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1.
Laryngoscope ; 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-39087526

RESUMEN

OBJECTIVES: Hearing loss (HL) is one of the most common chronic health conditions in the United States (US). This study aims to evaluate trends in HL prevalence among US adults over the past two decades. METHODS: Audiometric data of adults from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 were analyzed in 2-year intervals to evaluate changes in HL (defined as pure tone average greater than 25 dB in at least one ear) over time in using odds ratios (ORs). Multivariate logistic regression was used to control for age and sex, and linear regression was used to evaluate trends in HL prevalence over time. RESULTS: The study included 13,468 participants. In adult participants (20-69 years old), HL remained stable over time, with some fluctuations ranging from 14.8% to 16.8%. In elderly participants (70-years and older), HL remained stable over time, with some fluctuations ranging from 71.7% to 77.1%. Based on univariate and linear regression analysis, there were no differences in HL rates in the adult and elderly cohorts. Subjects 40-49 years old and adults with education level of less than high school had significant downward trends in HL prevalence over two decades (p < 0.001 and p = 0.029). CONCLUSIONS: HL prevalence may be declining in the adult population when correcting for age and gender; however, there has not been a significant downward trend for the elderly population. HL may be decreasing over time among adults 40-49 years old and with shorter education backgrounds. LEVEL OF EVIDENCE: IV Laryngoscope, 2024.

2.
Laryngoscope ; 2024 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-38837793

RESUMEN

OBJECTIVES: The effect of Medicaid expansion as a part of the Affordable Care Act on vestibular schwannoma (VS) incidence overall and in marginalized populations has not yet been elucidated. The goal of this study was to determine if Medicaid expansion was associated with increases in VS incidence overall, as well as in patients of non-white race or in counties of low socioeconomic status (SES). METHODS: We performed a difference-in-difference (DiD) analysis from January 1st 2010-December 31st 2017 utilizing the Surveillance, Epidemiology, and End Results (SEER) database. Our DiD method compared the change in VS rate between counties that did and did not expand Medicaid among patients of white and non-white race, in low and high SES counties, before and after expansion. RESULTS: The study included 17,312 cases across 1020 counties. Medicaid expansion was associated with a 15% increase (incidence rate ratio 95% CI: [11%, 19]) in VS incidence. White populations saw a 10% increase (CI: [1.06, 1.19]), Black populations saw a 20% increase (CI: [1.10, 1.29]), and patients of other races saw a 44% increase in incidence associated with expansion (CI: [1.21, 1.70]). Low SES counties saw an increase in incidence 1.12 times higher than that of high SES counties (CI:[1.04, 1.20]). CONCLUSION: Medicaid expansion was associated with increases in VS incidence across populations. Furthermore, this increase was more evident in disadvantaged populations, such as patients of non-white race and those from low SES counties. These findings emphasize the impact of Medicaid expansion on healthcare utilization for VS diagnosis. LEVEL OF EVIDENCE: Step/Level 3-Retrospective Cohort Study Laryngoscope, 2024.

3.
Laryngoscope ; 2024 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-38554009

RESUMEN

OBJECTIVE: To evaluate the literature and summarize cochlear implantation (CI) outcomes after intralabyrinthine schwannoma (ILS) excision and tumor observation with CI. DATA SOURCES: OVID Medline, Embase, Web of Science; conception to 2024. REVIEW METHODS: A literature review was performed using subject headings, MeSH terms, and keywords. Abstracts and full texts were reviewed by two independent reviewers and adjudicated by a third. Inclusion criteria included studies with ILS and CI with reported audiologic outcomes. Subjects were analyzed into two groups, ILS resection with CI and in situ ILS with CI. Patients with NF2 were included. The main outcome of interest was CI audiometric performance level, with secondary outcomes of CI user status and open-set speech attainment. RESULTS: There were 29 articles with a total of 93 patients who met inclusion criteria. The resection group had 17% low performers, 44% intermediate performers, and 38% high performers. The in situ group had 40% low performers, 32% intermediate performers, 27% high performers. The resection group had 69 patients with 97% maintaining user status and 92% with open-set speech recognition. The observation group had 24 patients, with 87% user rate and 86% achieving open-set speech recognition. There was a greater percentage of NF2 diagnosis seen in the in situ group. CONCLUSION: There is a paucity of literature on CI and ILS. Patients are managed with both resection of tumor and implantation in situ. Early data are limited, with improvement in hearing outcomes and high user rates in both populations. LEVEL OF EVIDENCE: N/A Laryngoscope, 2024.

