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BACKGROUND: An unmet need remains for sensitive outcome measures in neuroprotective trials. The study aims to determine whether a composite clinical motor score, combining the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III motor examination score, Purdue Pegboard Test, and Timed Up and Go, provides greater sensitivity in detecting motor change in early disease than the MDS-UPDRS III alone. METHODS: The Oxford Discovery longitudinal cohort study involves individuals with isolated rapid eye movement sleep behaviour disorder (iRBD) (n=272, confirmed polysomnographically, median follow-up: 1.6 years), idiopathic Parkinson's disease (PD) (n=909, median follow-up: 3.5 years, baseline: <3.5 years disease duration) and controls (n=316, age-matched and sex-matched, without a first-degree family history of PD). Motor and non-motor assessments were performed at each in-person visit. RESULTS: Compared with the MDS-UPDRS III, the composite clinical motor score demonstrated a wider score distribution in iRBD and controls, lower coefficient of variation (37% vs 67%), and higher correlation coefficients with self-reported measures of motor severity (0.65 vs 0.61) and overall health status (-0.40 vs -0.33). Greater score range in mild to moderate PD, higher magnitude of longitudinal change in iRBD and longitudinal score linearity suggest better sensitivity in detecting subtle motor change. The composite clinical motor score was more accurate than the MDS-UPDRS III in predicting clinical outcomes, requiring 64% fewer participants with PD and 51% fewer participants with iRBD in sample size estimations for a hypothetical 18-month placebo-controlled clinical trial. CONCLUSION: The composite clinical motor score may offer greater consistency and sensitivity in detecting change than the MDS-UPDRS III.
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Enfermedad de Parkinson , Trastorno de la Conducta del Sueño REM , Humanos , Estudios Longitudinales , Pruebas de Estado Mental y Demencia , Evaluación de Resultado en la Atención de Salud , Enfermedad de Parkinson/diagnóstico , Índice de Severidad de la EnfermedadRESUMEN
STUDY OBJECTIVES: To identify the prevalence of excessive daytime sleepiness (EDS) in a prospectively recruited patient population with traumatic brain injury (TBI) of mixed severity. Furthermore, the study aimed to assess the relationship between patient factors and EDS. METHOD: One-hundred and eighteen patients with TBI were assessed in a neurorehabilitation clinic after discharge from the emergency department. Enrolled participants were evaluated using several TBI-related outcome measures, 6-8 weeks after injury. RESULTS: EDS (defined using the Epworth Sleepiness Scale ≥10) occurred in 48 of 118 (41.7%) patients in this study. Anxiety; depression; change in ability to work; employment status; global outcome (GOSE); social and functional outcome (RHFUQ); and symptom severity (RPCS) were associated with EDS in a univariate analysis. Anxiety was the only factor associated with EDS in the multivariate analysis (OR: 0.28 [95% CI: 0.09-0.90], P = .032). CONCLUSION: EDS is common after TBI in a community setting and is associated with several factors, which likely interact to contribute toward worse outcome. Anxiety is a factor that, if routinely assessed and considered during patient care choices, may assist in favorable sleep-related outcome during and after post-TBI recovery.
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Lesiones Traumáticas del Encéfalo , Trastornos de Somnolencia Excesiva , Ansiedad/epidemiología , Ansiedad/etiología , Lesiones Traumáticas del Encéfalo/complicaciones , Lesiones Traumáticas del Encéfalo/epidemiología , Trastornos de Somnolencia Excesiva/epidemiología , Trastornos de Somnolencia Excesiva/etiología , Humanos , Prevalencia , SueñoRESUMEN
NMR diffusion measurements (or dNMR) provide a powerful tool for analysis of solution organization and microgeometry of the environment by probing random molecular motion. Being a very versatile method, dNMR can be applied to a large variety of samples and systems. Here, a brief introduction into dNMR and a summary of recent advances in the field are presented. The research topics include restricted diffusion, anisotropic diffusion, polymer dynamics, solution structuring and dNMR method development. The dNMR studied systems include plants, cells (cell models), liquid crystals, polymer solutions, ionic liquids, supercooled solutions, untreated water, amino acid solutions and more. It is demonstrated how a variety of dNMR methods can be applied to a system to extract the data on particular structures present among, formed by or surrounding the diffusing particles. It is also demonstrated how dNMR methods can be developed to allow probing larger geometries, low sample concentrations and faster processes. Copyright © 2016 John Wiley & Sons, Ltd.
