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1.
Open Forum Infect Dis ; 9(9): ofac442, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36172059

RESUMO

Background: Outpatient parenteral antibiotic treatment (OPAT) programs are increasingly used to manage infective endocarditis (IE), but current criteria for indicating OPAT are markedly conservative. We aimed to investigate whether more liberal criteria for indicating OPAT in IE can be safely used. Methods: This was a prospective multicenter nationwide cohort study (2008-2018). Rates of readmission, recurrences, and 1-year mortality were compared between hospital-based antibiotic treatment (HBAT) and OPAT. Risk factors for readmission and mortality in OPAT patients were investigated by logistic regression. Patients did not fulfill OPAT-GAMES (Grupos de Apoyo al Manejo de la Endocarditis en ESpaña) criteria if they had any of the following: cirrhosis, severe central nervous system emboli, undrained abscesses, severe conditions requiring cardiac surgery in nonoperable patients, severe postsurgical complications, highly difficult-to-treat microorganisms, or intravenous drug use. Results: A total of 2279 HBAT patients and 1268 OPAT patients were included. Among OPAT patients, 307 (24.2%) did not fulfill OPAT-GAMES criteria. Overall, OPAT patients presented higher rates of readmission than HBAT patients (18.2% vs 14.4%; P = .004), but no significant differences were found in the propensity analysis. Patients not fulfilling OPAT-GAMES criteria presented significantly higher rates of readmission than HBAT and OPAT-GAMES (23.8%, 14.4%, 16.4%; P < .001), whereas no significant differences were found in mortality (5.9%, 8%, 7.4%; P = .103) or recurrences (3.9%, 3.1%, 2.5%; P = .546). Not fulfilling OPAT-GAMES criteria was associated with higher risk of readmission (odds ratio [OR], 1.43; 95% CI, 1.03-1.97; P = .03), whereas cardiac surgery was associated with lower risk (OR, 0.72; 95% CI, 0.53-0.98; P = .03). Conclusions: OPAT-GAMES criteria allow identification of IE patients at higher risk of long-term complications to whom OPAT cannot be safely administered.

3.
Rev Mal Respir ; 37(6): 443-450, 2020 Jun.
Artigo em Francês | MEDLINE | ID: mdl-32439250

RESUMO

INTRODUCTION: The evolution of the microbial epidemiology of pleuropulmonary infections complicating community-acquired pneumonia has resulted in a change in empirical or targeted antibiotic therapy in children in the post Prevenar 13 era. The three main pathogens involved in pleural empyema in children are Streptococcus pneumoniae, Staphylococcus aureus and group A Streptococcus. METHODS: A questionnaire according to the DELPHI method was sent to experts in the field (paediatric pulmonologists and infectious disease specialists) in France with the purpose of reaching a consensus on the conservative antibiotic treatment of pleural empyema in children. Two rounds were completed as part of this DELPHI process. RESULTS: Our work has shown that in the absence of clinical signs of severity, the prescription of an intravenous monotherapy is consensual but there is no agreement on the choice of drug to use. A consensus was also reached on treatment adjustment based on the results of blood cultures, the non-systematic use of a combination therapy, the need for continued oral therapy and the lack of impact of pleural drainage on infection control. On the other hand, after the second round of DELPHI, there was no consensus on the duration of intravenous antibiotic therapy and on the treatment of severe pleural empyema, especially when caused by Staphylococci. CONCLUSIONS: The result of this work highlights the needed for new French recommendations based on the evolution of microbial epidemiology in the post PCV13 era.


