Noncontact diffuse optical assessment of blood flow changes in head and neck free tissue transfer flaps

Knowledge of tissue blood flow (BF) changes after free tissue transfer may enable surgeons to predict the failure of flap thrombosis at an early stage. This study used our recently developed noncontact diffuse correlation spectroscopy to monitor dynamic BF changes in free flaps without getting in contact with the targeted tissue. Eight free flaps were elevated in patients with head and neck cancer; one of the flaps failed. Multiple BF measurements probing the transferred tissue were performed during and post the surgical operation. Postoperative BF values were normalized to the intraoperative baselines (assigning "1") for the calculation of relative BF change (rBF). The rBF changes over the seven successful flaps were 1.89 ± 0.15, 2.26 ± 0.13, and 2.43 ± 0.13 (mean ± standard error), respectively, on postoperative days 2, 4, and 7. These postoperative values were significantly higher than the intraoperative baseline values (p<0.001), indicating a gradual recovery of flap vascularity after the tissue transfer. By contrast, rBF changes observed from the unsuccessful flaps were 1.14 and 1.34, respectively, on postoperative days 2 and 4, indicating less flow recovery. Measurement of BF recovery after flap anastomosis holds the potential to act early to salvage ischemic flaps.

miR-23b-3p regulates the chemoresistance of gastric cancer cells by targeting ATG12 and HMGB2

Chemotherapy is an important treatment modality for gastric cancer (GC); however, it usually fails because of drug resistance, especially multidrug resistance (MDR). Previously, we found a novel subset of MDR-associated microRNAs (miRNAs) through high-throughput functional screening. In this report, we investigated the exact roles and mechanisms of miR-23b-3p in the MDR of GC. Using gain or loss-of-function in in vitro and in vivo experiments, we found that overexpression of miR-23b-3p reversed cancer cell resistance to multiple chemotherapeutics in vitro and sensitize tumors to chemotherapy in vivo. Reporter gene assay and western blot analysis showed that ATG12 and HMGB2 were the direct targets of miR-23b-3p. Meanwhile, ATG12 and HMGB2 were positively associated with the occurrence of autophagy. Reducing the expression of these target genes by siRNA or inhibition of autophagy both sensitized GC cells to chemotherapy. These findings suggest that a miR-23b-3p/ATG12/HMGB2/autophagy-regulatory loop has a critical role in MDR in GC. In addition, miR-23b-3p could be used as a prognostic factor for overall survival in GC. In conclusion, our data demonstrated that miR-23b-3p inhibited autophagy mediated by ATG12 and HMGB2 and sensitized GC cells to chemotherapy, and suggested the potential application of miR-23b-3p in drug resistance prediction and treatment.

Size-fractioned ultrafine particles and black carbon associated with autonomic dysfunction in subjects with diabetes or impaired glucose tolerance in Shanghai, China

BACKGROUND

Particles in smaller size fractions, such as ultrafine particles (UFPs) (with diameter less than 100 nm), has become of significant cardiovascular health concerns. However, the biological plausibility underlying potential relationship between UFPs and cardiovascular outcomes is less studied.

METHODS

Fifty-three subjects living in Shanghai with type-2 diabetes (T2D) or impaired glucose tolerance (IGT) were followed for autonomic dysfunctions with three repeated measurements in 2010. Minute-to-minute concentrations of ambient particles in small size-fractions (5-560 nm), black carbon (BC), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) were monitored using a central monitoring laboratory equipped with real-time air monitors close to residential area of the subjects. Generalized linear mixed models, with adjustment for individual risk factors, were applied to assess the effects of air pollution on autonomic dysfunctions in subjects.

RESULTS

Our study showed that significant reduction in the standard deviation of all NN intervals (SDNN) ranging from 3.4% to 8.1% were associated with interquartile range (IQR) increase of number concentration of particles (PNC) in size fractions<100 nm, and reduction from 1.3% to 4.6% with particles of diameter 100-200 nm, in subjects with diabetes or glucose tolerance. Increased exposure to traffic-related pollutants BC, NO2 and CO, and combustion pollutant SO2, were also significantly associated with HRV reductions. However, no effect was observed for particles in size fraction of 200-560 nm and O3. Diabetic risk factor and gender appeared to have significant interactions on autonomic dysfunction associated with UFPs and traffic pollution exposures in certain time-window.

