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1.
J Neurosci ; 44(35)2024 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-39060178

RESUMEN

The fluid movement of an arm requires multiple spatiotemporal parameters to be set independently. Recent studies have argued that arm movements are generated by the collective dynamics of neurons in motor cortex. An untested prediction of this hypothesis is that independent parameters of movement must map to independent components of the neural dynamics. Using a task where three male monkeys made a sequence of reaching movements to randomly placed targets, we show that the spatial and temporal parameters of arm movements are independently encoded in the low-dimensional trajectories of population activity in motor cortex: each movement's direction corresponds to a fixed neural trajectory through neural state space and its speed to how quickly that trajectory is traversed. Recurrent neural network models show that this coding allows independent control over the spatial and temporal parameters of movement by separate network parameters. Our results support a key prediction of the dynamical systems view of motor cortex, and also argue that not all parameters of movement are defined by different trajectories of population activity.


Asunto(s)
Brazo , Macaca mulatta , Corteza Motora , Movimiento , Desempeño Psicomotor , Animales , Corteza Motora/fisiología , Masculino , Movimiento/fisiología , Brazo/fisiología , Desempeño Psicomotor/fisiología , Modelos Neurológicos
2.
AIDS Behav ; 28(2): 408-420, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38060112

RESUMEN

Exposure to discrimination has been linked to lower HIV antiretroviral therapy (ART) adherence and poor HIV care outcomes among Black Americans. Coping has been shown to mitigate the harmful effects of discrimination on health behaviors, but the use of cultural relevant Africultural coping strategies is understudied as a moderator of the association between intersectional discrimination and ART adherence among Black Americans. We used adjusted logistic regression to test whether Africultural coping strategies (cognitive/emotional debriefing; collective; spiritual-centered; ritual-centered) moderated associations between multiple forms of discrimination (HIV, sexual orientation, race) and good ART adherence (minimum of 75% or 85% of prescribed doses taken, as measured by electronic monitoring in separate analyses) among 92 sexual minority Black Americans living with HIV. Mean adherence was 66.5% in month 8 after baseline (36% ≥ 85% adherence; 49% ≥ 75% adherence). Ritual-centered coping moderated the relationship between each of the three types of discrimination at baseline and good ART adherence in month 8 (regardless of the minimum threshold for good adherence); when use of ritual coping was low, the association between discrimination and adherence was statistically significant. The other three coping scales each moderated the association between racial discrimination and good ART adherence (defined by the 75% threshold); cognitive/emotional debriefing was also a moderator for both HIV- and race-related discrimination at the 85% adherence threshold. These findings support the benefits of Africultural coping, particularly ritual-centered coping, to help sexual minority Black Americans manage stressors associated with discrimination and to adhere well to ART.


Asunto(s)
Antirretrovirales , Negro o Afroamericano , Asistencia Sanitaria Culturalmente Competente , Infecciones por VIH , Cumplimiento de la Medicación , Minorías Sexuales y de Género , Femenino , Humanos , Masculino , Antirretrovirales/uso terapéutico , Negro o Afroamericano/psicología , Habilidades de Afrontamiento , Asistencia Sanitaria Culturalmente Competente/etnología , Infecciones por VIH/psicología , Homofobia/etnología , Cumplimiento de la Medicación/psicología , Prejuicio/etnología , Racismo/etnología , Minorías Sexuales y de Género/psicología
3.
Magn Reson Med ; 90(3): 1130-1136, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37222226

RESUMEN

The British and Irish Chapter of the International Society for Magnetic Resonance in Medicine (BIC-ISMRM) held a workshop entitled "Steps on the path to clinical translation" in Cardiff, UK, on 7th September 2022. The aim of the workshop was to promote discussion within the MR community about the problems and potential solutions for translating quantitative MR (qMR) imaging and spectroscopic biomarkers into clinical application and drug studies. Invited speakers presented the perspectives of radiologists, radiographers, clinical physicists, vendors, imaging Contract/Clinical Research Organizations (CROs), open science networks, metrologists, imaging networks, and those developing consensus methods. A round-table discussion was held in which workshop participants discussed a range of questions pertinent to clinical translation of qMR imaging and spectroscopic biomarkers. Each group summarized their findings via three main conclusions and three further questions. These questions were used as the basis of an online survey of the broader UK MR community.