4.
J Surg Educ ; 80(10): 1484-1491, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37453898

RESUMEN

OBJECTIVE: To determine medical school characteristics that are associated with medical students entering otolaryngology residency programs. STUDY DESIGN: Cross-sectional study. SETTING: Publically available data on otolaryngology residents and academic otolaryngology programs. METHODS: Publicly available websites were used to collect demographic and bibliometric characteristics for 1527 residents in Accreditation Council for Graduate Medical Education (ACGME)-accredited otolaryngology programs accounting for the 2017 to 2021 match periods. For each medical school, information on class size, number of otolaryngology faculty, presence of a home academic otolaryngology program, NIH research funding, presence of a student interest group, and top 10 ranking by Doximity or U.S. News and World Report (USNWR) were collected. Univariate and multivariate analyses were performed between the medical school factors and the percentage of each medical school class that matriculated into an otolaryngology residency program. RESULTS: On multivariate analysis, the following factors were found to be associated with a higher percentage of graduates entering an otolaryngology residency program: presence of a home academic otolaryngology program (standardized beta value (ß) = 0.397, p < 0.0001), a 2021 top 10 ENT ranking according to USNWR (ß = 0.206, p = 0.0028), and the average h-index of students from a medical school (ß = 0.327, p < 0.0001). CONCLUSIONS: After controlling for multiple factors including research productivity, we found that the presence of a home academic program and a top 10 ranking on USNWR were associated with an increasing percentage of medical school graduates entering otolaryngology. NIH funding and the number of otolaryngology faculty were not associated with more students matriculating into an otolaryngology residency program. These findings can help guide medical schools and otolaryngology programs to recruit students into the field.


Asunto(s)
Internado y Residencia , Otolaringología , Estudiantes de Medicina , Humanos , Estados Unidos , Facultades de Medicina , Estudios Transversales , Educación de Postgrado en Medicina , Otolaringología/educación
5.
Otolaryngol Head Neck Surg ; 165(2): 339-343, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-33317418

RESUMEN

OBJECTIVE: To discuss indications for bilateral auditory brainstem implants (ABIs), compare audiometric outcomes of unilateral vs bilateral ABIs, and determine if patients have improved outcomes with addition of a second-side implant. STUDY DESIGN: Retrospective review of 24 patients with neurofibromatosis 2 (NF2) who underwent sequential placement of ABIs from 1989 to 2019. SETTING: Tertiary referral center. METHODS: Charts were reviewed for indication for second-side surgery, use of implants, and audiometric outcomes. Implants placed in the past 30 years were included in the study. Northwestern University Children's Perception of Speech (NU-CHIPS) and/or City University of New York (CUNY) sentence scores were compared in unilateral and bilateral conditions. RESULTS: Indications for a second-side implant included first-side implants with severe nonauditory symptoms (11), marginal audiometric results (9), outdated technology (2), or deterioration of first side (2). Seven patients are bilateral users and 1 patient discontinued bilateral use after a year due to no significant improvement over unilateral use. One patient with initial bilateral use was lost to follow-up. Thirteen patients are unilateral users due to nonaudiometric side effects or poor audiometric outcomes with the first side. Two patients are complete nonusers. Seventy-five percent had improved audiometric outcomes after the second-side implant, and 20% had stable findings. CONCLUSIONS: Second-side ABIs should be consider in patients with poor performance from a first-side implant. Most patients demonstrate subjective improvement with the second ABI. More research is needed for better objective assessments of improvements.


Asunto(s)
Implantación Auditiva en el Tronco Encefálico , Implantes Auditivos de Tronco Encefálico , Trastornos de la Audición/terapia , Neurofibromatosis 2/complicaciones , Adolescente , Audiometría , Niño , Preescolar , Femenino , Trastornos de la Audición/diagnóstico , Trastornos de la Audición/etiología , Humanos , Masculino , Neurofibromatosis 2/diagnóstico , Neurofibromatosis 2/terapia , Selección de Paciente , Estudios Retrospectivos , Resultado del Tratamiento
6.
Otol Neurotol ; 41(9): 1288-1295, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32925862

