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1.
Phys Rev Lett ; 120(22): 226001, 2018 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-29906184

RESUMEN

We present a mean-field theory to explain the thermo-orientation effect in an off-center Stockmayer fluid. This effect is the underlying cause of thermally induced polarization and thermally induced monopoles, which have recently been predicted theoretically. Unlike previous theories that are based either on phenomenological equations or on scaling arguments, our approach does not require any fitting parameters. Given an equation of state and assuming local equilibrium, we construct an effective Hamiltonian for the computation of local Boltzmann averages. This simple theoretical treatment predicts molecular orientations that are in very good agreement with simulation results for the range of dipole strengths investigated. By decomposing the overall alignment into contributions from the temperature and density gradients, we shed further light on how the nonequilibrium result arises from the competition between the two gradients.

2.
Phys Rev Lett ; 121(19): 195501, 2018 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-30468612

RESUMEN

The interaction of a propagating crack in implanted silicon with self-emitted acoustic waves results in periodic patterns on fractured surfaces. Direct measurement of the acoustic emission ahead of the fracture front shows the emergence of dominant acoustic frequency related to the crack velocity. It is shown that the surface modifications are made of roughness modulations due to periodic deviations of the crack front. A physical mechanism explaining the pattern formation is proposed, well in agreement with the observed pattern wavelengths.

3.
Bioconjug Chem ; 25(12): 2166-74, 2014 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-25428117

RESUMEN

Our study presents innovative research dealing with the synthesis and biological evaluation of conjugates out of antimicrobial peptides (AMPs) and imidazolium cations that are derived from ionic liquids. AMPs are considered as promising alternatives to common antibiotics due to their different activity mechanisms. Antibacterial effects have also been described for ionic liquids bearing imidazolium cations . Besides single coupling of carboxy-functionalized imidazolium cations to the peptide N-terminal we also developed conjugates bearing multiple copies of imidazolium cations. The combination of both compounds resulted in synergistic effects that were most pronounced when more imidazolium cations were attached to the peptides. In addition, antibacterial activity even in drug-resistant bacterial strains could be observed. Moreover, the novel compounds showed good selectivity only against bacterial cells, an observation that was further proven by lipid interaction studies using giant unilamellar vesicles.


Asunto(s)
Antiinfecciosos/química , Antiinfecciosos/farmacología , Imidazoles/química , Péptidos/química , Farmacorresistencia Bacteriana/efectos de los fármacos , Eritrocitos , Humanos , Líquidos Iónicos/química , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Péptidos/síntesis química , Péptidos/farmacología , Sales (Química)/química , Técnicas de Síntesis en Fase Sólida , Relación Estructura-Actividad
4.
An Acad Bras Cienc ; 86(4): 1631-9, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25590704

RESUMEN

A sequence of earthquakes occurred in 2008 in the Meruoca granitic pluton, located in the northwestern part of the Borborema Province, NE Brazil. A seismological study defined the seismic activity occurring along the seismically-defined Riacho Fundo fault, a 081° striking, 8 km deep structure. The objective of this study was to analyze the correlation between this seismic activity and geological structures in the Meruoca granite. We carried out geological mapping in the epicentral area, analyzed the mineralogy of fault rocks, and compared the seismically-defined Riacho Fundo fault with geological data. We concluded that the seismically-defined fault coincides with ∼E-W-striking faults observed at outcrop scale and a swarm of Mesozoic basalt dikes. We propose that seismicity reactivated brittle structures in the Meruoca granite. Our study highlights the importance of geological mapping and mineralogical analysis in order to establish the relationships between geological structures and seismicity at a given area.

