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The lack of large-area synthesis processes on substrates compatible with industry requirements has been one of the major hurdles facing the integration of 2D materials in mainstream technologies. This is particularly the case for the recently discovered monoelemental group V 2D materials which can only be produced by exfoliation or growth on exotic substrates. Herein, to overcome this limitation, we demonstrate a scalable method to synthesize antimonene on germanium substrates using solid-source molecular beam epitaxy. This emerging 2D material has been attracting a great deal of attention due to its high environmental stability and its outstanding optical and electronic properties. In situ low energy electron microscopy allowed the real time investigation and optimization of the 2D growth. Theoretical calculations combined with atomic-scale microscopic and spectroscopic measurements demonstrated that the grown antimonene sheets are of high crystalline quality, interact weakly with germanium, exhibit semimetallic characteristics, and remain stable under ambient conditions. This achievement paves the way for the integration of antimonene in innovative nanoscale and quantum technologies compatible with the current semiconductor manufacturing.
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The quantum Hall effect is observed in a two-dimensional electron gas formed in millimeter-scale hydrogenated graphene, with a mobility less than 10 cm2/V·s and corresponding Ioffe-Regel disorder parameter (k(F)λ)(-1) â« 1. In a zero magnetic field and low temperatures, the hydrogenated graphene is insulating with a two-point resistance of the order of 250h/e2. The application of a strong magnetic field generates a negative colossal magnetoresistance, with the two-point resistance saturating within 0.5% of h/2e2 at 45 T. Our observations are consistent with the opening of an impurity-induced gap in the density of states of graphene. The interplay between electron localization by defect scattering and magnetic confinement in two-dimensional atomic crystals is discussed.
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The lateral resolution of a surface sensitive low-energy electron microscope (LEEM) has been improved below 4 nm for the first time. This breakthrough has only been possible by simultaneously correcting the unavoidable spherical and chromatic aberrations of the lens system. We present an experimental criterion to quantify the aberration correction and to optimize the electron optical system. The obtained lateral resolution of 2.6 nm in LEEM enables the first surface sensitive, electron microscopic observation of the herringbone reconstruction on the Au(111) surface.
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Atrial fibrillation (AF) is a highly prevalent arrhythmia and responsible for significant morbidity, mortality and health care cost. The prevalence of AF is expected to increase markedly with the aging population. The use of conventional antiarrhythmic agents has been limited by potentially fatal ventricular proarrhythmia. Rhythm control could become the preferred treatment strategy for AF if antiarrhythmic agents that are similarly or more effective, but safer, than currently approved AF agents become available. A subanalysis of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) trial data showed that normal sinus rhythm confers a survival benefit in AF, suggesting that rhythm control, if achieved without the adverse effects related to current antiarrhythmic medications, may offer a significant survival advantage over rate control. Considerable work has been performed to explore novel, potentially safer antiarrhythmic drug targets for AF therapy, and some of these drug targets are currently being tested in experimental and clinical proof of concept studies. This article summarizes relevant aspects of the cellular electrophysiology of AF and reviews the actions of pharmacological agents being considered for the prevention and treatment of AF, focusing on atrial selective antiarrhythmic agents. A variety of drugs that inhibit the atrium-specific ultra rapid delayed rectifier potassium current (IKur) are being evaluated pre-clinically, but human experience with these agents is limited. The acetylcholine-activated current (IKACh) is another novel candidate target for atrial-specific drug therapy. The constitutively active form of this current is increased in human AF and pharmacological inhibition might be of therapeutic value. Certain drugs have IKACh blocking properties, but similar to IKur-blockers, none have been shown to have pure selectivity for this current. Newer agents being studied also include gap junction modulators and angiotensin-converting enzyme inhibitors. There is great hope that at least some of these agents will ultimately be available for effective and safer clinical treatment and prevention of AF.