Assuntos
Antibacterianos/uso terapêutico , Técnica Delphi , Empiema Pleural/tratamento farmacológico , Empiema Pleural/epidemiologia , Pediatria , Idade de Início , Antibacterianos/classificação , Gestão de Antimicrobianos/métodos , Gestão de Antimicrobianos/normas , Criança , Consenso , Empiema Pleural/microbiologia , Prova Pericial/estatística & dados numéricos , Feminino , França/epidemiologia , Humanos , Masculino , Testes de Sensibilidade Microbiana/estatística & dados numéricos , Pediatria/métodos , Pediatria/normas , Derrame Pleural/tratamento farmacológico , Derrame Pleural/epidemiologia , Padrões de Prática Médica/estatística & dados numéricos , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/microbiologia , Infecções Respiratórias/terapia
4.
S Afr J Commun Disord ; 67(2): e1-e7, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32242440

RESUMO

BACKGROUND: A relationship exists between occupational noise exposure and age, which remains poorly understood. OBJECTIVES: The aim of this study was to establish the relationship between hearing loss and age over time. METHOD: Audiological data from 2583 mine workers in South Africa were utilised. Data were received from a non-noise exposed group (NNEG) (n = 951) and a noise exposed group (NEG) (≥85 dBA) (n = 1632). Data comprised a low-frequency average (LFA512) (average of audiological thresholds for 0.5 kHz, 1 kHz and 2 kHz) and high-frequency average (HFA346) (average of audiological thresholds for 3 kHz, 4 kHz and 6 kHz). Data were compared by using mixed-effects regression analysis. RESULTS: Base threshold values were higher for the NEG than for the NNEG across frequencies. All year-to-year increases in mean hearing thresholds were statistically significant (p 0.01). When correcting for age, increases in mean hearing thresholds were higher for the NEG than for the NNEG for HFA346 (3.5 dB vs. 2.9 dB decline over a 4-year period) but similar for LFA512 (0.6 dB vs. 0.7 dB decline). Uncorrected for age, increases in mean hearing thresholds were higher than when age was corrected for. CONCLUSION: Age and occupational noise exposure influence hearing thresholds over time. The continued increase in hearing thresholds of the NEG above that of the NNEG can be related to ineffective noise management programmes and/or the fact that early noise exposure leads to a higher burden of hearing loss over time - even after noise exposure had stopped.


Assuntos
Perda Auditiva Provocada por Ruído/epidemiologia , Mineradores/estatística & dados numéricos , Ruído Ocupacional/efeitos adversos , Doenças Profissionais/epidemiologia , Adulto , Fatores Etários , Audiometria/estatística & dados numéricos , Estudos de Casos e Controles , Feminino , Ouro , Perda Auditiva Provocada por Ruído/etiologia , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Doenças Profissionais/etiologia , Estudos Retrospectivos , África do Sul/epidemiologia
6.
Clin Infect Dis ; 69(10): 1690-1700, 2019 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-30649282

RESUMO

BACKGROUND: Outpatient parenteral antibiotic treatment (OPAT) has proven efficacious for treating infective endocarditis (IE). However, the 2001 Infectious Diseases Society of America (IDSA) criteria for OPAT in IE are very restrictive. We aimed to compare the outcomes of OPAT with those of hospital-based antibiotic treatment (HBAT). METHODS: Retrospective analysis of data from a multicenter, prospective cohort study of 2000 consecutive IE patients in 25 Spanish hospitals (2008-2012) was performed. RESULTS: A total of 429 patients (21.5%) received OPAT, and only 21.7% fulfilled IDSA criteria. Males accounted for 70.5%, median age was 68 years (interquartile range [IQR], 56-76), and 57% had native-valve IE. The most frequent causal microorganisms were viridans group streptococci (18.6%), Staphylococcus aureus (15.6%), and coagulase-negative staphylococci (14.5%). Median length of antibiotic treatment was 42 days (IQR, 32-54), and 44% of patients underwent cardiac surgery. One-year mortality was 8% (42% for HBAT; P < .001), 1.4% of patients relapsed, and 10.9% were readmitted during the first 3 months after discharge (no significant differences compared with HBAT). Charlson score (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.04-1.42; P = .01) and cardiac surgery (OR, 0.24; 95% CI, .09-.63; P = .04) were associated with 1-year mortality, whereas aortic valve involvement (OR, 0.47; 95% CI, .22-.98; P = .007) was the only predictor of 1-year readmission. Failing to fulfill IDSA criteria was not a risk factor for mortality or readmission. CONCLUSIONS: OPAT provided excellent results despite the use of broader criteria than those recommended by IDSA. OPAT criteria should therefore be expanded.