Asunto(s)
Imagen por Resonancia Magnética , Humanos , Espectroscopía de Resonancia Magnética , Biomarcadores
4.
AIDS Behav ; 27(11): 3651-3660, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37195472

RESUMEN

The current study examined the prevalence and typology of unmet needs and the association between unmet needs and HIV antiretroviral therapy (ART) medication adherence among a sample of Black people living with HIV(PLHIV) (N = 304) in Los Angeles, CA. We found a high prevalence of unmet needs, with 32% of participants reporting having two or more unmet needs. The most common unmet needs category was basic benefits needs (35%), followed by subsistence needs (33%), and health needs (27%). Significant correlates of unmet needs included food insecurity, history of homelessness, and history of incarceration. A greater number of unmet needs and any unmet basic benefits needs were each significantly associated with lower odds of HIV ART medication adherence. These findings provide further evidence linking the social determinants of health and social disenfranchisement to ART medication adherence among Black PLHIV.

5.
AIDS Behav ; 27(5): 1573-1586, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36399252

RESUMEN

Structural inequities have led to HIV disparities, including relatively low antiretroviral therapy adherence and viral suppression rates among Black Americans living with HIV. We conducted a randomized controlled trial of Rise, a community-based culturally congruent adherence intervention, from January 2018 to December 2021 with 166 (85 intervention, 81 control) Black adults living with HIV in Los Angeles County, California [M (SD) = 49.0 (12.2) years-old; 76% male]. The intervention included one-on-one counseling sessions using basic Motivational Interviewing style to problem solve about adherence, as well as referrals to address unmet needs for social determinants of health (e.g., housing services, food assistance). Assessments included electronically monitored adherence; HIV viral load; and baseline, 7-month follow-up, and 13-month follow-up surveys of sociodemographic characteristics, HIV stigma, medical mistrust, and HIV-serostatus disclosure. Repeated-measures intention-to-treat regressions indicated that Rise led to significantly (two-fold) higher adherence likelihood, lower HIV stigmatizing beliefs, and reduced HIV-related medical mistrust. Effects on HIV viral suppression, internalized stigma, and disclosure were non-significant. Moreover, Rise was cost-effective based on established standards: The estimated cost per person to reach optimal adherence was $335 per 10% increase in adherence. Interventions like Rise, that are culturally tailored to the needs of Black populations, may be optimal for Black Americans living with HIV (ClinicalTrials.gov #NCT03331978).


RESUMEN: Las desigualdades estructurales han dado lugar a disparidades relacionadas con el VIH, incluyendo la relativamente baja adherencia a la terapia antirretroviral (TAR) y las tasas de supresión viral entre los afroamericanos que viven con el VIH. Conducimos una prueba controlada aleatoria de Rise, una intervención de adherencia culturalmente congruente basada en la comunidad, desde Enero de 2018 hasta Diciembre de 2021 con 166 (85 intervención, 81 controlada) adultos afroamericanos que viven con el VIH en el condado de Los Ángeles, California [M (SD) = 49.0 (12,2) años; 76% de hombres]. La intervención incluyó sesiones de asesoramiento individualizadas, usando el estilo básico Motivacional para las entrevistas, para resolver los problemas de adherencia como también referencias para confrontar sus necesidades insatisfechas de los determinantes sociales de la salud (por ejemplo, servicios de vivienda y asistencia de alimentos). Las evaluaciones incluyeron la adherencia monitoreada electrónicamente; la carga viral del VIH; y encuestas de referencia, seguimiento a los 7 meses y seguimiento a los 13 meses sobre características sociodemográficas, el estigma del VIH, la desconfianza médica y divulgación del estado serológico respecto al VIH. Los efectos sobre la supresión viral del VIH, el estigma interiorizado y la revelación de información no fueron significativos. Además, Rise fue rentable según los estándares establecidos: El costo estimado por persona para alcanzar la adherencia óptima fue de 335 dólares por cada 10% de aumento en la adherencia. Las intervenciones como Rise, que se adaptan culturalmente a las necesidades de las poblaciones afroamericana, podrían ser óptimas para los estadounidenses afroamericanos que viven con el VIH.