5.
Sci Adv ; 10(11): eadl4306, 2024 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-38478621

RESUMEN

Water in Earth's upper mantle is a minor and yet critically important component that dictates mantle properties such as strength and melting behavior. Minerals with stoichiometric water, such as those of the humite group, are important yet poorly characterized potential reservoirs for volatiles in the upper mantle. Here, we report observation of hydroxyl members of the humite group as inclusions in mantle-derived diamond. Hydroxylchondrodite and hydroxylclinohumite were found coexisting with olivine, magnesiochromite, Mg-bearing calcite, dolomite, quartz, mica, and a djerfisherite-group mineral in a diamond from Brazil. The olivine is highly forsteritic (Mg# 97), with non-mantle-like oxygen isotope composition (δ18O +6.2‰), and is associated with fluid inclusions and hydrous minerals-features that could be inherited from a serpentinite protolith. Our results constitute direct evidence for the presence of deserpentinized peridotitic protoliths in subcratonic mantle keels, placing important constraints on the stability of hydrous phases in the mantle and the origin of diamond-forming fluids.

6.
Phys Rev Lett ; 106(20): 203601, 2011 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-21668227

RESUMEN

We study collective scattering with Bose-Einstein condensates interacting with a high-finesse ring cavity. The condensate scatters the light of a transverse pump beam superradiantly into modes which, in contrast to previous experiments, are not determined by the geometrical shape of the condensate, but specified by a resonant cavity mode. Moreover, since the recoil-shifted frequency of the scattered light depends on the initial momentum of the scattered fraction of the condensate, we show that it is possible to employ the good resolution of the cavity as a filter selecting particular quantized momentum states.

7.
FEMS Microbes ; 2: xtab006, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-37334226

RESUMEN

Cyanobacteria are able to synthesize a high diversity of natural compounds that account for their success in the colonization of a variety of ecological niches. Many of them have beneficial properties. The mud from the thermal baths of Balaruc-Les-Bains, one of the oldest thermal baths in France, has long been recognized as a healing treatment for arthro-rheumatic diseases. To characterize the cyanobacteria living in these muds, several strains were isolated from the water column and biofilms of the retention basin and analyzed using a polyphasic approach. Morphological, ultrastructural and molecular (16S rRNA gene and 16S-23S ITS region sequencing) methods were employed to identify nine cyanobacterial strains belonging to the orders Chroococcales, Synechococcales, Oscillatoriales and Nostocales. The combination of morphological and genetic characteristics supported the description of a new genus and species with the type species as Pseudochroococcus coutei. The taxonomic diversity in the muds from Thermes de Balaruc-Les-Bains appears higher than previously documented, providing new candidate taxa for their observed therapeutic properties.

8.
Orthopade ; 39(6): 573-9, 2010 Jun.
Artículo en Alemán | MEDLINE | ID: mdl-20424821

RESUMEN

A growing number of interspinous process devices are currently under investigation. No long-term results are currently available for the X-STOP spacer, but short-term and midterm results are promising.The X-STOP spacer is a good alternative to decompression surgery in elderly patients with moderate spinal stenosis without spondylolisthesis or severe osteoporosis. Further prospective controlled randomized studies comparing the X-STOP with decompression surgery must be done to clearly define the indications and to allow prediction of long-term results.


Asunto(s)
Descompresión Quirúrgica/métodos , Desplazamiento del Disco Intervertebral/etiología , Desplazamiento del Disco Intervertebral/cirugía , Prótesis Articulares , Estenosis Espinal/etiología , Estenosis Espinal/cirugía , Descompresión Quirúrgica/instrumentación , Análisis de Falla de Equipo , Humanos , Estudios Longitudinales , Diseño de Prótesis , Estenosis Espinal/diagnóstico , Resultado del Tratamiento
9.
HNO ; 58(3): 244-54, 2010 Mar.
Artículo en Alemán | MEDLINE | ID: mdl-20182681

