with DCIS who underwent mastectomy underwent IR. In a multivariable model for IBC, increasing age, black race, being married, rural location, and increased comorbidities were associated with decreased IR. Odds ratios (OR) of IR increased with commercial insurance (OR 3.38) and Medicare (OR 1.66) insurance (vs. self-pay), high surgeon-volume (OR 1.19), high hospital-volume (OR 2.24), and large hospital size (OR 1.20). The results were identical for DCIS, and by age category. The absolute difference between the proportion of patients who received IR with commercial insurance compared to other insurance, increased over time. Immediate in-hospital complication rates were higher for flap reconstruction compared to implant or no reconstruction (15.2, 4.0, and 6.1 %, respectively, P < .0001). IR has increased significantly over time; however, modifiable factors such as insurance status, hospital size, hospital location, and physician volume strongly predict IR. Public policy should ensure that access to reconstructive surgery is universally available.


Asunto(s)
Neoplasias de la Mama/cirugía , Hospitales , Cobertura del Seguro , Seguro de Salud , Mamoplastia/estadística & datos numéricos , Médicos , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias de la Mama/economía , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/patología , Femenino , Humanos , Mamoplastia/economía , Mastectomía , Persona de Mediana Edad , Análisis Multivariante , Invasividad Neoplásica , Adulto Joven
3.
Rheumatology (Oxford) ; 44(6): 800-5, 2005 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15769790

RESUMEN

OBJECTIVES: To prospectively evaluate the incidence, spectrum of disease and relation to general health of shoulder disorders in primary care. METHODS: Patients presenting with shoulder pain to two large general practices in the Cambridge area over a 1-month period were invited to participate. After consulting their general practitioner, patients were administered a demographic information questionnaire, a shoulder pain and disability index (SPADI) and a short form 36 (SF-36) health survey. Subsequent review in a clinic held by a rheumatology registrar every 2 weeks was undertaken. RESULTS: The sex- and age-standardized incidence of shoulder pain was 9.5 per 1000 (95% confidence interval 7.9 to 11.2 per 1000). Rotator cuff tendinopathy was found in 85%, signs of impingement in 74%, acromioclavicular joint disease in 24%, adhesive capsulitis in 15% and referred pain in 7%. On the SPADI the mean disability subscale score was 45 (95% confidence interval 41 to 50) and the mean pain score was 58 (95% confidence interval 53 to 62) (range 0 to 100). Evaluation of general health status using the SF-36 showed the difference between population norms and those with shoulder pain was significant in six of the eight domains, being especially marked (greater than 20 point reduction) for emotional role, physical function and physical role. CONCLUSION: Shoulder pain, most commonly due to rotator cuff tendinopathy, is associated with significantly reduced health when measured by both specific and generic means. Effort towards prevention and early intervention in these complaints is warranted.


Asunto(s)
Estado de Salud , Dolor de Hombro/fisiopatología , Articulación Acromioclavicular/fisiopatología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Bursitis/complicaciones , Bursitis/fisiopatología , Evaluación de la Discapacidad , Femenino , Humanos , Artropatías/complicaciones , Artropatías/fisiopatología , Masculino , Persona de Mediana Edad , Dimensión del Dolor/métodos , Manguito de los Rotadores/fisiopatología , Síndrome de Abducción Dolorosa del Hombro/complicaciones , Síndrome de Abducción Dolorosa del Hombro/fisiopatología , Dolor de Hombro/etiología
4.
Ann Rheum Dis ; 63(10): 1288-92, 2004 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-15361389

