• Measuring Surface Tension Using the Pendant Drop Method

      Jaleel Bolden; Zane Corder; Charlene Higdon; Miller, Camille; College of Science and Mathematics; Millan, Josefa Guerrero (2015-04-17)
      Measuring surface tension between fluids is of a great practical importance in the oil, food, chemical, cosmetic, etc. industries. Also, the measurement of the contact angle tl1at is formed between the fluid interface and a restricting wall are of prime importance in surface science. Instruments that employ the DuNouy ring and Wilhelmy plate methods are in common use at industry and research laboratories but they are very labor intensive. Th ere is a need for a rapid, easy and low cost technique with satisfactory accuracy and reproducibility. Reliable measurement of these parameters require significant computer programming and image analysis. The goal of the project has been the development of a computer program written in Matlab which use the pendant drop method to measure t he surface tension between two fluids. In addition, an experimental setup has been developed to test the accuracy of this method. In the framework of the soft matter, where tl1e surface tension of tl1e fluids plays a key role, the use of more complex and biological fluids make harder to find data a bout how interact these fluids. This is the reason that codes like these are inclispensable tools in these laboratories.
    • Mechanisms of Neuroprotection by Estrogen and Selective Estrogen Receptor Modulators

      Dhandapani, Krishnan M.; Institute of Molecular Medicine and Genetics (2003-03)
      Specific Aim #1: To determine whether 17b-E2 and SERMs directly influence neuronal survival. Specific Aim #2: To determine whether astrocyte-derived TGF-b protects neurons from cell death. Specific Aim #3: To determine whether 17b-E2 or SERMs regulate the release of TGF-b from astrocytes. Specific Aim #4:To elucidate the mechanism of TGF-b mediated neuroprotection in GT1-7 Neurons. Specific Aim #5: To identify genes potentially mediating the neuroprotective effects of 17b-E2 and/or tamoxifen through the use of high density gene chip arrays.
    • Mechanisms of Vessel Obliteration in Oxygen-Induced Retinopathy

      Gu, Xiaolin; Vascular Biology Center (2001-11)
      The overall goal of this study was to explore the possible molecular mediators of vaso-obliteration in retinopathy o f prematurity. Vaso-obliteration is the early hyperoxiainduced pathology. It leads to the later relative hypoxia in the retina tissue, because the insufficient blood supply cannot meet the increasing demands o f oxygen from the developing retina. Such retinal hypoxia then causes the blinding outcome through the formation o f neovessels and subsequent vitreous bleeding and fibrotic change in both retina and vitreous. Therefore, identification o f the possible mediators o f hyperoxiainduced vaso-obliteration will help us to understand more about the pathogenesis o f ROP and provide new and better strategies of treating and preventing this disease. Previous studies have shown that administration o f exogenous antioxidants can attenuate retinopathy in certain animal models and that hyperoxia is able to upregulate the expression and activity o f eNOS in vascular endothelial cells (Liao et al., 1995; North et al., 1996; Phelan and Faller, 1996). Hyperoxia also increases formation o f O2 ' which rapidly combines with NO to form the highly reactive oxidant ONOO*. Therefore, it is hypothesized that the NO and O2 'derived oxidant, ONOO', play an important role in the initial vascular injury leading to obliteration of the developing retinal capillaries in oxygen-induced retinopathy (OIR). It is further proposed that ONOO' causes vascular injury by modifying the critical intracellular signaling pathway that controls endothelial cell survival (Fig 5). This hypothesis has been tested by accomplishing the following specific aims: 1. Establish the OIR mouse model for ROP. Analyze NOS expression and assay the formation of NO and ONOO' in the vaso-obliteration phase o f OIR. 2. Determine whether deletion o f the eNOS or iNOS gene alters the vaso-obliteration phase o f OIR. If so, determine whether the gene deletion also reduces ONOO' formation in the vaso-obliteration phase o f OIR. 3. Test whether or not pharmacological inhibition o f NOS reduces vascular obliteration in wild-type mice with OIR. 4. Establish a tissue culture model for oxygen-induced endothelial cell injury. Determine the effect o f hyperoxia on endothelial cell survival and test whether the effects are mediated by NO, O2 ', and /or ONOO'. 5. Test whether ONOO' alters the signal transduction pathway for endothelial cell survival by altering the activity o f PI3K/AKT.
    • Mechanosensory Hair Cell Precursors in the Zebrafish Lateral Line