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The synthesis and chromatographic behavior of an analytical size mixed-mode bonded silica monolith was investigated. The monolith was functionalized by an in situ modification process of a bare silica rod with chloro(3-cyanopropyl)dimethyl silane and chlorodimethyl propyl phenyl silane solutions. These ligands were selected in order to combine both resonance and nonresonance π-type bonding within a single separation environment. Selectivity studies were undertaken using n-alkyl benzenes and polycyclic aromatic hydrocarbons in aqueous methanol and acetonitrile mobile phases to assess the methylene and aromatic selectivities of the column. The results fit with the linear solvent strength theory suggesting excellent selectivity of the column was achieved. Comparison studies were performed on monolithic columns that were functionalized separately with cyano and phenyl ligands, suggesting highly conjugated molecules were able to successfully exploit both of the π-type selectivities afforded by the two different ligands on the mixed-mode column.
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Tear film stability decreases with age however the cause(s) of the instability are speculative. Perhaps the more saturated meibum from infants may contribute to tear film stability. The meibum lipid phase transition temperature and lipid hydrocarbon chain order at physiological temperature (33 °C) decrease with increasing age. It is reasonable that stronger lipid-lipid interactions could stabilize the tear film since these interactions must be broken for tear break up to occur. In this study, meibum from a pool of adult donors was saturated catalytically. The influence of saturation on meibum hydrocarbon chain order was determined by infrared spectroscopy. Meibum is in an anhydrous state in the meibomian glands and on the surface of the eyelid. The influence of saturation on the surface properties of meibum was determined using Langmuir trough technology. Saturation of native human meibum did not change the minimum or maximum values of hydrocarbon chain order so at temperatures far above or below the phase transition of human meibum, saturation does not play a role in ordering or disordering the lipid hydrocarbon chains. Saturation did increase the phase transition temperature in human meibum by over 20 °C, a relatively high amount. Surface pressure-area studies showing the late take off and higher maximum surface pressure of saturated meibum compared to native meibum suggest that the saturated meibum film is quite molecularly ordered (stiff molecular arrangement) and elastic (molecules are able to rearrange during compression and expansion) compared with native meibum films which are more fluid agreeing with the infrared spectroscopic results of this study. In saturated meibum, the formation of compacted ordered islands of lipids above the surfactant layer would be expected to decrease the rate of evaporation compared to fluid and more loosely packed native meibum. Higher surface pressure observed with films of saturated meibum compared to native meibum suggests greater film stability especially under the high shear stress of a blink.
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Lípidos/análisis , Glándulas Tarsales/química , Lágrimas/química , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Espectrofotometría Infrarroja , Propiedades de Superficie , TemperaturaRESUMEN
The multidimensional high-performance liquid chromatography separations of the complex sample matrix found in café espresso coffee were completed on the propyl phenyl and butyl phenyl columns that contain 3 and 4 carbon atoms in the spacer chain, respectively. Phenyl type stationary phases are able to undergo unique π-π interactions with aromatic compounds. Previous works have found that there are differences in retention characteristics between these chain lengths and this was explored further here. It was found that when analysing the separations by quadrants, using a geometric approach to factor analysis and by measuring the normalised mean radius, subtle differences in the separations were observed and the butyl phenyl phase was more selective for the high to medium polarity species. However, there was very little difference in separation behaviour for the hydrophobic components within the coffee sample. Overall, the analysis of the entire separation showed very little difference.
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Cromatografía Líquida de Alta Presión/instrumentación , Cromatografía Líquida de Alta Presión/métodos , Café/química , Electrones , Hidrocarburos Policíclicos Aromáticos/análisis , Solventes/químicaRESUMEN
PURPOSE: On 24/04/2018, the United Kingdom (UK) Medicines and Healthcare Products Regulatory Agency (MHRA) clarified previous policies by issuing a statement, that the use of sodium valproate is contraindicated in women of childbearing potential unless the conditions of a pregnancy prevention programme are met, and only if other treatments are ineffective or not tolerated. We evaluated the impact of this over the first year of implementation in a tertiary epilepsy centre. METHODS: Cross-sectional study of all women under active follow up, or newly referred, of childbearing age (16-55 years), taking valproate for the treatment of epilepsy, over 12 months from 01/05/2018. RESULTS: We identified 125 cases, with 31 newly referred in response to MHRA regulations. 9.6% of patients did not attend their appointment, 35.2% had a learning disability (LD), which in 19.2% was sufficiently severe that they could not consent to a sexual relationship. Patients with LD prescribed valproate were significantly younger, and more likely to have a focal or uncharacterised epilepsy than patients without LD. In 46.4% of patients, MHRA regulations were followed: women were already using highly active contraception (HAC), HAC was started, or valproate withdrawn. In 24.8% of cases, women elected to continue valproate, and were not willing to use HAC. CONCLUSIONS: In 53.6% of cases, MHRA regulations contraindicating the use valproate in women of childbearing potential could not be followed fully, due to lack of patient attendance, lack of applicability in severe LD, or ethical concerns relating to patient choice.
