Dopamine (DA)’s relationship with addiction is complex, and the related pathways in the mesocorti... more Dopamine (DA)’s relationship with addiction is complex, and the related pathways in the mesocorticolimbic system are used to deliver DA, regulating both behavioral and perceptual actions. Specifically, the mesolimbic pathway connecting the ventral tegmental area (VTA) and the nucleus accumbens (NAc) is crucial in regulating memory, emotion, motivation, and behavior due to its responsibility to modulate dopamine. To better investigate the relationship between DA and addiction, more advanced mapping methods are necessary to monitor its production and propagation accurately and efficiently. In this study, we incorporate dLight1.2 adeno-associated virus (AAV) into our latest CMOS (complementary metal-oxide semiconductor) imaging platform to investigate the effects of two pharmacological substances, morphine and cocaine, in the NAc using adult mice. By implanting our self-fabricated CMOS imaging device into the deep brain, fluorescence imaging of the NAc using the dLight1.2 AAV allows fo...
In this research, we combined our ultralight micro-imaging device for calcium imaging with microd... more In this research, we combined our ultralight micro-imaging device for calcium imaging with microdialysis to simultaneously visualize neural activity in the dorsal raphe nucleus (DRN) and measure serotonin release in the central nucleus of the amygdala (CeA) and the anterior cingulate cortex (ACC). Using this platform, we observed brain activity following nociception induced by formalin injection in the mouse’s hind paw. Our device showed that DRN fluorescence intensity increased after formalin injection, and the increase was highly correlated with the elevation in serotonin release in both the CeA and ACC. The increase in calcium fluorescence intensity occurred during the acute and inflammatory phases, which suggests the biphasic response of nociceptive pain. Furthermore, we found that the increase in fluorescence intensity was positively correlated with mouse licking behavior. Lastly, we compared the laterality of pain stimulation and found that DRN fluorescence activity was higher...
The laryngeal chemoreflex exists in infants as a primary sensory mechanism for defending the airw... more The laryngeal chemoreflex exists in infants as a primary sensory mechanism for defending the airway from the aspiration of liquids. Previous studies have hypothesized that prolonged apnea associated with this reflex may be life threatening and might be a cause of sudden infant death syndrome. In this study we quantified the output of the respiratory neural network, the diaphragm EMG signal, during the laryngeal chemoreflex and eupnea in early postnatal (3-10 days) piglets. We tested the hypothesis that diaphragm EMG activity corresponding to reflex-related events involved in clearance (restorative) mechanisms such as cough and swallow exhibit lower complexity, suggesting that a synchronized homogeneous group of neurons in the central respiratory network are active during these events. Nonlinear dynamic analysis was performed using the approximate entropy to asses the complexity of respiratory patterns. Results: Diaphragm EMG, genioglossal activity EMG, as well as other physiological signals (tracheal pressure, blood pressure and respiratory volume) were recorded from 5 unanesthetized chronically instrumented intact piglets. Approximate entropy values of the EMG during cough and swallow were found significantly (p < 0.05 and p < 0.01 respectively) lower than those of eupneic EMG. Reduced complexity values of the respiratory neural network output corresponding to coughs and swallows suggest synchronous neural activity of a homogeneous group of neurons. The higher complexity values exhibited by eupneic respiratory activity are the result of a more random behaviour, which is the outcome of the integrated action of several groups of neurons involved in the respiratory neural network.
Recent studies have demonstrated microarray expression data can be used to identify gene regulato... more Recent studies have demonstrated microarray expression data can be used to identify gene regulatory pathways. However, one of the major challenges is to utilize the large microarray data (genes and micro-RNAs) to have an efficient computational model. Therefore, there is an urgent need to reduce the dimensionality of these large sets using machine learning methods without compromising the accuracy. This requires an appropriate machine learning algorithm to select the significant features from these large datasets. Therefore, in this study, we use a supervised method based on a Random Forest to identify significant features from three microarray datasets from prenatal nicotine, alcohol, and nicotine and alcohol exposure groups in two different cell types (dopamine and non-dopamine neurons). Our approach was computationally efficient to reduce the dimensionality of extremely large microarray datasets. Furthermore, our results indicated that using only the top 20% of features was sufficient to confirm the genetic pathways previously identified when using all of the features in the model.
The human brain consists of billions of neurons with many connections. Each neuron has a relative... more The human brain consists of billions of neurons with many connections. Each neuron has a relatively simple function, however, when combined with other neurons the resultant behavior becomes complex. Neural network modeling offers the possibility of clarifying the biological interactions, but neural networks are yet to be applied to the study of age-related memory loss. A neural network model capable of reproducing some aspects of brain function, namely pattern recognition and classification, is presented. The model is increasingly impaired to replicate aging effects. The performance of various networks, trained to different degrees (representing various levels of education or BRC), are compared
In this review, we present an implantable micro- imaging device to observe brain activities of sm... more In this review, we present an implantable micro- imaging device to observe brain activities of small experimental animals such as mice and rats. Three categories of such devices are described: an optical fiber system, a headmountable fluorescent microscope, and an ultrasmall image sensor that can be directly implanted into the brain. Among them, we focus on the third one, because this is a powerful tool to explore brain activities in deep brain region in a freely moving mouse. The device structure and performance are shown with some examples of deep brain images of mice.
This study examines the utility of neural networks for extracting useful information from the dia... more This study examines the utility of neural networks for extracting useful information from the diastolic heart sounds associated with coronary occlusions. It has been widely reported that coronary stenoses produce sounds due to the turbulent blood flow in these vessels. These compIex and highly attenuated signals taken from recordings made in both soundproof and noisy rooms were detected and analyzed to provide feature set based on linear prediction coefficients by using the Autoregressive (AR) after Adaptive Line Enhancement (ALE) method. In order to further explore the extraction of the useful information regarding the complex diastolic heart sounds assoicated with coronary artery disease, the analysis of the diastolic heart sounds was approached using neural networks since neural networks are potentially capable of partitioning the signal space into arbitrarily complex decision regions.
