Oxygen Transport to Tissue XL

doi:10.1007/978-3-319-91287-5

Cited by 8 publications

(3 citation statements)

References 14 publications

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“…32 However, DPF has to generally be assumed a priori in CW-fNIRS. Although several works that attempted to provide reliable tabulated values or equation models of DPF to be employed for CW-fNIRS measurements, 10,21 the intersubjective variability and DPF dependence on a large number of factors, such as age, sex, head region, 33 and disease, make it particularly challenging to provide reliable estimation. Although it is not possible to quantitatively evaluate DPF from standard CW-fNIRS recordings because of the lack of photons' time-of-flight information, in this paper a procedure to estimate DPF spectral dependence was presented.…”

Section: Discussionmentioning

confidence: 99%

“…For example, in the current study, 64 channels over an area of ∼700 mm 2 were employed for a single EAC computation; thus, the underlying assumption of the procedure is that the EAC spatial changes within the investigated area are minor. Although it is known that DPF changes as a function of brain region, 33 these changes should be sufficiently smooth to employ such a multichannel algorithm relying on sufficient optode density. Another interesting application of the developed approach would be to study the time-varying properties of DPF spectral dependence as a function of functional brain activity.…”

Section: Discussionmentioning

confidence: 99%

“…In fact, brain activity indeed causes changes to the baseline optical parameters of several point percentages that influence DPF and are typically overlooked. 35 These changes might by assessed by the developed procedure through a sufficiently short integration time window of the algorithm. For this reason, the stability of the estimated EAC as a function of integration time was evaluated.…”

Section: Discussionmentioning

confidence: 99%

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Differential pathlength factor in continuous wave functional near-infrared spectroscopy: reducing hemoglobin’s cross talk in high-density recordings

Chiarelli¹,

Perpetuini²,

Filippini³

et al. 2019

Neurophoton.

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Functional near-infrared spectroscopy (fNIRS) estimates the functional oscillations of oxyhemoglobin and deoxyhemoglobin in the cortex through scalp-located multiwavelength recordings. Hemoglobin oscillations are inferred through temporal changes in continuous-wave (CW) light attenuation. However, because of the diffusive multilayered head tissue structures, the photon path is longer than the source-detector separation, complicating hemoglobin evaluation. This aspect is incorporated in the modified Beer-Lambert law where the source-detector distance is multiplied by the differential pathlength factor (DPF). Since DPF estimation requires photons' time-of-flight information, DPF is assumed a priori in CW-fNIRS. Importantly, errors in the DPF spectrum induce hemoglobin cross talk, which is detrimental for fNIRS. We propose to estimate subject-specific DPF spectral dependence relying on multidistance high-density measurements. The procedure estimates the effective attenuation coefficient (EAC), which is proportional to the geometric mean of absorption and reduced scattering. Since DPF depends on the scattering-to-absorption ratio, EAC limits the spectral dependence assumption to scattering. This approach was compared to a standard frequency-domain multidistance procedure. A good association between the two methods (r 2 ¼ 0.69) was obtained. This approach could estimate low-resolution maps of the DPF spectral dependence through large field of view, high-density systems, reducing hemoglobin cross talk, and increasing fNIRS sensitivity and specificity to brain activity without instrumentation modification.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Differential pathlength factor in continuous wave functional near-infrared spectroscopy: reducing hemoglobin’s cross talk in high-density recordings

Chiarelli¹,

Perpetuini²,

Filippini³

et al. 2019

Neurophoton.