RESUMEN

INTRODUCTION: The aim of this retrospective study was to present the postoperative development, therapy effectiveness, and parental satisfaction after an outpatient diode laser tonsillotomy in children with noninflammatory tonsillar hyperplasia. METHOD: The study included 183 children with noninflammatory tonsillar hyperplasia who were operated on between October 2004 and October 2006 (average age: 4 years and 7 months). All children underwent diode laser tonsillotomy in contact mode (812 nm, continuous wave, 13 W) with or without additional procedures (adenotomy, paracentesis, tympanic drainage). All surgeries were carried out under endotracheal anesthesia by two ENT physicians in private practice in an outpatient surgery center. The patients (n=82) of one of the physicians were given an oral antibiotic for the 7 days following the surgery (cefuroxime syrup), and all children were given standard pain medication after the surgery (ibuprofen syrup). The postoperative development, complications, or late complications, the recurrence frequency, the effectiveness of the treatment, and the parental satisfaction were assessed using the respective results of the follow-up exams (average follow-up period: 1 year) and a standardized parent questionnaire, completed on average 1 year and 8 months after the surgery. For data digitalizing and statistical analysis with SPSS the chi(2) test and the Wilcoxon test were used (p<0.05). RESULTS: Generally, patients experienced no or only very little pain, and there was no secondary bleeding after tonsillotomy. Occasionally, a conspicuous wound surface (2.9%), fever (2.3%), or reddened palatal arch (1.2%) were noted. There were no late complications such as scar tissue distortions on the soft palate or peritonsillar abscesses. The procedure's effectiveness with regard to snoring, obstructed respiration, apnea, lack of appetite, and susceptibility to infection was very good and the level of parental satisfaction very high. The postoperative development showed significant differences between the two groups (with and without oral antibiotic) concerning postoperative pain (point score: 0-3): in the antibiotics group there was no postsurgical pain (average point score: 0.1), and in the group without antibiotics there was slight postsurgical pain (point score: 0.5). CONCLUSION: Outpatient diode laser tonsillotomy for children with symptomatic tonsillar hyperplasia is a rather painless surgery method with a low perioperative risk, very high treatment effectiveness, and parental satisfaction. For this indication tonsillotomy is the therapy of choice. There were no differences in terms of postoperative development between the diode laser tonsillotomy compared to the literature of the more common CO(2) laser tonsillotomy.


Asunto(s)
Terapia por Láser/estadística & datos numéricos , Dolor Postoperatorio/epidemiología , Dolor Postoperatorio/prevención & control , Tonsila Palatina/patología , Tonsila Palatina/cirugía , Tonsilectomía/estadística & datos numéricos , Adolescente , Niño , Preescolar , Comorbilidad , Femenino , Alemania/epidemiología , Humanos , Hiperplasia/epidemiología , Hiperplasia/cirugía , Lactante , Láseres de Semiconductores/estadística & datos numéricos , Masculino , Prevalencia , Estudios Retrospectivos , Resultado del Tratamiento
10.
Sci Rep ; 10(1): 7855, 2020 May 12.
Artículo en Inglés | MEDLINE | ID: mdl-32398674

RESUMEN

New systematic Nd isotope and U-Pb geochronology data were applied to Precambrian rocks of northeastern Brazil to produce a crustal-age distribution map for a small basement inlier (1,500 km2). The results support episodic crustal growth with five short periods of crustal formation at ca. 2.9 Ga, 2.65 Ga, 2.25 Ga, 2.0 Ga, and 0.6 Ga. Based on the frequency histogram of U-Pb zircon ages and Nd isotopic data, we suggest that about 60% of the continental crust was formed during the Archean between 2.9 Ga and 2.65 Ga. The remaining 40% of crust was generated during the Rhyacian to Neoproterozoic (~2.0-0.6 Ga). This overall continental growth is manifested by accretionary processes that involved successive accretions surrounding an older core, becoming younger toward the margin. Strikingly, this repetitive history of terrane accretion show a change from lithospheric peeling dominated accretionary setting during the late Archean to a more, modern-day akin style of arc-accretion during the Proterozoic. Similar tectonic processes are observed only in large continental areas (>1,000,000 km2) as in the North American continent basement and in the Amazonian Craton.