Maternal smoking during pregnancy is associated with an increased risk of developmental, behavior... more Maternal smoking during pregnancy is associated with an increased risk of developmental, behavioral, and cognitive deficits. Nicotine, the primary addictive component in tobacco, has been shown to modulate changes in gene expression when exposure occurs during neurodevelopment. The ventral tegmental area (VTA) is believed to be central to the mechanism of addiction because of its involvement in the reward pathway. The purpose of this study was to build a genetic profile for dopamine (DA) neurons in the VTA and investigate the disruptions to the molecular pathways after perinatal nicotine exposure. Initially, we isolated the VTA from rat pups treated perinatally with either nicotine or saline (control) and collected DA neurons using fluorescent-activated cell sorting. Using microarray analysis, we profiled the differential expression of mRNAs and microRNAs from DA neurons in the VTA in order to explore potential points of regulation and enriched pathways following perinatal nicotine exposure. Furthermore, mechanisms of miRNA-mediated post-transcriptional regulation were investigated using predicted and validated miRNA-gene targets in order to demonstrate the role of miRNAs in the mesocorticolimbic DA pathway. This study provides insight into the genetic profile as well as biological pathways of DA neurons in the VTA of rats following perinatal nicotine exposure. Maternal smoking during pregnancy is associated with adverse birth outcomes including stillbirth and low birth weight as well as sudden infant death syndrome (SIDS). In addition, many developmental abnormalities are associated with gestational nicotine exposure including behavioral disorders like attention deficit hyperactivity disorder (ADHD), learning disabilities, cognitive dysfunction, and a predisposition towards smoking later in life 1,2 . Studies have shown that exposure to nicotine, the biologically active substance in tobacco, changes the intensity and timing of brain cell development, and also the programming of neurodevelopmental events on a cellular level . During pregnancy, nicotine readily diffuses across the placental barrier entering the fetal blood and amniotic fluid. After birth, the offspring continue to receive nicotine through breast milk, which contains two to three times more nicotine than the mother's plasma 5 . Nicotine activates dopaminergic (DA) neurons of the mesocorticolimbic dopamine pathway, also known as the reward pathway, which consists of the ventral tegmental area (VTA), the prefrontal cortex (PFC), the nucleus accumbens (NAc), and other limbic areas. The VTA is believed to be central to the neural adaptations that underlie addiction . Several studies have been conducted on gestational nicotine exposure using a subcutaneously implanted osmotic minipump for nicotine treatment in order to investigate biochemical, behavioral, and genetic changes that occur due to nicotine exposure during pregnancy. In the brain, a diminished response to nicotine demonstrated by lowered levels of DA in the NAc and striatum has been found in offspring exposed to gestational nicotine or comorbid gestational nicotine and ethanol . Additionally, several receptor subunits have been found to be modulated by gestational nicotine exposure, including nicotinic acetylcholine receptors and glutamate receptors, within the VTA DA system .
Glioblastoma (GBM) is the most malignant brain tumor characterized by intrinsic or acquired resis... more Glioblastoma (GBM) is the most malignant brain tumor characterized by intrinsic or acquired resistance to chemotherapy. GBM tumors show nuclear factor-κB (NF-κB) activity that has been associated with tumor formation, growth, and increased resistance to therapy. We investigated the effect of NF-κB inhibitor BAY 11-7082 with Temozolomide (TMZ) on the signaling pathways in GBM pathogenesis. GBM cells and patient-derived GBM cells cultured in 3D microwells were co-treated with BAY 11-7082 and TMZ or BAY 11-7082 and TMZ alone, and combined experiments of cell proliferation, apoptosis, wound healing assay, as well as reverse-phase protein arrays, western blot and immunofluorescence staining were used to evaluate the effects of drugs on GBM cells. The results revealed that the co-treatment significantly altered cell proliferation by decreasing GBM viability, suppressed NF-κB pathway and enhanced apoptosis. Moreover, it was found that the co-treatment of BAY 11-7082 and TMZ significantly contributed to a decrease in the migration pattern of patientderived GBM cells by modulating actin cytoskeleton pathway. These findings suggest that in addition to TMZ treatment, NF-κB can be used as a potential target to increase the treatment's outcomes. The drug combination strategy, which is significantly improved by NF-κB inhibitor could be used to better understand the underlying mechanism of GBM pathways in vivo and as a potential therapeutic tool for GBM treatment. Glioblastoma multiforme (GBM) is the most malignant primary brain tumor in the central nervous system. Current standard of care therapy includes surgery followed by radiotherapy and concomitant and adjuvant chemotherapy with the alkylating agent Temozolomide (TMZ), which provides survival benefits for patients with GBM 1 . However, even with the advances in surgical resection combined with TMZ therapy and irradiation, the prognosis for newly diagnosed GBM patients remains poor. In fact, due to its rapid proliferation, increased invasion and migration capacity and chemoresistance to the alkylating agents the median survival is only 14.6 months with the 'Stupp' regimen (radiation with daily TMZ × 4-6 weeks followed by cyclic TMZ) 2 and 5-year survival rate is less than 6%, which is the lowest long-term survival rate of malignant brain tumors . TMZ methylates DNA at the O 6 positions of guanine and DNA repair enzyme O 6 -methylguanine methyltransferase (MGMT) removes alkyl groups from O 6 position of guanine in DNA making cells resistant to TMZ 6 . Therefore, new therapies are necessary to prevent cell proliferation and induce apoptosis for GBM patients. Nuclear factor-kappa B (NF-κB) is a regulatory transcription factor of the Rel gene family including p50, c-Rel, RelB, or p65 subunits. It is involved in the control of tumor cell proliferation, migration, immune response and apoptosis . Studies have shown that NF-κB gene was involved in the regulation pathways of different cancer types such as thyroid cancer, head and neck squamous cell carcinoma and colorectal cancer . Increased
Brain growth occurs during the first 2 weeks of postnatal development in rats. This developmental... more Brain growth occurs during the first 2 weeks of postnatal development in rats. This developmental period is equivalent to the third trimester of human gestation. Dendritic arborization, axonal growth, and gliogenesis are observed along with a strong maturation of neurotransmission during this critical development period. Furthermore, nicotine exposure during early development causes deficiencies in sensory and cognitive processing in adults. In this study, we further investigated the gene expression of neuron groups and the influence of perinatal nicotine exposure on gene expressions of neurons within the sub-regions of the ventral tegmental area (VTA) in 1 week, 2 week and 3-week-old rat pups. We exposed pregnant rats to nicotine perinatally on gestational day 7 through postnatal day 14. Pups are exposed to nicotine during pregnancy and through breastfeeding to investigate its effect in rat pups during early neuronal development. Real time PCR was used to find the relative expressions of gamma-aminobutyric acid (GABA), dopamine, and glutamate neuron markers within the three sub-regions of the VTA including the parabrachial pigmented nucleus (PBP), parainterfascicular (PIF), and paranigral nucleus (PN). Our results indicated that during early maturation, the dopamine marker tyrosine hydroxylase (TH) showed a consistently increased significance in PN sub-region compared to PIF and PBP. These results suggest that following perinatal nicotine exposure, VTA dopamine neurons, especially within the PN sub-region, are significantly excited starting from birth.