Assuntos
Antibacterianos/uso terapêutico , Endocardite Bacteriana/tratamento farmacológico , Pacientes Ambulatoriais , Idoso , Feminino , Hospitais , Humanos , Infusões Parenterais , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Estudos Retrospectivos , Espanha , Resultado do Tratamento
7.
J Mech Behav Biomed Mater ; 78: 381-394, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29220822

RESUMO

Traditional implants made of bulk titanium are much stiffer than human bone and this mismatch can induce stress shielding. Although more complex to produce and with less predictable properties compared to bulk implants, implants with a highly porous structure can be produced to match the bone stiffness and at the same time favor bone ingrowth and regeneration. This paper presents the results of the mechanical and dimensional characterization of different regular cubic open-cell cellular structures produced by Selective Laser Melting (SLM) of Ti6Al4V alloy, all with the same nominal elastic modulus of 3GPa that matches that of human trabecular bone. The main objective of this research was to determine which structure has the best fatigue resistance through fully reversed fatigue tests on cellular specimens. The quality of the manufacturing process and the discrepancy between the actual measured cell parameters and the nominal CAD values were assessed through an extensive metrological analysis. The results of the metrological assessment allowed us to discuss the effect of manufacturing defects (porosity, surface roughness and geometrical inaccuracies) on the mechanical properties. Half of the specimens was subjected to a stress relief thermal treatment while the other half to Hot Isostatic Pressing (HIP), and we compared the effect of the treatments on porosity and on the mechanical properties. Fatigue strength seems to be highly dependent on the surface irregularities and notches introduced during the manufacturing process. In fully reversed fatigue tests, the high performances of stretching dominated structures compared to bending dominated structures are not found. In fact, with thicker struts, such structures proved to be more resistant, even if bending actions were present.


Assuntos
Lasers , Teste de Materiais , Estresse Mecânico , Titânio , Ligas , Dureza , Modelos Teóricos , Transição de Fase , Próteses e Implantes
8.
Rev Esp Quimioter ; 30 Suppl 1: 61-65, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28882019

RESUMO

Hospital at Home units allows ambulatory treatment and monitoring of complex and serious infections. Nosocomial infections produce an extension of the stay in hospital often specifying long intravenous treatments without any effective oral alternatives. Daily dosing of antimicrobial are easier to administer at home. The use of portable programmable pump infusion and elastomeric devices allow efficient and safe infu-sions for most antimicrobials at home. Some antibiotics against multidrug-resistant organisms of recent introduction have a suitable profile for outpatient intravenous treatment.


Assuntos
Assistência Ambulatorial , Infecção Hospitalar/tratamento farmacológico , Serviços de Assistência Domiciliar , Anti-Infecciosos/uso terapêutico , Infecção Hospitalar/microbiologia , Hospitais , Humanos
9.
Phys Rev Lett ; 118(22): 228101, 2017 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-28621979

RESUMO

We study the motility of model cells and biomimetic soft objects crawling over a substrate covered with adhesive linkers. The cell exerts traction forces on the substrate through the active periodic motion of molecular complexes to which the linkers bind and unbind stochastically. We first show that the diffusion coefficient of a force dipole (unable by symmetry to perform directed motion) is maximal for a finite ratio of the unbinding to binding rates, highlighting the role of adhesion kinetics on cell translocation. We next show that cells exerting more complex traction force distributions may exhibit directed motion only if the linkers are mechanosensitive, i.e., if the bonds' lifetime decreases (slip bonds) or increases (catch bonds) under stress. The average migration speed is higher in the catch-bond regime but so are the fluctuations, yielding a biased diffusive motion characterized by a Peclet number smaller than in the slip-bond regime.