      Floyd, Tiffany L.; Institute of Molecular Medicine and Genetics (2009-07)
      The vertebrate inner ear mediates the senses of hearing and balance. Contained within both the auditory and vestibular compartments of the inner ear are specialized mechanosensory hair cells that function as receptors and transducers of environmental stimuli. In all vertebrates, these sensory hair cells are particularly susceptible to ototoxic insults resulting in cell death and, in mammals, the irreversible loss of hair cells underlies deafness and balance disorders. In contrast to mammals, several non-mammalian vertebrates (including zebrafish) possess the innate capacity to produce new hair cells throughout life as well as regenerate hair cells that have been lethally damaged. A long-term strategy of the hearing research field is to determine the molecular mechanisms of hair cell regeneration using regenerating model systems such as zebrafish, then to apply this information to mammalian models where sensory hair cell regeneration is limited or nonexistent. During embryogenesis, sensory hair cell fates are specified through a mechanism of Notch-Delta-mediated lateral inhibition. The gamma secretase complex is an upstream regulator of Notch signaling, responsible for proteolytic\ cleavage and activation of the Notch receptor. Recent evidence suggests that Notch signaling may also play a role during the process of hair cell regeneration in zebrafish (Ma et al., 2008). I used a chemical inhibitor of the gamma secretase complex to examine the role of Notch signaling in the regulation of hair cell number maintenance in larval zebrafish. Results presented in this thesis provide novel insight into the mechanisms regulating the maintenance of resident hair cell precursors within the sensory epithelium. Moreover, this new information is directly relevant to research efforts in mammalian models by providing the molecular framework for therapeutic strategies designed to replace or regenerate lethally damaged hair cells in the mammalian cochlea by reactivating resident precursors to differentiate into hair cells.
    • MedEdPORTAL Module Guides Evaluation of Faculty Fellowship

      Richardson, D; Villarosa, M; Palladino, Christie; Thomas, Andria M.; Education Discovery Institute; Medical College of Georiga; Georgia Health Sciences University (Georgia Health Sciences University, 2011)
      Professional development of faculty is critical to the future of health sciences education. The Education Discovery Institute (EDI) at Georgia Health Sciences University (GHSU) developed a year-long Educational Research Fellowship designed to nurture faculty career progression by providing training in health sciences education research and fostering career development. As we developed the program, we realized the need for a careful evaluation plan.
    • Melanoma Cell Expression of CD200 Inhibits Tumor Formation and Lung Metastasis via Inhibition of Myeloid Cell Functions

      Talebian, Fatemeh; Liu, Jin-Qing; Liu, Zhenzhen; Khattabi, Mazin; He, Yukai; Ganju, Ramesh; Bai, Xue-Feng; Immunotherapy Center (2012-02-3)
      CD200 is a cell surface glycoprotein that functions through engaging CD200 receptor on cells of the myeloid lineage and inhibits their functions. Expression of CD200 has been implicated in a variety of human cancer cells including melanoma cells and has been thought to play a protumor role. To investigate the role of cancer cell expression of CD200 in tumor formation and metastasis, we generated CD200-positive and CD200-negative B16 melanoma cells. Subcutaneous injection of CD200-positive B16 melanoma cells inhibited tumor formation and growth in C57BL/6 mice but not in Rag1-/- C57BL/6 mice. However, i.v. injection of CD200-positive B16 melanoma cells dramatically inhibited tumor foci formation in the lungs of both C57BL/6 and Rag1-/- C57BL6 mice. Flow cytometry analysis revealed higher expression of CD200R in Gr1+ myeloid cells in the lung than in peripheral myeloid cells. Depletion of Gr1+ cells or stimulation of CD200R with an agonistic antibody in vivo dramatically inhibited tumor foci formation in the lungs. In addition, treatment with tumor antigen specific CD4 or CD8 T cells or their combination yielded a survival advantage for CD200 positive tumor bearing mice over mice bearing CD200-negative tumors. Taken together, we have revealed a novel role for CD200-CD200R interaction in inhibiting tumor formation and metastasis. Targeting CD200R may represent a novel approach for cancer immunotherapy.
    • Metabolic and Performance Effects of Different Warm-up Protocols on Aerobic Exercise in Physically Active Adults