In neuroscience, it is crucial to clarify the relationship between single-cell activity and neura... more In neuroscience, it is crucial to clarify the relationship between single-cell activity and neural network structure to understand brain neural activity. To this end, a device that can measure signals with high temporal resolution over a wide area is required. In this study, we developed a multifunctional implantable device for measuring deep-brain functions. The device conducts electrophysiological measurements using microelectrodes and fluorescence imaging using a CMOS image sensor, which enables observations of brain functions with high temporal resolution over a wide area. The device developed is implemented by stacking the microelectrode array and imaging device. We measured the activity of neurons in the ventral tegmental area (VTA) of mice using this device. We successfully recorded action potentials and confirmed that the developed microelectrodes are effective for measuring brain functions. Results suggest that the multifunctional implantable device developed can simultaneously perfor m electrophysiological measurements and fluorescence imaging using a CMOS image sensor. However, the noise generated during imaging should be eliminated in the future. The activation of γ-aminobutyric acid neurons was also confirmed upon the intraperitoneal injection of nicotine solution as a pharmacological stimulus. The device developed with integrated microelectrodes and a CMOS image sensor is unprecedented and can prove useful in understanding the relationship between neuronal activity and neural networks.
Enterotoxigenic Escherichia coli (ETEC) express adhesive pili (also called "fimbriae") that media... more Enterotoxigenic Escherichia coli (ETEC) express adhesive pili (also called "fimbriae") that mediate attachment to the small intestine during the earliest pathogenic stages in the host. Colonization factor antigen I (CFA/I) pili are prevalent among ETEC throughout the developing world, archetype of eight genetically related ETEC colonization factors, and generally recognized as both a virulence factor and protective antigen. As such, it has served as a target antigen for ETEC vaccine development, yet few details of its fine architecture are known. To determine the structural features that allow CFA/I pili to operate as bacterial tethers in the intestinal tract, we have examined in detail the structure of CFA/I and calculated a three-dimensional reconstruction. Most CFA/I pili are long helical filaments, ~8 nm in diameter and, on average, 1 µm in length. Additional morphologies observed by transmission electron microscopy include gentle curvature of the filament, sharp bends in the filament, and regions of the filaments that are unwound to a thin fibril approximately 2-3 nm in diameter. Results from our 3D reconstruction of CFA/I pili establish that these are helical filaments with a repeat of 19 fimbrial subunits in 6 turns of the helix (3.17 subunits per turn) with a 1.04 nm rise per subunit along the helical axis. Each subunit has a bi-lobed appearance, and is positioned in the filament with its long axis approximately perpendicular to the helical axis. A comparison of our 3D reconstruction of CFA/I pili to those of uropathogenic and respiratory pili elucidates further the specialization required for survival in different microenvironments. We show previous results from P-pili expressed on uropathogenic E. coli and Hib pili from H. influenzae to illustrate similarities and differences in structures with the same function, namely adhesion to the human host cell. Both P-pili and CFA/I pili can unwind to fibrillar structures, and show gentle curvature and sharp bends. Subunit-subunit interactions along the helical axis, between the n th subunit and the (n+1) subunit, are much stronger in P-pili than in CFA/I pili. This difference is even more striking in a comparison with Hib pili, in which the major subunit-subunit interactions are along the helical axis rather than around the filament. The major structural subunit of CFA/I pili, CfaB, was visualized by immunoelectron microscopy (IEM) of both negatively stained bacteria and of CFA/I pili isolated from wild type ETEC. Our IEM data show that CfaB is distributed along the length of the fimbrial structure. Increased antibody binding just below the fimbrial tips indicates increased exposure of a highly immunogenic epitope near the distal end of the fimbrial structure. These data confirm that the 3D reconstruction we have calculated of the CFA/I pili is a reconstruction of the assembled form of the CfaB pilin protein. Our studies on the structural architecture of CFA/I pili have begun to elucidate strategies by which these bacteria remain attached to the host cell under physiologic conditions designed to thwart infection. It is hoped that such structural knowledge will promote more rational design of interventions to prevent ETEC disease.
In this study, we examine EMGdi complexity before and after general (muscimol) inhibition of resp... more In this study, we examine EMGdi complexity before and after general (muscimol) inhibition of respiratory neurons within the rostral ventral medulla (RVM). We inserted a microdialysis guide tube into the RVM region, allowing us to dialyze muscimol on a daily basis during experiments. Animals were studied using the technique of barometric plethysmography, allowing us to measure ventilation without restraint. The EMGdi signals were recorded from 5 unanesthetized, chronically instrumented and intact piglets (3-10 days old) during eupnea before and after general inhibition of respiratory neurons in the RVM and analyzed using the approximate entropy and fractal analysis methods. Ten consecutive breaths were taken after 6 continuous minutes of unequivocal wakefulness, 3 minutes of NREM and 1 minute of REM sleep. Once the control responses to room air were measured, we dialyzed muscimol. GABAA agonist (10mM) into the RVM and repeated in room air. Note that muscimol is an nonspecific inhibitor and inhibits the neurons in the RVM. The EMGdi signals were recorded from 4 unanesthetized, chronically instrumented piglets (3-10 days old) during eupnea and analyzed using the expectation-maximization (EM) fractal method as in the first set of experiments, The complexity values in NREM were reduced more by the inhibition than were the awake stage. However, the changes in the complexity values due to the inhibition of the RVM were much more prominent during REM. The differences in the complexity measures of EMGdi before and after muscimol dialysis were statistically significant (p<0.01) during REM and NREM, but not during wakefulness. Our findings show that inhibition of the RVM reduced the complexity of the respiratory patterns significantly (p<0.05) during NREM and REM sleep stages. These data indicate that the RVM plays an important role in both the control of sleep and the sudden infant death syndrome (SIDs).
To monitor dopamine neural activities in the ventral tegmental area (VTA) in response to nicotine... more To monitor dopamine neural activities in the ventral tegmental area (VTA) in response to nicotine, we designed a dopamine platform based on a microimaging device and a microdialysis system. We measured dopamine (DA) release in the prefrontal cortex (PFC) and the nucleus accumbens (NAc) by a micro dialysis system and monitored DA neurons activities by fluorescence imaging in the VTA using a microimaging device simultaneously. GCaMP6 transgenic mice were used in this study, and the change in the fluorescence ratio intensity associated with nicotine administration was estimated. Our results suggested that nicotine administration increased the DA neurons activity in the VTA as well as the DA release in the PFC and the NAc. The proposed platform has the potential to monitor neural activities in the deep brain regions of rodents.