10.
J Mech Behav Biomed Mater ; 71: 295-306, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28376363

RESUMO

Fatigue resistance and biocompatibility are key parameters for the successful implantation of hard-tissue prostheses, which nowadays are more and more frequently manufactured by selective laser melting (SLM). For this purpose, the present paper is aimed at investigating the effect of post-sintering treatments on the fatigue behavior and biological properties of Ti samples produced by SLM. After the building process, all samples are heat treated to achieve a complete stress relief. The remaining ones are tribofinished with the aim of reducing the surface roughness of the as-sintered condition. Part of the tribofinished samples are then subjected to one of the following post-sintering treatments: (i) shot peening, (ii) hot isostatic pressing (HIP), and (iii) electropolishing. It is found that shot peening and HIP are the most effective treatments to improve the high and the very-high cycle fatigue resistance, respectively. At the same time, they preserve the good biocompatibility ensured by the biomedical Titanium Grade 23.


Assuntos
Lasers , Próteses e Implantes , Titânio/análise , Ligas , Dureza , Humanos , Teste de Materiais , Propriedades de Superfície
11.
Artigo em Inglês | MEDLINE | ID: mdl-25768544

RESUMO

We study a generic model for the polarization and motility of self-propelled soft objects, biological cells, or biomimetic systems, interacting with a viscous substrate. The active forces generated by the cell on the substrate are modeled by means of oscillating force multipoles at the cell-substrate interface. Symmetry breaking and cell polarization for a range of cell sizes naturally "emerge" from long range mechanical interactions between oscillating units, mediated both by the intracellular medium and the substrate. However, the harnessing of cell polarization for motility requires substrate-mediated interactions. Motility can be optimized by adapting the oscillation frequency to the relaxation time of the system or when the substrate and cell viscosities match. Cellular noise can destroy mechanical coordination between force-generating elements within the cell, resulting in sudden changes of polarization. The persistence of the cell's motion is found to depend on the cell size and the substrate viscosity. Within such a model, chemotactic guidance of cell motion is obtained by directionally modulating the persistence of motion, rather than by modulating the instantaneous cell velocity, in a way that resembles the run and tumble chemotaxis of bacteria.


Assuntos
Movimento Celular , Fenômenos Fisiológicos Celulares , Polaridade Celular , Quimiotaxia , Modelos Biológicos , Espaço Intracelular/fisiologia , Movimento (Física) , Viscosidade
12.
J Eur Acad Dermatol Venereol ; 29(3): 474-81, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25074756

RESUMO

BACKGROUND: Once-daily brimonidine tartrate (BT) 0.5% gel was shown to provide significantly greater efficacy vs. vehicle for the treatment of facial erythema in patients with rosacea. OBJECTIVES: To demonstrate that patient satisfaction with overall appearance is correlated with reduction in facial erythema, as measured by clinician and patient assessments. METHODS: Data from two identical phase III, multicentre, randomized, controlled trials of moderate facial erythema of rosacea (study A: n = 260; study B: n = 293) with topical BT 0.5% compared to vehicle gel once-daily for 4 weeks were analysed. Correlations of Patient's Assessment of Appearance (PAA) with Clinician's Erythema Assessment (CEA) and Patient's Self-Assessment (PSA) of erythema were evaluated by calculation of gamma statistics. RESULTS: PAA correlated with CEA post-application on Days 1, 15 and 29 for the intent-to-treat population and provided a median gamma value of 0.57 (min = 0.28, max = 0.61). PAA and PSA was also highly correlated post-application on Days 1, 15 and 29; with a median gamma value of 0.87 (min = 0.66, max = 0.89). Subjects who achieved a clinically meaningful improvement in both CEA and PSA scales were more likely to report satisfaction with the overall appearance of their skin (P < 0.001). CONCLUSIONS: Both one- and two-grade improvements in facial erythema assessed by subjects (PSA) and clinicians (CEA) correlate well with PAA, a patient-centered representation of meaningful change.