RESUMEN

BACKGROUND: Rotator cuff lesions are common in the community but reproducibility of tests for shoulder assessment has not been adequately appraised and there is no uniform approach to their use. OBJECTIVE: To study interrater reproducibility of standard tests for shoulder evaluation among a rheumatology specialist, rheumatology trainee, and research nurse. METHODS: 136 patients were reviewed over 12 months at a major teaching hospital. The three assessors examined each patient in random order and were unaware of each other's evaluation. Each shoulder was examined in a standard manner by recognised tests for specific lesions and a diagnostic algorithm was used. Between-observer agreement was determined by calculating Cohen's kappa coefficients (measuring agreement beyond that expected by chance). RESULTS: Fair to substantial agreement was obtained for the observations of tenderness, painful arc, and external rotation. Tests for supraspinatus and subscapularis also showed at least fair agreement between observers. 40/55 (73%) kappa coefficient assessments were rated at >0.2, indicating at least fair concordance between observers; 21/55 (38%) were rated at >0.4, indicating at least moderate concordance between observers. CONCLUSION: The reproducibility of certain tests, employed by observers of varying experience, in the assessment of the rotator cuff and general shoulder disease was determined. This has implications for delegation of shoulder assessment to nurse specialists, the development of a simplified evaluation schedule for general practitioners, and uniformity in epidemiological research studies.


Asunto(s)
Lesiones del Manguito de los Rotadores , Síndrome de Abducción Dolorosa del Hombro/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Bursitis/diagnóstico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Examen Físico/métodos , Rango del Movimiento Articular , Reproducibilidad de los Resultados , Dolor de Hombro/etiología
6.
J Pediatr Surg ; 38(7): 1090-3, 2003 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12861547

RESUMEN

Feeding jejunostomy is a recognized method of managing feeding difficulties and failure to thrive in neurologically impaired children. There are, however, significant associated complications. The authors report 4 cases of the potentially fatal complication of severe jejunoileitis, which has not been reported previously in children. The possible underlying mechanisms are discussed.


Asunto(s)
Ileítis/etiología , Enfermedades del Yeyuno/etiología , Yeyunostomía/efectos adversos , Preescolar , Nutrición Enteral , Femenino , Humanos , Lactante , Masculino
7.
Neurogastroenterol Motil ; 15(2): 121-8, 2003 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-12680911

RESUMEN

Nissen fundoplication is of proven effectiveness in the surgical control of gastro-oesophageal reflux. However, our understanding of the effects of fundoplication upon foregut physiology is incomplete and post-operative symptoms are often poorly understood. This experimental study aimed systematically to characterize the tissue response to fundoplication in an animal model, to improve understanding of the effects of anti-reflux surgery upon foregut physiology. Nissen-type fundoplication was performed in the ferret, and the tissue response at 3 months examined histologically. Sham-operated animals that underwent laparotomy but no dissection or wrap, acted as controls. In fundoplicated animals, serosal fibrosis was observed in the gut wall, with patchy replacement of muscle by fibrous tissue. The ventral and dorsal vagal nerve trunks were identified intact within the wrap. In cases where the wrap had spontaneously disrupted, fibrosis was more extensive and there was evidence of nerve damage. This is the first systematic description of the histopathological response to Nissen fundoplication. In the intact wrap, the vagal trunks appear spared, but there is fibrosis in the serosa, extending into the muscularis of the distal oesophagus and region of the cardia. These findings are discussed in relation to the effects of Nissen fundoplication upon gastric physiology and postoperative symptoms.


Asunto(s)
Esófago/patología , Hurones/cirugía , Fundoplicación , Estómago/patología , Animales , Unión Esofagogástrica/metabolismo , Unión Esofagogástrica/patología , Esófago/inervación , Esófago/metabolismo , Esófago/cirugía , Hurones/fisiología , Fibrosis , Mucosa Gástrica/metabolismo , Inmunohistoquímica , Estómago/inervación , Estómago/cirugía , Nervio Vago/patología , Nervio Vago/cirugía
8.
Arch Dis Child ; 87(5): 432-3, 2002 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-12390924

RESUMEN

Duodenal perforation is a rare, life threatening injury associated with non-accidental blunt abdominal trauma. Diagnostic delay is common, as the true history is concealed and signs may be minimal. Double contrast computed tomography is the most sensitive investigation to confirm clinical suspicion. We report three cases, all with other features typical of non-accidental injury.