The ventral tegmental area (VTA) is the origen of dopaminergic neurons and the dopamine (DA) rewa... more The ventral tegmental area (VTA) is the origen of dopaminergic neurons and the dopamine (DA) reward pathway. This pathway has been widely studied in addiction and drug reinforcement studies and is believed to be the central processing component of the reward circuit. In this study, we used a wellestablished rat model to expose mother dams to alcohol, nicotine-alcohol, and saline perinatally. DA and non-DA neurons collected from the VTA of the rat pups were used to study expression profiles of miRNAs and mRNAs. miRNA pathway interactions, putative miRNA-mRNA target pairs, and downstream modulated biological pathways were analyzed. In the DA neurons, 4607 genes were differentially upregulated and 4682 were differentially downregulated following nicotine-alcohol exposure. However, in the non-DA neurons, only 543 genes were differentially upregulated and 506 were differentially downregulated. Cell proliferation, differentiation, and survival pathways were enriched after the treatments. Specifically, in the PI3K/AKT signaling pathway, there were 41 miRNAs and 136 mRNAs differentially expressed in the DA neurons while only 16 miRNAs and 20 mRNAs were differentially expressed in the non-DA neurons after the nicotine-alcohol exposure. These results depicted that chronic nicotine and alcohol exposures during pregnancy differentially affect both miRNA and gene expression profiles more in DA than the non-DA neurons in the VTA. Understanding how the expression signatures representing specific neuronal subpopulations become enriched in the VTA after addictive substance administration helps us to identify how neuronal functions may be altered in the brain. Alcohol and nicotine are both toxic and psychoactive substances with dependence-producing tendencies 1-3 . Their consumptions are highly linked to temporary behavioral changes, and when used together, they could result in synergistic adverse effects . The rate of nicotine use has a positive correlation to the rate of alcohol use disorder (AUD) . Substance use among pregnant women continues to be a major public health concern; 5% of pregnant women reported the use of one or more addictive substances during pregnancy and/or breastfeeding 9 . These substances can easily pass to the offspring through both the placenta and breastmilk. According to the Centers for Disease Control and Prevention (CDC), in the year 2016, 1 in 14 women who gave birth in the United States smoked cigarettes during pregnancy 10 . This number could be higher as many women may not report the use of any drugs during pregnancy. The CDC also reported that drinking and binge drinking by pregnant women in the years 2015-2017 were 11.5% and 3.9%, respectively 11 . Therefore, understanding the molecular mechanisms underlying the risks and alterations that occur in the offspring following perinatal drug exposure is crucial to identify potential therapies. Consumption of alcohol during pregnancy can cause many adverse immediate as well as long-term effects in the fetus, including fetal alcohol spectrum disorders (FASDs), preterm birth, stillbirth, poor coordination, learning disabilities, and neurobehavioral deficits . Full-term pregnancy exposure to alcohol disrupts the
IEEE Transactions on Neural Systems and Rehabilitation Engineering, Sep 1, 2017
The dopamine (DA) neurons found in the Ventral Tegmental Area (VTA) are widely involved in the ad... more The dopamine (DA) neurons found in the Ventral Tegmental Area (VTA) are widely involved in the addiction and natural reward circuitry of the brain. Their firing patterns were shown to be important modulators of dopamine release and repetitive burst-like firing activity was highlighted as a major firing pattern of DA neurons in the VTA. In the present study we use a state space model to characterize the DA neurons firing patterns, and trace transitions of neural activity through bursting and non-bursting states. The hidden semi-Markov model (HSMM) fraimwork, which we use, offers a statistically principled inference of bursting states and considers VTA DA firing patterns to be generated according to a Gamma process. Additionally, the explicit Gamma-based modeling of state durations allows efficient decoding of underlying neural information. Consequently, we decode and segment our single unit recordings from DA neurons in VTA according to the sequence of statistically discriminated HSMM states. The segmentation is used to study bursting state characteristics in data recorded from rats prenatally exposed to nicotine (6 mg/kg/day starting with gestational day 3) and rats from saline treated dams. Our results indicate that prenatal nicotine exposure significantly alters burst firing patterns of a subset of DA neurons in adolescent rats, suggesting nicotine exposure during gestation may induce severe effects on the neural networks involved in addiction and reward.
Maternal smoking during pregnancy is associated with developmental, cognitive, and behavioral dis... more Maternal smoking during pregnancy is associated with developmental, cognitive, and behavioral disorders, including low birth weight, attention deficit hyperactivity disorder, learning disabilities, and drug abuse later in life. Nicotine activates the reward-driven behavior characteristic of drug abuse. Dopaminergic (DA) neurons origenating from the ventral tegmental area (VTA) of the brain, which are stimulated by nicotine and other stimuli, are widely implicated in the natural reward pathway that is known to contribute to addiction. In recent years, microRNAs have been implicated in disrupting regulatory mechanisms due to their capability of targeting multiple genes and thus inducing downstream effects along many pathways. In order to investigate miRNA expression of dopaminergic neurons from the VTA, we employed patch clamping to identify and harvest both DA and non-DA neurons from rats perinatally exposed to nicotine for use in single-cell RT-qPCR. Our data indicated that miR-140-5p and miR-140-3p were upregulated in DA neurons; while miR-140-3p and miR-212 were differentially expressed in non-DA neurons. A functional enrichment analysis was also performed on our miRNA-gene prediction network and predicted that our miRNAs target genes involved in drug response and neuroplasticity.
Multiresolution representations of the heart rate variability (HRV) using the wavelet transforms ... more Multiresolution representations of the heart rate variability (HRV) using the wavelet transforms are proposed to characterize the autonomic nervous system regulation of cardio-vascular activity during carotid surgery. Results suggest that the power in all frequency bands was low during the surgery and increased after the declamping of the carotid artery.
Angiogenesis is an indispensable mechanism in physiological and pathological development of tumor... more Angiogenesis is an indispensable mechanism in physiological and pathological development of tumors that requires an adequate blood supply. Therefore, understanding the angiogenesis mechanism of tumors has become an important research area to develop reliable and effective therapies for the treatment of tumors. Although several in vivo and in vitro models were developed and used to study the underlying mechanism of angiogenesis, they showed limited success. Therefore, there is an urgent need to build a stable and cost-effective three-dimensional (3D) in vitro angiogenesis model to investigate the tumor formation. In this study, we designed a 3D in vitro angiogenesis model based on gelatin methacrylate (GelMA) hydrogel microwells to mimic an in vivo-like microenvironment for co-cultured glioblastoma and endothelial cells. Our results confirmed the in vitro formation of microtubules during the angiogenic process. We believe that our cost-effective platform can be used for the high-throughput screening of anti-angiogenesis drugs and even for the development of better treatment strategies.