Asunto(s)
Infecciones por VIH , Adulto , Femenino , Humanos , Masculino , Antirretrovirales/uso terapéutico , Negro o Afroamericano , Consejo , Infecciones por VIH/psicología , Cumplimiento de la Medicación/psicología , Confianza/psicología , Persona de Mediana Edad
6.
Alcohol Clin Exp Res ; 46(10): 1913-1924, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-36059269

RESUMEN

BACKGROUND: Ecological momentary assessment (EMA) studies have provided conflicting evidence for the mood regulation tenet that people drink in response to positive and negative moods. The current study examined mood-to-alcohol relationships idiographically to quantify the prevalence and intensity of relationships between positive and negative moods and drinking across individuals. METHOD: We used two EMA samples: 96 heavy drinking college students (sample 1) and 19 young adults completing an ecological momentary intervention (EMI) for drinking to cope (sample 2). Mood and alcohol use were measured multiple times per day for 4-6 weeks. Mood-alcohol relationships were examined using three different analytic approaches: standard multilevel modeling, group causal modeling, and idiographic causal modeling. RESULTS: Both multilevel modeling and group causal modeling showed that participants in both samples drank in response to positive moods only. However, idiographic causal analyses revealed that only 63% and 21% of subjects (in samples 1 and 2, respectively) drank following any positive mood. Many subjects (24% and 58%) did not drink in response to either positive or negative mood in their daily lives, and very few (5% and 16%) drank in response to negative moods throughout the EMA protocol, despite sample 2 being selected specifically because they endorse drinking to cope with negative mood. CONCLUSION: Traditional group-level analyses and corresponding population-wide theories assume relative homogeneity within populations in mood-alcohol relationships, but this nomothetic approach failed to characterize accurately the relationship between mood and alcohol use in approximately half of the subjects in two samples that were demographically and clinically homogeneous. Given inconsistent findings in the mood-alcohol relationships to date, we conclude that idiographic causal analyses can provide a foundation for more accurate theories of mood and alcohol use. In addition, idiographic causal models may also help improve psychosocial treatments through direct use in clinical settings.


Asunto(s)
Afecto , Evaluación Ecológica Momentánea , Adulto Joven , Humanos , Afecto/fisiología , Estudiantes/psicología , Adaptación Psicológica , Consumo de Bebidas Alcohólicas/epidemiología , Consumo de Bebidas Alcohólicas/psicología
7.
AIDS Behav ; 26(3): 639-650, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-34389890

RESUMEN

We evaluated the effects of a culturally adapted evidence-based HIV prevention intervention (Mpowerment), named "Tayf", on condom use and HIV testing among young men who have sex with men (YMSM) in Beirut. A 2-year implementation of Tayf was carried out independently and in parallel with a research cohort of 226 YMSM who were surveyed at baseline and months 6, 12, 18 and 24 after Tayf initiation. Primary outcomes were (1) any condomless anal sex with HIV-positive or unknown status partners in the past 3 months, and (2) HIV testing in the past six months. Hierarchical logistic regression models examined the association of Tayf participation with the outcomes averaged across all assessments, and the moderating effect of Tayf participation on change in the outcomes over the follow-up period. A total of 331 YMSM attended at least one event, including 33% of the cohort. Tayf participation was associated with a higher rate of any condomless sex with HIV-positive or unknown status partners averaged across the five assessments, but there was no moderating effect of Tayf participation on change in this outcome over time. Tayf participation was associated with higher HIV testing when averaged across all assessments, but its interaction with time showed that the strength of this association diminished over time. In conclusion, Tayf proved feasible and acceptable in Beirut, but with limited effects. Further work is needed, including innovative publicity and marketing strategies, to bolster effects in high stigma settings where security and legal risks are prominent.


Asunto(s)
Infecciones por VIH , Minorías Sexuales y de Género , Infecciones por VIH/diagnóstico , Infecciones por VIH/epidemiología , Infecciones por VIH/prevención & control , Prueba de VIH , Homosexualidad Masculina , Humanos , Líbano , Masculino , Proyectos Piloto , Conducta Sexual , Sexo Inseguro
8.
AIDS Behav ; 26(9): 3089-3098, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35322311

RESUMEN

We are not aware of any validated sexual health communication scales for use with young men who have sex with men (YMSM). We used data from an HIV prevention study in Lebanon with 226 YMSM aged 18-29 to assess the psychometric characteristics of our scale, Judgmental Communication with Peers about Sex (JCPS). The construct validity of the JCPS scale was supported by it being negatively correlated with general social support, percentage of alters perceived to be supportive, and the percentage of peers who are perceived to use condoms. The scale was positively correlated with gay-related discrimination, feeling part of the gay community, and gay social integration. These findings reflect a reliable, valid measure to assess judgmental sexual health communication between YMSM.