Asunto(s)
Enfermedades Duodenales/diagnóstico por imagen , Perforación Intestinal/diagnóstico por imagen , Preescolar , Diagnóstico Diferencial , Enfermedades Duodenales/etiología , Femenino , Humanos , Lactante , Perforación Intestinal/etiología , Traumatismos Torácicos/complicaciones , Tomografía Computarizada por Rayos X/métodos , Heridas no Penetrantes/complicaciones
9.
J Pediatr Surg ; 36(9): 1401-4, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11528615

RESUMEN

BACKGROUND/PURPOSE: In neurologically impaired children, retching and recurrent vomiting are common after Nissen fundoplication. The aim of this study was to identify whether there are preoperative factors that predict their occurrence. METHODS: Twenty neurologically impaired children (8 boys, 12 girls; age range, 3 months to 8 years) were studied prospectively by taking a detailed history of behaviors and symptoms associated with feeding before and after Nissen fundoplication for gastroesophageal reflux. RESULTS: Preoperatively, children could be classified into 2 groups. Children in group A had symptoms suggestive of only gastroesophageal reflux (effortless "vomiting" or regurgitation), whereas children in group B exhibited one or more features associated with activation of the emetic reflex (pallor, sweating, retching, forceful vomiting). Postoperatively 0 of 8 in group A retched compared with 8 of 12 in group B (P <.005, Fishers Exact test). CONCLUSIONS: Children at high risk of retching, and ultimately vomiting, after antireflux surgery may be identified clinically preoperatively. They have symptoms that are specifically caused by activation of the emetic reflex rather than to gastroesophageal reflux. In these cases, antireflux surgery could be considered inappropriate and hence be avoided.


Asunto(s)
Enfermedades del Sistema Nervioso Central/diagnóstico , Fundoplicación/métodos , Reflujo Gastroesofágico/cirugía , Náusea y Vómito Posoperatorios/diagnóstico , Enfermedades del Sistema Nervioso Central/complicaciones , Niño , Preescolar , Femenino , Estudios de Seguimiento , Fundoplicación/efectos adversos , Reflujo Gastroesofágico/complicaciones , Reflujo Gastroesofágico/diagnóstico , Humanos , Incidencia , Lactante , Masculino , Náusea y Vómito Posoperatorios/epidemiología , Valor Predictivo de las Pruebas , Cuidados Preoperatorios , Probabilidad , Estudios Prospectivos , Factores de Riesgo , Resultado del Tratamiento
10.
Gene Ther ; 8(16): 1241-7, 2001 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-11509957

RESUMEN

Targeting of colorectal liver metastases by regional gene therapy was tested in a clinically relevant syngeneic model. First, the CEA-CD-113 retroviral vector containing the cytosine deaminase gene controlled by the CEA specific tumour cell promoter, was shown in vitro to convert 5-fluorocytosine to 5-fluorouracil, resulting in cancer cell killing with a large bystander effect. Second, 10 days after the establishment of liver metastases, retroviral vectors were delivered to the liver by hepatic artery injection. After 5-fluorocytosine administration for 7 days, most surface metastases disappeared and tumour volumes were suppressed up to 8.2-fold. The results support the development of this approach for patient treatment.


Asunto(s)
Carcinoma/terapia , Neoplasias del Colon/terapia , Terapia Genética/métodos , Neoplasias Hepáticas/secundario , Neoplasias Hepáticas/terapia , Nucleósido Desaminasas/genética , Animales , Antimetabolitos/uso terapéutico , Antígeno Carcinoembrionario/genética , Citosina Desaminasa , Flucitosina/uso terapéutico , Vectores Genéticos/administración & dosificación , Arteria Hepática , Inyecciones Intraarteriales , Inyecciones Intraperitoneales , Masculino , Modelos Animales , Trasplante de Neoplasias , Regiones Promotoras Genéticas , Ratas , Retroviridae/genética , Células Tumorales Cultivadas
12.
J Bacteriol ; 182(22): 6514-6, 2000 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11053399

RESUMEN

An Asp or Asn substitution for Gly247 in transmembrane helix 8 (TM-8) of Tet(B), the tetracycline efflux protein, eliminated tetracycline resistance. Second site suppressor mutations which partially restored resistance were located in TM-5, -8, -10, or -11 or in cytoplasmic loop 8-9 or loop 10-11. These results indicate physical proximity or functional relationships between TM-8 and these other regions of Tet(B).