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Anticonvulsivantes/uso terapéutico , Anticoncepción/estadística & datos numéricos , Contraindicaciones de los Medicamentos , Epilepsia/tratamiento farmacológico , Discapacidades para el Aprendizaje , Complicaciones del Embarazo/inducido químicamente , Complicaciones del Embarazo/prevención & control , Ácido Valproico/uso terapéutico , Adolescente , Adulto , Estudios Transversales , Epilepsia/epidemiología , Femenino , Humanos , Discapacidades para el Aprendizaje/epidemiología , Persona de Mediana Edad , Embarazo , Reino Unido/epidemiología , Adulto JovenRESUMEN
C1 and phenyl-type stationary phases were assessed in terms of their environmental impact on separations using as test solutes polycyclic aromatic hydrocarbons. Methanol (MeOH) and acetonitrile (ACN) mobile-phase gradients were employed. These stationary phases were examined to determine if different physical and chemical properties possessed by these surfaces decreased the organic solvent consumption, and yet maintained peak capacity. The cumulative energy demand (CED) was used to gauge the environmental impact of the separations. The separation of the polycyclic aromatic hydrocarbon test mixture using current methodologies (i.e. a C18/ACN combination) had a CED of 1.13 MJ-eq, and a peak capacity of 27 peaks (resolving 7 of 12 peak pairs with R(s)>1). In comparison, a butyl phenyl stationary phase with a methanol mobile phase had a peak capacity of 26, but with a CED of 0.670 MJ-eq. Monolithic columns containing C18 and C1 phases were also tested. A monolithic C18 column with MeOH had the lowest CED at 0.675 MJ-eq, a peak capacity of 28 peaks and good resolving power (resolving ten peak pairs with R(s)>1), suggesting that this is a viable option with respect to reducing environmental impact for these types of analyses.
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Cromatografía de Afinidad/métodos , Compuestos Policíclicos/aislamiento & purificaciónRESUMEN
The legal Australian cannabis industry has been rapidly expanding due to increased awareness of the plant's therapeutic potential, as well its diverse range of applications including biofuel, textiles, building materials, food, nutritional supplement, and animal feed. The objective of this paper is to describe the current landscape of the commercial Australian cannabis industry, summarise occupational health and safety (OHS) hazards in cannabis-related working environments, and provide suggestions for safeguarding worker health and well-being in this emerging industry. A comprehensive search of peer-reviewed and grey literature published between 1900 and 2017 was undertaken to identify case studies and original epidemiological research on OHS hazards associated with the cannabis cultivation and the manufacture of cannabis-based products. The review found that the majority of OHS studies were undertaken in the hemp textile industry during the late twentieth century, with a small number of articles published from a variety of occupational environments including forensic laboratories and recreational marijuana farms. Cannabis harvesting and initial processing is labour intensive, and presents a physical hazard Depending on the operation, workers may also be exposed to a variety of biological, chemical, and physical hazards including: organic dusts, bioaerosols, pollen/allergens, volatile organic compounds, psychoactive substances (tetrahydrocannabinol [THC])), noise, and ultraviolet radiation. Little research has been undertaken on the exposure to inhalable organic dust and other bioaerosols during the commercial cultivation and manufacture of cannabis-based products. Furthermore, there is an absence of Australian-based research and OHS guidance materials to help professionals develop risk management strategies in this evolving industry. It is recommended that: Investigation into the toxicological properties of cannabis dusts, specifically in relation to potential occupational exposures during cultivation and manufacture, should be a priority. The interim adoption of the respirable cotton dust exposure standard of 0.2 mg/m3 for workplace exposure in hemp facilities until a cannabis workplace exposure standard is developed, and that exposure to medicinal cannabis containing THC are kept as low as reasonably practicable. An industry partnership be established for the development of an Australian health and safety guideline for the production of medicinal cannabis and hemp. A classification to meet the requirements of the Global Harmonization Scheme should be undertaken to ensure consistency in the use of safety and risk phrases in cannabis-related industries.