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Antiarrítmicos/uso terapéutico , Fibrilación Atrial/tratamiento farmacológico , Fibrilación Atrial/fisiopatología , Electrofisiología Cardíaca , Sistemas de Liberación de Medicamentos , Atrios Cardíacos/efectos de los fármacos , Humanos , Nodo SinoatrialRESUMEN
The absolute cross sections for electronic excitations of thymine by electron impact between 5 and 12 eV are determined by means of electron-energy loss (EEL) spectroscopy for the molecule deposited at submonolayer coverage on an inert Ar substrate. The lowest EEL features at 3.7 and 4.0 eV are attributed to the excitation of the triplet 1 3A'(pi --> pi*) and 1 3A''(n --> pi*) valence states of the molecule. The higher EEL features located at 4.9, 6.3, 7.3, and 9 eV with a weak shoulder around 6 eV are ascribed mostly to triplet valence (pi --> pi*) excitation manifold of the molecule. The energy dependence of the cross section for both the lowest triplet valence excitations shows essentially a peak at about 5 eV reaching a value of 2.9 x 10(-17) cm2. The cross sections for the higher EEL features are generally characterized by a common broad maximum around 8 eV. The latter reaches a value of 1.36 x 10(-16) cm2 for the combined 6 and 6.3 eV excitation region. The maxima in the present cross sections are found to correspond to the resonances that have been reported at about the same energies in the O- yield from electron impact on thymine in the gas phase.
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Modelos Químicos , Dispersión de Radiación , Espectroscopía de Pérdida de Energía de Electrones/métodos , Timina/químicaRESUMEN
Low-energy vibrational and electronic electron-energy-loss (EEL) spectra of pyrimidine condensed on a thin film of solid argon held at 18 K are reported for the incident-energy range of 2-12 eV. Sensitivity to symmetry and spin forbidden transitions as well as correlations to the triplet states of benzene make it possible to ascribe the main features, below 7 eV in the electronic part of the EEL spectrum, to triplet transitions. The lowest EEL feature with an energy onset at 3.5 eV is attributed to a transition to the (3)B(1)(n-->pi(*)) valence electronic state and the next triplet n-->pi(*) transition to a (3)A(2) state located around 4.5 eV. The remaining EEL features at 4.3, 5.2, 5.8, and 6.5 eV are all assigned to pi-->pi(*) transitions to states of symmetry (3)B(2), (3)A(1), (3)B(2), and (3)B(2)+(3)A(1), respectively. The most intense maximum at 7.6 eV is found to correspond to both (1)B(2) and (1)A(1) transitions, as in the vacuum ultraviolet spectra. Absolute inelastic cross sections per scatterer are derived from a single collision treatment described herein. Their values are found to lie within the 10(-17) cm(2) range for both the electronic and the vibrational excitations. Features in the energy dependence of the cross sections are discussed, whenever possible, by comparison with data and mechanisms found in the gas phase. A maximum over the 4-5 eV range is attributed to a B (2)B(1) shape resonance and another one observed in the 6-7 eV range is ascribed to either or both sigma(*) shape resonances of (2)A(1) and (2)B(2) symmetries.
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Multiple delayed rectifier potassium currents, including I(Ks), are responsible for the repolarization and termination of the cardiac action potential, and blockers of these currents may be useful as antiarrhythmic agents. Modification of compound 5 produced 19(S) that is the most potent I(Ks) blocker reported to date with >5000-fold selectivity over other cardiac ion channels. Further modification produced 24A with 23% oral bioavailability.
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Benzamidas/síntesis química , Oxadiazoles/síntesis química , Bloqueadores de los Canales de Potasio , Bloqueadores de los Canales de Potasio/síntesis química , Canales de Potasio con Entrada de Voltaje , Administración Oral , Animales , Benzamidas/química , Benzamidas/farmacología , Disponibilidad Biológica , Cromatografía Líquida de Alta Presión , Cristalografía por Rayos X , Diseño de Fármacos , Técnicas In Vitro , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Oocitos/metabolismo , Oocitos/fisiología , Oxadiazoles/química , Oxadiazoles/farmacología , Técnicas de Placa-Clamp , Bloqueadores de los Canales de Potasio/química , Bloqueadores de los Canales de Potasio/farmacología , Canales de Potasio/metabolismo , Ratas , Estereoisomerismo , Relación Estructura-Actividad , XenopusRESUMEN
Benign familial neonatal convulsions (BFNC), a class of idiopathic generalized epilepsy, is an autosomal dominantly inherited disorder of newborns. BFNC has been linked to mutations in two putative K+ channel genes, KCNQ2 and KCNQ3. Amino acid sequence comparison reveals that both genes share strong homology to KvLQT1, the potassium channel encoded by KCNQ1, which is responsible for over 50% of inherited long QT syndrome. Here we describe the cloning, functional expression, and characterization of K+ channels encoded by KCNQ2 and KCNQ3 cDNAs. Individually, expression of KCNQ2 or KCNQ3 in Xenopus oocytes elicits voltage-gated, rapidly activating K+-selective currents similar to KCNQ1. However, unlike KCNQ1, KCNQ2 and KCNQ3 currents are not augmented by coexpression with the KCNQ1 beta subunit, KCNE1 (minK, IsK). Northern blot analyses reveal that KCNQ2 and KCNQ3 exhibit similar expression patterns in different regions within the brain. Interestingly, coexpression of KCNQ2 and KCNQ3 results in a substantial synergistic increase in current amplitude. Coexpression of KCNE1 with the two channels strongly suppressed current amplitude and slowed kinetics of activation. The pharmacological and biophysical properties of the K+ currents observed in the coinjected oocytes differ somewhat from those observed after injecting either KCNQ2 or KCNQ3 by itself. The functional interaction between KCNQ2 and KCNQ3 provides a framework for understanding how mutations in either channel can cause a form of idiopathic generalized epilepsy.