Asunto(s)
Proteínas Bacterianas/genética , Resistencia a la Tetraciclina/genética , Sustitución de Aminoácidos , Glicina/genética , Mutación , Supresión Genética
13.
Biotechniques ; 29(1): 146-54, 2000 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10907089

RESUMEN

A new system has been developed for generating recombinant adenoviruses by Tn7-mediated transposition in E. coli. Low copy number E. coli plasmids containing a full-length adenoviral genome with lacZattTn7 replacing E1 have been constructed. The adenovirus plasmid or admid, as well as high copy number progenitors, were stably maintained in E. coli strain DH10B. Several transfer vectors containing a mammalian expression cassette flanked by Tn7R and Tn7L were used as donors to transpose the mini-Tn7 into the E1 region of the adenoviral genome. Transposed recombinant admids are readily identified by their beta-galactosidase phenotype. Transfection of admid DNA into producer cells resulted in the efficient production of infectious adenovirus. This easy-to-use, efficient system generates pure, clonal stocks of recombinant adenovirus without successive rounds of plaque purification.


Asunto(s)
Adenoviridae/genética , Elementos Transponibles de ADN , ADN Recombinante , Escherichia coli/genética , Adenoviridae/aislamiento & purificación , Línea Celular , Vectores Genéticos , Humanos , Plásmidos/genética , Reacción en Cadena de la Polimerasa , Transfección , beta-Galactosidasa/genética
14.
J Biol Chem ; 275(9): 6101-6, 2000 Mar 03.
Artículo en Inglés | MEDLINE | ID: mdl-10692399

RESUMEN

An interdomain hybrid Tet protein consisting of a class C alpha domain and a class B beta domain (Tet(C/B)) lacks detectable efflux ability and provides only minimal levels of resistance to tetracycline (Tc) (3 microg/ml) compared with intact class B (256 microg/ml) and class C (64 microg/ml). Twenty-one independently isolated mutants of the Tet(C/B) protein with increased Tc resistance were generated by random chemical mutagenesis. Nine mutants with a Glu substitution for Gly-152 in helix 5 of the class C alpha domain produced a resistance of 48 microg/ml, whereas another 9 with an Asp replacement of Gly-247 in helix 8 of the class B beta domain mediated resistance at 32 microg/ml. The third type of mutation, found in 3 mutants expressing 24 microg/ml resistance, was a S202F replacement in the putative interdomain cytoplasmic loop of Tet(C/B). The latter underscores a previously unappreciated function of the interdomain cytoplasmic loop. All three types of Tet(C/B) mutant proteins were expressed in amounts comparable with that of the original protein and demonstrated restored energy-dependent efflux of tetracycline. Site-directed mutational analysis demonstrated that a Gly-247 to Asn mutation could also facilitate Tc resistance by the Tet(C/B) hybrid, and a negatively charged side chain at position 152 was required for Tet(C/B) activity. These mutations appear to promote the necessary functional interactions between the interclass domains that do not occur in the Tet(C/B) hybrid protein and suggest a direct association between helix 5 and helix 8 in the function of Tet efflux proteins.


Asunto(s)
Escherichia coli/metabolismo , Proteínas Represoras/genética , Resistencia a la Tetraciclina/genética , Secuencia de Aminoácidos , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Datos de Secuencia Molecular , Mutagénesis , Mutación , Estructura Secundaria de Proteína , Proteínas Represoras/química , Tetraciclina/farmacología
15.
Neurogastroenterol Motil ; 12(1): 65-74, 2000 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-10652115

RESUMEN

Recurrent vomiting with failure to thrive is a common problem in neurologically impaired children. Many undergo fundoplication to control the underlying gastro-oesophageal reflux. The results of surgery are not always satisfactory and post-operative retching may be a major problem - a symptom indicative of activation of the emetic reflex. An animal model of antireflux surgery has been developed and used to investigate the effects of such surgery upon the emetic reflex and vagal influences on gastric motility. Following surgery, animals responded to a previously subemetic dose of a centrally acting opiate receptor agonist (loperamide), suggesting that fundoplication may sensitize the emetic reflex. A gastric vago-vagal reflex (tonic inhibition of corpus tone) and responses to direct stimulation of vagal motor efferents (both cholinergic and nonadrenergic noncholinergic responses) were not significantly affected by antireflux surgery. Mechanisms by which neural damage may sensitize the emetic reflex are discussed, together with the possible clinical implications for the management of post-operative symptoms in neurologically impaired children.