Asunto(s)
Infecciones por VIH , Comunicación en Salud , Homosexualidad Masculina , Amigos , Infecciones por VIH/epidemiología , Infecciones por VIH/prevención & control , Homosexualidad Masculina/psicología , Humanos , Líbano/epidemiología , Masculino , Psicometría , Conducta Sexual , Minorías Sexuales y de Género
9.
J Behav Med ; 45(2): 285-296, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35028783

RESUMEN

Perceived discrimination and medical mistrust are contributors to HIV inequities. The current study examined whether medical mistrust mediated the associations between perceived discrimination and adherence to antiretroviral therapy (ART) as well as care engagement in a sample of 304 Black adults living with HIV. Perceived discrimination and medical mistrust were measured using validated scales; ART adherence was electronically monitored for a month; care engagement was determined by medical record data. Results support significant total indirect effects from perceived discrimination (due to HIV-serostatus, race, sexual orientation) to ART adherence through three types of medical mistrust (towards healthcare organizations, one's physician, and HIV-specific mistrust). The total indirect effects were also significant for care engagement and were largely driven by mistrust towards one's own physician. Findings suggest interventions at the provider or healthcare organization levels should address medical mistrust to improve the health and well-being of Black Americans living with HIV.


Asunto(s)
Infecciones por VIH , Confianza , Adulto , Negro o Afroamericano , Población Negra , Femenino , Infecciones por VIH/tratamiento farmacológico , Humanos , Masculino , Cumplimiento de la Medicación , Discriminación Percibida
10.
Neuroimage ; 242: 118445, 2021 11 15.
Artículo en Inglés | MEDLINE | ID: mdl-34375753

RESUMEN

Microscopic diffusion anisotropy imaging using diffusion-weighted MRI and multidimensional diffusion encoding is a promising method for quantifying clinically and scientifically relevant microstructural properties of neural tissue. Several methods for estimating microscopic fractional anisotropy (µFA), a normalized measure of microscopic diffusion anisotropy, have been introduced but the differences between the methods have received little attention thus far. In this study, the accuracy and precision of µFA estimation using q-space trajectory encoding and different signal models were assessed using imaging experiments and simulations. Three healthy volunteers and a microfibre phantom were imaged with five non-zero b-values and gradient waveforms encoding linear and spherical b-tensors. Since the ground-truth µFA was unknown in the imaging experiments, Monte Carlo random walk simulations were performed using axon-mimicking fibres for which the ground truth was known. Furthermore, parameter bias due to time-dependent diffusion was quantified by repeating the simulations with tuned waveforms, which have similar power spectra, and with triple diffusion encoding, which, unlike q-space trajectory encoding, is not based on the assumption of time-independent diffusion. The truncated cumulant expansion of the powder-averaged signal, gamma-distributed diffusivities assumption, and q-space trajectory imaging, a generalization of the truncated cumulant expansion to individual signals, were used to estimate µFA. The gamma-distributed diffusivities assumption consistently resulted in greater µFA values than the second order cumulant expansion, 0.1 greater when averaged over the whole brain. In the simulations, the generalized cumulant expansion provided the most accurate estimates. Importantly, although time-dependent diffusion caused significant overestimation of µFA using all the studied methods, the simulations suggest that the resulting bias in µFA is less than 0.1 in human white matter.


Asunto(s)
Anisotropía , Encéfalo/diagnóstico por imagen , Imagen de Difusión Tensora/instrumentación , Adulto , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/instrumentación , Masculino , Método de Montecarlo , Fantasmas de Imagen , Sustancia Blanca/diagnóstico por imagen
11.
Magn Reson Med ; 86(6): 3192-3200, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34337781

RESUMEN

PURPOSE: To characterize the diffusion time-dependence in muscle in healthy adult volunteers, boys with Duchenne's muscular dystrophy (DMD), and age-matched controls in a clinically feasible acquisition time for pediatric applications. METHODS: Diffusion data were acquired using a pulsed gradient stimulated echo diffusion preparation at 5 different diffusion times (70, 130, 190, 250, and 330 ms), at 4 different b-values (0, 200, 400, 600, and 800 s/mm2 ) and 6 directions (orthogonal x, y, and z and diagonal xy, xz, and yz) and processed to obtain standard diffusion indices (mean diffusivity [MD] and fractional anisotropy [FA]) at each diffusion time. RESULTS: Time-dependent diffusion was seen in muscle in healthy adult volunteers, boys with DMD, and age-matched controls. Boys with DMD showed reduced MD and increased FA values in comparison to age matched controls across a range of diffusion times. A diffusion time of Δ = 190 ms had the largest effect size. CONCLUSIONS: These results could be used to optimize diffusion imaging in this disease further and imply that these diffusion indices may become an important biomarker in monitoring progression in DMD in the future.