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Epilepsia Generalizada/genética , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/genética , Canales de Potasio/fisiología , Animales , Encéfalo/metabolismo , Clonación Molecular , Electrofisiología , Regulación de la Expresión Génica/genética , Humanos , Activación del Canal Iónico/fisiología , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Canal de Potasio KCNQ2 , Canal de Potasio KCNQ3 , Microinyecciones , Oocitos/fisiología , Canales de Potasio/metabolismo , ARN Mensajero/metabolismo , XenopusRESUMEN
OBJECTIVES: The sites of recurrent carcinoma of the prostate were localized with radiolabeled monoclonal antibody, and these sites were correlated with the response of patients treated with pelvic radiation after prostatectomy. METHODS: Radionuclide scans were performed with indium 111-labeled CYT-356, a monoclonal antibody that binds to prostate epithelial cells, in 48 men diagnosed with recurrent carcinoma detected by prostate-specific antigen (PSA) screening after radical retropubic prostatectomy. RESULTS: In 48 patients with recurrent carcinoma detected by PSA screening following radical retropubic prostatectomy, 73% had monoclonal antibody activity beyond the prostatic fossa, and only 3 patients (6%) had activity in the prostatic fossa alone; 65% had monoclonal antibody activity in pelvic lymph nodes despite the fact that lymph node dissections were pathologically negative at the time of prostatectomy in 90% of the patients; and 23% of patients had monoclonal antibody activity in abdominal and extrapelvic retroperitoneal nodes. Of 48 patients, 13 underwent external beam radiation therapy after monoclonal antibody scans. Six patients had scans showing activity beyond the field of radiation, and radiation therapy failed in 4 of these patients. Seven patients had scans with no activity beyond the field of radiation therapy, and radiation therapy failed in only 2 of these patients. CONCLUSIONS: The scans frequently show monoclonal antibody uptake in pelvic, abdominal, and extrapelvic retroperitoneal sites beyond the region of limited obturator node dissections and may account for the understaging and subsequent failure of radical prostatectomy in some patients. The monoclonal antibody scan seems to be a good predictor of which patients will respond to radiation therapy after radical prostatectomy, but because these patients often have nodal activity beyond the radiated field, this initial response may not be curative.
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Anticuerpos Monoclonales , Radioisótopos de Indio , Prostatectomía , Neoplasias de la Próstata/diagnóstico por imagen , Adulto , Anciano , Humanos , Masculino , Persona de Mediana Edad , Metástasis de la Neoplasia , Neoplasias de la Próstata/radioterapia , Neoplasias de la Próstata/cirugía , CintigrafíaRESUMEN
BACKGROUND: Mutations that map to the KvLQT1 gene on human chromosome 11 account for more than 50% of inherited long QT syndrome (LQTS). It has been discovered recently that the KvLQT1 and minK proteins functionally interact to generate a current with biophysical properties similar to I(Ks), the slowly activating delayed-rectifier cardiac potassium current. Since I(Ks) modulates the repolarization of cardiac action potentials it is reasonable to hypothesize that mutations in KvLQT1 reduce I(Ks), resulting in the prolongation of cardiac action potential duration. METHODS AND RESULTS: We expressed LQTS-associated KvLQT1 mutants in Xenopus oocytes either individually or in combination with wild-type KvLQT1 or in combination with both wild-type KvLQT1 and minK. Substitutions of alanine with proline in the S2-S3 cytoplasmic loop (A177P) or threonine with isoleucine in the highly conserved signature sequence of the pore (T311I) yield inactive channels when expressed individually, whereas substitution of leucine with phenylalanine in the S5 transmembrane domain (L272F) yields a functional channel with reduced macroscopic conductance. However, all these mutants inhibit wild-type KvLQT1 currents in a dominant-negative fashion. CONCLUSIONS: In LQTS-affected individuals these mutations would be predicted to result in a diminution of the cardiac I(Ks) current, subsequent prolongation of cardiac repolarization, and an increased risk of arrhythmias.
