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1.
Nanotechnology ; 31(37): 375204, 2020 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-32428882

RESUMEN

Palladium diselenide ([Formula: see text]) is a recently isolated layered material that has attracted a lot of interest for its pentagonal structure, air stability and electrical properties that are largely tunable by the number of layers. In this work, multilayer [Formula: see text] is used as the channel of back-gate field-effect transistors, which are studied under repeated electron irradiations. Source-drain [Formula: see text] electrodes enable contacts with resistance below [Formula: see text]. The transistors exhibit a prevailing n-type conduction in high vacuum, which reversibly turns into ambipolar electric transport at atmospheric pressure. Irradiation by [Formula: see text] electrons suppresses the channel conductance and promptly transforms the device from n-type to p-type. An electron fluence as low as [Formula: see text] dramatically changes the transistor behavior, demonstrating a high sensitivity of [Formula: see text] to electron irradiation. The sensitivity is lost after a few exposures, with a saturation condition being reached for fluence higher than [Formula: see text]. The damage induced by high electron fluence is irreversible as the device persists in the radiation-modified state for several hours, if kept in vacuum and at room temperature. With the support of numerical simulation, we explain such a behavior by electron-induced Se atom vacancy formation and charge trapping in slow trap states at the [Formula: see text] interface.

2.
Nutr Metab Cardiovasc Dis ; 23(4): 389-93, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22796347

RESUMEN

BACKGROUND AND AIM: Non-alcoholic fatty liver disease (NAFLD) has been found to be strongly related to an increased arterial stiffness in patients with essential hypertension, suggesting a pathophysiologic link between major cardiovascular and metabolic abnormalities associated with liver steatosis and the functional and structural alterations of the arterial wall. The aim of our study was to investigate, in a group of essential hypertensive patients without additional cardiovascular risk factors, the relationship between NAFLD and arterial stiffness. METHODS AND RESULTS: Sixty-eight consecutive patients with essential hypertension underwent 24-h ambulatory blood pressure monitoring (ABPM) and were separated according to the presence (n = 40) or absence (n = 28) of NAFLD at liver ultrasonography. The Ambulatory Arterial Stiffness Index (AASI) and Symmetric AASI (Sym-AASI) were derived from ABPM tracings. Patients with diabetes, obesity, hyperlipidaemia or other risk factors for cardiovascular or liver disease were excluded. Hypertensive patients were compared with a normotensive control group.The two hypertensive groups had comparable age, sex distribution and clinic/ABPM blood pressure levels. In hypertensive patients with NAFLD, body mass index, fasting glucose, insulin, homeostasis model of assessment of insulin resistance index and triglyceride levels were higher, whereas plasma adiponectin was lower than in patients without NAFLD. In hypertensive patients, AASI and Sym-AASI were higher (P < 0.001) than in normotensive subjects, but both indices of vascular stiffness were comparable in patients with and without NAFLD. CONCLUSIONS: In essential hypertensive patients without additional cardiovascular risk factors, NAFLD is associated with insulin resistance but not with increased arterial stiffness.


Asunto(s)
Hígado Graso/fisiopatología , Hipertensión/fisiopatología , Rigidez Vascular , Adulto , Análisis de Varianza , Presión Arterial , Monitoreo Ambulatorio de la Presión Arterial , Estudios de Casos y Controles , Estudios Transversales , Hígado Graso/diagnóstico por imagen , Hígado Graso/epidemiología , Femenino , Humanos , Hipertensión/diagnóstico , Hipertensión/epidemiología , Resistencia a la Insulina , Italia/epidemiología , Masculino , Persona de Mediana Edad , Enfermedad del Hígado Graso no Alcohólico , Valor Predictivo de las Pruebas , Prevalencia , Medición de Riesgo , Factores de Riesgo , Ultrasonografía
3.
Nat Genet ; 4(3): 272-9, 1993 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-8358436

RESUMEN

We have developed a 32-interval deletion panel for human chromosome Xp22 spanning about 30 megabases of genomic DNA. DNA samples from 50 patients with chromosomal rearrangements involving Xp22 were tested with 60 markers using a polymerase chain reaction strategy. The ensuing deletion map allowed us to confirm and refine the order of previously isolated and newly developed markers. Our mapping panel will provide the framework for mapping new sequences, for orienting chromosome walks in the region and for projects aimed at isolating genes responsible for diseases mapping to Xp22.


