scholarly journals Monitoring of rhythms in laser speckle data

2014 ◽  
Vol 07 (03) ◽  
pp. 1450015 ◽  
Author(s):  
D. E. Postnov ◽  
A. Y. Neganova ◽  
D. D. Postnov ◽  
A. R. Brazhe
Keyword(s):  
Blood Flow ◽  
Graphics Processing Units ◽  
Surrogate Data ◽  
Laser Speckle ◽  
Tubuloglomerular Feedback ◽  
Additional Information ◽  
3D Data ◽  
Kidney Blood Flow ◽  
Rhythm Analysis ◽  
Spatio Temporal

While the laser speckle imaging (LSI) is a powerful tool for multiple biomedical applications, such as monitoring of the blood flow, in many cases it can provide additional information when combined with spatio-temporal rhythm analysis. We demonstrate the application of Graphics Processing Units (GPU)-based rhythm analysis for the post processing of LSI data, discuss the relevant structure of GPU-based computations, test the proposed technique on surrogate 3D data, and apply this approach to kidney blood flow autoregulation. Experiments with surrogate data demonstrate the ability of the method to extract information about oscillation patterns from noisy data, as well as to detect the moving source of the rhythm. The analysis of kidney data allow us to detect and to localize the dynamics arising from autoregulation processes at the level of individual nephrons (tubuloglomerular feedback (TGF) rhythm), as well as to distinguish between the TGF-active and the TGF-silent zones.

scholarly journals Nephron blood flow dynamics measured by laser speckle contrast imaging

2011 ◽  
Vol 300 (2) ◽  
pp. F319-F329 ◽  
Author(s):  
Niels-Henrik Holstein-Rathlou ◽  
Olga V. Sosnovtseva ◽  
Alexey N. Pavlov ◽  
William A. Cupples ◽  
Charlotte Mehlin Sorensen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Signal Transmission ◽  
Experimental Studies ◽  
Flow Dynamics ◽  
Laser Speckle ◽  
Tubuloglomerular Feedback ◽  
Contrast Imaging ◽  
Laser Speckle Contrast Imaging ◽  
Speckle Contrast ◽  
Blood Flow Dynamics

Tubuloglomerular feedback (TGF) has an important role in autoregulation of renal blood flow and glomerular filtration rate (GFR). Because of the characteristics of signal transmission in the feedback loop, the TGF undergoes self-sustained oscillations in single-nephron blood flow, GFR, and tubular pressure and flow. Nephrons interact by exchanging electrical signals conducted electrotonically through cells of the vascular wall, leading to synchronization of the TGF-mediated oscillations. Experimental studies of these interactions have been limited to observations on two or at most three nephrons simultaneously. The interacting nephron fields are likely to be more extensive. We have turned to laser speckle contrast imaging to measure the blood flow dynamics of 50–100 nephrons simultaneously on the renal surface of anesthetized rats. We report the application of this method and describe analytic techniques for extracting the desired data and for examining them for evidence of nephron synchronization. Synchronized TGF oscillations were detected in pairs or triplets of nephrons. The amplitude and the frequency of the oscillations changed with time, as did the patterns of synchronization. Synchronization may take place among nephrons not immediately adjacent on the surface of the kidney.

scholarly journals Altered whole kidney blood flow autoregulation in a mouse model of reduced β-ENaC

2010 ◽  
Vol 298 (2) ◽  
pp. F285-F292 ◽  
Author(s):  
Samira C. Grifoni ◽  
Rumbidzayi Chiposi ◽  
Susan E. McKey ◽  
Michael J. Ryan ◽  
Heather A. Drummond
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Mouse Model ◽  
Tubuloglomerular Feedback ◽  
Initial Increase ◽  
Myogenic Response ◽  
Kidney Blood Flow ◽  
Induced Changes ◽  
Renal Vascular

