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Article ; Online: Protocol to assess extravasation of fluorescent molecules in mice after ultrasound-mediated blood-brain barrier opening

Lea Peko / Sharon Katz / Roni Gattegno / Tali Ilovitsh

STAR Protocols, Vol 5, Iss 1, Pp 102770- (2024)

2024

Abstract: Summary: Blood-brain barrier disruption (BBBD) using focused ultrasound (FUS) and microbubbles (MBs) is an effective tool for therapeutic delivery to the brain. Here, we present an optimized protocol for quantifying fluorescent molecules extravasation in ...

Abstract	Summary: Blood-brain barrier disruption (BBBD) using focused ultrasound (FUS) and microbubbles (MBs) is an effective tool for therapeutic delivery to the brain. Here, we present an optimized protocol for quantifying fluorescent molecules extravasation in mice. We describe steps for ultrasound treatment, injection of MBs and fluorescent dyes, brain harvesting, microscopy imaging, and image postprocessing algorithm. Our protocol has proven to successfully conduct a diameter-dependent analysis that measures vascular leakage following FUS-mediated BBBD at a single blood vessel resolution.For complete details on the use and execution of this protocol, please refer to Katz et al.1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
Keywords	Microscopy ; Neuroscience ; Biotechnology and bioengineering ; Physics ; Science (General) ; Q1-390
Language	English
Publishing date	2024-03-01T00:00:00Z
Publisher	Elsevier
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Protocol to assess extravasation of fluorescent molecules in mice after ultrasound-mediated blood-brain barrier opening.

Peko, Lea / Katz, Sharon / Gattegno, Roni / Ilovitsh, Tali

STAR protocols

2023 Volume 5, Issue 1, Page(s) 102770

Abstract: Blood-brain barrier disruption (BBBD) using focused ultrasound (FUS) and microbubbles (MBs) is an effective tool for therapeutic delivery to the brain. Here, we present an optimized protocol for quantifying fluorescent molecules extravasation in mice. We ...

Abstract	Blood-brain barrier disruption (BBBD) using focused ultrasound (FUS) and microbubbles (MBs) is an effective tool for therapeutic delivery to the brain. Here, we present an optimized protocol for quantifying fluorescent molecules extravasation in mice. We describe steps for ultrasound treatment, injection of MBs and fluorescent dyes, brain harvesting, microscopy imaging, and image postprocessing algorithm. Our protocol has proven to successfully conduct a diameter-dependent analysis that measures vascular leakage following FUS-mediated BBBD at a single blood vessel resolution. For complete details on the use and execution of this protocol, please refer to Katz et al.
MeSH term(s)	Mice ; Animals ; Blood-Brain Barrier/diagnostic imaging ; Brain/diagnostic imaging ; Brain/blood supply ; Ultrasonography ; Fluorescent Dyes
Chemical Substances	Fluorescent Dyes
Language	English
Publishing date	2023-12-29
Publishing country	United States
Document type	Journal Article
ISSN	2666-1667
ISSN (online)	2666-1667
DOI	10.1016/j.xpro.2023.102770
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Sensitivity and laboratory performances of a second-generation sub-epidermal moisture measurement device.

Peko, Lea / Gefen, Amit

International wound journal

2020 Volume 17, Issue 3, Page(s) 864–867

MeSH term(s)	Clinical Laboratory Techniques/instrumentation ; Epidermis ; Extracellular Fluid ; Face ; Heel ; Humans ; Pressure Ulcer/diagnosis ; Pressure Ulcer/etiology ; Sensitivity and Specificity
Language	English
Publishing date	2020-03-11
Publishing country	England
Document type	Letter
ZDB-ID	2170920-8
ISSN	1742-481X ; 1742-4801
ISSN (online)	1742-481X
ISSN	1742-4801
DOI	10.1111/iwj.13339
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Article ; Online: Diameter-dependent assessment of microvascular leakage following ultrasound-mediated blood-brain barrier opening.