Asunto(s)
Distrofia Muscular de Duchenne , Anisotropía , Estudios de Casos y Controles , Niño , Imagen de Difusión por Resonancia Magnética , Humanos , Masculino , Músculo Esquelético , Distrofia Muscular de Duchenne/diagnóstico por imagen
12.
Behav Med ; 47(2): 111-119, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-31851587

RESUMEN

The Middle East and North Africa (MENA) is one of only two global regions where rates of HIV are currently on the rise. In Lebanon, new HIV infections are increasing most rapidly among young men who have sex with men (YMSM). While, the majority of YMSM in Lebanon report having recently engaged in condomless anal intercourse, many report reluctance to seek HIV prevention services for fear of stigma and discrimination. Pre-exposure prophylaxis (PrEP) is an effective alternative HIV prevention strategy but there is a dearth of research looking at willingness to take PrEP among YMSM in MENA. This study is the first to delineate factors associated with willingness to take PrEP among a cohort of 218 YMSM recruited from Beirut, Lebanon. Over half (55.5%) reported willingness to take PrEP. At the bivariate level, knowledge of HIV risk, awareness of PrEP, being in a relationship, greater judgementalism about sex in communication with peers, greater number of types of gay-related discrimination experienced, sense of community among YMSM, having had recent condomless anal sex with positive or unknown status partner, and the use of substances just prior to or during sex were each associated with greater willingness to take PrEP. When entered into a linear regression analysis, use of substances just prior to or during sex and sense of community among YMSM remained significant predictors of PrEP willingness. Intervention efforts focused on increasing PrEP uptake among YMSM in MENA should consider the influence substance use and social factors on willingness to take PrEP.


Asunto(s)
Infecciones por VIH , Profilaxis Pre-Exposición , Minorías Sexuales y de Género , Infecciones por VIH/prevención & control , Homosexualidad Masculina , Humanos , Líbano , Masculino , Aceptación de la Atención de Salud
13.
Neuroimage ; 211: 116606, 2020 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-32032739

RESUMEN

To enable application of non-Gaussian diffusion magnetic resonance imaging (dMRI) techniques in large-scale clinical trials and facilitate translation to clinical practice there is a requirement for fast, high contrast, techniques that are sensitive to changes in tissue structure which provide diagnostic signatures at the early stages of disease. Here we describe a new way to compress the acquisition of multi-shell b-value diffusion data, Quasi-Diffusion MRI (QDI), which provides a probe of subvoxel tissue complexity using short acquisition times (1-4 â€‹min). We also describe a coherent framework for multi-directional diffusion gradient acquisition and data processing that allows computation of rotationally invariant quasi-diffusion tensor imaging (QDTI) maps. QDI is a quantitative technique that is based on a special case of the Continuous Time Random Walk model of diffusion dynamics and assumes the presence of non-Gaussian diffusion properties within tissue microstructure. QDI parameterises the diffusion signal attenuation according to the rate of decay (i.e. diffusion coefficient, D in mm2 s-1) and the shape of the power law tail (i.e. the fractional exponent, α). QDI provides analogous tissue contrast to Diffusional Kurtosis Imaging (DKI) by calculation of normalised entropy of the parameterised diffusion signal decay curve, Hn, but does so without the limitations of a maximum b-value. We show that QDI generates images with superior tissue contrast to conventional diffusion imaging within clinically acceptable acquisition times of between 84 and 228 â€‹s. We show that QDI provides clinically meaningful images in cerebral small vessel disease and brain tumour case studies. Our initial findings suggest that QDI may be added to routine conventional dMRI acquisitions allowing simple application in clinical trials and translation to the clinical arena.