CONCLUSIONS

Our results suggest that underlying diabetes or impaired glucose tolerance may confer reduced autonomic function of heart due to traffic pollution exposure.

Comparison of cellular toxicity caused by ambient ultrafine particles and engineered metal oxide nanoparticles

Objective

The development of nanotechnology has spurred concerns about the health effects of exposure to nanoparticles (NPs) and ultrafine particles (UFPs). Toxicological data on NPs and UFPs may provide evidence to support the development of regulations to reduce the risk of particle exposure. We tried to provide fundamental data to determine differences in cytotoxicity induced by ambient UFPs and engineered metal oxide NPs (ZnO, NiO, and CeO₂).

Methods

UFPs were sampled by using of a nano micro-orifice uniform deposit impactor. Physicochemical characterization of the UFPs and nano metal oxide particles were studied by scanning electron microscopy and transmission electron microscopy. Cellular toxicity induced by the different particles was assessed by using of comprehensive approaches and compared after A549 cells were exposured to the particles.

Results

All of the measured particles could damage A549 cells at concentrations ranging from 25 to 200 μg/mL. The lowest survival ratio and the highest lactate dehydrogenase level were caused by nano-ZnO particles, but the highest levels of intracellular reactive oxygen species (ROS) and percentages of apoptosis were observed in cells treated with the soluble fraction of ambient fine particles (PM_1.8) at 200 μg/mL. Relatively high concentrations of anthropogenic metals, including Zn, Ni, Fe, and Cu, may be responsible for the higher toxicity of fine ambient particles compared with the ambient coarse particles and UFPs. The selected heavy metals (Zn, Ni, Fe, and Cu) were found to be located in the perinuclear and cytoplasmic areas of A549 cells. The distribution pattern of metals from ambient particles showed that distributions of the metals in A549 cells were not uniform and followed the pattern Cu > Zn > Fe > Ni, suggesting that Cu was absorbed by A549 cells more easily than the other metals.

Conclusions

Metal nanoparticles oxides and UFPs at low concentration could damage to cells, but the manufactured metal oxide nanoparticles are not highly toxic to lung cells compared to environmental particles. The local concentration effect of heavy metals in A549 cells, as well as the induction of oxidative stress by the particles, may be responsible for the damage observed to the cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-015-0082-8) contains supplementary material, which is available to authorized users.

S100A7 acts as a dual regulator in promoting proliferation and suppressing squamous differentiation through GATA-3/caspase-14 pathway in A431 cells

S100A7 is expressed in many squamous cell carcinomas (SCCs), such as SCC of the skin, and well-differentiated SCC always displays stronger staining of this protein. A431 cells, an epidermal cancer cell line, were selected as a cell model to investigate the roles and mechanism of S100A7 in SCC of the skin. In this study, we demonstrated that the overexpression of S100A7 in A431 cells significantly promoted cell proliferation in vitro and tumor growth in vivo, whereas it suppressed the expression of GATA-3, caspase-14 and three squamous differentiation markers, keratin-1, TG-1 and involucrin. Conversely, the overexpression of caspase-14 not only significantly decreased cell proliferation and delayed tumor growth but also markedly induced the expression of three squamous differentiation markers, whereas S100A7 and GATA-3 were not influenced. Further evidence showed that silencing GATA-3 greatly inhibited the expression of caspase-14 and three differentiation markers, while the expression of S100A7 was not changed; contrary results were obtained when overexpressing GATA-3. Importantly, restoring the expression of GATA-3 and caspase-14 in A431-S100A7 cells could bypass the ability of S100A7 to increase cell viability and repress squamous differentiation. These data suggested that S100A7 expression in SCC may play an important role in the maintenance of SCC cell dedifferentiation, at least in SCC of the skin.