Assuntos
Tartarato de Brimonidina/uso terapêutico , Eritema/tratamento farmacológico , Face , Satisfação do Paciente , Rosácea/etiologia , Adulto , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
13.
J Neurol ; 262(1): 154-64, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25355454

RESUMO

PMM2-CDG (PMM2 gene mutations) is the most common congenital disorder of N-glycosylation. We conducted a nationwide survey to characterize the frequency, clinical features, glycosylation and genetic correlates in Italian patients with PMM2-CDG. Clinical information was obtained through a questionnaire filled in by the referral physicians including demographics, neurological and systemic features, neuroimaging data and genotype. Glycosylation analyses of serum transferrin were complemented by MALDI-Mass Spectrometry (MALDI-MS). Between 1996 and 2012, data on 37 Italian patients with PMM2-CDG were collected. All the patients with a severe phenotype were unable to walk unaided, 84 % had severe intellectual disability and 81 % microcephaly. Conversely, among 17 mildly affected patients 82 % had independent ambulation, 64 % had borderline to mild intellectual disability and 35 % microcephaly. Epilepsy and stroke-like events did not occur among patients with the mild phenotype. The rate and extent of systemic involvement were more pronounced in severely affected patients. The L32R misfolding mutation of the PMM2 gene occurred in 70 % of the patients with the mild phenotype and was associated with a less severe underglycosylation of serum Tf at MALDI-MS analyses. Despite their different disease severity, all patients had progressive (olivo)ponto-cerebellar atrophy that was the hallmark clinical feature for the diagnosis. A mild neurological phenotype of PMM2-CDG marked by preserved ambulatory ability and autonomy and associated with L32R mutation is particularly frequent in Italy. PMM2-CDG should be considered in patients with even mild developmental disability and/or unexplained progressive cerebellar atrophy.


Assuntos
Defeitos Congênitos da Glicosilação/genética , Defeitos Congênitos da Glicosilação/fisiopatologia , Atrofias Olivopontocerebelares/patologia , Fosfotransferases (Fosfomutases)/genética , Índice de Gravidade de Doença , Adolescente , Adulto , Criança , Pré-Escolar , Defeitos Congênitos da Glicosilação/complicações , Progressão da Doença , Feminino , Humanos , Itália , Masculino , Atrofias Olivopontocerebelares/etiologia , Fenótipo , Transferrina/análise , Adulto Jovem
14.
Phys Rev Lett ; 112(14): 148104, 2014 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-24766022

RESUMO

We introduce a phenomenological theory for a new class of soft active fluids with the ability to synchronize. Our theoretical framework describes the macroscopic behavior of a collection of interacting anisotropic elements with cyclic internal dynamics and a periodic phase variable. This system can (i) spontaneously undergo a transition to a state with macroscopic orientational order, with the elements aligned, a liquid crystal, (ii) attain another broken symmetry state characterized by synchronization of their phase variables, or (iii) a combination of both types of order. We derive the equations describing a spatially homogeneous system and also study the hydrodynamic fluctuations of the soft modes in some of the ordered states. We find that synchronization can promote or inhibit the transition to a state with orientational order, and vice versa. We provide an explicit microscopic realization: a suspension of microswimmers driven by cyclic strokes.

15.
Br J Dermatol ; 171(1): 162-9, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24506775

RESUMO

BACKGROUND: Persistent facial erythema is the most common primary pathological feature of rosacea, the only treatment for which is brimonidine tartrate (BT) gel. OBJECTIVES: To assess the relative bioavailability of topical BT gel in comparison with the ophthalmic BT solution. METHODS: A pharmacokinetic study was conducted to compare intraindividual systemic exposures after dermal application of BT gel (0·07%, 0·18% and 0·5%) under maximal use conditions in patients with moderate-to-severe facial erythema associated with rosacea, and administration of BT ophthalmic solution 0·2%. RESULTS: Patients who received BT ophthalmic solution 0·2% three times a day for 1 day had a mean Cmax of 54 ± 28 pg mL(-1) and a mean 0-24-h area under the curve (AUC0-24 h ) of 568 ± 277 pg h mL(-1) . Topical application of BT gel for 29 days resulted in quantifiable systemic exposure in 22%, 48%, 71% and 79% of patients who received BT gel 0·07% twice daily, 0·18% once daily, 0·18% twice daily and 0·5% once daily, respectively. The mean Cmax values for the BT gels ranged between 13 and 25 pg mL(-1) , and mean AUC0-24 h values ranged between 42 and 290 pg h mL(-1) . Systemic exposure increased with applied dose, with no drug accumulation for the duration of treatment. The systemic exposure observed with the highest dose of BT gel (0·5% once daily) was significantly lower than the systemic levels observed for the ophthalmic solution. 0·2% apply for all the concentrations. CONCLUSIONS: The systemic safety profile of BT gel may be considered better than that of the ophthalmic solution.