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Cannabis , Salud Laboral , Administración de la Seguridad , Aerosoles , Agricultura/métodos , Contaminantes Ocupacionales del Aire , Alérgenos , Cannabis/química , Humanos , Exposición Profesional/prevención & control , Fitoquímicos , Compuestos Orgánicos VolátilesRESUMEN
PURPOSE: Phenytoin is an effective anticonvulsant for focal epilepsy. Its use can be associated with long-term adverse effects including cerebellar ataxia. Whilst phenytoin is toxic to Purkinje cells in vitro; the clinical and radiological phenotype and mechanism of cerebellar degeneration in vivo remain unclear. We describe the prevalence, clinical and radiological characteristics of phenytoin-related ataxia. METHODS: Patients with epilepsy receiving treatment with phenytoin were recruited from the Epilepsy clinics at Royal Hallamshire Hospital, Sheffield, UK. Neurological examination was performed on all patients after recruitment. Patients were categorised into those with and without ataxia. We determined the severity of ataxia clinically (SARA score) and the pattern of cerebellar involvement by neuroimaging (MRI volumetry and MR spectroscopy). RESULTS: Forty-seven patients were recruited. Median duration of epilepsy was 24 years, median duration of phenytoin treatment was 15 years and current median phenytoin daily dose was 325â¯mg. Fifty-five percent of patients complained of poor balance. Clinical evidence of ataxia was seen in 40% patients. Gait, stance and heel-shin slide were the predominant features of cerebellar dysfunction. MRI demonstrated structural, volumetric and functional deficits of the cerebellum. Only one patient with ataxia had phenytoin levels above the normal range. CONCLUSIONS: Cerebellar ataxia is present in 40% of patients with epilepsy and chronic exposure to phenytoin. Patients on long-term phenytoin have reduced cerebellar volume even if they have no clinical evidence of ataxia. Evidence of structural deficits on imaging suggests a predilection for vermian involvement.
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Anticonvulsivantes/efectos adversos , Ataxia , Epilepsia/tratamiento farmacológico , Neuroimagen/métodos , Fenitoína/efectos adversos , Anticuerpos/sangre , Ataxia/inducido químicamente , Ataxia/diagnóstico por imagen , Ataxia/epidemiología , Encéfalo/diagnóstico por imagen , Encéfalo/efectos de los fármacos , Epilepsia/sangre , Femenino , Ácido Fólico/sangre , Proteínas de Unión al GTP/inmunología , Gliadina/inmunología , Humanos , Estudios Longitudinales , Masculino , Examen Neurológico , Fenitoína/sangre , Proteína Glutamina Gamma Glutamiltransferasa 2 , Trastornos de la Sensación/inducido químicamente , Trastornos de la Sensación/diagnóstico , Transglutaminasas/inmunologíaRESUMEN
OBJECTIVE: We sought to identify motor features that would allow the delineation of individuals with sleep study-confirmed idiopathic REM sleep behavior disorder (iRBD) from controls and Parkinson disease (PD) using a customized smartphone application. METHODS: A total of 334 PD, 104 iRBD, and 84 control participants performed 7 tasks to evaluate voice, balance, gait, finger tapping, reaction time, rest tremor, and postural tremor. Smartphone recordings were collected both in clinic and at home under noncontrolled conditions over several days. All participants underwent detailed parallel in-clinic assessments. Using only the smartphone sensor recordings, we sought to (1) discriminate whether the participant had iRBD or PD and (2) identify which of the above 7 motor tasks were most salient in distinguishing groups. RESULTS: Statistically significant differences based on these 7 tasks were observed between the 3 groups. For the 3 pairwise discriminatory comparisons, (1) controls vs iRBD, (2) controls vs PD, and (3) iRBD vs PD, the mean sensitivity and specificity values ranged from 84.6% to 91.9%. Postural tremor, rest tremor, and voice were the most discriminatory tasks overall, whereas the reaction time was least discriminatory. CONCLUSIONS: Prodromal forms of PD include the sleep disorder iRBD, where subtle motor impairment can be detected using clinician-based rating scales (e.g., Unified Parkinson's Disease Rating Scale), which may lack the sensitivity to detect and track granular change. Consumer grade smartphones can be used to accurately separate not only iRBD from controls but also iRBD from PD participants, providing a growing consensus for the utility of digital biomarkers in early and prodromal PD.