Asunto(s)
Neoplasias Encefálicas/diagnóstico por imagen , Enfermedades de los Pequeños Vasos Cerebrales/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética/métodos , Modelos Teóricos , Neuroimagen/métodos , Sustancia Blanca/diagnóstico por imagen , Adulto , Anciano , Imagen de Difusión por Resonancia Magnética/normas , Imagen de Difusión Tensora/métodos , Imagen de Difusión Tensora/normas , Femenino , Humanos , Masculino , Neuroimagen/normas , Adulto Joven
14.
Magn Reson Med ; 83(5): 1698-1710, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-31651995

RESUMEN

PURPOSE: Double diffusion encoding (DDE) MRI enables the estimation of microscopic diffusion anisotropy, yielding valuable information on tissue microstructure. A recent study proposed that the acquisition of rotationally invariant DDE metrics, typically obtained using a spherical "5-design," could be greatly simplified by assuming Gaussian diffusion, facilitating reduced acquisition times that are more compatible with clinical settings. Here, we aim to validate the new minimal acquisition scheme against the standard DDE 5-design, and to quantify the proposed method's noise robustness to facilitate future clinical use. THEORY AND METHODS: DDE MRI experiments were performed on both ex vivo and in vivo rat brains at 9.4 T using the 5-design and the proposed minimal design and taking into account the difference in the number of acquisitions. The ensuing microscopic fractional anisotropy (µFA) maps were compared over a range of b-values up to 5000 s/mm2 . Noise robustness was studied using analytical calculations and numerical simulations. RESULTS: The minimal protocol quantified µFA at an accuracy comparable to the estimates obtained by means of the more theoretically robust DDE 5-design. µFA's sensitivity to noise was found to strongly depend on compartment anisotropy and tensor magnitude in a nonlinear manner. When µFA < 0.75 or when mean diffusivity is particularly low, very high signal-to-noise ratio is required for precise quantification of µFA. CONCLUSION: Our work supports using DDE for quantifying microscopic diffusion anisotropy in clinical settings but raises hitherto overlooked precision issues when measuring µFA with DDE and typical clinical signal-to-noise ratio.


Asunto(s)
Imagen de Difusión por Resonancia Magnética , Procesamiento de Imagen Asistido por Computador , Anisotropía , Encéfalo/diagnóstico por imagen , Difusión , Distribución Normal
15.
Magn Reson Med ; 84(3): 1543-1551, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32060975

RESUMEN

INTRODUCTION: To combine numerical simulations, in vitro and in vivo experiments to evaluate the feasibility of measuring diffusion exchange across the cell membrane with diffusion exchange spectroscopy (DEXSY). METHODS: DEXSY acquisitions were simulated over a range of permeabilities in nerve tissue and yeast substrates. In vitro measurements were performed in a yeast substrate and in vivo measurements in mouse tumor xenograft models, all at 9.4 T. RESULTS: Diffusion exchange was observed in simulations over a physiologically relevant range of cell permeability values. In vitro and in vivo measures also provided evidence of diffusion exchange, which was quantified with the Diffusion Exchange Index (DEI). CONCLUSIONS: Our findings provide preliminary evidence that DEXSY can be used to make in vivo measurements of diffusion exchange and cell membrane permeability.


Asunto(s)
Modelos Teóricos , Animales , Membrana Celular , Permeabilidad de la Membrana Celular , Difusión , Ratones , Permeabilidad , Análisis Espectral
16.
NMR Biomed ; 33(5): e4276, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32101354

RESUMEN

Dystrophic muscles show a high variability of fibre sizes and altered sarcolemmal integrity, which are typically assessed by histology. Time-dependent diffusion MRI is sensitive to tissue microstructure and its investigation through age-related changes in dystrophic and healthy muscles may help the understanding of the onset and progression of Duchenne muscular dystrophy (DMD). We investigated the capability of time-dependent diffusion MRI to quantify age and disease-related changes in hind-limb muscle microstructure between dystrophic (mdx) and wild-type (WT) mice of three age groups (7.5, 22 and 44 weeks). Diffusion time-dependent apparent diffusion coefficients (ADCs) of the gastrocnemius and tibialis anterior muscles were determined versus age and diffusion-gradient orientation at six diffusion times (Δ; range: 25-350 ms). Mean muscle ADCs were compared between groups and ages, and correlated with T2 , using Student's t test, one-way analysis of variance and Pearson correlation, respectively. Muscle fibre sizes and sarcolemmal integrity were evaluated by histology and compared with diffusion measurements. Hind-limb muscle ADC showed characteristic restricted diffusion behaviour in both mdx and WT animals with decreasing ADC values at longer Δ. Significant differences in ADC were observed at long Δ values (≥ 250 ms; p < 0.05, comparison between groups; p < 0.01, comparison between ages) with ADC increased by 5-15% in dystrophic muscles, indicative of reduced diffusion restriction. No significant correlation was found between T2 and ADC. Additionally, muscle fibre size distributions showed higher variability and lower mean fibre size in mdx than WT animals (p < 0.001). The extensive Evans Blue Dye uptake shown in dystrophic muscles revealed substantial sarcolemmal damage, suggesting diffusion measurements as more consistent with altered permeability rather than changes in muscle fibre sizes. This study shows the potential of diffusion MRI to non-invasively discriminate between dystrophic and healthy muscles with enhanced sensitivity when using long Δ.