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Regeneration of hyaline cartilage in osteochondral lesion model using L‐lysine magnetic nanoparticles labeled mesenchymal stem cells and their in vivo imaging

Shelat

Bhatt

Paunipagar

et al. 2020

J Tissue Eng Regen Med

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Treatment of osteochondral defects continues to pose a major challenge for patients and orthopedic surgeons due to the limited healing potential of articular cartilage. Mesenchymal stem cells (MSCs) possess therapeutic potential for the treatment of osteochondral pain and pathology. However, it is necessary to use proper labeling and imaging agent of stem cells that can decipher its role posttransplantation. A major limitation of routinely used contrast agents is signal dilution over a period of time which limits its use for further studies. At the same time, regeneration of fibrocartilage over native hyaline cartilage also limits the use of conventional therapies. The present study evaluates the efficacy of bone marrow-derived mesenchymal stem cells (BMSCs) for the treatment of osteochondral defect in rats with the regeneration of hyaline cartilage in situ and in vivo monitoring of the stem cells using L-lysine functionalized magnetic iron oxide nanoparticles (lys-IONPs). L-lysine stabilizes the iron oxide nanoparticles, enhances the biocompatibility, and provides functionalities for efficient stem cell labeling. in vitro toxic effects of lys-IONPs on mitochondrial impairment, morphological alterations, and actin cytoskeleton reveal minimum damage to BM-MSCs. Histological data (H and E, Masson's trichrome and immunohistochemistry) describe the early initiation of healing and regeneration of hyaline-like cartilage over fibrocartilage in stem cell treated groups. MR scans demonstrate generation of hypointense signals in lys-IONPs-BMSCs with improved signal intensity and minimum loss over 28 days revealing its use as a long-term stem cell labeling and imaging agent. K E Y W O R D S bone marrow mesenchymal stem cells, iron oxide nanoparticles, L-lysine, magnetic resonance imaging, osteochondral defect 1 | INTRODUCTION Osteochondral defects in the knee joint remain to be the most challenging clinical problem for orthopedic surgeons with maximum disability in young athletes and older people (Kumbhar et al., 2017). The overall prevalence rate of osteochondral defect is found to be higher in males than in females (3:1) with young adults at the highest risk (Weiss et al., 2016). Owing to the restricted therapeutic ability of articular cartilage, it is complicated to treat osteochondral defects, leading to disabling pain and early osteoarthritis (Perera, Gikas, & Bentley, 2012). Thus,

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O2 permeability of lipid bilayers is low, but increases with membrane cholesterol

Al-Samir

Itel

Hegermann

et al. 2021

Cell. Mol. Life Sci.

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Oxygen on its transport route from lung to tissue mitochondria has to cross several cell membranes. The permeability value of membranes for O2 (PO2), although of fundamental importance, is controversial. Previous studies by mostly indirect methods diverge between 0.6 and 125 cm/s. Here, we use a most direct approach by observing transmembrane O2 fluxes out of 100 nm liposomes at defined transmembrane O2 gradients in a stopped-flow system. Due to the small size of the liposomes intra- as well as extraliposomal diffusion processes do not affect the overall kinetics of the O2 release process. We find, for cholesterol-free liposomes, the unexpectedly low PO2 value of 0.03 cm/s at 35 °C. This PO2 would present a serious obstacle to O2 entering or leaving the erythrocyte. Cholesterol turns out to be a novel major modifier of PO2, able to increase PO2 by an order of magnitude. With a membrane cholesterol of 45 mol% as it occurs in erythrocytes, PO2 rises to 0.2 cm/s at 35 °C. This PO2 is just sufficient to ensure complete O2 loading during passage of erythrocytes through the lung’s capillary bed under the conditions of rest as well as maximal exercise.

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Oxygen Transport to Tissue XL

Cited by 8 publications

References 14 publications

Differential pathlength factor in continuous wave functional near-infrared spectroscopy: reducing hemoglobin’s cross talk in high-density recordings

Differential pathlength factor in continuous wave functional near-infrared spectroscopy: reducing hemoglobin’s cross talk in high-density recordings

Regeneration of hyaline cartilage in osteochondral lesion model using L‐lysine magnetic nanoparticles labeled mesenchymal stem cells and their in vivo imaging

O2 permeability of lipid bilayers is low, but increases with membrane cholesterol

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