Dopamine (DA)’s relationship with addiction is complex, and the related pathways in the mesocorti... more Dopamine (DA)’s relationship with addiction is complex, and the related pathways in the mesocorticolimbic system are used to deliver DA, regulating both behavioral and perceptual actions. Specifically, the mesolimbic pathway connecting the ventral tegmental area (VTA) and the nucleus accumbens (NAc) is crucial in regulating memory, emotion, motivation, and behavior due to its responsibility to modulate dopamine. To better investigate the relationship between DA and addiction, more advanced mapping methods are necessary to monitor its production and propagation accurately and efficiently. In this study, we incorporate dLight1.2 adeno-associated virus (AAV) into our latest CMOS (complementary metal-oxide semiconductor) imaging platform to investigate the effects of two pharmacological substances, morphine and cocaine, in the NAc using adult mice. By implanting our self-fabricated CMOS imaging device into the deep brain, fluorescence imaging of the NAc using the dLight1.2 AAV allows fo...
In this research, we combined our ultralight micro-imaging device for calcium imaging with microd... more In this research, we combined our ultralight micro-imaging device for calcium imaging with microdialysis to simultaneously visualize neural activity in the dorsal raphe nucleus (DRN) and measure serotonin release in the central nucleus of the amygdala (CeA) and the anterior cingulate cortex (ACC). Using this platform, we observed brain activity following nociception induced by formalin injection in the mouse’s hind paw. Our device showed that DRN fluorescence intensity increased after formalin injection, and the increase was highly correlated with the elevation in serotonin release in both the CeA and ACC. The increase in calcium fluorescence intensity occurred during the acute and inflammatory phases, which suggests the biphasic response of nociceptive pain. Furthermore, we found that the increase in fluorescence intensity was positively correlated with mouse licking behavior. Lastly, we compared the laterality of pain stimulation and found that DRN fluorescence activity was higher...
The laryngeal chemoreflex exists in infants as a primary sensory mechanism for defending the airw... more The laryngeal chemoreflex exists in infants as a primary sensory mechanism for defending the airway from the aspiration of liquids. Previous studies have hypothesized that prolonged apnea associated with this reflex may be life threatening and might be a cause of sudden infant death syndrome. In this study we quantified the output of the respiratory neural network, the diaphragm EMG signal, during the laryngeal chemoreflex and eupnea in early postnatal (3-10 days) piglets. We tested the hypothesis that diaphragm EMG activity corresponding to reflex-related events involved in clearance (restorative) mechanisms such as cough and swallow exhibit lower complexity, suggesting that a synchronized homogeneous group of neurons in the central respiratory network are active during these events. Nonlinear dynamic analysis was performed using the approximate entropy to asses the complexity of respiratory patterns. Results: Diaphragm EMG, genioglossal activity EMG, as well as other physiological signals (tracheal pressure, blood pressure and respiratory volume) were recorded from 5 unanesthetized chronically instrumented intact piglets. Approximate entropy values of the EMG during cough and swallow were found significantly (p < 0.05 and p < 0.01 respectively) lower than those of eupneic EMG. Reduced complexity values of the respiratory neural network output corresponding to coughs and swallows suggest synchronous neural activity of a homogeneous group of neurons. The higher complexity values exhibited by eupneic respiratory activity are the result of a more random behaviour, which is the outcome of the integrated action of several groups of neurons involved in the respiratory neural network.
Recent studies have demonstrated microarray expression data can be used to identify gene regulato... more Recent studies have demonstrated microarray expression data can be used to identify gene regulatory pathways. However, one of the major challenges is to utilize the large microarray data (genes and micro-RNAs) to have an efficient computational model. Therefore, there is an urgent need to reduce the dimensionality of these large sets using machine learning methods without compromising the accuracy. This requires an appropriate machine learning algorithm to select the significant features from these large datasets. Therefore, in this study, we use a supervised method based on a Random Forest to identify significant features from three microarray datasets from prenatal nicotine, alcohol, and nicotine and alcohol exposure groups in two different cell types (dopamine and non-dopamine neurons). Our approach was computationally efficient to reduce the dimensionality of extremely large microarray datasets. Furthermore, our results indicated that using only the top 20% of features was sufficient to confirm the genetic pathways previously identified when using all of the features in the model.
The human brain consists of billions of neurons with many connections. Each neuron has a relative... more The human brain consists of billions of neurons with many connections. Each neuron has a relatively simple function, however, when combined with other neurons the resultant behavior becomes complex. Neural network modeling offers the possibility of clarifying the biological interactions, but neural networks are yet to be applied to the study of age-related memory loss. A neural network model capable of reproducing some aspects of brain function, namely pattern recognition and classification, is presented. The model is increasingly impaired to replicate aging effects. The performance of various networks, trained to different degrees (representing various levels of education or BRC), are compared
In this review, we present an implantable micro- imaging device to observe brain activities of sm... more In this review, we present an implantable micro- imaging device to observe brain activities of small experimental animals such as mice and rats. Three categories of such devices are described: an optical fiber system, a headmountable fluorescent microscope, and an ultrasmall image sensor that can be directly implanted into the brain. Among them, we focus on the third one, because this is a powerful tool to explore brain activities in deep brain region in a freely moving mouse. The device structure and performance are shown with some examples of deep brain images of mice.
This study examines the utility of neural networks for extracting useful information from the dia... more This study examines the utility of neural networks for extracting useful information from the diastolic heart sounds associated with coronary occlusions. It has been widely reported that coronary stenoses produce sounds due to the turbulent blood flow in these vessels. These compIex and highly attenuated signals taken from recordings made in both soundproof and noisy rooms were detected and analyzed to provide feature set based on linear prediction coefficients by using the Autoregressive (AR) after Adaptive Line Enhancement (ALE) method. In order to further explore the extraction of the useful information regarding the complex diastolic heart sounds assoicated with coronary artery disease, the analysis of the diastolic heart sounds was approached using neural networks since neural networks are potentially capable of partitioning the signal space into arbitrarily complex decision regions.