Katz, Sharon / Gattegno, Roni / Peko, Lea / Zarik, Romario / Hagani, Yulie / Ilovitsh, Tali

iScience

2023 Volume 26, Issue 6, Page(s) 106965

Abstract: Blood brain barrier disruption (BBBD) using focused ultrasound (FUS) and microbubbles (MB) is an effective tool for therapeutic delivery to the brain. BBBD depends to a great extent on MB oscillations. Because the brain vasculature is heterogenic in ... ...

Abstract	Blood brain barrier disruption (BBBD) using focused ultrasound (FUS) and microbubbles (MB) is an effective tool for therapeutic delivery to the brain. BBBD depends to a great extent on MB oscillations. Because the brain vasculature is heterogenic in diameter, reduced MB oscillations in smaller blood vessels, together with a lower number of MBs in capillaries, can lead to variations in BBBD. Therefore, evaluating the impact of microvasculature diameter on BBBD is of great importance. We present a method to characterize molecules extravasation following FUS-mediated BBBD, at a single blood vessel resolution. Evans blue (EB) leakage was used as marker for BBBD, whereas blood vessels localization was done using FITC labeled Dextran. Automated image processing pipeline was developed to quantify the extent of extravasation as function of microvasculature diameter, including a wide range of vascular morphological parameters. Variations in MB vibrational response were observed in blood vessel mimicking fibers with varied diameters. Higher peak negative pressures (PNP) were required to initiate stable cavitation in fibers with smaller diameters.
Language	English
Publishing date	2023-05-26
Publishing country	United States
Document type	Journal Article
ISSN	2589-0042
ISSN (online)	2589-0042
DOI	10.1016/j.isci.2023.106965
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Article ; Online: Phantom testing of the sensitivity and precision of a sub-epidermal moisture scanner.

Peko Cohen, Lea / Gefen, Amit

International wound journal

2019 Volume 16, Issue 4, Page(s) 979–988

Abstract: The majority of pressure ulcers (PUs) including deep tissue injuries (DTIs) are preventable, and even reversible if detected in their early phase. One of the greatest barriers in PU prevention is that clinicians traditionally depended on subjective and ... ...

Abstract	The majority of pressure ulcers (PUs) including deep tissue injuries (DTIs) are preventable, and even reversible if detected in their early phase. One of the greatest barriers in PU prevention is that clinicians traditionally depended on subjective and qualitative techniques, particularly routine visual skin assessments that would only document existing, macroscopic PUs/DTIs, rather than preventing them or detecting them at their microscopic phase. At the early phase of cell damage, when a forming PU is still microscopic, there is a local increase in extracellular fluid contents within affected tissues, which is called sub-epidermal moisture (SEM). This new understanding has led to an emerging technology, a SEM Scanner (BBI LLC, Bruin Biometrics) that has been designed to effectively examine the health status of tissues, by measuring local changes in the biophysical SEM marker. In the present work, the SEM Scanner was tested under controlled laboratory conditions to experimentally determine its sensitivity and precision in identifying small (1 mL) water content changes in phantoms of the human heel and skull/face, which simulated common PU development scenarios. In both phantom configurations, the locally increased water contents resulted in consistent, statistically significant elevated SEM readings, which confirms that the SEM Scanner is able to detect fluid content changes that are as small as 1 mL. In agreement with a simplified theoretical (mathematical) SEM model, which was also developed here, changes in water contents had a consistent trend of effect on SEM delta values, which increased with each 1 mL increment in intra-tissue-substitute water contents.
MeSH term(s)	Early Diagnosis ; Edema/physiopathology ; Epidermal Cells/physiology ; Extracellular Fluid/physiology ; Humans ; Monitoring, Physiologic/instrumentation ; Monitoring, Physiologic/methods ; Pressure Ulcer/prevention & control ; Sensitivity and Specificity
Language	English
Publishing date	2019-04-16
Publishing country	England
Document type	Journal Article
ZDB-ID	2170920-8
ISSN	1742-481X ; 1742-4801
ISSN (online)	1742-481X
ISSN	1742-4801
DOI	10.1111/iwj.13132
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Article ; Online: Diameter-dependent assessment of microvascular leakage following ultrasound-mediated blood-brain barrier opening