Asunto(s)
Imagen de Difusión por Resonancia Magnética , Distrofia Muscular de Duchenne/diagnóstico por imagen , Distrofia Muscular de Duchenne/patología , Envejecimiento/patología , Animales , Modelos Animales de Enfermedad , Masculino , Ratones Endogámicos C57BL , Ratones Endogámicos mdx , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/fisiología , Factores de Tiempo
17.
J Hum Evol ; 148: 102884, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-33038748

RESUMEN

The Fauresmith was a term first coined by archaeologists in the 1920s to describe a cultural development intermediate between the Earlier and Middle Stone Ages. From the late 1960s, many researchers abandoned the term in favor of sinking the Fauresmith within the Later Acheulean. More recently, however, some have supported the idea of the Fauresmith as the earliest Middle Stone Age, whereas other researchers continue to use the term to refer to a transitional technological development. In this article, we evaluate the status of the Fauresmith. We do this by describing a newly excavated assemblage from Canteen Kopje in the Northern Cape Province of South Africa and by comparing it with other assemblages published as Fauresmith. Although there is substantial variability across these assemblages, we present data to show that the relevant assemblages show the consistency of a regional technology that is indeed transitional between the Earlier and Middle Stone Ages. It includes prepared cores, blades, and very reduced numbers of large cutting tools compared with the Acheulean, and it often includes convergent flakes and retouched points. We argue that the Fauresmith, along with parallel developments both within and beyond Africa, is a term worth retaining to identify the slow process of decline of Acheulean technology in favor of a lighter toolkit, which includes varying degrees of more advanced core reduction strategies, larger numbers of formal tools, and hafting. Such developments are associated with populations linked to the development of Homo sapiens in Africa from ca. 600 to 160 ka.


Asunto(s)
Evolución Cultural , Hominidae , Animales , Arqueología , Fósiles , Humanos , Sudáfrica , Tecnología
18.
Arch Sex Behav ; 49(1): 321-330, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31127453

RESUMEN

In 2012, our research with young men who have sex with men (YMSM) in Beirut showed high rates of recent condomless anal sex and low rates of recent HIV testing. In 2017, we collected data from YMSM to assess for temporal changes and sociodemographic correlates. Propensity score weighting was used to eliminate any sociodemographic differences between the 2012 (n = 164) and 2017 (n = 226) samples of YMSM (age 18-29) recruited with long-chain peer referral sampling. Regression analysis was used to examine sociodemographic correlates of recent condomless anal sex and HIV testing using the 2017 sample, and whether these behaviors differed between the samples. Compared to the 2012 sample, the 2017 sample was about half as likely to report any condomless anal sex in the past 3 months with partners whose HIV status was positive or unknown (14% vs. 23%; OR [95%CI] 0.56 [0.32, 0.98]), and nearly 2.5 times as likely to report HIV testing in the past 6 months (48% vs. 27%; OR [95%CI] 2.44 [1.46, 4.10]). In the 2017 sample, any recent condomless anal sex with partners whose HIV status was positive or unknown was associated with employment and Christian religious affiliation. Low income was the sole correlate of having recently tested for HIV. These findings suggest a temporal trend toward increased HIV protective behaviors among YMSM in Beirut over the past 5 years. Further inroads could be secured if HIV prevention programming targeted economic influences.