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Síndrome de QT Prolongado/genética , Síndrome de QT Prolongado/fisiopatología , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/genética , Animales , Canales de Calcio/genética , Electrofisiología , Expresión Génica/fisiología , Humanos , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Mutagénesis Sitio-Dirigida , Oocitos/fisiología , Xenopus laevisRESUMEN
The clinical features of long QT syndrome result from episodic life-threatening cardiac arrhythmias, specifically the polymorphic ventricular tachycardia torsades de pointes. KVLQT1 has been established as the human chromosome 11-linked gene responsible for more than 50% of inherited long QT syndrome. Here we describe the cloning of a full-length KVLQT1 cDNA and its functional expression. KVLQT1 encodes a 676-amino acid polypeptide with structural characteristics similar to voltage-gated potassium channels. Expression of KvLQT1 in Xenopus oocytes and in human embryonic kidney cells elicits a rapidly activating, K+-selective outward current. The I(Kr)-specific blockers, E-4031 and dofetilide, do not inhibit KvLQT1, whereas clofilium, a class III antiarrhythmic agent with the propensity to induce torsades de pointes, substantially inhibits the current. Elevation of cAMP levels in oocytes nearly doubles the amplitude of KvLQT1 currents. Coexpression of minK with KvLQT1 results in a conductance with pharmacological and biophysical properties more similar to I(Ks) than other known delayed rectifier K+ currents in the heart.
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Corazón/fisiopatología , Canales de Potasio con Entrada de Voltaje , Canales de Potasio/fisiología , Taquicardia Ventricular/fisiopatología , Secuencia de Aminoácidos , Animales , Clonación Molecular , Expresión Génica , Humanos , Canales de Potasio KCNQ , Canal de Potasio KCNQ1 , Datos de Secuencia Molecular , Canales de Potasio/aislamiento & purificación , XenopusRESUMEN
PURPOSE: To assess the efficacy of the artificial urinary sphincter survival and continence were first evaluated 5 years ago. We now evaluated the effects of the artificial urinary sphincter more than a decade after implantation. MATERIALS AND METHODS: Before 1985 an artificial urinary sphincter was implanted in 22 male and 14 female consecutive patients 4 to 30 years old (median age 12). In addition, between 1985 and 1990, 18 other children underwent artificial urinary sphincter implantation. Results of both series were compared. RESULTS: Of the 25 sphincters in the original series that were functioning after 5 years 1 was removed and 2 patients were lost to followup, resulting in 22 functioning implants (61% of the patients). Mean survival time of the prostheses was 12.1 years and average followup for functioning sphincters was 13.7 years. There was no statistically significant difference in artificial urinary sphincter survival between the original group at 5 years and the second group treated after 1985. Of the patients in both groups with sphincters in place 32 of 39 (82%) were dry. Augmentation cystoplasty was performed in 9 of 18 patients (50%) in the second series (5 preoperatively and 4 postoperatively) compared to 10 of 36 (28%) in the original series at 5 years (3 preoperatively and 7 postoperatively). Renal failure developed in 6 patients from both series. CONCLUSIONS: The artificial urinary sphincter is a durable long-term solution for children with intractable incontinence. Long-term surveillance of the urinary tract is mandatory because of the potential for renal failure in patients who have bladder hypertonicity after placement of the device.