[Reconstitution of polyunsaturated fatty acid synthesis enzymes in mammalian cells to convert LA to DHA]

DHA (22:6n-3) is a Ω-3 polyunsaturated fatty acid with 22 carbon atoms and 6 double bonds, which has important biological functions in human body. Human and other mammals synthesize only limited amounts of DHA, more requirements must be satisfied from food resources. However, the natural resources of DHA (Mainly deep-sea fish and other marine products) are prone to depletion. New resources development is still insufficient to satisfy the growing market demand. Previous studies have revealed that the mammals can increase the synthesis of DHA and other long-chain polyunsaturated fatty acids after transgenic procedures. In this study, mammalian cells were transfected with Δ6, Δ5 desaturase, Δ6, Δ5 elongase, Δ15 desaturase (Isolated from nematode Caenorhabditis elegans) and Δ4 desaturase (Isolated from Euglena gracilis), simultaneously. Results show that the expression or overexpression of these 6 enzymes is capable of conversion of the o-6 linoleic acid (LA, 18:2n-6) in DHA (22:6n-3). DHA content has increased from 16.74% in the control group to 25.3% in the experimental group. The strategy and related technology in our research provided important data for future production the valuable DHA (22:6n-3) by using genetically modified animals.

Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise

Occlusion calibrations and gating techniques have been recently applied by our laboratory for continuous and absolute diffuse optical measurements of forearm muscle hemodynamics during handgrip exercises. The translation of these techniques from the forearm to the lower limb is the goal of this study as various diseases preferentially affect muscles in the lower extremity. This study adapted a hybrid near-infrared spectroscopy and diffuse correlation spectroscopy system with a gating algorithm to continuously quantify hemodynamic responses of medial gastrocnemius during plantar flexion exercises in 10 healthy subjects. The outcomes from optical measurement include oxy-, deoxy-, and total hemoglobin concentrations, blood oxygen saturation, and relative changes in blood flow (rBF) and oxygen consumption rate (rV̇O2). We calibrated rBF and rV̇O2 profiles with absolute baseline values of BF and V̇O2 obtained by venous and arterial occlusions, respectively. Results from this investigation were comparable to values from similar studies. Additionally, significant correlation was observed between resting local muscle BF measured by the optical technique and whole limb BF measured concurrently by a strain gauge venous plethysmography. The extensive hemodynamic and metabolic profiles during exercise will allow for future comparison studies to investigate the diagnostic value of hybrid technologies in muscles affected by disease.

Construction of multifunctional films based on graphene–TiO2 composite materials for strain sensing and photodegradation

The obtained multifunctional graphene–TiO₂ composite films showed excellent strain sensing property with gauge factors of 14–35 and enhanced photocatalytic properties.

[Combined effects of 1-nitropyrene and 1,2-naphthoquinone on cytotoxicity and DNA damage in A549 cells]

Using human lung epithelial A549 cells, viability was measured by MTT assay after treated with 1-nitropyrene (1-NP); lactate dehydrogenase (LDH) leakage was determined to evaluate the cellular membrane injury; DNA damage was detected with comet assay; reactive oxygen species (ROS) generation was measured with fluorescent probe. The combined toxic effects of 1-NP and 1,2-naphthoquinone (1,2-NQ) on A549 were also evaluated. 1-NP caused a significantly concentration-dependent and time-dependent viability decrease. The LC50 for 24 h and 48 h were 5.2 μmol x L(-1) and 2.8 μmol x L(-1), respectively. DNA damage and intracellular ROS levels were also increased significantly through a dose-dependent manner after exposure to 1-NP. The LDH leakage were not significantly changed. Compared with the groups treated with 1-NP alone, the viability and LDH leakage was not changed significantly in combined-treated groups with 1-NP and 1,2-NQ. However, the DNA damage and ROS levels were significantly reduced in the combined-treated groups compared with the groups treated with 1-NP alone. These results suggest that 1-NP may mediated the genotoxic and cytotoxic effects through ROS generation, and pretreatment with 1,2-NQ, may inhibit the ROS generation induced by 1-NP, and thereby reducing the DNA damage in A549 cells.

Sensitivity of Monilinia fructicola from Peach Farms in China to Four Fungicides and Characterization of Isolates Resistant to Carbendazim and Azoxystrobin