      Blanco, Chris; Brown, Julian; James, Torrian; Mojock, Chris; College of Education (2015-08-10)
      Pre-competition warm-up (WU) routines have long been prescribed as necessary components to optimize performance in athletic contests. Although WU routines are ubiquitous prior to competition, there is limited, inconclusive evidence on the impact to performance and the research focus has been on short to moderate duration exercise (< 7 min). This project was the first to investigate the effects of WU on metabolic responses and performance during long duration endurance performance. PURPOSE: To determine the metabolic and performance effects of different warm-up (WU) protocols on high-intensity aerobic exercise in physically active adults. METHODS: In a randomized, controlled crossover protocol, qualifying participants performed a continuous, graded maximal exercise test and multiple time-to-exhaustion (TTE) performance tests. On separate days, two 10-minute WU protocols, moderate and vigorous, were performed prior to the TTE. The near-threshold TTE used varied intensity (3-min 100% of ventilatory threshold (VT) power, 1-min 110% VT) to simulate the undulations common in races. Measurements of metabolic activity were recorded by indirect calorimetry. RESULTS: Physically active men (age: 24 ± 2.5 yr; body fat: 15.9 ± 6.51 %; VO2max: 40.2 ± 10.41 ml/kg/min; VT: 69.9 ± 0.72 %) were able to maintain high-intensity aerobic exercise longer (TTE increase: 8.05 ± 9.93 min) following a moderate vs. a vigorous warm-up protocol. CONCLUSION: The moderate intensity warm-up was more effective than a vigorous warm-up to increase time to exhaustion prior to high intensity aerobic exercise. Further research is needed to determine the metabolic and neuromuscular changes that contribute to the difference in performance.
    • Metabolomic Profiling Reveals a Role for Androgen in Activating Amino Acid Metabolism and Methylation in Prostate Cancer Cells

      Putluri, Nagireddy; Shojaie, Ali; Vasu, Vihas T.; Nalluri, Srilatha; Vareed, Shaiju K.; Putluri, Vasanta; Vivekanandan-Giri, Anuradha; Byun, Jeman; Pennathur, Subramaniam; Sana, Theodore R.; et al. (2011-07-18)
      Prostate cancer is the second leading cause of cancer related death in American men. Development and progression of clinically localized prostate cancer is highly dependent on androgen signaling. Metastatic tumors are initially responsive to anti-androgen therapy, however become resistant to this regimen upon progression. Genomic and proteomic studies have implicated a role for androgen in regulating metabolic processes in prostate cancer. However, there have been no metabolomic profiling studies conducted thus far that have examined androgen-regulated biochemical processes in prostate cancer. Here, we have used unbiased metabolomic profiling coupled with enrichment-based bioprocess mapping to obtain insights into the biochemical alterations mediated by androgen in prostate cancer cell lines. Our findings indicate that androgen exposure results in elevation of amino acid metabolism and alteration of methylation potential in prostate cancer cells. Further, metabolic phenotyping studies confirm higher flux through pathways associated with amino acid metabolism in prostate cancer cells treated with androgen. These findings provide insight into the potential biochemical processes regulated by androgen signaling in prostate cancer. Clinically, if validated, these pathways could be exploited to develop therapeutic strategies that supplement current androgen ablative treatments while the observed androgen-regulated metabolic signatures could be employed as biomarkers that presage the development of castrate-resistant prostate cancer.
    • Microtubules growth rate alteration in human endothelial cells.