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Enfermedad de Parkinson/diagnóstico , Trastorno de la Conducta del Sueño REM/diagnóstico , Teléfono Inteligente , Anciano , Femenino , Dedos/fisiopatología , Marcha , Humanos , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/psicología , Equilibrio Postural , Desempeño Psicomotor , Trastorno de la Conducta del Sueño REM/psicología , Tiempo de Reacción , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Temblor/diagnóstico , Temblor/psicología , VozRESUMEN
Rostral ventral medulla (RVM) contains significant numbers of local GABAergic neurons which may subserve respiratory chemosensory and baroreceptor reflexes. Nicotinic mechanisms stimulate release of GABA in certain brainstem neurons. Whether the GABAergic neurons at RVM express nicotinic cholinergic receptors (nAChRs) is not known. We used glutamic acid decarboxylase 67-kDa isoform (GAD67) and parvalbumin (PV) as anatomical markers to identify the GABAergic neurons of the RVM and caudal pons and performed double labeling to evaluate the expression of alpha-7 and alpha-4 nAChRs by GAD67 and PV-imnunoreactive (ir) cells at these sites. GAD67-ir cells were found at the ventrolateral pontomedullary border in areas adjacent to the A5 noradrenergic cell group and overlapping the facial nucleus lateral subnuclei and para-facial zones. Of 205 GAD67-ir cells labeled at these sites, 74% exhibited immunoreactivity for alpha-7 nAChRs. Alpha-4 immunoreactivity was also present in 35% of GAD67-ir cells at these sites. The PV-ir cells of RVM and caudal pons were found medial to the facial nucleus and lateral to the pyramid in a column distinct from the GAD67-ir cells. Virtually all the PV-ir cells demonstrated immunoreactivity for alpha-4 nAChR (95%) and alpha-7 (93%) subunits of nAChRs. Differential expression of GAD67 and PV by neurons at the pontomedullary border implies that PV may not be a valid marker for GABAergic neurons. The expression of alpha-4 and alpha-7 nAChRs by GAD67-ir cells suggests nicotinic cholinergic modulation of GABAergic signaling at these ventrolateral pontomedullary sites.
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Bulbo Raquídeo/citología , Neuronas/metabolismo , Puente/citología , Receptores Nicotínicos/metabolismo , Ácido gamma-Aminobutírico/metabolismo , Animales , Recuento de Células/métodos , Glutamato Descarboxilasa/metabolismo , Parvalbúminas/metabolismo , Ratas , Ratas Sprague-Dawley , Tirosina 3-Monooxigenasa/metabolismo , Receptor Nicotínico de Acetilcolina alfa 7RESUMEN
A study on the retention of PAHs on three Propyl-phenyl stationary phases was conducted, assessing absolute retention, selectivity, retention correlation and thermodynamic behaviour. The chromatographic retention data revealed that each of the three Propyl-phenyl columns exhibited differences in absolute retention, however, comparison of the compensation temperatures derived from enthalpy-entropy compensation plots showed that the underlying processes responsible for the retention on these columns were the same.
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Cromatografía Líquida de Alta Presión/métodos , Hidrocarburos Policíclicos Aromáticos/química , Reproducibilidad de los Resultados , TermodinámicaRESUMEN
The thermodynamic retention behaviour of a linear series of polycyclic aromatic hydrocarbons (PAHs) was investigated on C18 and selected phenyl-type reversed-phase stationary phases, namely C18, C18 Aqua, Propyl-phenyl and Synergi polar-RP stationary phases, using methanol mobile phases. The Propyl-phenyl stationary phase, despite having the lowest surface coverage, was found to exhibit significantly larger enthalpic interactions to the other Phenyl-type phase (Synergi polar-RP) even though this had a much higher surface coverage. This indicated that stronger interactions between the PAHs and the stationary phase ligands were occurring on the Propyl-phenyl phase. Evaluation of the elution band profile of the PAHs in the aqueous methanol mobile phase revealed fairly symmetrical bands for the C18, C18 Aqua and Synergi polar-RP, but severe peak tailing on the Propyl-phenyl phase. A change in mobile phase from methanol to acetonitrile improved the peak shape of the PAHs on the Propyl-phenyl phase, leading to the assumption that unfavourable pi-pi interactions were occurring between the electron-rich PAHs and the electron-rich phenyl rings of the Propyl-phenyl phase.