Asunto(s)
Fundoplicación/métodos , Vaciamiento Gástrico/fisiología , Reflejo/fisiología , Vómitos/fisiopatología , Animales , Antidiarreicos , Atropina/farmacología , Conducta Animal/efectos de los fármacos , Modelos Animales de Enfermedad , Estimulación Eléctrica , Hurones , Guanetidina/farmacología , Loperamida , Parasimpatolíticos/farmacología , Reflejo/efectos de los fármacos , Estómago/inervación , Estómago/fisiología , Estómago/cirugía , Simpaticolíticos/farmacología , Vagotomía , Nervio Vago/efectos de los fármacos , Nervio Vago/fisiología , Nervio Vago/cirugía , Vómitos/inducido químicamente , Vómitos/cirugía
16.
Cognition ; 72(2): B1-9, 1999 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-10553672

RESUMEN

When 4- and 6-year-olds are cued to use their imagination, they can overcome the belief bias effect and demonstrate deductive reasoning ability on syllogisms containing contrary-to-fact material. This study tested whether 2- and 3-year-olds could also reason with incongruent syllogisms when encouraged to use their imagination. Eighty-four 2-, 3- and 4-year-olds were randomly assigned to one of four conditions: no cue, word cue, fantasy planet or imagery. Children were then presented with six syllogistic reasoning problems containing incongruent information. In the imagination conditions, 2- and 3-year-olds performed as competently as 4-year-olds. The findings are discussed in relation to other research which suggests that under certain circumstances 2- and 3-year-olds have the capacity for counterfactual thinking.


Asunto(s)
Desarrollo Infantil , Cognición , Imaginación , Factores de Edad , Preescolar , Femenino , Humanos , Lógica , Masculino , Procesos Mentales , Distribución Aleatoria
17.
J Pediatr Surg ; 33(12): 1801-5, 1998 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-9869055

RESUMEN

BACKGROUND: Recurrent vomiting with failure to thrive is a common problem in neurologically impaired children. Many undergo fundoplication to control the underlying gastroesophageal reflux, but the results of surgery are not always satisfactory, and postoperative retching may be a major problem. Retching is part of the emetic reflex and is associated with nausea, which is itself associated with disturbed gastric electrical control activity, resulting in a gastric dysrhythmia. METHODS: By recording gastric electrical control activity before and after Nissen fundoplication using the noninvasive technique of surface electrogastrography, the authors have shown that (1) Neurologically impaired children with gastroesophageal reflux more commonly have a preexisting gastric dysrhythmia (65% neurologically impaired v 20% neurologically normal children with gastroesophageal reflux, P<.05), (2) Children who retch preoperatively are three times more likely to retch postoperatively, and (3) 25% of neurologically impaired children may start to retch postoperatively for the first time. CONCLUSION: The authors propose that in neurologically impaired children, loss of central inhibitory mechanisms may result in inappropriate activation of the emetic reflex, which may be heightened by antireflux surgery.


Asunto(s)
Fundoplicación , Reflujo Gastroesofágico/fisiopatología , Estómago/fisiopatología , Niño , Preescolar , Electromiografía , Reflujo Gastroesofágico/cirugía , Humanos , Lactante , Periodo Posoperatorio , Procesamiento de Señales Asistido por Computador , Vómitos/fisiopatología
18.
Gene Ther ; 5(9): 1213-20, 1998 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-9930322