      Alieva, Irina B; Zemskov, Evgeny A.; Kireev, Igor I; Gorshkov, Boris A; Wiseman, Dean A; Black, Stephen M.; Verin, Alexander D.; Vascular Biology Center (2010-05-06)
      To understand how microtubules contribute to the dynamic reorganization of the endothelial cell (EC) cytoskeleton, we established an EC model expressing EB3-GFP, a protein that marks microtubule plus-ends. Using this model, we were able to measure microtubule growth rate at the centrosome region and near the cell periphery of a single human EC and in the EC monolayer. We demonstrate that the majority of microtubules in EC are dynamic, the growth rate of their plus-ends is highest in the internal cytoplasm, in the region of the centrosome. Growth rate of microtubule plus-ends decreases from the cell center toward the periphery. Our data suggest the existing mechanism(s) of local regulation of microtubule plus-ends growth in EC. Microtubule growth rate in the internal cytoplasm of EC in the monolayer is lower than that of single EC suggesting the regulatory effect of cell-cell contacts. Centrosomal microtubule growth rate distribution in single EC indicated the presence of two subpopulations of microtubules with "normal" (similar to those in monolayer EC) and "fast" (three times as much) growth rates. Our results indicate functional interactions between cell-cell contacts and microtubules.
    • Mitochondrial BNIP3 upregulation precedes endonuclease G translocation in hippocampal neuronal death following oxygen-glucose deprivation.

      Zhao, Shen-Ting; Chen, Ming; Li, Shu-Ji; Zhang, Ming-Hai; Li, Bo-Xing; Das, Manas; Bean, Jonathan C; Kong, Ji-Ming; Zhu, Xin-Hong; Gao, Tian-Ming; et al. (2009-09-23)
      BACKGROUND: Caspase-independent apoptotic pathways are suggested as a mechanism for the delayed neuronal death following ischemic insult. However, the underlying signalling mechanisms are largely unknown. Recent studies imply the involvement of several mitochondrial proteins, including endonuclease G (EndoG) and Bcl-2/adenovirus E1B 19 kDa-interacting protein (BNIP3), in the pathway of non-neuronal cells. RESULTS: In this report, using western blot analysis and immunocytochemistry, we found that EndoG upregulates and translocates from mitochondria to nucleus in a time-dependent manner in cultured hippocampal neurons following oxygen-glucose deprivation (OGD). Moreover, the translocation of EndoG occurs hours before the observable nuclear pyknosis. Importantly, the mitochondrial upregulation of BNIP3 precedes the translocation of EndoG. Forced expression of BNIP3 increases the nuclear translocation of EndoG and neuronal death while knockdown of BNIP3 decreases the OGD-induced nuclear translocation of EndoG and neuronal death. CONCLUSION: These results suggest that BNIP3 and EndoG play important roles in hippocampal neuronal apoptosis following ischemia, and mitochondrial BNIP3 is a signal protein upstream of EndoG that can induce neuronal death.
    • Modulation of the DNA-binding activity of Saccharomyces cerevisiae MSH2-MSH6 complex by the high-mobility group protein NHP6A, in vitro.

      Labazi, Mohamed; Jaafar, Lahcen; Flores-Rozas, Hernan; GHSU Cancer Center (2009-12-16)
      DNA mismatch repair corrects mispaired bases and small insertions/deletions in DNA. In eukaryotes, the mismatch repair complex MSH2-MSH6 binds to mispairs with only slightly higher affinity than to fully paired DNA in vitro. Recently, the high-mobility group box1 protein, (HMGB1), has been shown to stimulate the mismatch repair reaction in vitro. In yeast, the closest homologs of HMGB1 are NHP6A and NHP6B. These proteins have been shown to be required for genome stability maintenance and mutagenesis control. In this work, we show that MSH2-MSH6 and NHP6A modulate their binding to DNA in vitro. Binding of the yeast MSH2-MSH6 to homoduplex regions of DNA significantly stimulates the loading of NHP6A. Upon binding of NHP6A to DNA, MSH2-MSH6 is excluded from binding unless a mismatch is present. A DNA binding-impaired MSH2-MSH6F337A significantly reduced the loading of NHP6A to DNA, suggesting that MSH2-MSH6 binding is a requisite for NHP6A loading. MSH2-MSH6 and NHP6A form a stable complex, which is responsive to ATP on mismatched substrates. These results suggest that MSH2-MSH6 binding to homoduplex regions of DNA recruits NHP6A, which then prevents further binding of MSH2-MSH6 to these sites unless a mismatch is present.
    • Molecular Biology of Amino Acid and Peptide Transport Systems