Asunto(s)
Mapeo Cromosómico , Eliminación de Secuencia , Cromosoma X , Secuencia de Bases , Línea Celular , Fragilidad Cromosómica , ADN/genética , Sondas de ADN , Femenino , Marcadores Genéticos , Humanos , Masculino , Datos de Secuencia Molecular , Lugares Marcados de Secuencia
4.
G Ital Med Lav Ergon ; 34(3 Suppl): 226-8, 2012.
Artículo en Italiano | MEDLINE | ID: mdl-23405626

RESUMEN

The reform of mandatory employment in Italy, performed by the national Law 68/99, represented a crucial step for the assertion of the right to work for disabled people. The aim of our experience is to obtain information about health and safety conditions of disabled people employed in targeted workplaces and about the issues for that workers keep or lose their job, possibly in order to take actions on workplaces and to improve job conditions for all other workers also. In this paper we used data regarding targeted employments of disabled people, collected during the year 2008 in the Province of Florence.


Asunto(s)
Personas con Discapacidad/legislación & jurisprudencia , Empleo/legislación & jurisprudencia , Adulto , Femenino , Humanos , Italia , Masculino
5.
Hernia ; 26(1): 325-334, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-33797680

RESUMEN

PURPOSE: Low-cost meshes (LCM) were repurposed for the repair of hernias in the developing world. In vivo studies have shown LCM to have comparable results to commercial meshes (CM) at a fraction of the cost. However, little has been done to characterise the mechanical and biocompatible properties of LCM, preventing its clinical use in the UK. The objectives of the research are to assess mechanical and ultrastructural properties of two UK-sourced low-cost meshes (LCM) and the characterisation of the LCMs in vitro biocompatibility. METHODS: Mechanical properties of the two LCM were measured through uniaxial tensile test and ultrastructure was evaluated with Scanning Electron Microscopy. LIVE/DEAD® Viability/Cytotoxicity Assay kit and alamarBlue were used to assess cellular viability and proliferation, respectively. Images were acquired with a fluorescence microscope and analysed using ImageJ (NIH, USA). RESULTS: LCM1 and LCM2 were both multifilament meshes, with the first having smaller pores than the latter. LCM1 exhibited significantly higher tensile strength (p < 0.05) than LCM2 but significantly lower extensibility (p < 0.0001), while Young's Modulus of the two samples was not significantly different. No significant difference was found in the cellular viability and morphology cultured in LCM1 and LCM2 conditioned media. Metabolic assay and fluorescence imaging showed cellular attachment and proliferation on both LCMs over 14 days. CONCLUSION: The characterisation of the two UK-sourced LCMs showed in vitro biocompatibility and mechanical and ultrastructural properties comparable to the equivalent CM. This in vitro data represents a step forward for the feasibility of adopting LCM for surgical repair of hernias in the UK.


Asunto(s)
Herniorrafia , Mallas Quirúrgicas , Hernia , Humanos , Ensayo de Materiales , Resistencia a la Tracción , Reino Unido
6.
J Neural Eng ; 17(4): 046030, 2020 08 11.
Artículo en Inglés | MEDLINE | ID: mdl-32780719

RESUMEN

OBJECTIVE: Poor clinical outcomes following peripheral nerve injury (PNI) are partly attributable to the limited rate of neuronal regeneration. Despite numerous potential drug candidates demonstrating positive effects on nerve regeneration rate in preclinical models, no drugs are routinely used to improve restoration of function in clinical practice. A key challenge associated with clinical adoption of drug treatments in nerve injured patients is the requirement for sustained administration of doses associated with undesirable systemic sideeffects. Local controlled-release drug delivery systems could potentially address this challenge, particularly through the use of biomaterials that can be implanted at the repair site during the microsurgical repair procedure. APPROACH: In order to test this concept, this study used various biomaterials to deliver ibuprofen sodium or sulindac sulfide locally in a controlled manner in a rat sciatic nerve injury model. Following characterisation of release parameters in vitro, ethylene vinyl acetate tubes or polylactic-co-glycolic acid wraps, loaded with ibuprofen sodium or sulindac sulfide, were placed around directly-repaired nerve transection or nerve crush injuries in rats. MAIN RESULTS: Ibuprofen sodium, but not sulindac sulfide caused an increase in neurites in distal nerve segments and improvements in functional recovery in comparison to controls with no drug treatment. SIGNIFICANCE: This study showed for the first time that local delivery of ibuprofen sodium using biomaterials improves neurite growth and functional recovery following PNI and provides the basis for future development of drug-loaded biomaterials suitable for clinical translation.