RESUMEN

HYPOTHESIS: The presence and distribution of ionized calcium binding adaptor 1 and CD68 macrophages in the human cochlea is altered in cochlear implantation (CI) compared with the normative or nonimplanted cochlea. BACKGROUND: It has been hypothesized that CI induces an immunological response in macrophages leading to implant failure or reduced hearing. Macrophages are resident immune cells in human cochlea and have been shown to phagocytize implant material. In animal models, macrophage populations increase with surgical stress and with the introduction of a foreign body. However, the function and response of inner ear macrophages to CI are only beginning to be understood. This study seeks to investigate the inflammatory response to CI by comparing cochlear macrophages in implanted and nonimplanted human temporal bones. METHODS: Nineteen temporal bones from nine implanted ears, seven contralateral controls, and three normal control ears were evaluated for the presence and distribution of CD68 and Iba1 expressing positive macrophages. RESULTS: Three types of macrophage populations were detected 1) CD68 positive macrophages, 2) Iba1 positive macrophages, and 3) CD68 and Iba1 colocalizing macrophages. Macrophage distribution was ubiquitous: the stria vascularis, Rosenthal canal, and the mid-modiolus intermingled in the spiral ganglia. Iba1 and CD68 macrophages were found in the CI and non-CI contralateral and normal human cochlea. Most ionized calcium binding adaptor 1 expressing macrophages were ramified/amoeboid cells, while CD68 expressing macrophages were round shaped with foamy appearance in some areas. In the CI cochlea, both types of macrophages were detected in the fibrous sheath surrounding the CI path and within fibrotic areas within the scala tympani and the scala vestibuli in the case of CI translocation. In four cases, the density of macrophages was unchanged in the CI compared with the contralateral nonimplanted side, and in three cases, there was an increased number of macrophages in the implanted CI side compared with the nonimplanted side. CONCLUSION: Multiple populations of macrophages exist within the cochlea which are present at baseline and in response to trauma from CI. These results further support evidence for a macrophage response to cochlear implantation. Further studies are indicated to evaluate whether these macrophages have a beneficial, detrimental, or a mixed effect in CI patients.


Asunto(s)
Implantación Coclear , Implantes Cocleares , Animales , Cóclea , Humanos , Inmunidad , Macrófagos , Rampa Timpánica , Hueso Temporal
7.
Otolaryngol Head Neck Surg ; 161(1): 130-136, 2019 07.
Artículo en Inglés | MEDLINE | ID: mdl-30832543

RESUMEN

OBJECTIVE: To compare outcomes for patients undergoing a transmastoid approach versus a middle fossa craniotomy approach with plugging and/or resurfacing for repair of superior semicircular canal dehiscence. Outcome measures include symptom resolution, hearing, operative time, hospital stay, complications, and revision rates. STUDY DESIGN: Multicenter retrospective comparative cohort study. SETTINGS: Three tertiary neurotology centers. SUBJECTS AND METHODS: All adult patients undergoing repair for superior canal dehiscence between 2006 and 2017 at 3 neurotology centers were included. Demographics and otologic history collected by chart review. Imaging, audiometric data, and vestibular evoked myogenic potential measurements were also collected for analysis. RESULTS: A total of 68 patients (74 ears) were included in the study. Twenty-one patients underwent middle fossa craniotomy repair (mean age, 47.9 years), and 47 underwent transmastoid repair (mean age, 48.0 years). There were no significant differences in age or sex distribution between the groups. The transmastoid group experienced a significantly shorter duration of hospitalization and lower recurrence rate as compared with the middle fossa craniotomy group (3.8% vs 33%). Both groups experienced improvement in noise-induced vertigo, autophony, pulsatile tinnitus, and nonspecific vertigo. There was no significant difference among symptom resolution between groups. Additionally, there was no significant difference in audiometric outcomes between the groups. CONCLUSION: Both the transmastoid approach and the middle fossa craniotomy approach for repair of superior canal dehiscence offer symptom resolution with minimal risk. The transmastoid approach was associated with shorter hospital stays and lower recurrence rate as compared with the middle fossa craniotomy approach.


Asunto(s)
Fosa Craneal Media/cirugía , Craneotomía/métodos , Enfermedades del Laberinto/patología , Enfermedades del Laberinto/cirugía , Apófisis Mastoides/cirugía , Procedimientos Quirúrgicos Otológicos/métodos , Canales Semicirculares/patología , Canales Semicirculares/cirugía , Femenino , Humanos , Tiempo de Internación/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Tempo Operativo , Complicaciones Posoperatorias/epidemiología , Reoperación/estadística & datos numéricos , Estudios Retrospectivos
8.
Otol Neurotol ; 40(3): e233-e239, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30742600