11.
Herzschrittmacherther Elektrophysiol ; 30(2): 225-228, 2019 Jun.
Artículo en Alemán | MEDLINE | ID: mdl-31049655

RESUMEN

The therapy for heart failure in patients with uncompromised systolic ventricular function (HfpEF) is still challenging because there is an obvious lack of effective therapy options. Several of these particular patients are additionally presenting atrioventricular (AV) block. In these patients HIS bundle pacing could be a hopeful therapy strategy due to the option of an AV resynchronisation as illustrated in the following case.


Asunto(s)
Bloqueo Atrioventricular , Fascículo Atrioventricular , Insuficiencia Cardíaca , Estimulación Cardíaca Artificial , Electrocardiografía , Humanos , Volumen Sistólico
12.
Clin Med (Lond) ; 8(5): 517-21, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18975486

RESUMEN

Non-invasive ventilation (NIV) in the management of acute type 2 respiratory failure in patients with chronic obstructive pulmonary disease (COPD) represents one of the major technical advances in respiratory care over the last decade. This document updates the 2002 British Thoracic Society guidance and provides a specific focus on the use of NIV in COPD patients with acute type 2 respiratory failure. While there are a variety of ventilator units available most centres now use bi-level positive airways pressure units and this guideline refers specifically to this form of ventilatory support although many of the principles encompassed are applicable to other forms of NIV. The guideline has been produced for the clinician caring for COPD patients in the emergency and ward areas of acute hospitals.


Asunto(s)
Respiración con Presión Positiva/instrumentación , Enfermedad Pulmonar Obstructiva Crónica , Insuficiencia Respiratoria/terapia , Enfermedad Aguda , Humanos , Respiración con Presión Positiva/normas , Guías de Práctica Clínica como Asunto , Respiración Artificial , Reino Unido
13.
Mol Biochem Parasitol ; 225: 73-83, 2018 10.
Artículo en Inglés | MEDLINE | ID: mdl-30179636

RESUMEN

Helminths are complex pathogens that ensure their long-term survival by influencing the immune responses of their host. Excretory/secretory products (ESP) can exert immunoregulatory effects which foster parasite survival. Galectins represent a widespread group of ß-galactoside-binding proteins which are involved in a multitude of biological processes operative in parasite-host interaction. We had earlier identified seven galectins in Strongyloides ratti, four of them detected in the ESP of distinct developmental stages of the parasite. In the present report, we focused on the characterization of two of them, Sr-galectin-1 (Sr-Gal-1) and Sr-galectin-3 (Sr-Gal-3). While Sr-Gal-3 expression was strongest in parasitic females, Sr-Gal-1 was predominantly expressed in free-living females. Both proteins were cloned and recombinantly expressed in an E. coli expression system. Their glycan-binding activity was verified by haemagglutination and glycan array analysis. Furthermore, primary immunological activities of the Sr-galectins were initially investigated by the application of an in vitro mucosal 3D-culture model, comprising of mucosa-associated epithelial and dendritic cells. The Sr-galectins stimulated preferentially the release of the type 2 cytokines thymic stromal lymphopoietin and IL-22, a first indication for immunoregulatory activity. In addition, the Sr-galectins dose-dependently fostered cell migration. Our results confirm the importance of these carbohydrate-binding proteins in host-parasite-interaction by indicating possible interaction with the host mucosa-associated cells.


Asunto(s)
Galectinas/metabolismo , Intestinos/parasitología , Polisacáridos/metabolismo , Strongyloides ratti/metabolismo , Animales , Clonación Molecular , Citocinas/metabolismo , Células Dendríticas/efectos de los fármacos , Células Dendríticas/metabolismo , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Femenino , Galectinas/genética , Expresión Génica , Perfilación de la Expresión Génica , Hemaglutinación , Masculino , Unión Proteica , Ratas Wistar , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Strongyloides ratti/genética
14.
Physiol Meas ; 28(1): 25-40, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17151417