      Li, Huiwu; Georgia Cancer Center (1999)
      (First Paragraph) Amino acids are essential components in cellular metabolism. Some of these amino acids can be synthesized within the cells from other biological molecules and these amino acids are termed ‘nonessential’. These ‘nonessential’ amino acids are alanine, aspartate, cysteine, glutamate, glycine, pro line, serine, tyrosine, glutamine and asparagine. In contrast, some amino acids cannot be synthesized endogenously and have to be supplied in the diet (1). These amino acids are termed ‘essential’. These ‘essential’ amino acids are histidine, arginine, leucine, isoleucine, lysine, methionine, threonine, phenylalanine, tryptophan, and valine. Mammalian cells require ‘essential’ as well as ‘nonessential’ amino acids for their metabolic activity. Even though the cells can synthesize the ‘nonessential’ amino acids to some extent, most of the amino acids have to be supplied to the cells via specific membrane transport mechanisms.
    • Molecular cloning and characterization of the mouse Acdp gene family.

      Wang, Cong-Yi; Yang, Ping; Shi, Jing-Da; Purohit, Sharad; Guo, Dehuang; An, Haiqian; Gu, Jian-Guo; Ling, Jennifer X; Dong, Zheng; She, Jin-Xiong; et al. (2004-05-11)
      BACKGROUND: We have recently cloned and characterized a novel gene family named ancient conserved domain protein (ACDP) in humans. To facilitate the functional study of this novel gene family, we have cloned and characterized Acdp, the mouse homologue of the human ACDP gene family. RESULTS: The four Acdp genes (Acdp1, Acdp2, Acdp3 and Acdp4) contain 3,631 bp, 3,244 bp, 2,684 bp and 2,743 bp of cDNA sequences, and encode deduced proteins of 951, 874, 713 and 771 amino acids, respectively. The mouse Acdp genes showed very strong homologies (>90%) in both nucleotide and amino acid sequences to their human counterparts. In addition, both nucleotide and amino acid sequences within the Ancient Conserved Domain (ACD) are highly conserved in many different taxonomic species. Particularly, Acdp proteins showed very strong AA homologies to the bacteria CorC protein (35% AA identity with 55% homology), which is involved in magnesium and cobalt efflux. The Acdp genes are widely expressed in all tissues tested except for Acdp1, which is only highly expressed in the brain with low levels of expression in kidney and testis. Immunostaining of Acdp1 in hippocampus neurons revealed a predominant localization on the plasma membrane. CONCLUSION: The Acdp genes are evolutionarily conserved in diverse species and ubiquitously expressed throughout development and adult tissues suggesting that Acdp may be an essential gene. Acdp showed strong homology to bacteria CorC protein and predominantly localized on the plasma membrane. These results suggest that Acdp is probably a family of proteins involved in ion transport in mammalian cells
    • Molecular Mechanisms of High Glucose-Induced Vascular Endothelial Growth Factor Expression in Retinal Endothelial Cells