RESUMEN

HYPOTHESIS: In children, the distance between the carotid canal (CC) and Eustachian tube (ET) is not significantly narrower than the adult population. BACKGROUND: ET dysfunction treated with ET dilation is FDA approved for adults. Several studies describe the close relationship between the CC and the ET in adults, but the anatomy of the ET has not been well defined in children. This study seeks to investigate these relationships in the pediatric population. METHODS: Histologic sections from 23 temporal bones of pediatric patients ages 0 to 18 were reviewed by two independent observers. The distance between the CC and the cartilaginous Eustachian tube (CET), bony-cartilaginous junction (BCJ), and bony Eustachian tube (BET) were measured. Fifteen adult temporal bones were used as a control group. RESULTS: The distance to the CC was narrowest at the BET, and was actually higher in the pediatric population when compared to adults (0.5 mm and 0.2 mm, respectively, p = 0.06). The CC-CET distance was smaller in the pediatric group (2.3 mm vs 3.3 mm, p < 0.01). The bony-cartilaginous junction is often the region of most concern during dilation. There was no significant difference between the CC-BET distance in pediatric and adult groups (1.9 vs 2.3 mm, p = 0.20). CONCLUSIONS: CET-CC is smaller in the pediatric population, as expected due to smaller anatomic structures. However, the variable incline of the ET results in a CC-BCJ distance that is similar to the adult population. Although imaging studies are necessary.


Asunto(s)
Arterias Carótidas/anatomía & histología , Trompa Auditiva/anatomía & histología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Enfermedades del Oído/patología , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Hueso Temporal/anatomía & histología , Adulto Joven
9.
Otol Neurotol ; 39(9): e837-e842, 2018 10.
Artículo en Inglés | MEDLINE | ID: mdl-30199500

RESUMEN

OBJECTIVE: Ciprofloxacin resistance has been reported in 4.5% of patients with otorrhea and is increasing in prevalence. Due to ototoxicity, only fluoroquinolones are Food and Drug Administration approved for topical therapy in the middle ear. Furthermore, there is an assumption that antibiotic resistance is less relevant to topical therapy due to in vivo concentrations much higher than the minimum inhibitory concentration used to determine resistance. This study investigates ciprofloxacin-resistant infections and seeks to develop a better understanding of treatment options and outcomes. STUDY DESIGN: Retrospective review of 141 ciprofloxacin-resistant otologic infections. SETTING: Tertiary-care hospital. PATIENTS: Patients with culture-proven ciprofloxacin-resistant infections from 2008 to 2017. INTERVENTION(S): Antibiotic treatment with ciprofloxacin topical drops, ciprofloxacin plus oral antibiotics, and nonciprofloxacin therapy. MAIN OUTCOME MEASURE(S): Bacteriology for ciprofloxacin-resistant infections and treatment effectiveness of various therapies. RESULTS: Methicillin-resistant Staphylococcus aureus (33%), Corynebacterium striatum (19%), and non-Methicillin-resistant Staphylococcus aureus (11%) are the most frequent causes of ciprofloxacin-resistant infections. Topical ciprofloxacin monotherapy was successful in 2.7% of infections compared with a 64.7% success rate with the addition of an oral antibiotic (p < 0.001). Nonciprofloxacin drops are more effective with a 70% cure rate compared with the 2.7% of the ciprofloxacin drops p < 0.001. There was no difference in treatment efficacy when comparing nonciprofloxacin topical therapy (70% cure) to nonciprofloxacin topical therapy plus oral antibiotic (83% cure, p = 0.17). CONCLUSIONS: Using ciprofloxacin drops to treat ciprofloxacin-resistant bacteria is ineffective and patients do significantly better with alternative therapy. This finding supports the conclusion that high concentrations achieved in topical applications are not sufficient to overcome antibiotic resistance.


Asunto(s)
Antibacterianos/uso terapéutico , Ciprofloxacina/uso terapéutico , Farmacorresistencia Microbiana/efectos de los fármacos , Otitis/tratamiento farmacológico , Infecciones Estafilocócicas/tratamiento farmacológico , Humanos , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Ventilación del Oído Medio , Estudios Retrospectivos , Resultado del Tratamiento
10.
Otolaryngol Clin North Am ; 51(3): 515-534, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29773124

RESUMEN

The Global Burden of Disease (GBD) project provides longitudinal analysis of the global burden of otolaryngologic diseases by measuring the all-cause mortality, years of life lost, the years of life lived with disability, and disability-adjusted life years. Hearing loss burden is assessed overall and as sequelae of other diseases, such as otitis media or meningitis. Using these measures, we can appreciate the high prevalence and disability related to hearing loss globally. Other otolaryngologic diseases that contribute to the GBD include otitis media, cleft lip and palate, head and neck cancer, facial trauma, and oral disorders.