Assuntos
Agonistas de Receptores Adrenérgicos alfa 2/farmacocinética , Dermatoses Faciais/tratamento farmacológico , Soluções Oftálmicas/farmacocinética , Quinoxalinas/farmacocinética , Rosácea/tratamento farmacológico , Administração Cutânea , Agonistas de Receptores Adrenérgicos alfa 2/administração & dosagem , Agonistas de Receptores Adrenérgicos alfa 2/sangue , Adulto , Área Sob a Curva , Disponibilidade Biológica , Tartarato de Brimonidina , Esquema de Medicação , Dermatoses Faciais/metabolismo , Feminino , Géis , Humanos , Masculino , Quinoxalinas/administração & dosagem , Quinoxalinas/sangue , Rosácea/metabolismo
16.
Eur Phys J E Soft Matter ; 35(12): 9803, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23224111

RESUMO

We present a simple dynamical model of self-propeller at low Reynolds number in which self-propulsion is achieved via rotary elements (rotors). In this model by changing the sense of rotation of the rotors, the self-propeller can switch between a "linear swimming" phase where it swims in a straight line and a "tumbling" phase in which it can change direction in a controllable way via a global rotation of its body. We study the dynamics of this propeller in detail. To do this we provide an analytic framework within which the non-perturbative aspects of the internal dynamics can be treated allowing us to study the swimming process for arbitrary values of the swimmer deformations. Using it, we compute the averages (over a deformation cycle) of a number of characteristic properties of the swimmer such as its self-propulsion velocity, the dissipated power, its efficiency and the fluid flow patterns it generates. We compare these results to the corresponding average quantities for another class of model swimmers, where self-propulsion is achieved via periodic translations. Finally, we provide an explanation of why non-perturbative results can be obtained for these models using the geometrical language of gauge theory.


Assuntos
Modelos Teóricos , Natação/fisiologia , Humanos , Rotação
17.
J Biol Regul Homeost Agents ; 26(1 Suppl): S105-8, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22691256

RESUMO

PTX3 behaves as an acute-phase response protein as its blood levels rapidly and dramatically increase during endotoxic shock, sepsis, and other inflammatory and infectious conditions. Therefore, this study was designed to investigate a possible role of PTX3 in children with Atopic Dermatitis (AD). One-hundred-and-thirty-six patients (37 females, 99 males, mean age 10.4 years) were enrolled in the study. One hundred patients (74%) had only respiratory symptoms (allergic rhinitis and/or bronchial asthma); thirty-six patients (26%) showed dermatitis associated with respiratory allergy (allergic rhinitis and/or bronchial asthma). PTX3 levels were higher in children with AD and there was a significant correlation between serum PTX3 levels and SCORAD index (p-value=0.0001, rho=0.658). Therefore, this study may show that PTX3 might be a reliable marker for the severity of AD in children with respiratory allergy.