RESUMEN

Habitual snoring without episodes of apnea or hypoventilation and without respiratory related arousals is considered to be annoying and without any need for treatment. However, studies seem to suggest an enormous psychosocial impact of annoyance for the bed partner. Apart from subjective questionnaires there still exists no generally accepted mode of measurement that can describe snoring objectively. We therefore adapted methods developed for environmental medicine and established a new snore score using psycho-acoustic parameters. For quantification of snoring noise we conducted nocturnal measurements in 19 habitual snorers. Free-field snore sounds were acquired with two low-cost non-contact microphones and transferred to a PC (sampling frequency 11 kHz). The data were recorded, analysed and stored automatically using a MATLAB script. Following the analysis of sound characteristics and levels, the score was computed from relevant parameters containing the rating level (L(R)), maximum level, two percentile levels for frequent maxima (L(5)S; L(1)) and snoring time. The determined values substantially exceeded the prescribed limits defined by WHO noise guidelines, and mainly affected the equivalent continuous sound exposure level, rating level and the immission standard values of brief noise peaks, whose maximum was exceeded by up to 32 dB(A). The Berlin snore score illustrated the objective acoustic annoyance on a scale from 0 to 100. It allows inter-individual comparison and objectifies the need for therapy. The clinical applicability of evaluating the reduction of snoring after surgical therapy is discussed exemplarily. The presented measuring method was found to be suitable for quantifying snoring noise and can be easily integrated into existing polysomnographic applications. In the case of habitual snoring with objective evidence of psychosocially disturbing acoustic annoyance, health fund providers should assume the costs of mandatory medical therapy.


Asunto(s)
Ruido , Ronquido/diagnóstico , Ronquido/terapia , Esposos/psicología , Acústica , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto , Ronquido/cirugía , Espectrografía del Sonido , Estadísticas no Paramétricas , Encuestas y Cuestionarios
15.
Appl Biochem Biotechnol ; 143(3): 199-211, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18057448

RESUMEN

Propionibacterium acnes strain ATCC 6919 catalyzes the isomerization of the double bond at the C9 position in linoleic acid (c9,c12, 18:2) to form t10,c12 conjugated linoleic acid (CLA, 18:2). CLA has significant health benefits in animal and human. The linoleic acid C9 isomerase was purified to an apparent homogeneity by successive chromatography on diethylaminoethyl (DEAE) anion exchange, hydrophobic interaction, and chromatofocusing columns. Two degenerated oligonucleotide primers were synthesized according to the N-terminal peptide sequence to clone, by polymerase chain reaction (PCR), a short nucleotide sequence (62 bp) of the isomerase gene. The linoleic acid isomerase gene (lai) was subsequently cloned by inverse PCR. The amino acid sequence deduced from the lai coding sequence predicts a protein of 424 amino acid residues (48 kDa), excluding the N-terminal methionine, which was absent in the polypeptide purified from the native host. The isomerase shares no significant sequence homology to other enzymes except a flavin-binding domain in the N-terminal region. The recombinant isomerase purified from Escherichia coli showed a typical ultraviolet spectrum for FAD-bound proteins. The recombinant enzyme produced a single isomer of t10,c12-CLA from linoleic acid, as demonstrated by gas chromatography and gas chromatography-mass spectrum analysis. The recombinant isomerase protein was expressed at high levels in E. coli, but it was almost totally sequestered in inclusion bodies. The level of active isomerase was increased 376-fold by medium and process optimization in bench-scale fermentors.


Asunto(s)
Ácido Linoleico/metabolismo , Propionibacterium acnes/enzimología , cis-trans-Isomerasas/genética , cis-trans-Isomerasas/metabolismo , Animales , Cromatografía de Gases , Cromatografía por Intercambio Iónico , Clonación Molecular , Escherichia coli/genética , Fermentación , Expresión Génica , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Cinética , Limosilactobacillus reuteri/enzimología , Ácidos Linoleicos Conjugados/química , Espectrometría de Masas , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes/química , cis-trans-Isomerasas/química , cis-trans-Isomerasas/aislamiento & purificación
16.
Arch Gen Psychiatry ; 34(6): 687-91, 1977 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-326217