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Esfínter Urinario Artificial , Adolescente , Adulto , Niño , Preescolar , Femenino , Estudios de Seguimiento , Humanos , Masculino , Insuficiencia Renal/etiología , Análisis de Supervivencia , Factores de Tiempo , Vejiga Urinaria/cirugía , Esfínter Urinario Artificial/efectos adversosRESUMEN
cAMP-dependent chloride channels in heart contribute to autonomic regulation of action potential duration and membrane potential and have been inferred to be due to cardiac expression of the epithelial cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. In this report, a cDNA from rabbit ventricle was isolated and sequenced, which encodes an exon 5 splice variant (exon 5-) of CFTR, with >90% identity to human CFTR cDNA present in epithelial cells. Expression of this cDNA in Xenopus oocytes gave rise to robust cAMP-activated chloride currents that were absent in control water-injected oocytes. Antisense oligodeoxynucleotides directed against CFTR significantly reduced the density of cAMP-dependent chloride currents in acutely cultured myocytes, thereby establishing a direct functional link between cardiac expression of CFTR protein and an endogenous chloride channel in native cardiac myocytes.
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Canales de Cloruro/genética , AMP Cíclico/metabolismo , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Fibrosis Quística/genética , Ventrículos Cardíacos/metabolismo , Empalme Alternativo , Secuencia de Aminoácidos , Animales , Células Cultivadas , Canales de Cloruro/fisiología , Clonación Molecular , Regulador de Conductancia de Transmembrana de Fibrosis Quística/fisiología , ADN Complementario , Exones , Cobayas , Humanos , Datos de Secuencia Molecular , Procesamiento Proteico-Postraduccional , Conejos , Función Ventricular , XenopusRESUMEN
Recent whole-cell studies have shown that Ca(2+)-activated Cl- currents contribute to the Ca(2+)-dependent 4-aminopyridine-insensitive component of the transient outward current and to the arrhythmogenic transient inward current in rabbit and canine cardiac cells. These Cl(-)-sensitive currents are activated by Ca2+ release from the sarcoplasmic reticulum and are inhibited by anion transport blockers; however, the unitary single channels responsible have yet to be identified. We used inside-out patches from canine ventricular myocytes and conditions under which the only likely permeant ion is Cl- to identify 4-aminopyridine-resistant unitary Ca(2+)-activated Cl- channels, Ca2+ applied to the cytoplasmic surface of membrane patches activated small-conductance (1.0 to 1.3 pS) channels. These channels were Cl- selective, with rectification properties that could be described by the Goldman-Hodgkin-Katz current equation. Channel activity exhibited time independence when cytoplasmic Ca2+ was held constant and was blocked by the anion transport blockers, DIDS and niflumic acid. Ca2+ (ranging from pCa > or = 6 to pCa 3) applied to the cytoplasmic surface of inside-out patches increased, in a dose-dependent manner, NPo, where N is the number of channels opened and Po is open probability. At negative membrane potentials (-60 to -130 mV), an estimate of the dependence of NPo on cytoplasmic Ca2+ yielded an apparent Kd of 150.2 mumol/L. At pCa 3, an average channel density of approximately equal to 3 microns-2 was estimated. Calculations based on these estimates of cytoplasmic Ca2+ sensitivity and channel current amplitude and density suggest that these small-conductance Cl- channels contribute significant whole-cell membrane current in response to changes in intracellular Ca2+ within the physiological range. We suggest that these small-conductance Ca(2+)-activated Cl- channels underlie the transient Ca(2+)-activated 4-aminopyridine-insensitive current, which contributes to phase-1 repolarization, and under conditions of Ca2+ overload, these channels may generate transient inward currents, contributing to the development of triggered cardiac arrhythmias.
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Calcio/fisiología , Canales de Cloruro/metabolismo , Citoplasma/química , Miocardio/metabolismo , Ácido 4,4'-Diisotiocianostilbeno-2,2'-Disulfónico/farmacología , Animales , Canales de Cloruro/antagonistas & inhibidores , Canales de Cloruro/fisiología , Perros , Conductividad Eléctrica , Femenino , Ventrículos Cardíacos/citología , Ventrículos Cardíacos/efectos de los fármacos , Masculino , Miocardio/citología , Ácido Niflúmico/farmacología , Técnicas de Placa-ClampRESUMEN
1. Fever is a common problem among long-term care residents, and the clinical manifestations of fever and infections may be vague or nonspecific. 2. The majority of fevers in this study were staff-detected versus resident-initiated; this implies that staff vigilance is important in the detection of fever. 3. Staff documentation of impaired oral intake during febrile episodes was associated highly with either elevated serum sodium or blood urea nitrogen/creatinine ratios. Therefore, nursing assessment and interventions to hydrate residents at the first indication of impaired oral intake may prevent dehydration. 4. Routine mandated vital signs were found to be of little or no value in detecting fevers.