Assuntos
Proteína C-Reativa/análise , Dermatite Atópica/sangue , Componente Amiloide P Sérico/análise , Adolescente , Criança , Feminino , Humanos , Masculino
18.
Phys Rev E Stat Nonlin Soft Matter Phys ; 85(4 Pt 1): 040901, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22680412

RESUMO

We introduce a generic model of a weakly nonlinear self-sustained oscillator as a simplified tool to study synchronization in a fluid at low Reynolds number. By averaging over the fast degrees of freedom, we examine the effect of hydrodynamic interactions on the slow dynamics of two oscillators and show that they can lead to synchronization. Furthermore, we find that synchronization is strongly enhanced when the oscillators are nonisochronous, which on the limit cycle means the oscillations have an amplitude-dependent frequency. Nonisochronity is determined by a nonlinear coupling α being nonzero. We find that its (α) sign determines if they synchronize in phase or antiphase. We then study an infinite array of oscillators in the long-wavelength limit, in the presence of noise. For α>0, hydrodynamic interactions can lead to a homogeneous synchronized state. Numerical simulations for a finite number of oscillators confirm this and, when α<0, show the propagation of waves, reminiscent of metachronal coordination.


Assuntos
Modelos Químicos , Modelos Moleculares , Dinâmica não Linear , Oscilometria/métodos , Reologia/métodos , Água/química , Simulação por Computador
19.
Acta Crystallogr A ; 68(Pt 3): 382-92, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22514070

RESUMO

The effects of thermal vibrations on X-ray powder diffraction patterns are discussed. Special considerations for extremely small crystallites are described, including the occurrence of surface and edge vibrational modes, and a restriction on the maximum phonon wavelength. In doing so, a complete temperature diffuse scattering (TDS) model is presented, which includes the influence of these features on: the Debye-Waller parameter; first-order TDS; and higher-order TDS terms. The importance of using an accurate TDS representation is studied as a function of temperature and crystallite size. It is found that a misrepresentation of the TDS for small crystallites can lead to an error in the determined Debye-Waller parameter on the order of 20-40% and a slight overestimation of the peak broadening. While the presented theory is primarily developed considering X-ray scattering, the same expressions are expected to describe the TDS in faster-than-sound neutron powder diffraction measurements.

20.
Br J Dermatol ; 166(3): 633-41, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22050040

RESUMO

BACKGROUND: Erythema of rosacea is thought to result from abnormal cutaneous vasomotor activity. Brimonidine tartrate (BT) is a highly selective α(2) -adrenergic receptor agonist with vasoconstrictive activity. OBJECTIVE: To determine the optimal concentration and dose regimen of topical BT gel for the treatment of erythema of rosacea and to evaluate its efficacy and safety. METHODS: In study A, 122 subjects were randomized to receive a single application of BT 0·07%, 0·18%, 0·5% or vehicle. In study B (4-week treatment and 4-week follow-up), 269 subjects were randomized to receive BT 0·5% once daily, BT 0·18% once daily, vehicle once daily, BT 0·18% twice daily or vehicle twice daily. Evaluations included Clinician's Erythema Assessment (CEA), Patient's Self-Assessment (PSA), Chroma Meter measurements and adverse events. RESULTS: In study A, a single application of topical BT gel reduced facial erythema in a dose-dependent fashion. A significant difference between BT 0·5% and vehicle in Chroma Meter redness value was observed from 30min to 12h after application. In study B, BT 0·5% once daily had a statistically superior success profile (defined as a two-grade improvement on both CEA and PSA over 12h) compared with vehicle once daily on days 1, 15 and 29 (all P<0·001). No tachyphylaxis, rebound of erythema or aggravation of other disease signs (telangiectasia, inflammatory lesions) was observed. All regimens were safe and well tolerated with similarly low incidence of adverse events. CONCLUSIONS: Once-daily BT gel 0·5% is well tolerated and provides significantly greater efficacy than vehicle gel for the treatment of moderate to severe erythema of rosacea.


Assuntos
Agonistas de Receptores Adrenérgicos alfa 2/administração & dosagem , Fármacos Dermatológicos/administração & dosagem , Eritema/tratamento farmacológico , Dermatoses Faciais/tratamento farmacológico , Quinoxalinas/administração & dosagem , Rosácea/tratamento farmacológico , Administração Cutânea , Adolescente , Adulto , Idoso , Tartarato de Brimonidina , Relação Dose-Resposta a Droga , Esquema de Medicação , Feminino , Géis , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto Jovem
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