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Cromatografía Liquida/métodos , Hidrocarburos Policíclicos Aromáticos/química , Termodinámica , Adsorción , Cromatografía Liquida/instrumentación , Modelos Moleculares , Conformación MolecularRESUMEN
The interface between two fluids that have different viscosities and are percolating through a porous bed is unstable. Sooner or later, a flow instability termed viscous fingering (VF) develops. This phenomenon is important in chromatography because the solute plug does not have the same viscosity as the mobile phase. Because the sample is often much more viscous than the mobile phase, it is the interface at the rear of the sample band that is usually unstable. This situation is frequent in many modes of chromatography, e.g., in preparative and in multidimensional chromatography, in size exclusion chromatography, in frontal analysis, and in other physicochemical measurements (e.g., determination of adsorption isotherms and of mass transfer parameters). When the solute plug is more viscous than the mobile phase, we observed that the solute band compressed. When the viscosity contrast increased up to 0.30 cP, fingers appeared to trail behind the solute plug. The development of fingers then became more substantial as the viscosity contrast increased. To avoid effects associated with VF, the mobile phase and the solute plug should have nearly the same viscosity.
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Adsorción , Química Física , Cromatografía Líquida de Alta Presión/métodos , Fenómenos Químicos , ViscosidadRESUMEN
Objectives: Rapid eye movement (REM) sleep behavior disorder (RBD) is the most specific marker of prodromal alpha-synucleinopathies. We sought to delineate the baseline clinical characteristics of RBD and evaluate risk stratification models. Methods: Clinical assessments were performed in 171 RBD, 296 control, and 119 untreated Parkinson's (PD) participants. Putative risk measures were assessed as predictors of prodromal neurodegeneration, and Movement Disorders Society (MDS) criteria for prodromal PD were applied. Participants were screened for common leucine-rich repeat kinase 2 (LRRK2)/glucocerebrosidase gene (GBA) gene mutations. Results: Compared to controls, participants with RBD had higher rates of solvent exposure, head injury, smoking, obesity, and antidepressant use. GBA mutations were more common in RBD, but no LRRK2 mutations were found. RBD participants performed significantly worse than controls on Unified Parkinson's Disease Rating Scale (UPDRS)-III, timed "get-up-and-go", Flamingo test, Sniffin Sticks, and cognitive tests and had worse measures of constipation, quality of life (QOL), and orthostatic hypotension. For all these measures except UPDRS-III, RBD and PD participants were equally impaired. Depression, anxiety, and apathy were worse in RBD compared to PD participants. Stratification of people with RBD according to antidepressant use, obesity, and age altered the odds ratio (OR) of hyposmia compared to controls from 3.4 to 45.5. 74% (95% confidence interval [CI] 66%, 80%) of RBD participants met the MDS criteria for probable prodromal Parkinson's compared to 0.3% (95% CI 0.009%, 2%) of controls. Conclusions: RBD are impaired across a range of clinical measures consistent with prodromal PD and suggestive of a more severe nonmotor subtype. Clinical risk stratification has the potential to select higher risk patients for neuroprotective interventions.
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Enfermedad de Parkinson/complicaciones , Síntomas Prodrómicos , Trastorno de la Conducta del Sueño REM/complicaciones , Anciano , Antidepresivos/farmacología , Ansiedad , Apatía , Estudios de Casos y Controles , Depresión , Femenino , Humanos , Masculino , Persona de Mediana Edad , Mutación/genética , Obesidad , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/fisiopatología , Enfermedad de Parkinson/psicología , Fenotipo , Calidad de Vida , Trastorno de la Conducta del Sueño REM/genética , Trastorno de la Conducta del Sueño REM/fisiopatología , Trastorno de la Conducta del Sueño REM/psicología , Medición de Riesgo , FumarRESUMEN
In this manuscript the retention and selectivity of a set of linear and non-linear PAHs were evaluated on five different reversed-phase columns. These phases included C18 and C18 Aqua stationary phases, as well as three phenyl phases: Propyl-phenyl, Synergi polar-RP and Cosmosil 5PBB phase. Overall, the results revealed that the phenyl-type columns offered better separation performance for the linear PAHs, while the separation of the structural isomer PAHs was enhanced on the C18 columns. The Propyl-phenyl column was found to have the highest molecular-stationary phase interactions, as evidenced by the greatest rate of change in 'S' (0.71) as a function of the molecular weight in the PAH homologous series, despite having the lowest surface coverage (3% carbon load) (where S is the slope of a plot of logk versus the solvent composition). In contrast, the C18 Aqua column, having the highest surface coverage (15% carbon load) was found to have the second lowest molecular-stationary phase interactions (rate of change in S=0.61). Interestingly, the Synergi polar-RP column, which also is a phenyl stationary phase behaved more 'C18-like' than 'phenyl-like' in many of the tests undertaken. This is probably not unexpected since all five phases were reversed phase.