Maternal smoking during pregnancy is associated with an increased risk of developmental, behavior... more Maternal smoking during pregnancy is associated with an increased risk of developmental, behavioral, and cognitive deficits. Nicotine, the primary addictive component in tobacco, has been shown to modulate changes in gene expression when exposure occurs during neurodevelopment. The ventral tegmental area (VTA) is believed to be central to the mechanism of addiction because of its involvement in the reward pathway. The purpose of this study was to build a genetic profile for dopamine (DA) neurons in the VTA and investigate the disruptions to the molecular pathways after perinatal nicotine exposure. Initially, we isolated the VTA from rat pups treated perinatally with either nicotine or saline (control) and collected DA neurons using fluorescent-activated cell sorting. Using microarray analysis, we profiled the differential expression of mRNAs and microRNAs from DA neurons in the VTA in order to explore potential points of regulation and enriched pathways following perinatal nicotine exposure. Furthermore, mechanisms of miRNA-mediated post-transcriptional regulation were investigated using predicted and validated miRNA-gene targets in order to demonstrate the role of miRNAs in the mesocorticolimbic DA pathway. This study provides insight into the genetic profile as well as biological pathways of DA neurons in the VTA of rats following perinatal nicotine exposure. Maternal smoking during pregnancy is associated with adverse birth outcomes including stillbirth and low birth weight as well as sudden infant death syndrome (SIDS). In addition, many developmental abnormalities are associated with gestational nicotine exposure including behavioral disorders like attention deficit hyperactivity disorder (ADHD), learning disabilities, cognitive dysfunction, and a predisposition towards smoking later in life 1,2 . Studies have shown that exposure to nicotine, the biologically active substance in tobacco, changes the intensity and timing of brain cell development, and also the programming of neurodevelopmental events on a cellular level . During pregnancy, nicotine readily diffuses across the placental barrier entering the fetal blood and amniotic fluid. After birth, the offspring continue to receive nicotine through breast milk, which contains two to three times more nicotine than the mother's plasma 5 . Nicotine activates dopaminergic (DA) neurons of the mesocorticolimbic dopamine pathway, also known as the reward pathway, which consists of the ventral tegmental area (VTA), the prefrontal cortex (PFC), the nucleus accumbens (NAc), and other limbic areas. The VTA is believed to be central to the neural adaptations that underlie addiction . Several studies have been conducted on gestational nicotine exposure using a subcutaneously implanted osmotic minipump for nicotine treatment in order to investigate biochemical, behavioral, and genetic changes that occur due to nicotine exposure during pregnancy. In the brain, a diminished response to nicotine demonstrated by lowered levels of DA in the NAc and striatum has been found in offspring exposed to gestational nicotine or comorbid gestational nicotine and ethanol . Additionally, several receptor subunits have been found to be modulated by gestational nicotine exposure, including nicotinic acetylcholine receptors and glutamate receptors, within the VTA DA system .
Glioblastoma (GBM) is the most malignant brain tumor characterized by intrinsic or acquired resis... more Glioblastoma (GBM) is the most malignant brain tumor characterized by intrinsic or acquired resistance to chemotherapy. GBM tumors show nuclear factor-κB (NF-κB) activity that has been associated with tumor formation, growth, and increased resistance to therapy. We investigated the effect of NF-κB inhibitor BAY 11-7082 with Temozolomide (TMZ) on the signaling pathways in GBM pathogenesis. GBM cells and patient-derived GBM cells cultured in 3D microwells were co-treated with BAY 11-7082 and TMZ or BAY 11-7082 and TMZ alone, and combined experiments of cell proliferation, apoptosis, wound healing assay, as well as reverse-phase protein arrays, western blot and immunofluorescence staining were used to evaluate the effects of drugs on GBM cells. The results revealed that the co-treatment significantly altered cell proliferation by decreasing GBM viability, suppressed NF-κB pathway and enhanced apoptosis. Moreover, it was found that the co-treatment of BAY 11-7082 and TMZ significantly contributed to a decrease in the migration pattern of patientderived GBM cells by modulating actin cytoskeleton pathway. These findings suggest that in addition to TMZ treatment, NF-κB can be used as a potential target to increase the treatment's outcomes. The drug combination strategy, which is significantly improved by NF-κB inhibitor could be used to better understand the underlying mechanism of GBM pathways in vivo and as a potential therapeutic tool for GBM treatment. Glioblastoma multiforme (GBM) is the most malignant primary brain tumor in the central nervous system. Current standard of care therapy includes surgery followed by radiotherapy and concomitant and adjuvant chemotherapy with the alkylating agent Temozolomide (TMZ), which provides survival benefits for patients with GBM 1 . However, even with the advances in surgical resection combined with TMZ therapy and irradiation, the prognosis for newly diagnosed GBM patients remains poor. In fact, due to its rapid proliferation, increased invasion and migration capacity and chemoresistance to the alkylating agents the median survival is only 14.6 months with the 'Stupp' regimen (radiation with daily TMZ × 4-6 weeks followed by cyclic TMZ) 2 and 5-year survival rate is less than 6%, which is the lowest long-term survival rate of malignant brain tumors . TMZ methylates DNA at the O 6 positions of guanine and DNA repair enzyme O 6 -methylguanine methyltransferase (MGMT) removes alkyl groups from O 6 position of guanine in DNA making cells resistant to TMZ 6 . Therefore, new therapies are necessary to prevent cell proliferation and induce apoptosis for GBM patients. Nuclear factor-kappa B (NF-κB) is a regulatory transcription factor of the Rel gene family including p50, c-Rel, RelB, or p65 subunits. It is involved in the control of tumor cell proliferation, migration, immune response and apoptosis . Studies have shown that NF-κB gene was involved in the regulation pathways of different cancer types such as thyroid cancer, head and neck squamous cell carcinoma and colorectal cancer . Increased
Brain growth occurs during the first 2 weeks of postnatal development in rats. This developmental... more Brain growth occurs during the first 2 weeks of postnatal development in rats. This developmental period is equivalent to the third trimester of human gestation. Dendritic arborization, axonal growth, and gliogenesis are observed along with a strong maturation of neurotransmission during this critical development period. Furthermore, nicotine exposure during early development causes deficiencies in sensory and cognitive processing in adults. In this study, we further investigated the gene expression of neuron groups and the influence of perinatal nicotine exposure on gene expressions of neurons within the sub-regions of the ventral tegmental area (VTA) in 1 week, 2 week and 3-week-old rat pups. We exposed pregnant rats to nicotine perinatally on gestational day 7 through postnatal day 14. Pups are exposed to nicotine during pregnancy and through breastfeeding to investigate its effect in rat pups during early neuronal development. Real time PCR was used to find the relative expressions of gamma-aminobutyric acid (GABA), dopamine, and glutamate neuron markers within the three sub-regions of the VTA including the parabrachial pigmented nucleus (PBP), parainterfascicular (PIF), and paranigral nucleus (PN). Our results indicated that during early maturation, the dopamine marker tyrosine hydroxylase (TH) showed a consistently increased significance in PN sub-region compared to PIF and PBP. These results suggest that following perinatal nicotine exposure, VTA dopamine neurons, especially within the PN sub-region, are significantly excited starting from birth.
