scholarly journals Fractal Dimension Characterization of in-vivo Laser Doppler Flowmetry signals

2011 ◽  
Vol 19 ◽  
pp. 49-54 ◽  
Author(s):  
Gayathri Srinivasan ◽  
N. Sujatha
Keyword(s):  
Fractal Dimension ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Doppler Flowmetry

scholarly journals A Minimally Invasive Technique for Serial Intraosseous Perfusion Measurements in the Murine Tibia Using Laser Doppler Flowmetry

2019 ◽  
Author(s):  
Nicholas J Hanne ◽  
Elizabeth D Easter ◽  
Sandra Stangeland-Molo ◽  
Jacqueline H Cole
Keyword(s):  
Minimally Invasive ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Invasive Technique ◽  
List Type ◽  
Current Standard ◽  
Preclinical Research ◽  
Modified Technique ◽  
Doppler Flowmetry

AbstractIn biomedical and preclinical research, the current standard method for measuring blood perfusion inside murine bone, radiolabeled microspheres, is a terminal procedure that cannot be used to monitor longitudinal perfusion changes. Laser Doppler flowmetry (LDF) can quantify perfusion within the proximal tibial metaphysis of mice in vivo but requires a surgical procedure to place the measurement probe directly onto the bone surface. Sustained inflammation for over a month following this technique was previously reported, and previous studies have used LDF as an endpoint-only procedure. We developed a modified, minimally invasive LDF procedure to measure intraosseous perfusion in the murine tibia without stimulating local or systemic inflammation or inducing gait abnormalities. This modified technique can be used to measure perfusion weekly for up to at least a month. Unlike previous endpoint-only techniques, this modified LDF procedure can be performed weekly to monitor serial changes to intraosseous perfusion in the murine tibiaThe modified LDF technique utilizes a smaller, more localized incision to minimize invasiveness and speed recovery

Laser-Doppler Flowmetry in the Study of in Vivo Liver Ischemia and Reperfusion in the Rat

1994 ◽  
Vol 56 (5) ◽  
pp. 473-477 ◽  
Author(s):  
Rafael E. Chávez-Cartaya ◽  
Pablo Ramirez-Romero ◽  
Sir Roy Y. Calne ◽  
Neville V. Jamieson
Keyword(s):  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Ischemia And Reperfusion ◽  
Liver Ischemia ◽  
Doppler Flowmetry

scholarly journals About the in vivo discriminatory capacity of photoplethysmography versus laser Doppler flowmetry

2017 ◽  
Vol 14 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Clemente Rocha ◽  
Henrique Silva ◽  
Hugo Ferreira ◽  
L Monteiro Rodrigues
Keyword(s):  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Discriminatory Capacity

scholarly journals In-Vivo Measurement of Rotator Cuff Perfusion Using Laser Doppler Flowmetry (SS-38)

2007 ◽  
Vol 23 (6) ◽  
pp. e19-e20 ◽  
Author(s):  
Kenneth J. Accousti ◽  
James Gladstone ◽  
Bradford Parsons ◽  
Raymond Klug ◽  
Evan Flatow
Keyword(s):  
Rotator Cuff ◽  
Laser Doppler Flowmetry ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
In Vivo Measurement

Cold-induced cutaneous vasoconstriction is mediated by Rho kinase in vivo in human skin

2007 ◽  
Vol 292 (4) ◽  
pp. H1700-H1705 ◽  
Author(s):  
Caitlin S. Thompson-Torgerson ◽  
Lacy A. Holowatz ◽  
Nicholas A. Flavahan ◽  
W. Larry Kenney
Keyword(s):  
Laser Doppler Flowmetry ◽  
Combined Treatment ◽  
Rho Kinase ◽  
Laser Doppler ◽  
Whole Body ◽  
Local Skin ◽  
Doppler Flowmetry ◽  
Thermoregulatory Model ◽  
Cutaneous Vasoconstriction

Cutaneous vasoconstriction (VC) is the initial thermoregulatory response to cold exposure and can be elicited through either whole body or localized skin cooling. However, the mechanisms governing local cold-induced VC are not well understood. We tested the hypothesis that Rho kinase participates in local cold-induced cutaneous VC. In seven men and women (20–27 yr of age), up to four ventral forearm skin sites were instrumented with intradermal microdialysis fibers for localized drug delivery during cooling. Skin blood flow was monitored at each site with laser-Doppler flowmetry while local skin temperature was decreased and maintained at 24°C for 40 min. Cutaneous vascular conductance (CVC; laser-Doppler flowmetry/mean arterial pressure) was expressed as percent change from 34°C baseline. During the first 5 min of cooling, CVC decreased at control sites (lactated Ringer solution) to −45 ± 6% ( P < 0.001), increased at adrenoceptor-antagonized sites (yohimbine + propranolol) to 15 ± 14% ( P = 0.002), and remained unchanged at both Rho kinase-inhibited (fasudil) and adrenoceptor-antagonized + Rho kinase-inhibited sites (yohimbine + propranolol + fasudil) (−9 ± 1%, P = 0.4 and −6 ± 2%, P = 0.4, respectively). During the last 5 min of cooling, CVC further decreased at all sites when compared with baseline values (control, −77 ± 4%, P < 0.001; adrenoceptor antagonized, −61 ± 3%, P < 0.001; Rho kinase inhibited, −34 ± 7%, P < 0.001; and adrenoceptor antagonized + Rho kinase inhibited sites, −35 ± 3%, P < 0.001). Rho kinase-inhibited and combined treatment sites were significantly attenuated when compared with both adrenoceptor-antagonized ( P < 0.01) and control sites ( P < 0.0001). Rho kinase mediates both early- and late-phase cold-induced VC, supporting in vitro findings and providing a putative mechanism through which both adrenergic and nonadrenergic cold-induced VC occurs in an in vivo human thermoregulatory model.