      Platt, Daniel H.; Vascular Biology Center (2004-10)
      Studies in diabetic patients, experimental animal models and tissue culture cells treated with high glucose have shown a close association between pathologic vascular growth, over-expression o f the angiogenic factor vascular endothelial growth factor .5 (VEGF) and oxidative stress. Studies o f diabetic patients and high glucose treated cells have also shown increased levels o f tyrosine nitration, a marker for the formation o f the reactive nitrogen species peroxynitrite. Excess formation o f reactive oxygen/nitrogen species has been shown to activate two transcription factors that regulate the expression o f VEGF, hypoxia-inducible factor-1 (HIF-1) and signal transducer and activator o f transcription 3 (STAT3). These observations suggest that diabetes causes increases in VEGF expression due to the effects o f high glucose in stimulating the formation o f peroxynitrite, which leads to the activation o f the transcription factors HIF-1 and/or STAT3 and increases in VEGF expression. This hypothesis was tested by experiments using primary cultures o f retinal endothelial cells treated with peroxynitrite or high glucose. Both treatments increased VEGF mRNA and protein levels. Further, pretreatment with the specific peroxynitrite decomposition catalyst FeTPPs blocked the increase in VEGF expression. To determine if HIF-1 and/or STAT3 play a role in the peroxynitrite-induced VEGF expression, studies were done to analyze the activation patterns o f both transcription factors. These studies showed that peroxynitrite had no effect on the activation or nuclear translocation o f HIF-1 a , but did induce a rapid activation and nuclear translocation o f STAT3. To further explore the role o f STAT3 in the VEGF expression, cells were treated with peroxynitrite or high glucose in the presence or absence o f an adenoviral vector expressing dominant-negative STAT3. Overexpression o f the dominant-negative STAT3 blocked the effects o f either peroxynitrite or high glucose in increasing VEGF mRNA. Further, treatment with FeTPPS blocked the effects o f high glucose in stimulating activation o f STAT3. A non-receptor tyrosine kinase, cSrc, has been shown to play a role in the activation o f STAT3 as well as the induction o f VEGF expression during tumor angiogenesis. To determine if cSrc plays a role in STAT3 regulated VEGF transcriptional activation, retinal endothelial cells were transduced with an adenovirus over-expressing a constitutively active Src (vSrc). The vSrc transduction induced activation o f STAT3 and increased VEGF expression. Further, FeTPPs blocked the effects o f peroxynitrite and high glucose in stimulating activation o f cSrc. Additionally, the Src inhibitor PP1 blocked the effects o f peroxynitrite and high glucose in increasing VEGF mRNA and protein expression. This work is the first to show that 1) high glucose-induced peroxynitrite formation increases VEGF expression, 2) STAT3 activation by high glucose-induced peroxynitrite formation regulates VEGF expression and 3) cSrc activation by high glucose-induced peroxynitrite formation activates STAT3 and increases VEGF expression.
    • Molecular Mechanisms Underlying ATP- And Adenosine Induced Microvascular Endothelial Barrier Preservation

      Batori, Robert; Vascular Biology Center (2016-03)
      Endothelial barrier integrity has critical importance in vascular homeostasis. Disruption of the endothelial cell (EC) barrier results in increased vascular permeability. Extracellular purines, ATP and adenosine (Ado) can restore the barrier function, involving the activation of myosin light chain phosphatase (MLCP). Both ATP and Ado increase protein kinase-A (PKA) activity, however a direct link between purine-induced EC barrier enhancement, MLCP and PKA was not described. Here we show that Ado and a stable analog of ATP, ATPγS, induced human lung microvascular EC (HLMVEC) barrier enhancement and PKA activation leads to decrease in MLC and MYPT1T696 phosphorylation. Surprisingly, PKA catalytic subunit (PKAc) depletion attenuates ATPγS, but not Ado-induced increase in transendothelial electrical resistance (TER), indicating that PKA activation is involved in ATP-induced EC barrier enhancement. Depletion of PKAc leads to increase in MLC and MYPTT696 phosphorylation in ATPγS challenged EC supporting the role of PKA in MLCP activation. To elucidate the role of PKA signaling in ATP-induced EC barrier enhancement we depleted several PKA-anchoring proteins (AKAPs). AKAP2 depletion attenuates ATPγS, but not Ado-induced TER increase. Furthermore, AKAP2 co-immunoprecipitates with MYPT1. This interaction was also confirmed by PLA. In conclusion ATP- and Ado-induced barrier enhancement requires different signaling with PKA promoting ATP-, but not Ado-induced EC barrier strengthening.
    • Myr 8: The First Member of a Novel Myosin Class Is Expressed During Brain Development