Asunto(s)
Materiales Biocompatibles , PPAR gamma/agonistas , Traumatismos de los Nervios Periféricos , Neuropatía Ciática , Animales , Liberación de Fármacos , Regeneración Nerviosa , Traumatismos de los Nervios Periféricos/tratamiento farmacológico , Ratas , Nervio Ciático , Neuropatía Ciática/tratamiento farmacológico
7.
Endoscopy ; 41(11): 997-1000, 2009 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19802777

RESUMEN

Endoscopic submucosal dissection is a difficult procedure with frequent complications. Our aim was to test the feasibility of utilizing a second endoscopic arm to improve the dissection. An Olympus prototype blind probe, with an external diameter of 6 mm and a 2.8-mm working channel, was used as a second endoscopic arm. Its purpose was to lift the lesion during dissection. The main endoscope served both to perform the dissection and to visualize the second endoscopic arm in the monitor. Eight patients with polypoid lesions in the rectum or distal sigmoid were treated successfully. The procedure was feasible, and submucosal exposure was ameliorated allowing easier dissection. The resection was curative in all cases. No recurrences have been detected during up to 18-months of follow-up. A small perforation and two cases of delayed bleeding were managed nonsurgically. Applying counter-traction with a second endoscopic arm can facilitate submucosal dissection of distal colorectal lesions.


Asunto(s)
Recto/cirugía , Enfermedades del Sigmoide/cirugía , Sigmoidoscopios , Sigmoidoscopía/métodos , Anciano , Estudios de Factibilidad , Femenino , Humanos , Mucosa Intestinal/cirugía , Masculino , Persona de Mediana Edad , Resultado del Tratamiento
8.
Gen Hosp Psychiatry ; 58: 77-82, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30965163

RESUMEN

OBJECTIVE: This study established a link between intimate partner violence (IPV) and eating disorders (EDs) via mediators of depression and posttraumatic stress disorder (PTSD) symptoms in female veterans. METHOD: A nationally representative sample of female veterans (N = 190, Mean age = 48.41 years) completed online surveys assessing IPV and symptoms of depression, PTSD, and EDs, at three time points from 2014 to 2017. RESULTS: Approximately 14.11% of participants met criteria for any ED (7.83% Bulimia Nervosa; 6.28% Binge Eating Disorder), and 49.42% reported lifetime histories of IPV. Eating disorder symptoms were significantly associated with lifetime IPV, PTSD and depression symptoms at the bivariate level. Mediation model results revealed that lifetime IPV was indirectly associated with EDDS scores, via PTSD symptoms and depression symptoms. CONCLUSION: Findings confirmed elevated rates of probable EDs and lifetime IPV among female veterans; significant associations between EDs, lifetime IPV, depression, and PTSD; and mediation of the association between IPV and EDs by PTSD and depression symptoms. Implications for screening, treatment and research are discussed.


Asunto(s)
Trastorno Depresivo/epidemiología , Trastornos de Alimentación y de la Ingestión de Alimentos/epidemiología , Violencia de Pareja/estadística & datos numéricos , Trastornos por Estrés Postraumático/epidemiología , Veteranos/estadística & datos numéricos , Adulto , Comorbilidad , Correlación de Datos , Estudios Transversales , Trastorno Depresivo/psicología , Trastornos de Alimentación y de la Ingestión de Alimentos/psicología , Femenino , Humanos , Violencia de Pareja/psicología , Persona de Mediana Edad , Trastornos por Estrés Postraumático/psicología , Estados Unidos , Veteranos/psicología
9.
Endocrine ; 60(1): 129-137, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-28702887

RESUMEN

INTRODUCTION: Primary hyperparathyroidism is associated with a cluster of cardiovascular manifestations, including hypertension, leading to increased cardiovascular risk. PURPOSE: The aim of our study was to investigate the ambulatory blood pressure monitoring-derived short-term blood pressure variability in patients with primary hyperparathyroidism, in comparison with patients with essential hypertension and normotensive controls. METHODS: Twenty-five patients with primary hyperparathyroidism (7 normotensive,18 hypertensive) underwent ambulatory blood pressure monitoring at diagnosis, and fifteen out of them were re-evaluated after parathyroidectomy. Short-term-blood pressure variability was derived from ambulatory blood pressure monitoring and calculated as the following: 1) Standard Deviation of 24-h, day-time and night-time-BP; 2) the average of day-time and night-time-Standard Deviation, weighted for the duration of the day and night periods (24-h "weighted" Standard Deviation of BP); 3) average real variability, i.e., the average of the absolute differences between all consecutive BP measurements. RESULTS: Baseline data of normotensive and essential hypertension patients were matched for age, sex, BMI and 24-h ambulatory blood pressure monitoring values with normotensive and hypertensive-primary hyperparathyroidism patients, respectively. Normotensive-primary hyperparathyroidism patients showed a 24-h weighted Standard Deviation (P < 0.01) and average real variability (P < 0.05) of systolic blood pressure higher than that of 12 normotensive controls. 24-h average real variability of systolic BP, as well as serum calcium and parathyroid hormone levels, were reduced in operated patients (P < 0.001). A positive correlation of serum calcium and parathyroid hormone with 24-h-average real variability of systolic BP was observed in the entire primary hyperparathyroidism patients group (P = 0.04, P = 0.02; respectively). CONCLUSION: Systolic blood pressure variability is increased in normotensive patients with primary hyperparathyroidism and is reduced by parathyroidectomy, and may potentially represent an additional cardiovascular risk factor in this disease.