Asunto(s)
Costo de Enfermedad , Personas con Discapacidad/estadística & datos numéricos , Carga Global de Enfermedades/tendencias , Salud Global , Enfermedades Otorrinolaringológicas/mortalidad , Pérdida Auditiva/epidemiología , Humanos , Mortalidad , Otolaringología , Enfermedades Otorrinolaringológicas/clasificación , Años de Vida Ajustados por Calidad de Vida , Factores de Riesgo
11.
Otol Neurotol ; 37(10): 1583-1588, 2016 12.
Artículo en Inglés | MEDLINE | ID: mdl-27631835

RESUMEN

OBJECTIVE: To investigate the prevalence and relative risk of semicircular canal dehiscence (SCD) in pediatric patients with CDH23 pathogenic variants (Usher syndrome or non-syndromic deafness) compared with age-matched controls. STUDY DESIGN: Retrospective cohort study. SETTING: Multi-institutional study. PATIENTS: Pediatric patients (ages 0-5 years) were compared based on the presence of biallelic pathogenic variants in CDH23 with pediatric controls who underwent computed tomography (CT) temporal bone scan for alternative purposes. INTERVENTIONS: Retrospective review of diagnostic high resolution CT temporal bone scans and magnetic resonance imaging (MRI) for evaluation of SCD. MAIN OUTCOME MEASURES: Superior and posterior semicircular canals were evaluated by a neuroradiologist for presence of SCD or abnormal development. RESULTS: Forty-two CT scans were reviewed for SCD. Eighty-six percent of the CDH23 variant group had abnormalities in at least one canal compared with only 12% in age-matched controls. In the CDH23 variant group there were four patients with superior SCD (57%, RR = 10.0) and three patients with posterior canal abnormalities (43%, RR = 7.5) compared with two, and two patients, respectively, in the control population. Four CDH23 variant children had bilateral abnormalities. One child had thinning or dehiscence in both the superior and posterior canals. Relative risk of SCD in children with CDH23 pathogenic variants is 7.5 (p < 0.001) compared with the pediatric control population. CONCLUSIONS: Children with a CDH23 pathogenic variants are at significantly increased risk of having SCD and this may be a contributing factor to the vestibular dysfunction in Usher syndrome type 1D patient population.


Asunto(s)
Cadherinas/genética , Enfermedades del Oído/genética , Canales Semicirculares/patología , Alelos , Proteínas Relacionadas con las Cadherinas , Preescolar , Enfermedades del Oído/diagnóstico por imagen , Enfermedades del Oído/epidemiología , Enfermedades del Oído/patología , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Lactante , Recién Nacido , Imagen por Resonancia Magnética , Masculino , Prevalencia , Estudios Retrospectivos , Factores de Riesgo , Canales Semicirculares/diagnóstico por imagen , Tomografía Computarizada por Rayos X
12.
Otolaryngol Head Neck Surg ; 155(4): 657-62, 2016 10.
Artículo en Inglés | MEDLINE | ID: mdl-27301896

RESUMEN

OBJECTIVES: This study compares the functional outcomes of nevus intermedius impairment following surgery, radiation, or observation for the treatment of vestibular schwannoma. STUDY DESIGN: Retrospective cohort study. SETTINGS: Tertiary care medical center. SUBJECTS AND METHODS: We retrospectively examined 141 charts of patients with a vestibular schwannoma seen in the Dartmouth-Hitchcock Acoustic Neuroma Clinic between 2012 and 2014. Seventy-one patients underwent intervention (including radiation) as their primary treatment, and 70 were treated with observation. As part of routine care, patients were interviewed at clinic visits and with a questionnaire assessing nervus intermedius impairment. RESULTS: At presentation, 25 patients (19%) reported nervus intermedius impairment. Most common disturbances were xerophthalmia (dry eyes, 13%) and dysgeusia (taste alteration, 7.6%). Postintervention, 35 patients (53%) had ≥1 symptoms of nervus intermedius dysfunction, which is increased in comparison with patients in the observation group (17 patients, 26.5%, P < .05). Twelve intervention patients had symptoms resolve postoperatively, making no long-term difference between the observation and intervention groups (P = .20). Motor function of the facial nerve postoperatively is correlated with nervus intermedius symptoms. Surgical approaches were compared with radiation therapy, and no significant difference in nervus intermedius outcomes was found. CONCLUSION: This study demonstrates the clinical importance of monitoring nervus intermedius symptoms, since a high percentage of all patients undergoing intervention will be symptomatic during management. Patients with motor dysfunction are at a higher risk of developing nervus intermedius sequelae and need close follow-up. Although impairment is common, many symptoms will improve over time with no long-term difference between intervention patients and those under observation.