Sharon Katz / Roni Gattegno / Lea Peko / Romario Zarik / Yulie Hagani / Tali Ilovitsh

iScience, Vol 26, Iss 6, Pp 106965- (2023)

2023

Abstract: Summary: Blood brain barrier disruption (BBBD) using focused ultrasound (FUS) and microbubbles (MB) is an effective tool for therapeutic delivery to the brain. BBBD depends to a great extent on MB oscillations. Because the brain vasculature is ... ...

Abstract	Summary: Blood brain barrier disruption (BBBD) using focused ultrasound (FUS) and microbubbles (MB) is an effective tool for therapeutic delivery to the brain. BBBD depends to a great extent on MB oscillations. Because the brain vasculature is heterogenic in diameter, reduced MB oscillations in smaller blood vessels, together with a lower number of MBs in capillaries, can lead to variations in BBBD. Therefore, evaluating the impact of microvasculature diameter on BBBD is of great importance. We present a method to characterize molecules extravasation following FUS-mediated BBBD, at a single blood vessel resolution. Evans blue (EB) leakage was used as marker for BBBD, whereas blood vessels localization was done using FITC labeled Dextran. Automated image processing pipeline was developed to quantify the extent of extravasation as function of microvasculature diameter, including a wide range of vascular morphological parameters. Variations in MB vibrational response were observed in blood vessel mimicking fibers with varied diameters. Higher peak negative pressures (PNP) were required to initiate stable cavitation in fibers with smaller diameters. In vivo in the treated brains, EB extravasation increased as a function of blood vessel diameter. The percentage of strong BBBD blood vessels increased from 9.75% for 2–3 μm blood vessels to 91.67% for 9–10 μm. Using this method, it is possible to conduct a diameter-dependent analysis that measures vascular leakage resulting from FUS-mediated BBBD at a single blood vessel resolution.
Keywords	Biomedical engineering ; Engineering ; Materials science ; Biomaterials ; Science ; Q
Subject code	610
Language	English
Publishing date	2023-06-01T00:00:00Z
Publisher	Elsevier
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Protecting prone positioned patients from facial pressure ulcers using prophylactic dressings: A timely biomechanical analysis in the context of the COVID-19 pandemic.

Peko, Lea / Barakat-Johnson, Michelle / Gefen, Amit

International wound journal

2020 Volume 17, Issue 6, Page(s) 1595–1606

Abstract: Prone positioning is used for surgical access and recently in exponentially growing numbers of coronavirus disease 2019 patients who are ventilated prone. To reduce their facial pressure ulcer risk, prophylactic dressings can be used; however, the ... ...

Abstract	Prone positioning is used for surgical access and recently in exponentially growing numbers of coronavirus disease 2019 patients who are ventilated prone. To reduce their facial pressure ulcer risk, prophylactic dressings can be used; however, the biomechanical efficacy of this intervention has not been studied yet. We, therefore, evaluated facial soft tissue exposures to sustained mechanical loads in a prone position, with versus without multi-layered silicone foam dressings applied as tissue protectors at the forehead and chin. We used an anatomically realistic validated finite element model of an adult male head to determine the contribution of the dressings to the alleviation of the sustained tissue loads. The application of the dressings considerably relieved the tissue exposures to loading. Specifically, with respect to the forehead, the application of a dressing resulted in 52% and 71% reductions in soft tissue exposures to effective stresses and strain energy densities, respectively. Likewise, a chin dressing lowered the soft tissue exposures to stresses and strain energy densities by 78% and 92%, respectively. While the surgical context is clear and there is a solid, relevant need for biomechanical information regarding prophylaxis for the prone positions, the projected consequences of the coronavirus pandemic make the present work more relevant than ever before.
MeSH term(s)	Bandages ; COVID-19/complications ; COVID-19/epidemiology ; COVID-19/therapy ; Computer Simulation ; Face ; Humans ; Pandemics ; Patient Positioning/methods ; Posture ; Pressure Ulcer/etiology ; Pressure Ulcer/prevention & control ; SARS-CoV-2
Keywords	covid19
Language	English
Publishing date	2020-07-03
Publishing country	England
Document type	Comparative Study ; Journal Article
ZDB-ID	2170920-8
ISSN	1742-481X ; 1742-4801
ISSN (online)	1742-481X
ISSN	1742-4801
DOI	10.1111/iwj.13435
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Article ; Online: Physiological measurements of facial skin response under personal protective equipment.