Renal blood flow (RBF) autoregulation is mediated by at least two mechanisms, the fast acting myogenic response (∼5 s) and slow acting tubuloglomerular feedback (TGF; ∼25 s). Previous studies suggest epithelial Na+ channel (ENaC) family proteins, β-ENaC in particular, mediate myogenic constriction in isolated renal interlobar arteries. However, it is unknown whether β-ENaC-mediated myogenic constriction contributes to RBF autoregulation in vivo. Therefore, the goal of this investigation was to determine whether the myogenic mediated RBF autoregulation is inhibited in a mouse model of reduced β-ENaC (m/m). To address this goal, we evaluated the temporal response of RBF and renal vascular resistance (RVR) to a 2-min step increase in mean arterial pressure (MAP). Pressure-induced changes in RBF and RVR at 0–5, 6–25, and 110–120 s after step increase in MAP were used to assess the contribution of myogenic and TGF mechanisms and steady-state autoregulation, respectively. The rate of the initial increase in RVR, attributed to the myogenic mechanism, was reduced by ∼50% in m/m mice, indicating the speed of the myogenic response was inhibited. Steady-state autoregulation was similar between β-ENaC +/+ and m/m mice. Although the rate of the secondary increase in RVR, attributed to TGF, was similar in β-ENaC +/+ and m/m mice, however, it occurred over a longer period (+10 s), which may have allowed TGF to compensate for a loss in myogenic autoregulation. Our findings suggest β-ENaC is an important mediator of renal myogenic constriction-mediated RBF autoregulation in vivo.

scholarly journals Dynamic Spatio-Temporal Imaging of Early Reflow in a Neonatal Rat Stroke Model

2012 ◽  
Vol 33 (1) ◽  
pp. 137-145 ◽  
Author(s):  
Pierre-Louis Leger ◽  
Philippe Bonnin ◽  
Pierre Lacombe ◽  
Elisabeth Couture-Lepetit ◽  
Sebastien Fau ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arterial Occlusion ◽  
Tissue Perfusion ◽  
Laser Speckle ◽  
Neonatal Rat ◽  
Immature Rat ◽  
Collateral Pathway ◽  
Flow Changes ◽  
Spatio Temporal ◽  
Blood Flow Velocities

The aim of the study was to better understand blood-flow changes in large arteries and microvessels during the first 15 minutes of reflow in a P7 rat model of arterial occlusion. Blood-flow changes were monitored by using ultrasound imaging with sequential Doppler recordings in internal carotid arteries (ICAs) and basilar trunk. Relative cerebral blood flow (rCBF) changes were obtained by using laser speckle Doppler monitoring. Tissue perfusion was measured with [14C]-iodoantipyrine autoradiography. Cerebral energy metabolism was evaluated by mitochondrial oxygen consumption. Gradual increase in mean blood-flow velocities illustrated a gradual perfusion during early reflow in both ICAs. On ischemia, the middle cerebral artery (MCA) territory presented a residual perfusion, whereas the caudal territory remained normally perfused. On reflow, speckle images showed a caudorostral propagation of reperfusion through anastomotic connections, and a reduced perfusion in the MCA territory. Autoradiography highlighted the caudorostral gradient, and persistent perfusion in ventral and medial regions. These blood-flow changes were accompanied by mitochondrial respiration impairment in the ipsilateral cortex. Collectively, these data indicate the presence of a primary collateral pathway through the circle of Willis, providing an immediate diversion of blood flow toward ischemic regions, and secondary efficient cortical anastomoses in the immature rat brain.