Asunto(s)
Presión Sanguínea/fisiología , Hiperparatiroidismo Primario/fisiopatología , Adulto , Anciano , Monitoreo Ambulatorio de la Presión Arterial , Estudios Transversales , Femenino , Humanos , Hiperparatiroidismo Primario/cirugía , Masculino , Persona de Mediana Edad , Paratiroidectomía
10.
Endoscopy ; 39(9): 813-7, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17703391

RESUMEN

BACKGROUND AND STUDY AIMS: Biliary stents have been found to interfere with endoscopic ultrasound (EUS) tumor (T) and nodal (N) staging in patients with periampullary cancer. Our aim was to determine whether this also occurs in patients with pancreatic head cancer. PATIENTS AND METHODS: We studied a consecutive series of patients who were undergoing preoperative EUS for diagnosis and staging of suspected pancreatic cancer, some of whom had biliary stents in situ and some of whom did not. The main end point was the uni- and multivariate association of biliary stenting with T and N mis-staging by EUS. The surgical T and N stages were used as gold standards. RESULTS: A total of 65 patients were identified (19 with biliary stents in situ and 46 without). Surgical stage T4 was found more frequently in patients with stents (53% vs. 22%, P = 0.014). The T stage by EUS was correct in 85% of the patients without biliary stents and in 47% of the patients with stents. The frequency of mis-staging by EUS was significant only among patients with a biliary stent. The distribution by EUS N stage did not differ significantly from the surgical N-stage distribution in the two groups of patients. According to the multivariate analysis, patients with stents were 6.55 times more likely to be incorrectly T staged (95% confidence interval [CI] 1.69-25.49) and 3.71 times more likely to be incorrectly N staged (95% CI 1.11-12.45) than patients without stents. CONCLUSIONS: The results add support to the recommendation that EUS staging of pancreatic head neoplasms should be performed prior to stent placement.


Asunto(s)
Conductos Biliares , Endosonografía , Neoplasias Pancreáticas/diagnóstico por imagen , Stents/efectos adversos , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Neoplasias Pancreáticas/patología , Reproducibilidad de los Resultados
11.
Biomech Model Mechanobiol ; 6(3): 139-50, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16506020

RESUMEN

The integrity of articular cartilage depends on the proper functioning and mechanical stimulation of chondrocytes, the cells that synthesize extracellular matrix and maintain tissue health. The biosynthetic activity of chondrocytes is influenced by genetic factors, environmental influences, extracellular matrix composition, and mechanical factors. The mechanical environment of chondrocytes is believed to be an important determinant for joint health, and chondrocyte deformation in response to mechanical loading is speculated to be an important regulator of metabolic activity. In previous studies of chondrocyte deformation, articular cartilage was described as a biphasic material consisting of a homogeneous, isotropic, linearly elastic solid phase, and an inviscid fluid phase. However, articular cartilage is known to be anisotropic and inhomogeneous across its depth. Therefore, isotropic and homogeneous models cannot make appropriate predictions for tissue and cell stresses and strains. Here, we modelled articular cartilage as a transversely isotropic, inhomogeneous (TI) material in which the anisotropy and inhomogeneity arose naturally from the microstructure of the depth-dependent collagen fibril orientation and volumetric fraction, as well as the chondrocyte shape and volumetric fraction. The purpose of this study was to analyse the deformation behaviour of chondrocytes using the TI model of articular cartilage. In order to evaluate our model against experimental results, we simulated indentation and unconfined compression tests for nominal compressions of 15%. Chondrocyte deformations were analysed as a function of location within the tissue. The TI model predicted a non-uniform behaviour across tissue depth: in indentation testing, cell height decreased by 43% in the superficial zone and between 11 and 29% in the deep zone. In unconfined compression testing, cell height decreased by 32% in the superficial zone, 25% in the middle, and 18% in the deep zones. This predicted non-uniformity is in agreement with experimental studies. The novelty of this study is the use of a cartilage material model accounting for the intrinsic inhomogeneity and anisotropy of cartilage caused by its microstructure.


