Publications by authors named "Yousefian O"

Article Synopsis
  • Hyaluronic acid (HA) is widely used in moisturizers, but traditional formulas only work on the skin's surface, limiting their rejuvenating effects.
  • A study compared a lotion containing multi-weight HA and antioxidants with a single-weight HA and ceramide lotion, focused on improving facial dryness and fine lines in 70 women aged 25-65 over eight weeks.
  • Results showed that the multi-weight HA lotion significantly improved skin dryness, roughness, and fine lines as early as two weeks, indicating its better penetration and effectiveness compared to the single-weight HA lotion.
View Article and Find Full Text PDF

Background: Late potential (LP) elimination has been proposed as a surrogate endpoint for scar-related ventricular tachycardia (VT) ablation procedures. The characteristics, distribution, and predictors of persistent late potentials (pLPs) after ablation have not been studied.

Objective: The purpose of this study was to characterize the spatial distribution and features of pLP after catheter ablation of VT substrate with high-resolution mapping.

View Article and Find Full Text PDF
Article Synopsis
  • Focused ultrasound (FUS) combined with microbubbles shows potential for enhancing drug delivery across the blood-brain barrier (BBB) in Alzheimer's disease, but current methods are limited by their reliance on MRI facilities or invasive procedures.
  • A pilot study evaluated a new portable system, neuronavigation-guided FUS (NgFUS), in six mild to moderate Alzheimer’s patients, using real-time mapping of microbubble activity to ensure safety and efficacy during treatment.
  • Results indicated that BBB opening was achieved in 5 out of 6 subjects, with significant correlations between cavitation dose, BBB opening volume, and increased levels of Alzheimer’s biomarkers, demonstrating the system's capability for real-time monitoring and safety in outpatient settings.
View Article and Find Full Text PDF
Article Synopsis
  • Focused ultrasound (FUS) combined with microbubbles shows potential for opening the blood-brain barrier (BBB) to improve drug delivery in Alzheimer's disease, but current methods are limited to MRI-equipped settings or invasive implants.
  • A pilot study involving 6 mild to moderate AD patients tested a new portable, non-invasive NgFUS system that monitored real-time microbubble activity to confirm safety and effectiveness during a single treatment session.
  • The results indicated that BBB opening was successfully achieved in 5 out of 6 patients, with significant correlations observed between microbubble activity and BBB opening volume, alongside increases in Alzheimer-related biomarkers in the blood, suggesting effective drug delivery methods can emerge from this technology.
View Article and Find Full Text PDF

In this work we infer the underlying distribution on pore radius in human cortical bone samples using ultrasonic attenuation data. We first discuss how to formulate polydisperse attenuation models using a probabilistic approach and the Waterman Truell model for scattering attenuation. We then compare the Independent Scattering Approximation and the higher-order Waterman Truell models' forward predictions for total attenuation in polydisperse samples.

View Article and Find Full Text PDF

This work proposes the use of two physics-based models for wave attenuation to infer the microstructure of cortical bone-like structures. One model for ultrasound attenuation in porous media is based on the independent scattering approximation (ISA) and the other model is based on the Waterman Truell (WT) approximation. The microstructural parameters of interest are pore radius and pore density.

View Article and Find Full Text PDF

The effect of matrix viscoelastic absorption on frequency-dependent attenuation in porous structures mimicking simplified cortical bone is addressed in this numerical study. An apparent absorption is defined to quantify the difference between total attenuation (resulting from both absorption and scattering) and attenuation exclusively due to scattering. A power-law model is then used to describe the frequency-dependent apparent absorption as a function of pore diameter and density.

View Article and Find Full Text PDF

The mode-converted (longitudinal to transverse, L-T) ultrasonic scattering method was utilized to characterize the structural anisotropy of a phantom mimicking the structural properties of trabecular bone. The sample was fabricated using metal additive manufacturing from high-resolution computed tomography (CT) images of a sample of trabecular horse bone with strong anisotropy. Two focused transducers were used to perform the L-T ultrasonic measurements.

View Article and Find Full Text PDF

The goal of this study is to estimate micro-architectural parameters of cortical porosity such as pore diameter (φ), pore density (ρ) and porosity (ν) of cortical bone from ultrasound frequency dependent attenuation using an artificial neural network (ANN). First, heterogeneous structures with controlled pore diameters and pore densities (mono-disperse) were generated, to mimic simplified structure of cortical bone. Then, more realistic structures were obtained from high resolution CT scans of human cortical bone.