Interactions between TGF-dependent and myogenic oscillations in tubular pressure and whole kidney blood flow in both SDR and SHR

2006 ◽  
Vol 290 (3) ◽  
pp. F720-F732 ◽  
Author(s):  
Ramakrishna Raghavan ◽  
Xinnian Chen ◽  
Kay-Pong Yip ◽  
Donald J. Marsh ◽  
Ki H. Chon
Keyword(s):  
Blood Flow ◽  
Tubuloglomerular Feedback ◽  
Nonlinear Interactions ◽  
Time Varying ◽  
Nonlinear Coupling ◽  
Flow Data ◽  
Sprague Dawley ◽  
Spontaneously Hypertensive ◽  
Kidney Blood Flow ◽  
Time Invariant

We previously showed that nonlinear interactions between the two renal autoregulatory mechanics (tubuloglomerular feedback and the myogenic mechanism) were observed in the stop flow pressure (SFP) and whole kidney blood flow data from Sprague-Dawley rats (SDR) using time-invariant bispectrum analysis ( 3 , 4 ). No such nonlinear interactions were observed in either SFP or whole kidney blood flow data obtained from spontaneously hypertensive rats (SHR). We speculated that the failure to detect nonlinear interactions in the SHR data may be related to our observation that these interactions were not continuous and therefore had time-varying characteristics. Thus the absence of such nonlinear interactions may be due to an inappropriate time-invariant method being applied to data that are especially time varying in nature. We examine this possibility in this paper by using a time-varying bispectrum approach, which we developed for this purpose. Indeed, we found significant nonlinear interactions in SHR ( n = 18 for SFP; n = 12 for whole kidney blood flow). Moreover, the duration of nonlinear coupling is found statistically to be longer ( P = 0.001) in SFP data from either SDR or SHR than it is in whole kidney data from either type of rat. We conclude that nonlinear coupling is present at both the single nephron as well as the whole kidney level for SDR and SHR. In addition, SHR data at the whole kidney level exhibit the most transient nonlinear coupling phenomena.

Evaluation of skin blood flow using laser speckle phenomena (V)

1986 ◽  
Vol 6 (3) ◽  
pp. 335-338
Author(s):  
Hitoshi Fujii ◽  
Toshimitsu Asakura ◽  
Yasuhiro Harada ◽  
Kunihiko Nohira ◽  
Yoshihisa Shintomi ◽  
...  
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Laser Speckle

scholarly journals Hallucal thenar index: A new index to detect peripheral arterial disease using laser speckle flowgraphy

Vascular ◽  
2020 ◽  
pp. 170853812093893
Author(s):  
Kazuhiro Tsunekawa ◽  
Fumio Nagai ◽  
Tamon Kato ◽  
Ikkei Takashimizu ◽  
Daisuke Yanagisawa ◽  
...  
Keyword(s):  
Blood Flow ◽  
Peripheral Arterial Disease ◽  
Operating Characteristic ◽  
Ankle Brachial Index ◽  
Arterial Disease ◽  
Laser Speckle ◽  
Laser Speckle Flowgraphy ◽  
Skin Perfusion ◽  
Peripheral Arterial ◽  
Cutaneous Blood