RESUMEN

The reduction in state hospital populations in the last two decades is most often attributed to psychotropic medication and community mental health centers. The role the proprietary nursing home has played in this reduction has not been adequately studied. Using data routinely collected for Medicaid utilization review, we studied characteristics of psychiatric nursing home patients in Utah. One third of the nursing home patients had a psychiatric diagnosis; more than half of this group were classified as psychotic. Most psychotic patients were significantly younger than their nonpsychiatric counterparts. Nonpsychiatric patients received a higher mean number of psychoactive drugs than did psychiatric or mentally retarded patients. Over time, all groups of patients showed an increase in prescribed psychoactive medication and a decrease in activity. The consequence of this pattern of care raise serious questions about our current reliance on nursing homes for the care of the psychiatric patient.


Asunto(s)
Instituciones Privadas de Salud/estadística & datos numéricos , Instituciones de Salud/estadística & datos numéricos , Trastornos Mentales/terapia , Casas de Salud/estadística & datos numéricos , Adulto , Factores de Edad , Anciano , Atención a la Salud/normas , Utilización de Medicamentos , Femenino , Humanos , Discapacidad Intelectual/terapia , Masculino , Medicaid/estadística & datos numéricos , Trastornos Mentales/tratamiento farmacológico , Persona de Mediana Edad , Casas de Salud/normas , Trastornos Psicóticos/terapia , Psicotrópicos/uso terapéutico , Estados Unidos , Utah , Revisión de Utilización de Recursos
17.
Urology ; 32(2): 111-4, 1988 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-3400133

RESUMEN

Renal pelvic pressures were studied in 4 patients with indwelling nephrostomy tubes undergoing extracorporeal shock-wave lithotripsy (ESWL). The pressures were monitored by attaching the patients' nephrostomy tubes to an electrical pressure transducer. Three of these patients had ureteral stents placed to prevent outflow obstruction from disintegrated stone fragments. The mean pelvic pressure increased from 17.0 cm H2O at the start to 52 cm H2O at the conclusion of ESWL. Two hours post-ESWL, the pressures declined to a mean of 27.0 cm H2O. The maximum pelvic urine volume as determined by aspirating the nephrostomy tubes at the conclusion of the procedure was 6 cc. The observed rise in pelvic pressure may be explained by a sustained contraction of the pelvic smooth musculature.


Asunto(s)
Cálculos Renales/terapia , Pelvis Renal/fisiopatología , Litotricia , Humanos , Cálculos Renales/fisiopatología , Nefrostomía Percutánea , Presión , Cateterismo Urinario
18.
Toxicol Lett ; 85(3): 151-6, 1996 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8644127

RESUMEN

Five nitro musk compounds widely used in cosmetics and detergents were examined for DNA-damaging and mutation-inducing properties. For this purpose two short-time assays were used, the SOS chromotest and the Salmonella/mammalian microsome test. Musk ambrette showed mutagenicity in Salmonella typhimurium TA 100 requiring metabolic activation by rat liver postmitochondrial supernatant (S9) but it lacked mutagenicity in the absence of S9 and genotoxicity in the SOS chromotest. Musk xylene, musk ketone, musk moskene and musk tibetene showed neither mutagenicity nor genotoxicity in the presence and absence of S9.


Asunto(s)
Daño del ADN , Dinitrobencenos/toxicidad , Mutágenos/toxicidad , Fosfatasa Alcalina/metabolismo , Animales , Arocloros/toxicidad , Biotransformación , Carcinógenos/toxicidad , Relación Dosis-Respuesta a Droga , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Indanos/toxicidad , Mitocondrias Hepáticas/metabolismo , Pruebas de Mutagenicidad , Mutación/efectos de los fármacos , Mutación/genética , Perfumes , Ratas , Respuesta SOS en Genética/efectos de los fármacos , Respuesta SOS en Genética/genética , Salmonella typhimurium/efectos de los fármacos , Relación Estructura-Actividad , Contaminantes Químicos del Agua/toxicidad , Xilenos/toxicidad , beta-Galactosidasa/metabolismo
19.
Vet Microbiol ; 88(1): 47-58, 2002 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-12119137