Asunto(s)
Fenómenos Biomecánicos/métodos , Biofisica/métodos , Cartílago Articular/química , Condrocitos/fisiología , Animales , Anisotropía , Colágeno/química , Fuerza Compresiva , Elasticidad , Humanos , Modelos Biológicos , Modelos Estadísticos , Modelos Teóricos
12.
Drugs Today (Barc) ; 53(7): 393-397, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28837183

RESUMEN

The objective of this review was to collect reports of keratitis in association with herpes zoster virus (HZV) or varicella zoster virus (VZV) vaccines. HZV vaccination is intended for at-risk adult populations and VZV vaccination is intended for all pediatric patients. We reviewed the literature and reports of keratitis in association with herpes zoster or varicella vaccine from the National Registry of Drug-Induced Ocular Side Effects and the World Health Organization. Twenty-four cases of unilateral keratitis in association with VZV vaccines were collected from the adverse reaction databases and literature. In most cases, the onset of keratitis occurred within days of vaccination and resolved with topical steroid eye drops and oral acyclovir. Data suggest that keratitis in association with herpes zoster or varicella vaccine is rare, is usually self-limited or resolves with treatment. The mechanism may be the persistence of viral antigens in the cornea after VZV vaccination or herpes zoster ophthalmicus. This reaction is probable, given the plausible biological mechanism, the temporal relationship between vaccination and keratitis, and overall patterns of presentation after vaccination.


Asunto(s)
Vacuna contra la Varicela/efectos adversos , Herpesvirus Humano 3/patogenicidad , Queratitis/inmunología , Queratitis/virología , Vacunación/efectos adversos , Adolescente , Antivirales/uso terapéutico , Vacuna contra la Varicela/inmunología , Niño , Preescolar , Femenino , Herpes Zóster Oftálmico/complicaciones , Herpes Zóster Oftálmico/tratamiento farmacológico , Herpes Zóster Oftálmico/virología , Herpesvirus Humano 3/efectos de los fármacos , Humanos , Queratitis/tratamiento farmacológico , Queratitis/etiología , Masculino
13.
Philos Trans A Math Phys Eng Sci ; 375(2093)2017 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-28373381

RESUMEN

We prove theoretically that when a soft solid is subjected to an extreme deformation, wrinkles can form on its surface at an angle that is oblique to a principal direction of stretch. These oblique wrinkles occur for a strain that is smaller than the one required to obtain wrinkles normal to the direction of greatest compression. We go on to explain why they will probably never be observed in real-world experiments.This article is part of the themed issue 'Patterning through instabilities in complex media: theory and applications.'

14.
Int J Immunopathol Pharmacol ; 19(3): 647-59, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17026850

RESUMEN

It is well known that change in apoptosis may modulate the natural story of illness, and that many drugs may act through modulation of apoptosis, but the role of steroids in acting through apoptosis in different settings, including renal diseases, has still to be elucidated. We studied the in vivo effects of steroids by oral assumption (10 to 25 mg/deltacortene) or by intravenous pulses (300 to 1000 mg/dose) on apoptosis and cellular subsets of peripheral lymphocytes, by evaluating DNA-fragmentation and lymphocyte subsets in 79 subjects: 22 controls and 57 patients with various renal diseases (25 Lupus-GN, 19 membranous-GN (MGN), 6 rapidly progressive-GN (RPGN), 2 acute interstitial nephritis (AIN), 5 on chronic dialysis. Baseline apoptosis was present in 1/22 (4.5%) of controls, 3/25 (12%) SLE, 2/6 (33.3%) RPGN and 10/19 (52.6%) MGN. A significant decrease in CD3+CD8+ cell count and a significant increase of the CD3+CD4/CD3+CD8+ ratio were found in apoptosis-positive subjects. DNA fragmentation did not change after oral steroids, paralleling a 22 to 32% decrease in total lymphocytes. Following intravenous methylprednisolone pulses, a deeper drop of all lymphocyte subsets was observed, while DNA fragmentation turned from present to absent in 2 MGN, but not in 2 RPGN, and from absent to present in 1 ARF and 1 SLE, independently of the dosage. We demonstrated that the presence of apoptosis in renal diseases is associated with decreased CD3+CD8+ cell count. Furthermore, steroid intravenous pulses, besides inducing a profound decrease in lymphocyte subsets, do exert a dual effect on baseline leukocyte apoptosis, eventually leading to a reversal of baseline patterns, either turning from negative to positive or from positive to negative. Oral steroid therapy did not influence baseline apoptosis.


