RESUMEN

Monitoring membrane-mediated dialysis in real time with static and dynamic light scattering revealed distinctive differences, including reversibility/irreversibility, in the effects of ionic strength (NaCl) and the denaturant guanidine-HCl (Gd) on a synthetic polyelectrolyte and several types of biomacromolecules: protein, polysaccharide, and polyampholyte. Dialysis cycles against aqueous NaCl and Gd, and reverse back to the original aqueous solution, were monitored. The behavior of Na-polystyrenesulfonate was reversible and yielded a detailed polymer physics description. The biomacromolecules additionally showed hydrogen-bonding/hydrophobic (HP) interactions. An interpretive model was developed that considers the interplay among polyelectrolyte, polyampholyte, and HP potential energies in determining the different associative, aggregative, and dissociative behaviors. NaCl isolated purely electrostatic effects, whereas Gd combined electrostatic and HP effects. Some macromolecules showed partially reversible behavior, and others were completely irreversible. The dialysis monitoring method should prove useful for investigating fundamental macromolecular and colloid properties and for drug formulation and stability optimization.

Asunto(s)

Sustancias Macromoleculares , Concentración Osmolar , Sustancias Macromoleculares/química , Guanidina/química , Diálisis/métodos , Enlace de Hidrógeno , Cloruro de Sodio/química , Interacciones Hidrofóbicas e Hidrofílicas , Polisacáridos/química , Electricidad Estática

RESUMEN

OBJECTIVE: To assess associations between secure patient-clinician email use and clinical services utilisation over time. DESIGN: Retrospective cohort study between July 2010 and December 2013. Controlling for a utilisation surge around first secure email use, we analysed difference of differences between propensity score-matched groups of secure patient-clinician email users and non-users for utilisation 1-12 months before and 7-18 months after first email (users) or a randomly assigned index date (non-users). SETTING: US integrated healthcare delivery system. PARTICIPANTS: 9345 adults with first secure email use between July 2011 and July 2012 and continuous enrolment for ≥30 months and 9345 adults without secure email use between July 2010 and July 2012 matched to users on demographics, health status, and baseline utilisation. PRIMARY OUTCOME MEASURES: Rates of office visits, patient-initiated phone calls, scheduled telephone visits, after-hours clinic visits, emergency department visits, and hospitalisations. RESULTS: After controlling for multiple factors, no statistically significant differences in utilisation between secure email users and non-users occurred. Utilisation transiently increased by 88-237% around first email use. Annual rates of patient-initiated phone calls decreased among secure email users, 0.2 fewer calls per person (95% CI -0.3 to -0.1), from a mean of 4.1 calls per person 1-12 months before first use to a mean of 3.8 calls per person 7-18 months after first use. Rates of patient-initiated phone calls also decreased among non-users, 0.1 fewer calls per person (95% CI -0.2 to 0.0), from a mean of 4.2 calls per person 1-12 months before the index date to mean of 4.1 calls per person 7-18 months after the index date. CONCLUSIONS: Compared with non-users, patient use of secure email with clinicians was not associated with statistically significant differences in clinical services utilisation 7-18 months after first use.

Asunto(s)

Atención Ambulatoria/estadística & datos numéricos , Prestación Integrada de Atención de Salud/estadística & datos numéricos , Correo Electrónico/estadística & datos numéricos , Servicio de Urgencia en Hospital/estadística & datos numéricos , Hospitalización/estadística & datos numéricos , Adolescente , Adulto , Anciano , Colorado , Femenino , Humanos , Masculino , Persona de Mediana Edad , Evaluación de Resultado en la Atención de Salud , Estudios Retrospectivos , Adulto Joven