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Deshidratación/enfermería , Fiebre/enfermería , Cuidados a Largo Plazo , Evaluación en Enfermería , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Investigación en Evaluación de Enfermería , Estudios ProspectivosRESUMEN
OBJECTIVE: The aim was to test for the presence of cAMPi activated and ATPo activated chloride conductances (ICl(cAMP) and ICl(ATP)) in mouse ventricular myocytes. METHODS: Membrane currents were measured in enzymatically dissociated ventricular myocytes using the whole cell configuration of the patch clamp technique. RESULTS: After inhibiting the activation of sodium, calcium, and potassium currents, increasing [cAMP]i with isoprenaline (1 microM), forskolin (10 microM), or isobutylmethylxanthine (500 microM) had no effect on residual membrane current but extracellular ATP (100 microM) elicited a time independent background conductance. The ATP-activated conductance was observed during voltage steps ranging from +40 to -110 mV from a holding potential of -30 mV within 1 min after adding ATP to the bath. The reversal potential for the ATP activated conductance varied with changes in the chloride gradient and was within several mV of the predicted Nernst potential for chloride. Partially substituting external chloride with aspartate attenuated the ATP activated currents and shifted the reversal potential to values close to those predicted for ECl, suggesting the chloride selective nature of the conductance. The poorly hydrolysable ATP analogue ATP gamma S (100 microM) also elicited the chloride conductance, suggesting purinoceptor linked activation rather than a mechanism dependent on hydrolysis of ATP by ectoATPases. The conductance may be activated following P2 and not P1 purinoceptor stimulation, since the P1 purinoceptor agonists adenosine (500 microM) and adenosine monophosphate (500 microM) had no effect in seven and four cells, respectively. Activation of ICl(ATP) is not likely to be dependent on increased [Ca2+]i since ATP activated the current in cells dialysed with 10 mM EGTA or 20 mM BAPTA. CONCLUSIONS: (1) cAMPi does not activate a chloride conductance in mouse ventricular myocytes; (2) ATPo does activate a chloride conductance, through stimulation of a P2 purinoceptor; and (3) Ca2+i and cAMPi are not involved in activation of ICl(ATP). Also, macroscopic ICl(ATP) from mouse ventricle and ICl(cAMP) from other species appear to be indistinguishable in terms of time independence and rectification properties that depend on the concentration and permeability of intracellular anions. ICl(ATP) could be of physiological and pathophysiological significance considering the ability of chloride channels to modulate cardiac electrical activity and the fact that ATP may be an important neuromediator in the heart.
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Adenosina Trifosfato/metabolismo , Canales de Cloruro/efectos de los fármacos , AMP Cíclico/metabolismo , Miocardio/metabolismo , 1-Metil-3-Isobutilxantina/farmacología , Adenosina/farmacología , Animales , Células Cultivadas , Colforsina/farmacología , Fibrosis Quística/metabolismo , Isoproterenol/farmacología , Potenciales de la Membrana/efectos de los fármacos , Ratones , Ratones Noqueados , Miocardio/citología , Técnicas de Placa-Clamp , Estimulación QuímicaRESUMEN
BACKGROUND: Urinary cytology has long been used as a noninvasive screen for the detection of urinary tract cancer but is limited by the generation of false positive and false negative results. More recently, molecular changes associated with urothelial neoplastic progression have been identified in DNA from urine sediments, demonstrating an alternative approach for identifying neoplastic change in the bladder. PURPOSE: The purpose of this prospective study was to determine the value of detection of H-ras (also known as HRAS) mutations in urine sediment DNA as a clinical indicator of tumor presence, recurrence, and/or progression. METHODS: Urine sediments were collected from 100 patients presenting with bladder tumors, with follow-up samples collected from 19 patients. DNA extracted from urine sediments was analyzed for changes in exon 1 of the H-ras gene, using single-strand conformation polymorphism (SSCP) analysis. A representative number of aberrant H-ras/SSCP migrating bands were excised and sequenced to confirm the presence of a mutation. Human bladder specimens were obtained from patients (93 of the 100 patients initially and 18 of the 19 patients studied by follow-up) and histologically evaluated for tumor content and grade. RESULTS: Mutations in exon 1 of the H-ras gene were detected in urine sediments from 44% (44 of 100) of the patients; concordant results were obtained by cytologic analysis, where 33% (31 of 93) of the patients displayed positive cytology. Analysis of the distribution of abnormalities with tumor grade revealed greater detection of low-grade (1-2) lesions using ras analysis (47%) compared with cytology (16%). In contrast, cytology was more effective in identifying the presence of carcinoma in situ. Combined results from these two approaches substantially increased the sensitivity of tumor detection, resulting in the identification of tumors in 60% of patients. CONCLUSIONS: Identification of H-ras mutations in DNA from urine sediments facilitates the detection of low-grade bladder tumors and, in combination with cytology, increases the overall tumor detection from 33% to 60%. Preliminary results in patient follow-up suggest that detection of H-ras mutations may have some clinical utility in detecting the presence of abnormal cells in the absence of an overt lesion following cystoscopy or positive cytology.