RESUMEN

The in vitro emergence of resistance to enrofloxacin, erythromycin, tylosin, tiamulin, and oxytetracycline in three avian Mycoplasma species, Mycoplasma gallisepticum, Mycoplasma synoviae and Mycoplasma iowae was studied. Mutants were selected stepwise and their MICs were determined after 10 passages in subinhibitory concentrations of antibiotic. High-level resistance to erythromycin and tylosin developed within 2-6 passages in the three Mycoplasma species. Resistance to enrofloxacin developed more gradually. No resistance to tiamulin or oxytetracycline could be evidenced in M. gallisepticum or M. synoviae after 10 passages whereas, resistant mutants were obtained with M. iowae. Cross-sensitivity tests performed on mutants demonstrated that mycoplasmas made resistant to tylosin were also resistant to erythromycin, whereas mutants made resistant to erythromycin were not always resistant to tylosin. Some M. iowae tiamulin-resistant mutants were also resistant to both macrolide antibiotics. Enrofloxacin and oxytetracycline did not induce any cross-resistance to the other antibiotics tested. These results show that Mycoplasma resistance to macrolides can be quickly selected in vitro, and thus, providing that similar results could be obtained under field conditions, that development of resistance to these antibiotics in vivo might also be a relatively frequent event.


Asunto(s)
Antibacterianos/farmacología , Antiinfecciosos/farmacología , Farmacorresistencia Bacteriana Múltiple , Fluoroquinolonas , Mycoplasmataceae/efectos de los fármacos , Quinolonas/farmacología , Animales , Antiinfecciosos/uso terapéutico , Diterpenos/farmacología , Enrofloxacina , Eritromicina/farmacología , Pruebas de Sensibilidad Microbiana , Mycoplasmataceae/genética , Infecciones por Mycoplasmatales/tratamiento farmacológico , Oxitetraciclina/farmacología , Tilosina/farmacología
20.
Mutat Res ; 356(2): 237-45, 1996 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-8841491

RESUMEN

In the present study, musk xylene (MX) and musk ketone (MK) were examined for their potency to induce toxifying enzymes in the liver of Sprague-Dawley rats, using an in vivo/in vitro model. After i.p. application of 10, 20 and 40 mg/day MX and MK over a period of 5 days, 9000 x g liver fractions (S9M) were used to study the toxification of a number of well-known pregenotoxicants in the SOS chromotest, i.e., benzo[a]pyrene (B[a]P), 2-aminoanthracene (2-AA), and aflatoxin B1 (AFB1). The genotoxic potencies of B[a]P, 2-AA and AFB1 in the presence of S9M were compared to those obtained in the presence of S9 fractions of untreated animals (S9O, negative control). S9M fractions derived from MK-treated rats showed an increased potency to toxify B[a]P, 2-AA and AFB1 in comparison to S9O fractions (for instance: TIP[toxifying induction potency] = 70 per nmol AFB1 using 10 mg MK treatment). In comparison, S9M fractions from MX-pretreated rats exhibited an increased genotoxicity only when using 2-AA (TIP = 0.04) and AFB1 (TIP = 61) as pregenotoxicants, but not when using B[a]P. To summarize the results, both MX and MK were strong inducers of toxifying liver enzymes. Therefore, these compounds seem to be cogenotoxicants for a number of well-known pregenotoxicants. Synergistic effects were found when using inducers of toxifying enzymes and pregenotoxicants in the in vivo/in vitro induction model.


Asunto(s)
Inducción Enzimática , Hígado/enzimología , Xilenos/farmacología , Animales , Escherichia coli/genética , Masculino , Ratas , Ratas Sprague-Dawley , Respuesta SOS en Genética
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