RESUMEN

STUDY OBJECTIVE: To determine if the use of acid-suppressing drugs is increased before the occurrence of ischemic events. DESIGN: Population-based, nested case-control analysis. DATA SOURCE: Administrative databases in Saskatchewan, Canada. PATIENTS: Cases were 1612 patients (aged ≥ 40 yrs) who started a first-ever antihypertensive drug between January 1, 1994, and December 31, 2003, and were hospitalized for a first ischemic heart event of either myocardial infarction (1002 patients) or unstable angina (610 patients); five control patients were matched to each case patient by age, sex, and year of first antihypertensive prescription (8060 controls). MEASUREMENTS AND MAIN RESULTS: Within the case and control groups, we calculated exposure to acid-suppressing therapy, defined as proton pump inhibitors (PPIs) or histamine(2)-receptor antagonists (H(2)RAs), within 90 days leading up to the event. Exposure to acid-suppressing therapy was higher among cases than controls (15.3% [246/1612] vs 10.4% [837/8060], adjusted odds ratio [AOR] 1.26, 95% confidence interval [CI] 1.06-1.49, p<0.009). Exposure to each acid suppressant was similarly higher among cases than controls: H(2)RA users (11.7% [188/1612] vs 8.4% [678/8060], AOR 1.21, 95% CI 1.00-1.46, p<0.048) and PPI users (4.0% [64/1612] vs 2.2% [179/8060], AOR 1.32, 95% CI 0.95-1.84, p=0.094). Use of other drugs was also significantly increased during this period. CONCLUSIONS: Use of acid-suppressing drugs increased before the occurrence of ischemic events regardless of the type (PPI or H(2)RA) or whether other drugs, such as clopidogrel, were concurrently administered. In addition, significant increases in overall drug use were observed during this time frame, suggesting that many patients exhibit warning signs before an acute hospitalization. Thus, PPI use before the occurrence of ischemic events may simply be a marker of unmeasured and uncontrolled confounding in observational studies that have implicated a PPI-clopidogrel interaction as a cause of recurrent ischemic events.

Asunto(s)

Quimioterapia Combinada/efectos adversos , Isquemia Miocárdica/epidemiología , Inhibidores de Agregación Plaquetaria/uso terapéutico , Inhibidores de la Bomba de Protones/efectos adversos , Ticlopidina/análogos & derivados , Adulto , Anciano , Angina Inestable/tratamiento farmacológico , Angina Inestable/epidemiología , Enfermedades Cardiovasculares/tratamiento farmacológico , Enfermedades Cardiovasculares/epidemiología , Clopidogrel , Estudios de Cohortes , Factores de Confusión Epidemiológicos , Estudios Epidemiológicos , Femenino , Antagonistas de los Receptores H2 de la Histamina/metabolismo , Antagonistas de los Receptores H2 de la Histamina/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/tratamiento farmacológico , Infarto del Miocardio/epidemiología , Isquemia Miocárdica/tratamiento farmacológico , Inhibidores de la Bomba de Protones/metabolismo , Inhibidores de la Bomba de Protones/uso terapéutico , Proyectos de Investigación , Factores de Riesgo , Ticlopidina/uso terapéutico , Factores de Tiempo

RESUMEN

PURPOSE: To measure the amount of light energy that dental students actually deliver to a Class I preparation in a dental mannequin. MATERIALS AND METHODS: Approval for the study was obtained from the Dalhousie University Health Sciences Research Ethics Board. Each of 20 third-year dental students light-cured a Class I preparation in tooth 27 in a mannequin head. A photodetector located at the bottom of the cavity preparation measured how much light would be received by a restoration. Each student cured the simulated restoration for 20 seconds using a quartz-tungsten-halogen curing light (Optilux 401). The irradiance received (mW/cm2) was recorded in real time, and the energy per unit area (J/cm2) delivered to the detector by each student was calculated. The students were then given detailed instructions on how to effectively use the curing light, and the experiment was repeated. RESULTS: When the curing light was fixed directly over the tooth, the greatest amount of light energy delivered to the detector in 20 seconds was 13.9 +/- 0.4 J/cm2. Before instruction, the students delivered between 2.0 and 12.0 J/cm2 (mean +/- standard deviation [SD]: 7.9 +/- 2.7 J/cm2). After receiving detailed instructions, the same students delivered between 7.7 and 13.4 J/cm2 (mean +/- SD: 10.0 +/- 1.4 J/cm2). A paired student"s t test showed that instruction resulted in a significant improvement (p < 0.001). CONCLUSIONS: Although instruction yielded improvements, the mean energy delivered was much less (7.9 J/cm2 before instruction and 10.0 J/cm2 after instruction) than the expected 13.9 J/cm2. To maximize the energy delivered, the operator should wear eye protection, should watch what he or she is doing and should hold the light both close to and perpendicular to the restoration.