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Biomarcadores de Tumor/orina , ADN de Neoplasias/orina , Genes ras/genética , Mutación , Neoplasias de la Vejiga Urinaria/genética , Secuencia de Bases , ADN de Neoplasias/genética , Progresión de la Enfermedad , Humanos , Datos de Secuencia Molecular , Recurrencia Local de Neoplasia , Polimorfismo Conformacional Retorcido-Simple , Estudios Prospectivos , Células Tumorales Cultivadas , Neoplasias de la Vejiga Urinaria/diagnóstico , Orina/citologíaRESUMEN
OBJECTIVE: To determine the incidence of early hypernatremic dehydration among residents of a nursing home care unit (NHCU) presenting with significant febrile episodes (FE). DESIGN: Prospective cohort analytic study. FE were defined as temperature (T) > 100 degrees F oral (o) or 101 degrees F rectal (r) for > or = 24 hours. SETTING: NHCU in a Veterans Administration hospital. PATIENTS: A total of 130 residents of the NHCU were monitored for FE during a 4-month study period. MAIN OUTCOME MEASURES: Blood urea nitrogen (BUN)/creatinine (Cr) (abnormal > or = 25) and serum sodium (Na)(abnormal > or = 146 mmol/L) were drawn within 24-48 hours of the onset of all FE; documentation of impaired oral intake (OI) by staff; necessity of transfer to acute medical wards and mortality were recorded. RESULTS: There were 48 FE among 42 residents (39 M, 3 F; mean age 75 +/- 11.3). Maximum recorded T during the FE ranged from 100.1 degrees F-102.2 degrees F o and 101.2 degrees F-105.3 degrees F r. Laboratory values were available for 40/48 FE. Twenty-three percent (9/40) had elevated BUN/Cr ratios, 25% (10/40) had elevated serum Na, and 12.5% (5/40) had both. In patients noted to have impaired OI (n = 11) as documented by staff, increased serum Na or BUN/Cr ratio was observed in 82% (9/11). A random control group of 37 nonacutely ill, nonfebrile NHCU residents (33 M, 4 F; mean age 75 +/- 10.1) having routine annual laboratory tests revealed only 1 resident (age 95) with an elevated Na of 146 and BUN/Cr ratio of 26 and 1 resident with an increased BUN/Cr ratio of 28. None of the controls had any staff documentation of impaired OI. Of the 5 deaths in the febrile group with laboratory data (total deaths = 6; 14%), 100% had either elevated serum Na and/or elevated BUN/Cr ratios, and 80% (4/5) had both. Comparing the febrile group with controls, BUN/Cr ratios were found to be significantly elevated in the febrile group (P < 0.05). Serum sodium values were also significantly elevated in the febrile group (P < 0.01). CONCLUSIONS: Staff documentation of impaired OI was highly associated with either elevated serum Na or increased BUN/Cr ratios. These data show that many older NHCU patients with significant fevers often have early impaired OI and laboratory evidence of dehydration. These data indicate that staff should institute appropriate monitoring for dehydration at the time of earliest detection of fever in this population.