Brown rot of peach caused by Monilinia fructicola can cause considerable preharvest and postharvest losses in China. Fungicides are increasingly utilized to minimize such losses. Eighty isolates of M. fructicola were collected from commercial peach orchards located in five provinces in China and the sensitivity to carbendazim, azoxystrobin, tebuconazole, and boscalid was determined. Resistance to carbendazim was detected only in the Yunnan province in 15 of 16 isolates. Characterization of carbendazim-resistant isolates revealed stable resistance, no fitness penalty, and negative cross resistance to diethofencarb. Resistant isolates produced disease symptoms on detached fruit sprayed with label rates of formulated carbendazim and possessed the amino acid mutation E198A in β-tubulin. Resistance to azoxystrobin was detected in 3 of 10 isolates from Fujian. In contrast to carbendazim resistance, however, azoxystrobin resistance was unstable, associated with a fitness penalty, and not associated with mutations in the target gene cytochrome b. The concentration at which mycelial growth is inhibited 50% (EC₅₀) values of the azoxystrobin-sensitive isolates were 0.02 to 1.94 μg/ml, with a mean value of 0.54 μg/ml. All isolates were sensitive to tebuconazole, with a mean EC₅₀ value of 0.03 μg/ml. The EC₅₀ values for boscalid were 0.01 to 3.85 μg/ml, with a mean value of 1.02 μg/ml. Our results indicate that methyl benzimidazole carbamates (MBCs), quionon outside inhibitors, demethylation inhibitor fungicides, and succinate dehydrogenase inhibitors are likely to be very effective in controlling brown rot in many peach production areas in China, but that resistance to MBCs is emerging.

A Nth-order linear algorithm for extracting diffuse correlation spectroscopy blood flow indices in heterogeneous tissues

Conventional semi-infinite analytical solutions of correlation diffusion equation may lead to errors when calculating blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements in tissues with irregular geometries. Very recently, we created an algorithm integrating a Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in homogenous tissues with arbitrary geometries for extraction of BFI (i.e., αDB ). The purpose of this study is to extend the capability of the Nth-order linear algorithm for extracting BFI in heterogeneous tissues with arbitrary geometries. The previous linear algorithm was modified to extract BFIs in different types of tissues simultaneously through utilizing DCS data at multiple source-detector separations. We compared the proposed linear algorithm with the semi-infinite homogenous solution in a computer model of adult head with heterogeneous tissue layers of scalp, skull, cerebrospinal fluid, and brain. To test the capability of the linear algorithm for extracting relative changes of cerebral blood flow (rCBF) in deep brain, we assigned ten levels of αDB in the brain layer with a step decrement of 10% while maintaining αDB values constant in other layers. Simulation results demonstrate the accuracy (errors < 3%) of high-order (N ≥ 5) linear algorithm in extracting BFIs in different tissue layers and rCBF in deep brain. By contrast, the semi-infinite homogenous solution resulted in substantial errors in rCBF (34.5% ≤ errors ≤ 60.2%) and BFIs in different layers. The Nth-order linear model simplifies data analysis, thus allowing for online data processing and displaying. Future study will test this linear algorithm in heterogeneous tissues with different levels of blood flow variations and noises.

Obstructive sleep apnea-hypopnea results in significant variations in cerebral hemodynamics detected by diffuse optical spectroscopies

The objective of this study was to adapt a novel near-infrared diffuse correlation spectroscopy (DCS) flow-oximeter for simultaneous and continuous monitoring of relative changes in cerebral blood flow (rCBF) and cerebral oxygenation (i.e. oxygenated/deoxygenated/total hemoglobin concentration: Δ[HbO2]/Δ[Hb]/ΔTHC) during overnight nocturnal polysomnography (NPSG) diagnostic test for obstructive sleep apnea-hypopnea (OSAH). A fiber-optic probe was fixed on subject's frontal head and connected to the DCS flow-oximeter through a custom-designed fiber-optic connector, which allowed us to easily connect/detach the optical probe from the device when the subject went to bathroom. To minimize the disturbance to the subject, the DCS flow-oximeter was remotely operated by a desktop located in the control room. The results showed that apneic events caused significant variations in rCBF and ΔTHC. Moreover, the degrees of variations in all measured cerebral variables were significantly correlated with the severity of OSAH as determined by the apnea-hypopnea index (AHI), demonstrating the OSAH influence on both CBF and cerebral oxygenation. Large variations in arterial blood oxygen saturation (SaO2) were also found during OSAH. Since frequent variations/disturbances in cerebral hemodynamics may adversely impact brain function, future study will investigate the correlations between these cerebral variations and functional impairments for better understanding of OSAH pathophysiology.