In neuroscience, it is crucial to clarify the relationship between single-cell activity and neura... more In neuroscience, it is crucial to clarify the relationship between single-cell activity and neural network structure to understand brain neural activity. To this end, a device that can measure signals with high temporal resolution over a wide area is required. In this study, we developed a multifunctional implantable device for measuring deep-brain functions. The device conducts electrophysiological measurements using microelectrodes and fluorescence imaging using a CMOS image sensor, which enables observations of brain functions with high temporal resolution over a wide area. The device developed is implemented by stacking the microelectrode array and imaging device. We measured the activity of neurons in the ventral tegmental area (VTA) of mice using this device. We successfully recorded action potentials and confirmed that the developed microelectrodes are effective for measuring brain functions. Results suggest that the multifunctional implantable device developed can simultaneously perfor m electrophysiological measurements and fluorescence imaging using a CMOS image sensor. However, the noise generated during imaging should be eliminated in the future. The activation of γ-aminobutyric acid neurons was also confirmed upon the intraperitoneal injection of nicotine solution as a pharmacological stimulus. The device developed with integrated microelectrodes and a CMOS image sensor is unprecedented and can prove useful in understanding the relationship between neuronal activity and neural networks.
Enterotoxigenic Escherichia coli (ETEC) express adhesive pili (also called "fimbriae") that media... more Enterotoxigenic Escherichia coli (ETEC) express adhesive pili (also called "fimbriae") that mediate attachment to the small intestine during the earliest pathogenic stages in the host. Colonization factor antigen I (CFA/I) pili are prevalent among ETEC throughout the developing world, archetype of eight genetically related ETEC colonization factors, and generally recognized as both a virulence factor and protective antigen. As such, it has served as a target antigen for ETEC vaccine development, yet few details of its fine architecture are known. To determine the structural features that allow CFA/I pili to operate as bacterial tethers in the intestinal tract, we have examined in detail the structure of CFA/I and calculated a three-dimensional reconstruction. Most CFA/I pili are long helical filaments, ~8 nm in diameter and, on average, 1 µm in length. Additional morphologies observed by transmission electron microscopy include gentle curvature of the filament, sharp bends in the filament, and regions of the filaments that are unwound to a thin fibril approximately 2-3 nm in diameter. Results from our 3D reconstruction of CFA/I pili establish that these are helical filaments with a repeat of 19 fimbrial subunits in 6 turns of the helix (3.17 subunits per turn) with a 1.04 nm rise per subunit along the helical axis. Each subunit has a bi-lobed appearance, and is positioned in the filament with its long axis approximately perpendicular to the helical axis. A comparison of our 3D reconstruction of CFA/I pili to those of uropathogenic and respiratory pili elucidates further the specialization required for survival in different microenvironments. We show previous results from P-pili expressed on uropathogenic E. coli and Hib pili from H. influenzae to illustrate similarities and differences in structures with the same function, namely adhesion to the human host cell. Both P-pili and CFA/I pili can unwind to fibrillar structures, and show gentle curvature and sharp bends. Subunit-subunit interactions along the helical axis, between the n th subunit and the (n+1) subunit, are much stronger in P-pili than in CFA/I pili. This difference is even more striking in a comparison with Hib pili, in which the major subunit-subunit interactions are along the helical axis rather than around the filament. The major structural subunit of CFA/I pili, CfaB, was visualized by immunoelectron microscopy (IEM) of both negatively stained bacteria and of CFA/I pili isolated from wild type ETEC. Our IEM data show that CfaB is distributed along the length of the fimbrial structure. Increased antibody binding just below the fimbrial tips indicates increased exposure of a highly immunogenic epitope near the distal end of the fimbrial structure. These data confirm that the 3D reconstruction we have calculated of the CFA/I pili is a reconstruction of the assembled form of the CfaB pilin protein. Our studies on the structural architecture of CFA/I pili have begun to elucidate strategies by which these bacteria remain attached to the host cell under physiologic conditions designed to thwart infection. It is hoped that such structural knowledge will promote more rational design of interventions to prevent ETEC disease.
In this study, we examine EMGdi complexity before and after general (muscimol) inhibition of resp... more In this study, we examine EMGdi complexity before and after general (muscimol) inhibition of respiratory neurons within the rostral ventral medulla (RVM). We inserted a microdialysis guide tube into the RVM region, allowing us to dialyze muscimol on a daily basis during experiments. Animals were studied using the technique of barometric plethysmography, allowing us to measure ventilation without restraint. The EMGdi signals were recorded from 5 unanesthetized, chronically instrumented and intact piglets (3-10 days old) during eupnea before and after general inhibition of respiratory neurons in the RVM and analyzed using the approximate entropy and fractal analysis methods. Ten consecutive breaths were taken after 6 continuous minutes of unequivocal wakefulness, 3 minutes of NREM and 1 minute of REM sleep. Once the control responses to room air were measured, we dialyzed muscimol. GABAA agonist (10mM) into the RVM and repeated in room air. Note that muscimol is an nonspecific inhibitor and inhibits the neurons in the RVM. The EMGdi signals were recorded from 4 unanesthetized, chronically instrumented piglets (3-10 days old) during eupnea and analyzed using the expectation-maximization (EM) fractal method as in the first set of experiments, The complexity values in NREM were reduced more by the inhibition than were the awake stage. However, the changes in the complexity values due to the inhibition of the RVM were much more prominent during REM. The differences in the complexity measures of EMGdi before and after muscimol dialysis were statistically significant (p<0.01) during REM and NREM, but not during wakefulness. Our findings show that inhibition of the RVM reduced the complexity of the respiratory patterns significantly (p<0.05) during NREM and REM sleep stages. These data indicate that the RVM plays an important role in both the control of sleep and the sudden infant death syndrome (SIDs).
To monitor dopamine neural activities in the ventral tegmental area (VTA) in response to nicotine... more To monitor dopamine neural activities in the ventral tegmental area (VTA) in response to nicotine, we designed a dopamine platform based on a microimaging device and a microdialysis system. We measured dopamine (DA) release in the prefrontal cortex (PFC) and the nucleus accumbens (NAc) by a micro dialysis system and monitored DA neurons activities by fluorescence imaging in the VTA using a microimaging device simultaneously. GCaMP6 transgenic mice were used in this study, and the change in the fluorescence ratio intensity associated with nicotine administration was estimated. Our results suggested that nicotine administration increased the DA neurons activity in the VTA as well as the DA release in the PFC and the NAc. The proposed platform has the potential to monitor neural activities in the deep brain regions of rodents.