Asunto(s)

Luces de Curación Dental , Restauración Dental Permanente/métodos , Curación por Luz de Adhesivos Dentales/métodos , Análisis de Varianza , Resinas Compuestas/efectos de la radiación , Restauración Dental Permanente/clasificación , Operatoria Dental/educación , Dispositivos de Protección de los Ojos , Pruebas de Dureza , Humanos , Maniquíes , Fotometría , Estudiantes de Odontología

RESUMEN

Self-etch bonding systems are easy to use and popular in dental practice. The current study examined the in vitro shear bond strengths to dentin and ground enamel of four self-etch bonding systems and a two-step etch-and-rinse bonding system. Two hundred extracted non-carious human molars were used. Approximately 0.5 mm of enamel was removed from the buccal surface of 100 teeth and the bond strengths of this enamel surface were determined. The buccal surface of the remaining 100 teeth was ground away to create a standardized smear layer on dentin. Five adhesive systems were used: Adper Single Bond Plus (ASB): two-step etch-and-rinse); Adper Scotchbond SE (AS), Clearfil SE Bond (CSE-both two-step self-etch); XENO V (X) and Adper Easy Bond (AE): both one-step self-etch). Filtek Z250 composite was bonded to the tooth using each adhesive system in a low configuration (C) factor (0.2) and a high C-factor (4.4) mold (10 teeth in each group). The specimens were thermal cycled 2,000x, then subjected to a shear bond strength test. The data were compared with analysis of variance using the Fisher's PLSD multiple comparison tests. A three-factor ANOVA showed that, overall, the shear bond strength was significantly higher in the low C-factor group 4.33 MPa (p < 0.0001). There was also a significant difference in the shear bond strengths among the bonding systems (p < 0.0001). The higher C-factor molds had the same adverse effect on all bonding systems and on both enamel and dentin, but the bonding systems acted differently on enamel and dentin (three-factor ANOVA p < 0.0001). The two-step etch-and-rinse system (ASB) consistently delivered the highest bond strengths (34.6-41.5 MPa). Fisher's PLSD comparisons showed that, in the high C-factor mold, there was no significant difference between the shear bond strengths of SB, EB and CSE to dentin, and SB, X and SE to enamel (p > 0.05). The one-step self-etch AE system delivered the lowest shear bond strengths (23.9 MPa) to enamel (p < 0.05). The two-step self-etch system AS delivered the lowest shear bond strengths (23.9 MPa) to dentin (p < 0.05).

Asunto(s)

Recubrimiento Dental Adhesivo , Esmalte Dental/ultraestructura , Recubrimientos Dentinarios/química , Dentina/ultraestructura , Grabado Ácido Dental , Bisfenol A Glicidil Metacrilato/química , Compómeros/química , Resinas Compuestas/química , Preparación de la Cavidad Dental/clasificación , Humanos , Ensayo de Materiales , Cementos de Resina/química , Resistencia al Corte , Capa de Barro Dentinario , Estrés Mecánico , Propiedades de Superficie , Temperatura , Factores de Tiempo

Asunto(s)

Trastorno por Déficit de Atención con Hiperactividad/tratamiento farmacológico , Estimulantes del Sistema Nervioso Central/uso terapéutico , Metilfenidato/uso terapéutico , Terapia Conductista/métodos , Estimulantes del Sistema Nervioso Central/administración & dosificación , Niño , Relación Dosis-Respuesta a Droga , Estudios de Seguimiento , Humanos , Masculino , Metilfenidato/administración & dosificación , Cooperación del Paciente

RESUMEN

OBJECTIVE: To determine the prevalences of overweight and obesity in children aged 4 to 12 years, using the standard definitions proposed by the International Obesity Taskforce. DESIGN: Population prevalence cross-sectional survey involving measurement of height and weight. Data collection took place in 1998. SETTING: Schools in Gibraltar. SUBJECTS: In total 2994 children, aged 4-12 years, attending these schools (1540 boys, 1454 girls). RESULTS: Prevalence of overweight in boys was 19.7%, while obesity prevalence was 10.8%. For the girls, overweight prevalence was 21.4%, while obesity prevalence was 10.6%. There were no significant differences in the proportions of overweight or obesity between boys and girls. CONCLUSIONS: This was the first time that the prevalences of overweight and obesity have been estimated in children from Gibraltar. These data provide further information on prevalence rates of overweight and obesity, using defined cut-offs for comparison with data from other countries.

Asunto(s)

Obesidad/epidemiología , Estatura , Peso Corporal , Niño , Preescolar , Estudios Transversales , Femenino , Gibraltar/epidemiología , Humanos , Masculino , Encuestas Nutricionales , Prevalencia , Estándares de Referencia , Valores de Referencia , Distribución por Sexo