Extraction of diffuse correlation spectroscopy flow index by integration of Nth-order linear model with Monte Carlo simulation

Conventional semi-infinite solution for extracting blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements may cause errors in estimation of BFI (αDB ) in tissues with small volume and large curvature. We proposed an algorithm integrating Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in tissue for the extraction of αDB . The volume and geometry of the measured tissue were incorporated in the Monte Carlo simulation, which overcome the semi-infinite restrictions. The algorithm was tested using computer simulations on four tissue models with varied volumes/geometries and applied on an in vivo stroke model of mouse. Computer simulations shows that the high-order (N ≥ 5) linear algorithm was more accurate in extracting αDB (errors < ±2%) from the noise-free DCS data than the semi-infinite solution (errors: -5.3% to -18.0%) for different tissue models. Although adding random noises to DCS data resulted in αDB variations, the mean values of errors in extracting αDB were similar to those reconstructed from the noise-free DCS data. In addition, the errors in extracting the relative changes of αDB using both linear algorithm and semi-infinite solution were fairly small (errors < ±2.0%) and did not rely on the tissue volume/geometry. The experimental results from the in vivo stroke mice agreed with those in simulations, demonstrating the robustness of the linear algorithm. DCS with the high-order linear algorithm shows the potential for the inter-subject comparison and longitudinal monitoring of absolute BFI in a variety of tissues/organs with different volumes/geometries.

CHIP/Stub1 interacts with eIF5A and mediates its degradation

eIF5A, containing the unusual amino acid hypusine, is a highly conserved protein essential for the proliferation of eukaryotic cells. Previous studies have demonstrated that the activity of eIF5A was regulated through modification of hypusine, phosphorylation and acetylation. However, no study was documented for regulation of the protein stability. Here, we report that eIF5A is a target of CHIP (the carboxyl terminus of Hsc70-interacting protein, also named Stub1), an E3 ligase with a U-box domain, through a proteomics analysis. CHIP directly interacted with eIF5A, preferably through the U-box domain, to mediate eIF5A ubiquitination and degradation. Simultaneously, we investigated that CHIP expression inversely correlated with eIF5A levels in colorectal cancers, consistent with the fact that the protein level of eIF5A was increased in the CHIP knock-out MEF cells. Taken together, we propose that CHIP regulates the eIF5A protein stability via a protein degradation mechanism. This study provides a new insight into understanding the regulation of the eIF5A stability.

Airborne quinones induce cytotoxicity and DNA damage in human lung epithelial A549 cells: the role of reactive oxygen species

Ambient particulate matter (PM) is associated with adverse health effects. Quinones present in PM are hypothesized to contribute to these harmful effects through the generation of reactive oxygen species (ROS). However, whether the ROS induced by quinones is involved in mediating DNA damage as well as other biological responses in pulmonary cells is less well known. In this study, the toxic effects of five typical airborne quinones, including 1,2-naphthoquinone, 2-methylanthraquinone, 9,10-phenanthrenequinone, 2-methyl-1,4-naphthoquinone, and acenaphthenequinone, on cytotoxicity, DNA damage, intracellular calcium homeostasis, and ROS generation, were studied in human lung epithelial A549 cells. An antioxidant N-acetylcysteine (NAC) was used to examine the involvement of ROS in adverse biological responses induced by quinones. The quinones caused a concentration-dependent viability decrease, cellular LDH release, DNA damage, and ROS production in A549 cells. 1,2-Naphthoquinone, but not the other four quinones, increased intracellular calcium (Ca(2+)) levels in a dose-dependent manner. These toxic effects were abolished by administration of NAC, suggesting that ROS played a key role in the observed toxic effects of quinones in A549 cells. These results emphasize the importance of quinones in PM on the adverse health effects of PMs, which has been underestimated in the past few years, and highlight the need, when evaluating the effects on health and exposure management, to always consider their qualitative chemical compositions in addition to the size and concentration of PMs.

Three-dimensional flow contrast imaging of deep tissue using noncontact diffuse correlation tomography

This study extended our recently developed noncontact diffuse correlation spectroscopy flowmetry system into noncontact diffuse correlation tomography (ncDCT) for three-dimensional (3-D) flow imaging of deep tissue. A linear array of 15 photodetectors and two laser sources connected to a mobile lens-focusing system enabled automatic and noncontact scanning of flow in a region of interest. These boundary measurements were combined with a finite element framework for DCT image reconstruction implemented into an existing software package. This technique was tested in computer simulations and using a tissue-like phantom with anomaly flow contrast design. The cylindrical tube-shaped anomaly was clearly reconstructed in both simulation and phantom. Recovered and assigned flow contrast changes in anomaly were found to be highly correlated: regression slope = 1.00, R2 = 1.00, and p < 10-5 in simulation and regression slope ≥ 0.97, R2 ≥ 0.96, and p < 10-3 in phantom. These results exhibit promise of our ncDCT technique for 3-D imaging of deep tissue blood flow heterogeneities.