Asunto(s)
Apoptosis/efectos de los fármacos , Enfermedades Renales/tratamiento farmacológico , Leucocitos/efectos de los fármacos , Metilprednisolona/farmacología , Adulto , Complejo CD3/análisis , Ritmo Circadiano , Femenino , Humanos , Enfermedades Renales/inmunología , Enfermedades Renales/patología , Leucocitos/citología , Masculino , Metilprednisolona/administración & dosificación , Persona de Mediana Edad , Estudios Prospectivos , Subgrupos de Linfocitos T/efectos de los fármacos
15.
Eur Rev Med Pharmacol Sci ; 10(1): 7-11, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-16494104

RESUMEN

Patients with inflammatory bowel disease (IBD) have an increased risk of thrombotic complications. Arterial and venous system may be involved. Moreover, mesenteric microvascular thrombosis has been hypothesised as a contributing factor in the pathogenesis of IBD. Early atherosclerosis is a clinical feature common to several inflammatory and immunological diseases in which atherothrombotic complication represents one of the most important cause of mortality and morbidity. We investigate the prevalence and the entity of the early stages of vascular disease in a population of IBD patients without the classical cardiovascular risk factors, by measuring the intima-media thickness (IMT) of the common carotid artery. We found that IBD patients have an increased risk of early atherosclerosis than healthy controls as showed by greater values of carotid IMT and that homocysteine levels and age were independently associated with the increased arterial wall thickness.


Asunto(s)
Aterosclerosis/etiología , Arterias Carótidas/patología , Colitis Ulcerosa/complicaciones , Enfermedad de Crohn/complicaciones , Factores de Edad , Aterosclerosis/epidemiología , Aterosclerosis/patología , Arterias Carótidas/diagnóstico por imagen , Estudios de Casos y Controles , Colitis Ulcerosa/epidemiología , Colitis Ulcerosa/patología , Enfermedad de Crohn/epidemiología , Enfermedad de Crohn/patología , Homocisteína/metabolismo , Humanos , Túnica Íntima/patología , Túnica Media/patología , Ultrasonografía
16.
J Mol Biol ; 295(1): 17-28, 2000 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-10623505

RESUMEN

The DNA-binding properties of two super-repressor mutants of the Escherichia coli trp repressor, EK18 and AV77, have been investigated using steady-state fluorescence anisotropy measurements, in order to further elucidate the basis for their super-repressor phenotypes. Several suggestions have been previously proposed as the basis for the super-repressor phenotype of EK18 and AV77. For the negative to positive charge change EK18 mutant, increased electrostatic interactions between the EK18 mutant and the operator and increased protein-protein interactions between EK18 dimers have been suggested as contributing to the super-repressor phenotype of this mutant. We show that EK18 dimers actually bind to wild-type and variant operator sequences with a decrease in apparent cooperativity and an increase in affinity, compared to WTTR dimers. Thus, the EK18 super-repressor phenotype is not due to increased cooperative binding between EK18 dimers. These results support the hypothesis that the super-repressor phenotype of EK18 arises from increased electrostatic interactions between the mutant and DNA. In the case of the AV77 mutant, weaker binding affinity of apo-AV77 to non-specific DNA, increased selectivity of binding of AV77 for the operator, and a higher population of folded functional AV77 dimers available to bind the operator under limiting L-Trp conditions in vivo, have been proposed for the super-repressor phenotype of this mutant. We show that like the EK18 mutant, apoAV77 binds with higher affinity to non-specific DNA compared to apo-WTTR and that the holo-AV77 mutant does not bind with higher selectivity to the operator, has had been previously proposed. We therefore conclude that the super-repressor phenotype of the AV77 mutant is due to an increase in the population of folded, functional AV77 dimers, under limiting L-Trp conditions in vivo.


Asunto(s)
Mutación/genética , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Apoproteínas/química , Apoproteínas/genética , Apoproteínas/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Secuencia de Bases , Sitios de Unión , ADN/genética , ADN/metabolismo , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Dimerización , Escherichia coli , Fluoresceína/metabolismo , Polarización de Fluorescencia , Modelos Moleculares , Oligodesoxirribonucleótidos/genética , Oligodesoxirribonucleótidos/metabolismo , Regiones Operadoras Genéticas/genética , Operón/genética , Fenotipo , Proteínas Represoras/química , Electricidad Estática , Termodinámica , Triptófano/metabolismo
17.
J Mol Biol ; 287(3): 539-54, 1999 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-10092458