View Article and Find Full Text PDF

While osteoporosis assessment has long focused on the characterization of trabecular bone, the cortical bone micro-structure also provides relevant information on bone strength. This numerical study takes advantage of ultrasound multiple scattering in cortical bone to investigate the effect of pore size and pore density on the acoustic diffusion constant. Finite-difference time-domain simulations were conducted in cortical microstructures that were derived from acoustic microscopy images of human proximal femur cross sections and modified by controlling the density (Ct.

View Article and Find Full Text PDF

Background: Hemodynamic-guided therapy using the CardioMEMS™ system has been shown to reduce heart failure hospitalization (HFH) in both clinical trials and real-world settings. However, the CardioMEMS system requires input from multiple independent elements to achieve its effect, and no studies have been done to investigate those elements. Consistent patient participation and health care provider participation are two of those key elements, and this study sought to assess how they affect HFHs.

View Article and Find Full Text PDF

The goal of this paper is to predict the micro-architectural parameters of cortical bone such as pore diameter and porosity from ultrasound attenuation measurements using an artificial neural network (ANN). Slices from a 3-D CT scan of human femur are obtained. The micro-architectural parameters of porosity such as average pore size and porosity are calculated using image processing.

View Article and Find Full Text PDF

The validity of the independent scattering approximation (ISA) to predict the frequency dependent attenuation in 2D models of simplified structures of cortical bone is studied. Attenuation of plane waves at central frequencies ranging from 1 to 8 MHz propagating in structures with mono-disperse random pore distributions with pore diameter and pore density in the range of those of cortical bone are evaluated by finite difference time domain numerical simulations. An approach to assess the multiple scattering of waves in random media is discussed to determine the pore diameter ranges at which the ISA is applicable.

View Article and Find Full Text PDF

Osteoporosis affects porosity in cortical bone. Quantifying levels of osteoporosis by inferring the micro-architectural properties from ultrasonic wave attenuation in cortical bone has yet to be done. In this work we use a phenomenological, power law model to describe the frequency dependent attenuation in non-absorbing porous media mimicking a simplified cortical bone structure.

View Article and Find Full Text PDF

This work proposes a power law model to describe the attenuation of ultrasonic waves in non-absorbing heterogeneous media with randomly distributed scatterers, mimicking a simplified structure of cortical bone. This paper models the propagation in heterogeneous structures with controlled porosity using a two-dimensional finite-difference time domain numerical simulation in order to measure the frequency dependent attenuation. The paper then fits a phenomenological model to the simulated frequency dependent attenuation by optimizing parameters under an ordinary least squares framework.

View Article and Find Full Text PDF

Introduction: Ventricular fibrillation is a common life-threatening arrhythmia. The ECG of VF appears chaotic but may allow identification of sustaining mechanisms to guide therapy.

Hypothesis: We hypothesized that rotors and focal sources manifest distinct features on the ECG, and computational modeling may identify mechanisms of such features.

View Article and Find Full Text PDF

Objective: Heart failure (HF) management guided by implantable hemodynamic monitoring reduces hospitalization rates. Hemodynamic data from the CardioMEMS HF system includes device-averaged pulmonary artery pressures (PAP) and heart rate. Agreement of device-averaged values compared to the standard method of visual inspection of pressure waveforms at end-expiration is unknown.

View Article and Find Full Text PDF

Aims: Outcomes among patients who do not receive device reimplantation after cardiovascular implantable electronic device (CIED) extraction have not been well studied. The present study aims to investigate the outcomes of patients without device reimplantation after lead extraction and device removal.

Methods And Results: We retrospectively searched for consecutive patients who underwent CIED extraction at Mayo Clinic, Rochester, MN and University of California San Diego Medical Center from 2001 through 2012.

View Article and Find Full Text PDF

Background: Children with perinatal stroke may show evidence of contralateral spatial neglect. The goal of this study was to determine whether the Clock Drawing Test commonly used in adults to identify neglect would be effective in detecting neglect in children with perinatal stroke.

Methods: Thirty-eight individuals (age range 6-21 years) with left hemisphere or right hemisphere perinatal onset unilateral lesions and 179 age-matched controls were given a free-drawn Clock Drawing Test in a cross-sectional design.

View Article and Find Full Text PDF