Objectives Laser speckle flowgraphy is a technology using reflected scattered light for visualization of blood distribution, which can be used to measure relative velocity of blood flow easily without contact with the skin within a short time. It was hypothesized that laser speckle flowgraphy may be able to identify foot ischemia. This study was performed to determine whether laser speckle flowgraphy could distinguish between subjects with and without peripheral arterial disease. Materials and methods All subjects were classified based on clinical observations using the Rutherford classification: non-peripheral arterial disease, class 0; peripheral arterial disease group, class 2–5. Rutherford class 6 was one of the exclusion criteria. Laser speckle flowgraphy measured the beat strength of skin perfusion as an indicator of average dynamic cutaneous blood flow change synchronized with the heartbeat. The beat strength of skin perfusion indicates the strength of the heartbeat on the skin, and the heartbeat strength calculator in laser speckle flowgraphy uses the blood flow data to perform a Fourier transform to convert the temporal changes in blood flow to a power spectrum. A total of 33 subjects with peripheral arterial disease and 40 subjects without peripheral arterial disease at a single center were prospectively examined. Laser speckle flowgraphy was used to measure hallucal and thenar cutaneous blood flow, and the measurements were repeated three times. The hallucal and thenar index was defined as the ratio of beat strength of skin perfusion value on hallux/beat strength of skin perfusion value on ipsilateral thenar eminence. The Mann–Whitney U-test was used to compare the median values of hallucal and thenar index and ankle brachial index between the two groups. A receiver operating characteristic curve for hallucal and thenar index of beat strength of skin perfusion was plotted, and a cutoff point was set. The correlation between hallucal and thenar index of beat strength of skin perfusion and ankle brachial index was explored in all subjects, the hemodialysis group, and the non-hemodialysis (non-hemodialysis) group. Results The median value of the hallucal and thenar index of beat strength of skin perfusion was significantly different between subjects with and without peripheral arterial disease (0.27 vs. 0.87, respectively; P <  0.001). The median value of ankle brachial index was significantly different between subjects with and without peripheral arterial disease (0.8 vs. 1.1, respectively; P <  0.001). Based on the receiver operating characteristic of hallucal and thenar index, the cutoff was 0.4416 and the sensitivity, specificity, positive predictive value, and negative predictive value were 68.7%, 95%, 91.7%, and 77.6%, respectively. The correlation coefficients of all subjects, the hemodialysis group, and the non-hemodialysis group were 0.486, 0.102, and 0.743, respectively. Conclusions Laser speckle flowgraphy is a noninvasive, rapid, and widely applicable method. Laser speckle flowgraphy using hallucal and thenar index would be helpful to determine the differences between subjects with and without peripheral arterial disease. The correlation between hallucal and thenar index of beat strength of skin perfusion and ankle brachial index indicated that this index was especially useful in the non-hemodialysis group.

scholarly journals Detection of significantly high vitreous concentrations of fatty acid-binding protein 4 in patients with proliferative diabetic retinopathy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaku Itoh ◽  
Masato Furuhashi ◽  
Yosuke Ida ◽  
Hiroshi Ohguro ◽  
Megumi Watanabe ◽  
...  
Keyword(s):  
Blood Flow ◽  
Diabetic Retinopathy ◽  
Fatty Acid ◽  
Proliferative Diabetic Retinopathy ◽  
Ocular Blood Flow ◽  
Laser Speckle ◽  
Laser Speckle Flowgraphy ◽  
Fatty Acid Binding ◽  
High Positive Correlation ◽  
Blood Biochemical

AbstractThe fatty acid-binding protein4 (FABP4) and vascular endothelial growth factor A (VEGFA) play key roles in the metabolic and cardiovascular diseases, and proliferative diabetic retinopathy (PDR), respectively. To identify FABP4 in vitreous fluid in PDR, vitreous concentrations of FABP4 (V-FABP4) and VEGFA (V-VEGFA) from PDR (n = 20) and non-PDR (n = 20) patients were determined by Enzyme-Linked ImmunoSorbent Assays. The data, which included height and weight, systemic blood pressures, several blood biochemical parameters and blood flow at the optic nerve head (ONH) by laser speckle flowgraphy (LSFG) were collected. The levels of V-FABP4 and V-VEGFA were significantly higher in PDR patients than in non-PDR patients (P < 0.001) with a high positive correlation (r = 0.72, P < 0.001) between them. The findings were not affected by body mass index values and the presence of vitreous hemorrhaging. Among the clinical parameters, V-FABP4 correlated positively with creatinine and negatively with age and aspartate transaminase (AST) levels, while V-VEGFA correlated positively with fasting plasma glucose and hemoglobin A1c (HbA1c) levels but negatively with AST. Multiple regression analyses indicated that V-VEGFA, or V-FABP4, AST and HbA1c were independent predictors of V-FABP4 or V-VEGFA, respectively. Both were negatively correlated, but more evident in V-FABP4, with the ONH ocular blood flow.

Sign in / Sign up

Export Citation Format

Share Document