      Patel, Krishna G.; Institute of Molecular Medicine and Genetics (2000-05)
      Neuronal cell migration and cellular differentiation, major phases in the assembly process o f the mammalian neocortex, involve considerable organelle and cellular motility. While the cytoskeletal organization of migrating neurons is well documented, and the involvement of the cytoskeleton in modulating intracellular membrane transport events during neuronal cell differentiation is well appreciated, identification of selective cytoskeletal components underlying these processes is only beginning to emerge. Observations over the past two decades reveal that myosin motors are involved intimately in multiple actin-dependent membrane movements, including vesicular trafficking, organelle localization and organization, endocytosis, exocytosis, phagocytosis, lamellopodial extension, and the more classically defined functions such as cytokinesis, contractility, and cell motility or migration. Accordingly, our studies have been directed toward the identification and characterization of unconventional myosins that may participate in neuronal cell migration and/or differentiation events within the developing mammalian brain. Our analyses identified two myosin isoforms that contribute to a novel unconventional myosin class. We have cloned, sequenced, and designated these myosin isoforms as myr 8a and 8b (8th unconventional myosin from rat). Structurally, the head domain o f myr 8 contains a large N-terminal extension composed of multiple ankyrin repeats similar to myosin phosphatase. The motor domain is followed by a single putative light chain binding domain. The tail domain of myr 8a is comparatively shortwith a net positive charge, whereas the elongated tail domain of myr 8b bears an overall neutral charge and reveals several streches o f poly-proline residues. Phylogenetic analysis indicates that myr 8 is sufficiently divergent from known myosins as to comprise a new class of myosins. Northern analyses demonstrate that the m yr 8 myosins are expressed predominantly in the nervous system, and are detected principally at developmental timeperiods. Indirect-im munofluorescent studies reveal a pattern of im m unoreactivity within forming neuronal and astroglial cell processes located throughout the developing brain. Taken together these data suggest that this novel myosin may play a crucial role in membrane biogenetic events during neuronal and astroglial cell differentiation. Given the increasing identification of neurological dysfunctions that arise as a consequence of defective myosins, as well as from other cytoskeletal components, it is essential to unravel the selective roles in which this novel unconventional myosin may participate during neocortical development.
    • Narcan (naloxone nasal spray) availability in Georgia retail pharmacies

      Johnson, J. Aaron; Chung, Yunmi; Covington, Katherine; Augusta University (2018)
    • Neural population-level memory traces in the mouse hippocampus.

      Chen, Guifen; Wang, Lei Phillip; Tsien, Joe Z.; Brain & Behavior Discovery Institute; Department of Neurology (2009-12-17)
      One of the fundamental goals in neurosciences is to elucidate the formation and retrieval of brain's associative memory traces in real-time. Here, we describe real-time neural ensemble transient dynamics in the mouse hippocampal CA1 region and demonstrate their relationships with behavioral performances during both learning and recall. We employed the classic trace fear conditioning paradigm involving a neutral tone followed by a mild foot-shock 20 seconds later. Our large-scale recording and decoding methods revealed that conditioned tone responses and tone-shock association patterns were not present in CA1 during the first pairing, but emerged quickly after multiple pairings. These encoding patterns showed increased immediate-replay, correlating tightly with increased immediate-freezing during learning. Moreover, during contextual recall, these patterns reappeared in tandem six-to-fourteen times per minute, again correlating tightly with behavioral recall. Upon traced tone recall, while various fear memories were retrieved, the shock traces exhibited a unique recall-peak around the 20-second trace interval, further signifying the memory of time for the expected shock. Therefore, our study has revealed various real-time associative memory traces during learning and recall in CA1, and demonstrates that real-time memory traces can be decoded on a moment-to-moment basis over any single trial.
    • Neuropathology of Anxiety Disorders Comorbid with Alcohol Dependence

      O'Connor, Tara; Keough, Kelsey; Layton, James; Carpenter, Timothy; Crethers, Danielle; Patton, Tadd; Vazdarjanova, Almira; College of Science and Mathematics (2015-08-11)
      Anxiety disorders commonly occur along with other mental or physical illnesses, including alcohol use disorders (AUDs). Like most coexisting disorders, treatment for individuals who suffer from an anxiety disorder and an AUD is particularly challenging, contributing to an increased risk for suicide attempts, more intense withdrawal symptoms, and a higher probability of alcoholism relapse. Previous research has shown that a dysregulation of certain neuronal plasticity-related events in the prefrontal cortex (PFC) is implicated in anxiety disorders and alcohol dependence. However, the exact role this dysregulation plays in the comorbidity of these disorders is not well understood. The experiments conducted here were part of a larger study aimed at understanding the neuropathological characteristics present when anxiety disorders and AUDs coexist. We examined anxiety-like behavior and plasticity-related activity in the brains of rats bred to consume large or small quantities ethanol. After obtaining a prestress baseline of alcohol drinking behavior, rats were exposed to a standard shock procedure in which a mild footshock (paired with a tone) was administered. Drinking activity and anxiety-like behavior were assessed on multiple days following footshock. The rats were then euthanized so that the brains could be examined for activation of plasticity-related activity in the PFC. Significant differences in alcohol consumption and anxiety-like behavior were observed between alcohol-preferring and alcohol-non-preferring rats and are discussed in relation to drinking alcohol as a means to reduce anxiety. These findings will be included in our larger study and will ultimately lead to a better understanding of the neuropathological substrates associated with comorbid anxiety disorders and AUDs.
    • Neurotransmitter Gases as Modulators of GnRH and the Preovulatory LH Surge