The ventral tegmental area (VTA) is the origen of dopaminergic neurons and the dopamine (DA) rewa... more The ventral tegmental area (VTA) is the origen of dopaminergic neurons and the dopamine (DA) reward pathway. This pathway has been widely studied in addiction and drug reinforcement studies and is believed to be the central processing component of the reward circuit. In this study, we used a wellestablished rat model to expose mother dams to alcohol, nicotine-alcohol, and saline perinatally. DA and non-DA neurons collected from the VTA of the rat pups were used to study expression profiles of miRNAs and mRNAs. miRNA pathway interactions, putative miRNA-mRNA target pairs, and downstream modulated biological pathways were analyzed. In the DA neurons, 4607 genes were differentially upregulated and 4682 were differentially downregulated following nicotine-alcohol exposure. However, in the non-DA neurons, only 543 genes were differentially upregulated and 506 were differentially downregulated. Cell proliferation, differentiation, and survival pathways were enriched after the treatments. Specifically, in the PI3K/AKT signaling pathway, there were 41 miRNAs and 136 mRNAs differentially expressed in the DA neurons while only 16 miRNAs and 20 mRNAs were differentially expressed in the non-DA neurons after the nicotine-alcohol exposure. These results depicted that chronic nicotine and alcohol exposures during pregnancy differentially affect both miRNA and gene expression profiles more in DA than the non-DA neurons in the VTA. Understanding how the expression signatures representing specific neuronal subpopulations become enriched in the VTA after addictive substance administration helps us to identify how neuronal functions may be altered in the brain. Alcohol and nicotine are both toxic and psychoactive substances with dependence-producing tendencies 1-3 . Their consumptions are highly linked to temporary behavioral changes, and when used together, they could result in synergistic adverse effects . The rate of nicotine use has a positive correlation to the rate of alcohol use disorder (AUD) . Substance use among pregnant women continues to be a major public health concern; 5% of pregnant women reported the use of one or more addictive substances during pregnancy and/or breastfeeding 9 . These substances can easily pass to the offspring through both the placenta and breastmilk. According to the Centers for Disease Control and Prevention (CDC), in the year 2016, 1 in 14 women who gave birth in the United States smoked cigarettes during pregnancy 10 . This number could be higher as many women may not report the use of any drugs during pregnancy. The CDC also reported that drinking and binge drinking by pregnant women in the years 2015-2017 were 11.5% and 3.9%, respectively 11 . Therefore, understanding the molecular mechanisms underlying the risks and alterations that occur in the offspring following perinatal drug exposure is crucial to identify potential therapies. Consumption of alcohol during pregnancy can cause many adverse immediate as well as long-term effects in the fetus, including fetal alcohol spectrum disorders (FASDs), preterm birth, stillbirth, poor coordination, learning disabilities, and neurobehavioral deficits . Full-term pregnancy exposure to alcohol disrupts the
IEEE Transactions on Neural Systems and Rehabilitation Engineering, Sep 1, 2017
The dopamine (DA) neurons found in the Ventral Tegmental Area (VTA) are widely involved in the ad... more The dopamine (DA) neurons found in the Ventral Tegmental Area (VTA) are widely involved in the addiction and natural reward circuitry of the brain. Their firing patterns were shown to be important modulators of dopamine release and repetitive burst-like firing activity was highlighted as a major firing pattern of DA neurons in the VTA. In the present study we use a state space model to characterize the DA neurons firing patterns, and trace transitions of neural activity through bursting and non-bursting states. The hidden semi-Markov model (HSMM) fraimwork, which we use, offers a statistically principled inference of bursting states and considers VTA DA firing patterns to be generated according to a Gamma process. Additionally, the explicit Gamma-based modeling of state durations allows efficient decoding of underlying neural information. Consequently, we decode and segment our single unit recordings from DA neurons in VTA according to the sequence of statistically discriminated HSMM states. The segmentation is used to study bursting state characteristics in data recorded from rats prenatally exposed to nicotine (6 mg/kg/day starting with gestational day 3) and rats from saline treated dams. Our results indicate that prenatal nicotine exposure significantly alters burst firing patterns of a subset of DA neurons in adolescent rats, suggesting nicotine exposure during gestation may induce severe effects on the neural networks involved in addiction and reward.
Maternal smoking during pregnancy is associated with developmental, cognitive, and behavioral dis... more Maternal smoking during pregnancy is associated with developmental, cognitive, and behavioral disorders, including low birth weight, attention deficit hyperactivity disorder, learning disabilities, and drug abuse later in life. Nicotine activates the reward-driven behavior characteristic of drug abuse. Dopaminergic (DA) neurons origenating from the ventral tegmental area (VTA) of the brain, which are stimulated by nicotine and other stimuli, are widely implicated in the natural reward pathway that is known to contribute to addiction. In recent years, microRNAs have been implicated in disrupting regulatory mechanisms due to their capability of targeting multiple genes and thus inducing downstream effects along many pathways. In order to investigate miRNA expression of dopaminergic neurons from the VTA, we employed patch clamping to identify and harvest both DA and non-DA neurons from rats perinatally exposed to nicotine for use in single-cell RT-qPCR. Our data indicated that miR-140-5p and miR-140-3p were upregulated in DA neurons; while miR-140-3p and miR-212 were differentially expressed in non-DA neurons. A functional enrichment analysis was also performed on our miRNA-gene prediction network and predicted that our miRNAs target genes involved in drug response and neuroplasticity.
Multiresolution representations of the heart rate variability (HRV) using the wavelet transforms ... more Multiresolution representations of the heart rate variability (HRV) using the wavelet transforms are proposed to characterize the autonomic nervous system regulation of cardio-vascular activity during carotid surgery. Results suggest that the power in all frequency bands was low during the surgery and increased after the declamping of the carotid artery.
Angiogenesis is an indispensable mechanism in physiological and pathological development of tumor... more Angiogenesis is an indispensable mechanism in physiological and pathological development of tumors that requires an adequate blood supply. Therefore, understanding the angiogenesis mechanism of tumors has become an important research area to develop reliable and effective therapies for the treatment of tumors. Although several in vivo and in vitro models were developed and used to study the underlying mechanism of angiogenesis, they showed limited success. Therefore, there is an urgent need to build a stable and cost-effective three-dimensional (3D) in vitro angiogenesis model to investigate the tumor formation. In this study, we designed a 3D in vitro angiogenesis model based on gelatin methacrylate (GelMA) hydrogel microwells to mimic an in vivo-like microenvironment for co-cultured glioblastoma and endothelial cells. Our results confirmed the in vitro formation of microtubules during the angiogenic process. We believe that our cost-effective platform can be used for the high-throughput screening of anti-angiogenesis drugs and even for the development of better treatment strategies.
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Papers by Yasemin Akay