Asunto(s)
Deshidratación/etiología , Fiebre/complicaciones , Adulto , Anciano , Estudios de Cohortes , Deshidratación/diagnóstico , Deshidratación/mortalidad , Femenino , Fiebre/etiología , Hospitales de Veteranos , Humanos , Infecciones/complicaciones , Institucionalización , Masculino , Persona de Mediana Edad , Casas de Salud , Estudios Prospectivos , Estados UnidosRESUMEN
OBJECTIVE: Depolarisation-induced Na+ influx through tetrodotoxin sensitive Na+ channels causes a rapid increase in intracellular Ca2+ concentration ([Ca2+]i). The Na+ current (INa) induced [Ca2+]i transients: (a) occur after blocking sarcolemmal Ca2+ channels with nisoldipine or D-600, (b) are inhibited by ryanodine, and (c) are dependent upon extracellular Ca2+. Thus the INa induced [Ca2+]i transients arise from sarcoplasmic reticular Ca2+ release triggered by Ca2+ entering the myocyte, following a transient rise in intracellular Na+ ([Na+]i), via a pathway distinct from sarcolemmal Ca2+ channels. Reverse mode Na(+)-Ca2+ exchange could provide such a pathway for Ca2+ entry. The aim of this study was to ascertain directly whether Na(+)-Ca2+ exchange mediates the INa induced release of Ca2+ from sarcoplasmic reticulum. METHODS: Whole cell voltage and current clamped guinea pig ventricular myocytes dialysed with indo-1 were used; Ca2+ transients elicited upon activation of INa before and after inhibiting the exchanger were measured. RESULTS: Following conditioning protocols to load Ca2+ stores, activation of INa during a test pulse to -50 mV from a holding potential of -80 mV elicited [Ca2+]i transients in caesium loaded myocytes superfused with solutions containing 2.5 mM Ca2+ and 5 microM nisoldipine. When extracellular Na+ was replaced with equimolar lithium, which carries current through Na+ channels but does not readily substitute for Na+ on the Na(+)-Ca2+ exchanger, or when Ni2+ (5 mM) or dichlorobenzamil (10 microM), which block the exchanger, were added to superfusion solutions, activation of INa failed to elicit [Ca2+]i transients. Lithium and Ni2+ also inhibited nisoldipine insensitive [Ca2+]i transients elicited by action potentials, indicating that INa and Na(+)-Ca2+ exchange may play a role in excitation-contraction coupling under physiological conditions. CONCLUSIONS: Activation of INa appears to promote Ca2+ entry into cardiac cells by stimulation of reverse mode Na(+)-Ca2+ exchange, triggering Ca2+ release from the sarcoplasmic reticulum.
Asunto(s)
Calcio/metabolismo , Corazón/fisiología , Retículo Sarcoplasmático/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/fisiología , Potenciales de Acción/fisiología , Amilorida/análogos & derivados , Amilorida/farmacología , Animales , ATPasas Transportadoras de Calcio/fisiología , Cobayas , Corazón/efectos de los fármacos , Ventrículos Cardíacos/citología , Litio/farmacología , Níquel/farmacología , Nisoldipino/farmacologíaRESUMEN
Recent electrophysiological data suggests a number of similarities in the properties of cAMP-dependent Cl- channels in heart and cAMP-dependent Cl- channels encoded by the cystic fibrosis transmembrane conductance regulator (CFTR) gene product in various epithelial cells. We tested the hypothesis that cAMP-dependent Cl- channels in heart may be due to cardiac expression of CFTR by amplification and sequencing of several regions of CFTR from myocardial tissue derived from various species and areas of the heart. Regions corresponding to the first nucleotide binding domain (NBD1), transmembrane segments I-VI (TS I-VI), transmembrane segments VII-XII (TS VII-XII), and the regulatory domain (R domain) were amplified and sequenced from rabbit ventricle (see Fig. 1). Comparison of the known amino acid sequence of human epithelial CFTR with the deduced sequence from rabbit heart indicated deletion of exon 5 in the first cytoplasmic loop of TS I-VI suggesting that CFTR is an alternatively spliced isoform in rabbit ventricle. Outside of the alternatively spliced region, the heart CFTR Cl- channel isoform displayed greater than 95% identity to human epithelial CFTR Cl- channels. We have also compared the molecular distribution of the CFTR gene product to the distribution of cAMP-dependent Cl- channels in native cardiac myocytes derived from various species and areas of the heart. Amplification of regions corresponding to NBD1, R domain, and TS VII-XII from atrium and ventricle of guinea pigs, rabbit, and dog hearts exhibited a distribution which closely matched the distribution of cAMP-dependent Cl- channels assessed using electrophysiological techniques.(ABSTRACT TRUNCATED AT 250 WORDS)