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Cromatografía Líquida de Alta Presión/métodos , Hidrocarburos Policíclicos Aromáticos/aislamiento & purificación , Derivados del Benceno/química , Cromatografía Líquida de Alta Presión/instrumentación , Dimetilpolisiloxanos/química , Modelos Moleculares , Hidrocarburos Policíclicos Aromáticos/químicaRESUMEN
Viscous fingering is an important fluid transport phenomenon that manifests itself when two fluids having different viscosities move in the same direction. Their interface is unstable and a complex fingering pattern may arise. This phenomenon is important in chromatography because it may lead to a decrease or even a failure in separations. The onset of viscous fingering was visually observed by packing a glass column with particles having the same refractive index as the mobile phase and injecting plugs of dye solutions having viscosities different from that of the mobile phase. Severe fingering effects are observed if the viscosity difference exceeds 0.17 cP. However, for smaller viscosity differences, band distortions are observed that may affect retention data, band efficiency, and band resolution. Careful attention should be paid to matching the mobile phase viscosity and that of the injection plug when accurate chromatographic information is required.
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Cromatografía Líquida de Alta Presión/métodosRESUMEN
PURPOSE: Ocular mucins are thought to contribute to the stability of the tear film by reducing surface tension. The purpose of this study was to compare the effect of different mucins and hyaluronic acid (HA) alone and mixed with meibomian lipids on the surface pressure at an air-liquid interface. METHODS: A Langmuir trough and Wilhelmy balance were used to measure and compare the surface activity of bovine submaxillary gland mucin (BSM), purified BSM, purified bovine ocular mucin and HA, and mixtures of these with meibomian lipids, phosphatidylcholine, and phosphatidylglycerol. Their appearance at the surface of an air-buffer interface was examined using epifluorescence microscopy. RESULTS: Purified ocular mucin had no surface activity even at concentrations that were 100 times more than normally occur in tears. By contrast, commercial BSM caused changes to surface pressure that were concentration dependent. The surface pressure-area profiles showed surface activity with maximum surface pressures of 12.3-22.5 mN/m depending on the concentration. Purified BSM showed no surface activity at low concentrations, whereas higher concentrations reached a maximum surface pressure of 25 mN/m. HA showed no surface activity, at low or high concentrations. Epifluorescence showed that the mucins were located at the air-buffer interface and changed the appearance of lipid films. CONCLUSION: Purified bovine ocular mucin and HA have no surface activity. However, despite having no surface activity in their own right, ocular mucins are likely to be present at the surface of the tear film, where they cause an increase in surface pressure by causing a compression of the lipids (a reorganization of the lipids) and alter the viscoelastic properties at the surface.
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Proteínas del Ojo/química , Glándulas Tarsales/química , Mucinas/química , Fosfatidilcolinas/química , Fosfatidilgliceroles/química , Propiedades de Superficie , Aire , Animales , Bovinos , Proteínas del Ojo/aislamiento & purificación , Ácido Hialurónico/química , Microscopía Fluorescente , Mucinas/aislamiento & purificación , Lágrimas/químicaRESUMEN
Active Flow Technology (AFT) is a form of column technology that increases the separation performance of a HPLC column through the use of a specially purpose built multiport end-fitting(s). Curtain Flow (CF) columns belong to the AFT suite of columns, specifically the CF column is designed so that the sample is injected into the radial central region of the bed and a curtain flow of mobile phase surrounding the injection of solute prevents the radial dispersion of the sample to the wall. The column functions as an 'infinite diameter' column. The purpose of the design is to overcome the radial heterogeneity of the column bed, and at the same time maximize the sample load into the radial central region of the column bed, which serves to increase detection sensitivity. The protocol described herein outlines the system and CF column set up and the tuning process for an optimized infinite diameter 'virtual' column.