Cucurbitacin-B inhibits neuroblastoma cell proliferation through up-regulation of PTEN

OBJECTIVE

Cucurbitacins belong to a class of highly oxidized tetracyclic triterpenoids. Recent studies suggest that the use of Cucurbitacin could repress cancer cell progression. However, the biological effect of Cucurbitacin-B in neuroblastoma cells remains unexplored.

MATERIALS AND METHODS

MTT and BrdU (bromodeoxyuridine) incorporation assays were used to determine the anti-proliferation roles of Cucurbitacin-B. Real-time PCR and Western blot assays were used to detect the expression of cell cycle regulators. Small interfering RNAs (siRNAs) were used to silence the expression of PTEN (phosphatase and tensin homolog gene).

RESULTS

We found that Cucurbitacin-B inhibited growth and modulated expression of cell-cycle regulators in SHSY5Y cells. At the molecular level, we found that Cucurbitacin-B inhibited AKT signaling activation through up-regulation of PTEN. Indeed, PTEN deficiency using siRNA oligos attenuated the anti-proliferative roles of Cucurbitacin-B.

CONCLUSIONS

These results provide evidence for a mechanism that may contribute to the antineoplastic effects of Cucurbitacin-B in neuroblastoma.

Near-infrared diffuse optical monitoring of cerebral blood flow and oxygenation for the prediction of vasovagal syncope

Significant drops in arterial blood pressure and cerebral hemodynamics have been previously observed during vasovagal syncope (VVS). Continuous and simultaneous monitoring of these physiological variables during VVS is rare, but critical for determining which variable is the most sensitive parameter to predict VVS. The present study used a novel custom-designed diffuse correlation spectroscopy flow-oximeter and a finger plethysmograph to simultaneously monitor relative changes of cerebral blood flow (rCBF), cerebral oxygenation (i.e., oxygenated/deoxygenated/total hemoglobin concentration: r[HbO2]/r[Hb]/rTHC), and mean arterial pressure (rMAP) during 70 deg head-up tilt (HUT) in 14 healthy adults. Six subjects developed presyncope during HUT. Two-stage physiological responses during HUT were observed in the presyncopal group: slow and small changes in measured variables (i.e., Stage I), followed by rapid and dramatic decreases in rMAP, rCBF, r[HbO2], and rTHC (i.e., Stage II). Compared to other physiological variables, rCBF reached its breakpoint between the two stages earliest and had the largest decrease (76±8%) during presyncope. Our results suggest that rCBF has the best sensitivity for the assessment of VVS. Most importantly, a threshold of ∼50% rCBF decline completely separated the subjects from those without presyncope, suggesting its potential for predicting VVS.

Noninvasive evaluation of electrical stimulation impacts on muscle hemodynamics via integrating diffuse optical spectroscopies with muscle stimulator

Technologies currently available for the monitoring of electrical stimulation (ES) in promoting blood circulation and tissue oxygenation are limited. This study integrated a muscle stimulator with a diffuse correlation spectroscopy (DCS) flow-oximeter to noninvasively quantify muscle blood flow and oxygenation responses during ES. Ten healthy subjects were tested using the integrated system. The muscle stimulator delivered biphasic electrical current to right leg quadriceps muscle, and a custom-made DCS flow-oximeter was used for simultaneous measurements of muscle blood flow and oxygenation in both legs. To minimize motion artifact of muscle fibers during ES, a novel gating algorithm was developed for data acquisition at the time when the muscle was relaxed. ES at 2, 10, and 50 Hz were applied for 20 min on each subject in three days sequentially. Results demonstrate that the 20-min ES at all frequencies promoted muscle blood flow significantly. However, only the ES at 10 Hz resulted in significant and persistent increases in oxy-hemoglobin concentration during and post ES. This pilot study supports the application of the integrated system to quantify tissue hemodynamic improvements for the optimization of ES treatment in patients suffering from diseases caused by poor blood circulation and low tissue oxygenation (e.g., pressure ulcer).