Asunto(s)
Traumatismos del Nervio Facial/etiología , Nervio Facial/efectos de la radiación , Neuroma Acústico/radioterapia , Neuroma Acústico/cirugía , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Observación , Estudios Retrospectivos , Encuestas y Cuestionarios , Resultado del Tratamiento
13.
Appl Spectrosc ; 63(7): 742-7, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19589210

RESUMEN

The ability to accurately and noninvasively analyze illicit drugs is important for criminal investigations and prosecution. Current methods involve significant sample pretreatment and most are destructive. The goal of this work is to develop a method based on Raman spectroscopy to classify simulated street drug mixtures composed of one drug component and up to three cutting agents including those routinely found in confiscated illicit street drug mixtures. Spectra were collected on both a homebuilt instrument using a HeNe laser and on a handheld commercial instrument with a 785 nm light source. Mixtures were prepared with drug concentrations ranging from 10 to 100 percent. Optimal preprocessing for the data set included truncating, Savitzky-Golay smoothing, normalization, differentiating, and mean centering. Using principal component analysis (PCA), it was possible to resolve the spectral differences between benzocaine, lidocaine, isoxsuprine, and norephedrine and correctly classify them 100 percent of the time.


Asunto(s)
Mezclas Complejas/análisis , Drogas Ilícitas/análisis , Análisis de Componente Principal , Espectrometría Raman/métodos , Algoritmos , Benzocaína/análisis , Mezclas Complejas/química , Diseño de Equipo , Drogas Ilícitas/clasificación , Lidocaína/análisis , Procaína/análisis
14.
Electrophoresis ; 28(14): 2385-90, 2007 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-17632806

RESUMEN

CE separations are known for their high separation efficiencies. In systems with EOF, the high efficiencies benefit from the flat, plug profile that is characteristic of EOF. When a velocity gradient is present, such as in separations which have nonuniform buffer ionic strength, surface adsorption or differences in the height of the ends of the capillary, a parabolic flow component is introduced. This deviation from purely EOF yields increased peak dispersion and a subsequent decrease in separation performance. This work details a rapid method for detecting deviations from ideal plug flow during the course of a separation using the radially averaged flow profile of a photobleached fluorophore added to the BGE. By comparing the ratio of two different data analysis procedures, deviations from ideal plug flow can be detected. This method allows rapid measurement of flow character and does not interfere with the concurrent separation. We demonstrate easy detection of the onset of hydrodynamic flow induced by both gravity siphoning and an ionic strength buffer discontinuity. A brief analysis of the radially averaged peak shapes is also presented.


Asunto(s)
Electroforesis Capilar/métodos , Electroforesis Capilar/normas , Colorantes Fluorescentes/química , Tampones (Química) , Electroósmosis , Concentración Osmolar , Fotoblanqueo
15.
Appl Spectrosc ; 59(12): 1493-7, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16390588

RESUMEN

Measurement of illicit drugs on paper currency is of interest for evidentiary purposes in legal cases involving the drug trade. Current methods, primarily based on mass spectrometry, are destructive and prevent re-analysis of the evidence. This article details a method based on Raman microspectroscopy that is able to collect spectra from individual crystals on the surface of paper currency. Mixtures of isoxsuprine and norephedrine, which are non-pharmacologically active drug surrogates, as well as lidocaine and benzocaine, common excipients in street drugs, were doped in small quantities onto US currency. Significant fluorescence interference resulted from the underlying dollar bill. This work presents two methods for reducing the fluorescence background, photobleaching and background subtraction, which both worked well. Finally, a method for determining the percent composition of individual components in heterogeneous mixtures was developed by systematically sampling the surface of the dollar bill. Results were accurate within a few percent, although the method was quite time consuming.


Asunto(s)
Mezclas Complejas/análisis , Drogas Ilícitas/análisis , Microquímica/métodos , Papel , Espectrometría de Fluorescencia/métodos , Espectrometría Raman/métodos , Detección de Abuso de Sustancias/métodos , Algoritmos , Mezclas Complejas/química , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
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