scholarly journals Impaired Cerebral Autoregulation After Subarachnoid Hemorrhage: A Quantitative Assessment Using a Mouse Model

2021 ◽  
Vol 12 ◽  
Author(s):  
Masayo Koide ◽  
Hannah R. Ferris ◽  
Mark T. Nelson ◽  
George C. Wellman
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Laser Doppler Flowmetry ◽  
Cerebral Autoregulation ◽  
Cerebrovascular Disorders ◽  
Delayed Cerebral Ischemia ◽  
Laser Doppler ◽  
Neurological Deficits ◽  
Doppler Flowmetry ◽  
The Impact

Subarachnoid hemorrhage (SAH) is a common form of hemorrhagic stroke associated with high rates of mortality and severe disability. SAH patients often develop severe neurological deficits days after ictus, events attributed to a phenomenon referred to as delayed cerebral ischemia (DCI). Recent studies indicate that SAH-induced DCI results from a multitude of cerebral circulatory disturbances including cerebral autoregulation malfunction. Cerebral autoregulation incorporates the influence of blood pressure (BP) on arterial diameter in the homeostatic regulation of cerebral blood flow (CBF), which is necessary for maintaining constant brain perfusion during physiological swings in systemic BP. In this study, we quantitatively examined the impact of SAH on cerebral autoregulation using a mouse endovascular perforation model and a newly developed approach combining absolute and relative CBF measurements. This method enables a direct quantitative comparison of cerebral autoregulation between individual animals (e.g., SAH vs. control or sham-operated mice), which cannot be done solely using relative CBF changes by laser Doppler flowmetry. Here, absolute CBF was measured via injection of fluorescent microspheres at a baseline BP. In separate groups of animals, in vivo laser Doppler flowmetry was used to measure relative CBF changes over a range of BP using phlebotomy and the pressor phenylephrine to lower and raise BP, respectively. Absolute CBF measurements from microspheres were then used to calibrate laser Doppler measurements to calculate the relationship between CBF and BP, i.e., “cerebral autoregulation curves.” Un-operated and sham-operated groups exhibited similar cerebral autoregulatory curves, showing comparable levels of relatively constant CBF over a range of BP from ~80 mmHg to ~130 mmHg. In contrast, SAH animals exhibited a narrower autoregulatory range of BP, which was primarily due to a decrease in the upper limit of BP whereby cerebral autoregulation was maintained. Importantly, SAH animals also exhibited a marked decrease in CBF throughout the entire range of BP. In sum, this study provides evidence of the dramatic reduction in cortical CBF and the diminished range of autoregulation after SAH. Furthermore, this novel methodology should pave the way for future studies examining pathological mechanisms and/or therapeutic strategies targeting impaired cerebral autoregulation, a pathology common to many cardiovascular and cerebrovascular disorders.

scholarly journals Validating Minimally Invasive Laser Doppler Flowmetry for Serial Bone Perfusion Measurements in Mice

2019 ◽  
Author(s):  
Nicholas J. Hanne ◽  
Elizabeth D. Easter ◽  
Jacqueline H. Cole
Keyword(s):  
Minimally Invasive ◽  
Laser Doppler Flowmetry ◽  
Femoral Artery ◽  
Interleukin 6 ◽  
Blood Perfusion ◽  
Laser Doppler ◽  
Serum Concentrations ◽  
Gait Patterns ◽  
Doppler Flowmetry

AbstractIn vivo laser Doppler flowmetry (LDF) has previously been used to quantify blood perfusion accurately at a single timepoint in the murine tibial metaphysis. However, this procedure entailed substantial disruption to soft tissues overlying the bone and caused notable localized inflammation for several weeks after the procedure, impeding serial measurements in the same mouse. In this study, we tested a less invasive technique to measure perfusion in the tibia with LDF and validated that it can be used serially in the same mouse without causing inflammation or gait perturbations. Twenty 14-week-old C57Bl/6J mice were evenly divided into groups that either had daily treadmill exercise or remained sedentary. Within these activity groups, mice were evenly subdivided into groups that received LDF measurements either weekly or only once at the study endpoint. Bone perfusion was measured with LDF in the anteromedial region of the right tibial metaphysis. Serum concentrations of interleukin 6, incision site wound area, and interlimb coordination during gait were measured weekly for four weeks. Tibial perfusion did not differ significantly between exercise and sedentary groups within the weekly or endpoint-only LDF groups at any timepoint. Perfusion was significantly increased in the third week in the weekly LDF group relative to measurements in the second and fourth weeks. Ligation of the femoral artery caused consistent, rapid reductions in tibial perfusion, validating that LDF is sensitive to changes in tibial blood supply. Weekly LDF procedures did not adversely affect gait, as interlimb coordination during treadmill locomotion was similar between weekly and endpoint-only LDF groups at every timepoint. Images of the incision site show wound closure within one week, and serum concentrations of interleukin 6 were not significantly different between weekly and endpoint-only groups. Together, these findings demonstrate that our minimally invasive LDF technique can be used for serial in vivo measurements of intraosseous blood perfusion without inducing localized inflammation or negatively affecting gait patterns in mice.HighlightsModified, minimally invasive laser Doppler flowmetry (LDF) technique was validated for serial measures of tibial perfusion in mice.Weekly LDF procedures did not induce inflammation or alter gait patterns that could confound metrics of interest in bone studies.Ligation of the femoral artery confirmed the LDF technique measures functional perfusion within the bone.

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