Asunto(s)
Infecciones por VIH/etiología , Homosexualidad Masculina/estadística & datos numéricos , Conducta Sexual/estadística & datos numéricos , Parejas Sexuales/psicología , Minorías Sexuales y de Género/estadística & datos numéricos , Adolescente , Adulto , Estudios Transversales , Humanos , Líbano , Estudios Longitudinales , Masculino , Asunción de Riesgos , Encuestas y Cuestionarios , Adulto Joven
19.
J Oncol Pharm Pract ; 26(3): 742-746, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31390960

RESUMEN

INTRODUCTION: We describe a case of alemtuzumab (Campath®) hypersensitivity requiring desensitization within the medical intensive care unit (MICU) in a patient with T-cell prolymphocytic leukemia. CASE REPORT: We adopted a desensitization protocol from Gutierrez-Fernandez et al., which included three aliquots (0.15 mg intravenously (IV), 1.5 mg IV, and 28.5 mg IV) given approximately 1 h apart on day 1 followed by a full 30 mg dose IV on day 3. Unlike prior attempts to administer alemtuzumab to this patient, she tolerated the medication well and did not require any rescue medications. MANAGEMENT AND OUTCOME: Successful plan development required a significant amount of strategic communication between hematology/oncology and MICU-related physicians, pharmacists, and nurses to ensure a safe and effective desensitization. The first step of planning required creation of a desensitization order set with directions for medication preparation and administration, premedications, and available medications in the event of an adverse reaction or anaphylaxis. Anaphylactoid-related medications were prepared at bedside and ready for administration prior to beginning the desensitization. Alemtuzumab was compounded in a chemotherapy-certified hood and verified by at least two chemotherapy-certified pharmacists. Foreword planning was also necessary to ensure multiple people were available or present at bedside for the desensitization, including a chemotherapy-certified nurse, a second chemotherapy-certified nurse for verification, a critical care-certified pharmacist, a pulmonary/critical care attending physician, and hematology attending physician. DISCUSSION: This case exemplifies the importance of clear and coordinated communication between different healthcare fields to safely and effectively complete extensive protocols such as desensitization strategies.


Asunto(s)
Alemtuzumab/efectos adversos , Desensibilización Inmunológica/métodos , Hipersensibilidad a las Drogas , Alemtuzumab/administración & dosificación , Anafilaxia/etiología , Comunicación , Femenino , Humanos , Persona de Mediana Edad , Farmacéuticos/organización & administración , Médicos/organización & administración
20.
Int J Behav Med ; 27(2): 160-169, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31797284

RESUMEN

BACKGROUND: Aspects of sexual identity development, including integration into gay community, have been found to be associated with sexual risk behavior among men who have sex with men (MSM), but not in the Middle East. METHOD: Drawing on the minority stress model and integrated theory of health behavior, we examined the relationships between measures of sexual identity development and HIV protective behaviors (condomless anal sex and HIV testing) and the mediating roles of HIV knowledge, peer judgmentalism, and discrimination, in a sample of 226 young MSM in Beirut, Lebanon. A cross-sectional, mediation analysis was conducted using a bootstrapping approach and logistic regression models. RESULTS: Fifteen percent of the sample reported recent condomless anal sex with partners whose HIV status was positive or unknown, and 82.3% had ever been tested for HIV. Multivariate logistic regression analysis showed that greater integration into the gay community was significantly associated with having recent condomless anal sex with positive/unknown HIV status partners and having any history of HIV testing, after controlling for covariates. Knowledge of HIV risk was associated with gay integration as well as both condomless anal sex with positive or unknown HIV status partners and any history of HIV testing, but it only served as a (partial) mediator of HIV testing. Peer judgmental communication about sex and sexuality-related discrimination were related in bivariate analysis to gay integration and condomless anal sex, but they too did not prove to be significant mediators of the relationship between these two constructs. CONCLUSION: These findings highlight the potential sexual health benefits and vulnerabilities associated with increased integration into the gay community for young MSM in Beirut and the need to better understand how to increase HIV knowledge while limiting its potential to increase sexual risk behavior.


Asunto(s)
Integración a la Comunidad , Infecciones por VIH/prevención & control , Homosexualidad Masculina/estadística & datos numéricos , Minorías Sexuales y de Género/estadística & datos numéricos , Adulto , Estudios Transversales , Humanos , Masculino , Asunción de Riesgos , Conducta Sexual/estadística & datos numéricos , Parejas Sexuales , Adulto Joven
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