      Lamar, Charisee; Institute of Molecular Medicine and Genetics (1998-04)
      Until recently nitric oxide (NO) and carbon monoxide (CO) were viewed only as toxic substances. However, there has been a substantial amount of evidence in the past decade that has redefined these gaseous molecules as physiological messengers. Along these lines, NO and CO are now recognized as modulators of immunological defense, vasodilation, endocrine signaling, and neurotransmission (1-8). As neurotransmitters, NO and CO are unique when compared to classical neurotransmitters. For instance, unlike all other classical neurotransmitters NO and CO are, 1) lipophilic gases with short half lives, 2) not stored in synaptic vesicles, 3) their effects are not mediated through classic receptor proteins - rather their effects result from NO and CO binding to the heme moiety of heme-proteins such as guanylate cyclase and cyclooxygenase, and 4) their effects are terminated by diffusion from target tissues ( 1,2,5,7,9). Production of NO and CO relies on the activity of the enzymes nitric oxide synthase (NOS) and heme oxygenase (HO), respectively. NOS uses the substrate Larginine to generate NO (2, 10), while HO uses the substrate heme to generate CO (9,11-16). NOS exists as three isoforms, macrophage NOS (mNOS), endothelial NOS (eNOS), and neuronal NOS (nNOS) (17-21). HO also exists as three isoforms, heme oxygenase-1 (HO-1), heme oxygenase-2 (HO-2), and heme oxygenase-3 (HO-3) HO-1 is inducible, while HO-2 and HO-3 are constitutive enzymes; however, HO-3 is currently viewed as a poor heme catalyst (12,13,22). There is a growing body of evidence that suggests that NO and CO regulate hypothalamic function. For example, recent studies have shown that the hypothalamus produces significant quantities of NO, primarily through the actions of nNOS (23,24). Likewise, the hypothalamus possesses one of the largest production rates of CO in the brain (25,26). That NO and CO can regulate neurohormone release from the hypothalamus is evidenced by findings demonstrating that NO and CO regulate corticotropin-releasing hormone (CRH) (27-33), vasopressin (29-31,34,35), and oxytocin secretion (29,36). With respect to reproductive function, numerous studies (23,37-45) have provided evidence for a significant role of NO in the control of the hypothalamic releasing factor, gonadotropin-releasing hormone (GnRH). For instance, it has been demonstrated (37,46,47) that NO neurons are located in close proximity to GnRH generating cells bodies in the hypothalamus and thus strategically located to exert regulatory effects over GnRH neurons. That NO can exert regulatory effects on GnRH neurons was demonstrated in studies where exogenously applied NO markedly stimulated GnRH release from male hypothalamic fragments (1,48,49) and immortalized GnRH (GT1-7) cells in vitro (1,48). A physiological role for NO in the steroid-induced luteinizing hormone (LH) surge has been suggested based on studies in which the LH surge was attenuated by the administration of NOS inhibitors (43,44) or NOS antisense oligonucleotides (38) No studies, however, have reported nNOS mRNA, protein, or NOS activity levels in the hypothalamus during the LH surge so as to verify that an increased NO tone actually occurs during this critical time. To address this deficit, Aim 1 of this study was designed to examine NO tone on proestrus in the cycling female rat-the day the natural preovulatory LH surge occurs. Since heme oxygenase, the enzyme that produces CO from heme molecule metabolism, is located in the hypothalamus (2,11,12,14,15), and CO production in the hypothalamus is one of the highest in the brain (25,26), it is conceivable that CO could play a role in regulating GnRH secretion. This possibility has not been investigated and thus studies on this issue appear warranted. Therefore, Aims 2-4 of this study were designed to assess the possible role of CO in the control of GnRH and LH secretion.