Peko, Lea / Ovadia-Blechman, Zehava / Hoffer, Oshrit / Gefen, Amit

Journal of the mechanical behavior of biomedical materials

2021 Volume 120, Page(s) 104566

Abstract: Medical device-related pressure ulcers (MDRPUs) were traditionally associated with skin-contacting medical devices applied to patients, eventually causing tissue damage. The coronavirus-2019 pandemic has brought a new variant of MDRPUs: facial skin ... ...

Abstract	Medical device-related pressure ulcers (MDRPUs) were traditionally associated with skin-contacting medical devices applied to patients, eventually causing tissue damage. The coronavirus-2019 pandemic has brought a new variant of MDRPUs: facial skin irritation or damage associated with extended use of protective personal equipment (PPE), e.g. facemasks and respirators. In this context, we report here a comprehensive experimental evaluation including facial contact forces, skin temperatures and sub-epidermal moisture (SEM) measurements pre/post-PPE usage, to determine how these physiological parameters change under the effects of surgical facemasks and KN95 respirators and whether such potential changes can explain the commonly reported skin irritation or damage. We found that a surgical mask is potentially less irritating to facial skin than the KN95 respirator, as it applies lower forces and facilitates faster return of facial temperatures to their basal levels. Further, we demonstrated that use of dressing cuts for padding under a KN95 respirator considerably reduced localized forces and did not worsen the thermal and SEM readings at the skin-device contact sites. This study provides a basis for improvement of PPE designs, as it describes physiological measurement methodologies for quantitative comparisons of the effects of different PPE types on facial skin status.
MeSH term(s)	COVID-19 ; Humans ; Masks ; Pandemics ; Personal Protective Equipment ; Skin
Language	English
Publishing date	2021-04-29
Publishing country	Netherlands
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2378381-3
ISSN	1878-0180 ; 1751-6161
ISSN (online)	1878-0180
ISSN	1751-6161
DOI	10.1016/j.jmbbm.2021.104566
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Article ; Online: Deep tissue loads in the seated buttocks on an off-loading wheelchair cushion versus air-cell-based and foam cushions: finite element studies.

Peko Cohen, Lea / Gefen, Amit

International wound journal

2017 Volume 14, Issue 6, Page(s) 1327–1334

Abstract: For wheelchair users, a common injury is a sitting-acquired pressure ulcer (PU) which typically onsets near the interface between the ischial tuberosity (IT) and the overlying soft tissues. The risk of developing PUs can be reduced considerably if an ... ...