RESUMEN

The bacterial repressor protein, trp repressor, is one of the best studied transcriptional regulatory proteins in terms of function, structure, dynamics and stability. Despite these significant advances, the structural and energetic basis for the specific recognition of its operator sites by trp repressor remains poorly understood. In fact, recognition in this system is controled by the binding of the co-repressor ligand, l-tryptophan, as well as by conformational and dynamic properties of the operator targets, DNA sequence-dependent control of the oligomerization properties of the repressor, water-mediated interactions, and specific interactions involving the peptide backbone and phosphate moieties. Moreover, only one direct contact between the protein and the DNA is evident from the crystallographically determined structure of the complex. In an attempt to better define how the various sequence elements in the operator target contribute to this complex control of affinity and cooperativity of trp repressor binding, we have studied the binding of trp repressor to a series of mutated operator targets using fluorescence anisotropy, which provides very high quality data allowing fairly precise estimations of the affinities involved. We conclude from these studies that even on very small (25 bp) targets, the repressor binds slightly cooperatively, populating a 2:1 dimer/DNA complex, and then at higher concentrations a third dimer is bound with significantly lower affinity, revealing an inherent asymmetry in the trpEDCBA-derived target. Investigation of the basis for the asymmetry implicates the identity of the second base in the so-called structural half-site GNACT, which apparently influences the switch between tandem and simple binding. Mutation of the C or the T bases in the structural half-site abolishes all specificity in binding, and alteration of the single direct contact, the G of the structural half-site, or the central TTAA significantly lowers the affinity of the dimer for its site, without modifying the apparent cooperativity. Finally, we note that the order of affinity is conserved in the absence of the co-repressor, and moreover, it is in all cases significantly higher than that observed for holo-repressor binding to non-specific DNA, indicating that one cannot simply equate apo-repressor and non-specific binding.


Asunto(s)
Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Regiones Operadoras Genéticas , Proteínas Represoras/química , Proteínas Represoras/metabolismo , Proteínas Bacterianas/genética , Secuencia de Bases , Sitios de Unión/genética , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Bacteriano/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Secuencias Hélice-Giro-Hélice , Sustancias Macromoleculares , Modelos Biológicos , Modelos Moleculares , Mutación , Conformación de Ácido Nucleico , Unión Proteica , Conformación Proteica , Proteínas Represoras/genética , Termodinámica , Triptófano/metabolismo
18.
J Mol Biol ; 273(3): 572-85, 1997 Oct 31.
Artículo en Inglés | MEDLINE | ID: mdl-9356247

RESUMEN

Fluorescence-based solution methods have been used to study the binding of the trp repressor of Escherichia coli to a series of oligonucleotides bearing all or partial determinants for high affinity specific binding. The tryptophan, salt concentration and competitor DNA dependence of the binding affinities was examined for these targets. Binding to a fluorescein-labeled 20 base-pair hairpin structure oligonucleotide, which contains a palindromic repressor binding site (GAACTAGTTAACTAGTAC) and is known to bind repressor in a 1 : 1 dimer-DNA complex, resulted in a protein concentration-dependent, competable static quenching of fluorescence in presence of co-repressor, l-tryptophan. The affinity recovered from the fits of these intensity profiles at 100 mM KCl was on the order of 4x10(8) M-1. In absence of co-repressor an increase in intensity at high repressor concentration (>10(-7) M) was observed. The salt concentration dependence of the specific binding of the holo-repressor to this oligonucleotide was approximately half as large as what would be predicted by the number of phosphate contacts in the crystal structures of the complex. Repressor binding to the fluorescein-labeled hairpin 20mer was compared with binding to a rhodamine-labeled 36 base-pair oligonucleotide bearing two inverted structural half-sites GNACT separated by an eight base-pair spacer containing none of the natural intervening sequence. The rather low affinity observed for the 36mer revealed that the intervening sequence in the natural operators contains energetic specificity determinants. Binding to a rhodamine-labeled oligonucleotide bearing a completely non-specific sequence was shown to occur over the same concentration range (>100 nM), regardless of tryptophan concentration, whereas binding to sequences bearing partial specificity ratio between 100 and 1000, depending upon the salt concentration. Even in absence of added KCl, the specificity ratio of trp repressor was greater than 100, implicating a significant free energy contribution from non-electrostatic interaction forces.


Asunto(s)
Proteínas Bacterianas/metabolismo , ADN/metabolismo , Escherichia coli/metabolismo , Proteínas Represoras/metabolismo , Triptófano/metabolismo , Proteínas Bacterianas/química , Sitios de Unión , Escherichia coli/genética , Fluoresceína/metabolismo , Colorantes Fluorescentes , Humanos , Conformación de Ácido Nucleico , Oligodesoxirribonucleótidos/química , Oligodesoxirribonucleótidos/metabolismo , Cloruro de Potasio/farmacología , Conformación Proteica , Proteínas Represoras/química , Rodaminas/metabolismo , Relación Estructura-Actividad , Triptófano/farmacología
19.
Aliment Pharmacol Ther ; 22(9): 839-46, 2005 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-16225493