RESUMEN

Controllable gene expression is a desirable feature both in gene therapy protocols and for the study of gene function in animals and plants. We have exploited the modular character of the tetracycline (tc)-regulatable genetic switch to show that its components can be encoded by any combination of recombinant adenovirus and/or transgenic mice. Transgenic mice were constructed that express the tc-regulatable trans-activator tTA muscle specifically. These were injected with recombinant adenovirus expressing a luciferase reporter controlled by the tTA-regulatable promoter. Virus injected into muscle, but not into a control organ (brain) resulted in luciferase activity. Conversely, injection of tTA producing adenovirus into mice that were transgenic for a trkB/Fc fusion protein gene under tc promoter control resulted in swift expression of serum trkB/Fc receptor-body. Both modes of gene induction were fully inhibited by administration of tc. We demonstrate that a careful choice of these tools allows exquisite in vivo control over transgene expression in a temporal, tc-regulatable, topical and tissue-specific manner.


Asunto(s)
Regulación de la Expresión Génica , Terapia Genética/métodos , Regiones Promotoras Genéticas , Inhibidores de la Síntesis de la Proteína/farmacología , Tetraciclina/farmacología , Transactivadores/efectos de los fármacos , Adenoviridae , Animales , Northern Blotting , Cruzamiento , Vectores Genéticos , Luciferasas/genética , Ratones , Ratones Transgénicos , Músculo Esquelético/enzimología , Activación Transcripcional , Transfección/métodos
19.
Todays Surg Nurse ; 20(3): 20-2, 1998.
Artículo en Inglés | MEDLINE | ID: mdl-10026634

RESUMEN

Maintaining immunity is an essential part of prevention and infection control programs. The ACIP strongly recommends all health care workers be vaccinated against hepatitis B influenza measles, mumps, rubella varicella.


Asunto(s)
Personal de Salud , Salud Laboral , Vacunación/métodos , Humanos , Guías de Práctica Clínica como Asunto , Ausencia por Enfermedad
20.
J Bacteriol ; 179(16): 5171-7, 1997 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-9260961

RESUMEN

Mannitol-specific enzyme II, or mannitol permease, of the phosphoenolpyruvate-dependent carbohydrate phosphotransferase system of Escherichia coli carries out the transport and phosphorylation of D-mannitol and is most active as a dimer in the membrane. We recently reported the importance of a glutamate residue at position 257 in the binding and transport of mannitol by this protein (C. Saraceni-Richards and G. R. Jacobson, J. Bacteriol. 179:1135-1142, 1997). Replacing Glu-257 with alanine (E257A) or glutamine (E257Q) eliminated detectable mannitol binding and transport by the permease. In contrast, an E257D mutant protein was able to bind and phosphorylate mannitol in a manner similar to that of the wild-type protein but was severely defective in mannitol uptake. In this study, we have coexpressed proteins containing mutations at position 257 with other inactive permeases containing mutations in each of the three domains of this protein. Activities of any active heterodimers resulting from this coexpression were measured. The results show that various inactive mutant permease proteins can complement proteins containing mutations at position 257. In addition, we show that both Glu at position 257 and His at position 195, both of which are in the membrane-bound C domain of the protein, must be on the same subunit of a permease dimer in order for efficient mannitol phosphorylation and uptake to occur. The results also suggest that mannitol bound to the opposite subunit within a permease heterodimer can be phosphorylated by the subunit containing the E257A mutation (which cannot bind mannitol) and support a model in which there are separate binding sites on each subunit within a permease dimer. Finally, we provide evidence from these studies that high-affinity mannitol binding is necessary for efficient transport by mannitol permease.


Asunto(s)
Escherichia coli/enzimología , Manitol/metabolismo , Sistema de Fosfotransferasa de Azúcar del Fosfoenolpiruvato/metabolismo , Sitios de Unión , Transporte Biológico , Dimerización , Escherichia coli/genética , Proteínas de Escherichia coli , Fermentación , Prueba de Complementación Genética , Ácido Glutámico/química , Histidina/química , Proteínas de Transporte de Monosacáridos , Mutación , Sistema de Fosfotransferasa de Azúcar del Fosfoenolpiruvato/química , Sistema de Fosfotransferasa de Azúcar del Fosfoenolpiruvato/genética , Fosforilación
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