Abstract	For wheelchair users, a common injury is a sitting-acquired pressure ulcer (PU) which typically onsets near the interface between the ischial tuberosity (IT) and the overlying soft tissues. The risk of developing PUs can be reduced considerably if an adequate cushion is placed on the wheelchair in order to protect tissues from PUs by minimising interface mechanical loads between the body and cushion and also, exposure to internal soft tissue loads. In this work, we studied the biomechanical performances of an off-loading (OL) cushion with limited adjustability, in comparison to a standard foam cushion and a fully adjustable air-cell-based (ACB) cushion. These different cushion design approaches were methodologically and quantitatively analysed and compared here using a finite element (FE) modelling framework. We determined the internal mechanical deformations, strains and stresses in soft tissues of the seated buttocks during symmetric sitting, in a specific anatomy of a person with a spinal cord injury that was acquired during sitting in an open, magnetic resonance imaging configuration. Our results have shown that strains and stresses in muscle, fat and skin tissues are orders of magnitude lower for the ACB cushion with respect to the standard foam and OL cushions. The OL cushion design has taken the approach of protecting at-risk sites of the buttocks by transferring local internal tissue loads away from the ITs and towards the greater trochanters, at the price of increasing exposure to internal tissue loads at sites other than the ITs. The ACB cushion design, however, has taken a different approach, that is, immersion and envelopment of the entire buttocks structure, which is useful for minimising the exposure to internal tissue loads throughout the whole buttocks. Quantifying performances of wheelchair cushions using FE modelling provides insights into deep tissue loads, which is essential for informed decision-making in developing sitting solutions for individuals at risk, as well as for patient groups.
MeSH term(s)	Adult ; Aged ; Aged, 80 and over ; Biomechanical Phenomena/physiology ; Buttocks/physiopathology ; Equipment Design ; Female ; Humans ; Male ; Middle Aged ; Posture/physiology ; Pressure Ulcer/physiopathology ; Pressure Ulcer/prevention & control ; Protective Devices ; Stress, Mechanical ; Wheelchairs
Language	English
Publishing date	2017-09-06
Publishing country	England
Document type	Comparative Study ; Journal Article
ZDB-ID	2170920-8
ISSN	1742-481X ; 1742-4801
ISSN (online)	1742-481X
ISSN	1742-4801
DOI	10.1111/iwj.12807
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Article ; Online: Ultrasound elastography reveals the relation between body posture and soft-tissue stiffness which is relevant to the etiology of sitting-acquired pressure ulcers.

Mansur, Ruba / Peko, Lea / Shabshin, Nogah / Cherbinski, Leonid / Neeman, Ziv / Gefen, Amit

Physiological measurement

2021 Volume 41, Issue 12, Page(s) 124002

Abstract: Objective: Sitting-acquired pressure ulcers (PUs) are common in wheelchair users. These PUs are often serious and may involve deep tissue injury (DTI). Investigating the mechanical properties of the tissues susceptible to DTI may help in guiding the ... ...

Abstract	Objective: Sitting-acquired pressure ulcers (PUs) are common in wheelchair users. These PUs are often serious and may involve deep tissue injury (DTI). Investigating the mechanical properties of the tissues susceptible to DTI may help in guiding the prevention and early detection of PUs. In this study, shear wave elastography (SWE) was used to measure the normative mechanical properties of the soft tissues of the buttocks, i.e. skeletal muscle and subcutaneous fat, under the ischial tuberosities, in a convenient sample of healthy adults without weight bearing and with weight bearing of different times. Approach: We compared the stiffness properties of these soft tissues between the lying prone and sitting postures, to determine whether there are detectable property changes that may be associated with the type of posture. We hypothesized that muscle contractions and 3D tissue configurations associated with the posture may influence the measured tissue stiffnesses. Main results: Our results have shown that indeed, SWE values differed significantly across postures, but not over time in a specific posture or for the right versus left sides of the body. Significance: We have therefore demonstrated that soft-tissue stiffness increases when sitting with weight bearing and may contribute to increasing the potential PU risk in sitting compared to lying prone, given the stiffer behavior of tissues observed in sitting postures.
MeSH term(s)	Adult ; Buttocks/diagnostic imaging ; Elasticity Imaging Techniques ; Humans ; Posture ; Pressure Ulcer/diagnostic imaging ; Pressure Ulcer/etiology ; Sitting Position ; Ultrasonography ; Weight-Bearing
Language	English
Publishing date	2021-01-01
Publishing country	England
Document type	Journal Article
ZDB-ID	1149545-5
ISSN	1361-6579 ; 0967-3334
ISSN (online)	1361-6579
ISSN	0967-3334
DOI	10.1088/1361-6579/abc66d
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