RESUMEN

BACKGROUND: Patients with inflammatory bowel disease have an increased risk of thrombotic complications; moreover, mesenteric microvascular thrombosis has been hypothesized as a contributing factor in the pathogenesis of inflammatory bowel disease. AIM: To assess the extent of subclinical atherosclerosis in inflammatory bowel disease by measuring the intima-media thickness of the common carotid artery. METHODS: Fifty-two patients were enrolled in the study. Patients aged >45 years, with a history of cardiovascular disease and known risk factors for atherosclerosis were excluded from the study. Twenty healthy subjects were studied as controls. Carotid ultrasonography was performed in all patients and controls. intima-media thickness was measured proximal to the carotid bifurcation over both right and left common carotid arteries. The clinical characteristics and the laboratory parameters relevant to disease activity were recorded for all inflammatory bowel disease patients. In particular, plasma homocysteine, a well-known risk factor for thrombosis, was assessed. RESULTS: Common carotid artery intima-media thickness was significantly higher in inflammatory bowel disease patients (0.63 +/- 0.15 mm) compared with controls (0.53 +/- 0.08 mm). Multiple regression analysis revealed a significant association of carotid intima-media thickness with homocysteine levels and age. CONCLUSIONS: Inflammatory bowel disease patients have an increased risk of early atherosclerosis than healthy controls as showed by greater values of carotid intima-media thickness. Homocysteine levels and age resulted independently associated with the increased arterial wall thickness.


Asunto(s)
Arteria Carótida Común/diagnóstico por imagen , Enfermedades Inflamatorias del Intestino/diagnóstico por imagen , Túnica Íntima/diagnóstico por imagen , Adulto , Anticuerpos Monoclonales/uso terapéutico , Presión Sanguínea/fisiología , Sedimentación Sanguínea , Proteína C-Reactiva/análisis , Enfermedades de las Arterias Carótidas/sangre , Enfermedades de las Arterias Carótidas/diagnóstico por imagen , Enfermedades de las Arterias Carótidas/etiología , Arteria Carótida Común/patología , Colesterol/sangre , Femenino , Fármacos Gastrointestinales/uso terapéutico , Homocisteína/sangre , Humanos , Enfermedades Inflamatorias del Intestino/sangre , Enfermedades Inflamatorias del Intestino/tratamiento farmacológico , Infliximab , Masculino , Factores de Riesgo , Túnica Íntima/patología , Ultrasonografía
20.
Dig Liver Dis ; 37(5): 320-9, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-15843081

RESUMEN

BACKGROUND AND AIMS: Probiotics have been used for cure and prevention of several clinical conditions. However, further insights into the mechanism of action are needed to understand the rationale of their use. The aim of this study was to investigate the influence of Lactobacillus GG on the genetic expression patterns in the small bowel mucosa. METHODS: Six male patients (38+/-5 years) with endoscopically proven oesophagitis were enrolled. All patients were treated for 1 month with esomeprazole and randomised to receive Lactobacillus GG or placebo. After 1 month of treatment, upper endoscopy was repeated. Biopsies of the duodenal mucosa were taken prior to and after the treatment, and the genes expression patterns were assessed using GeneChip Human U133A array. Genes with significant expression changes were selected and analysed to identify specific cellular pathways modified by Lactobacillus GG. To support the array data, 10 target genes were studied using Syber-Green PCR. RESULTS: Microarray analysis showed that Lactobacillus GG administration determined the up- and down-regulation of 334 and 92 genes, respectively. Real-time PCR confirmed the reliability of the analysis. Lactobacillus GG mainly affected the expression of genes involved in immune response and inflammation (TGF-beta and TNF family members, cytokines, nitric oxide synthase 1, defensin alpha 1), apoptosis, cell growth and cell differentiation (cyclins and caspases, oncogenes), cell-cell signalling (ICAMs and integrins), cell adhesion (cadherins), signal transcription and transduction. CONCLUSIONS: These data indicate that administration of Lactobacillus GG is associated with a complex genetic response of the duodenal mucosa, reflected by the up- and down-regulation of several genes involved in specific cellular pathways.


Asunto(s)
Esofagitis/genética , Perfilación de la Expresión Génica , Expresión Génica/efectos de los fármacos , Mucosa Intestinal/metabolismo , Lactobacillus , Probióticos/farmacología , Adulto , Regulación hacia Abajo/efectos de los fármacos , Células Epiteliales , Esofagitis/tratamiento farmacológico , Humanos , Inflamación/genética , Masculino , Óxido Nítrico Sintasa , Óxido Nítrico Sintasa de Tipo II , Análisis de Secuencia por Matrices de Oligonucleótidos , Regulación hacia Arriba/efectos de los fármacos
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