• Bilateral Hand-Assisted Laparoscopic Renal Surgery in the Supine Position: The Spleen at Risk

      Brown, James A.; Siddiqi, Kashif; Department of Surgery (2011)
      Objective
    • Binge-Pattern Alcohol Exposure during Puberty Induces Long-Term Changes in HPA Axis Reactivity

      Przybycien-Szymanska, Magdalena M.; Mott, Natasha N.; Paul, Caitlin R.; Gillespie, Roberta A.; Pak, Toni R.; Brann, Darrell W; Department of Neurology; College of Graduate Studies (2011-04-13)
      Adolescence is a dynamic and important period of brain development however, little is known about the long-term neurobiological consequences of alcohol consumption during puberty. Our previous studies showed that binge-pattern ethanol (EtOH) treatment during pubertal development negatively dysregulated the responsiveness of the hypothalamo-pituitary-adrenal (HPA) axis, as manifested by alterations in corticotrophin-releasing hormone (CRH), arginine vasopressin (AVP), and corticosterone (CORT) during this time period. Thus, the primary goal of this study was to determine whether these observed changes in important central regulators of the stress response were permanent or transient. In this study, juvenile male Wistar rats were treated with a binge-pattern EtOH treatment paradigm or saline alone for 8 days. The animals were left undisturbed until adulthood when they received a second round of treatments consisting of saline alone, a single dose of EtOH, or a second binge-pattern treatment paradigm. The results showed that pubertal binge-pattern EtOH exposure induced striking long-lasting alterations of many HPA axis parameters. Overall, our data provide strong evidence that binge-pattern EtOH exposure during pubertal maturation has long-term detrimental effects for the healthy development of the HPA axis.
    • Biocompatibility and mechanical/physical properties of 3D printed, milled, and conventionally processed denture base materials

      Ulmer, Mallory; Biomedical Sciences (Augusta University, 2019-12)
      According to the American College of Prosthodontists, over 36 million people in the USA are edentulous with a 2:1 predilection for geriatric patients1. Each year, an estimated 15% of edentulous Americans will seek denture treatment1. Conventional dentures require multiple visits and lab processing time. 3D printing technology offers the potential to reduce the number of appointments and speed up the time until patient rehabilitation. However, the newly FDA-certified 3D printer denture resins, featuring secretive and proprietary formulae, lack studies concerning their biocompatibility/safety and mechanical strength. This study aims to investigate the biocompatibility and physical properties of one such 3D printer resin, NextDent® Base (Vertex, Soesterberg, The Netherlands), and compare it to pre-existing conventional polymethyl methacrylate (PMMA) denture base (Lucitone 199, Dentsply Sirona, York, Pennsylvania) and milled PMMA denture base (IvoBase CAD®, Ivoclar Vivadent AG, Schaan, Liechtenstein). The cytotoxicity was examined using of 12 discs: conventional PMMA, milled PMMA, as-printed 3D printer resin, post-cured 3D printer resin, and Teflon controls. An MTT assay using human periodontal ligament (900L) cells was employed, and specimens were aged for 1, 3, 7, 10, and 14 days. After day 7, there were no statistically significant differences among the groups, excluding the Teflon control, which showed significantly less cell viability on day 14. Bars of conventional PMMA, milled PMMA, as-printed 3D printer resin, and post-cured 3D printer resin were subjected to a 3-point bend test to examine flexural strength and moduli differences. The mean flexural strength was 63.8 ± 3.06, 82.6 ± 1.9, 5.1 ± 0.4, and 22.1 ± 6.4 MPa, respectively, while the flexural moduli were 1757.3 ± 109.5, 2226.7 ± 76.3, 110.3 ± 20.3, and 537.0 ± 210.6 MPa, respectively. The flexural strength and modulus were significantly different among all groups. Weibull analyses for conventional PMMA, milled PMMA, as-printed 3D printer resin, and post-cured 3D printer resin revealed a Weibull modulus of 23.5, 42.8, 16.6, and 3.7, respectively, and a characteristic strength of 65.2, 83.5, 5.3, and 24.5 MPa, respectively. The characteristic strength was significantly different among all groups as well. The Weibull modulus was significantly different between all groups, except for conventional vs. as-printed, which were not significantly different. In summary, milled PMMA featured significantly greater mechanical properties. Both 3D printed groups proved to be very weak, with the as-printed group being the weakest of all. The differences between the as-printed and post-cured groups highlight the importance of properly post-curing the resin. While the biocompatibility results showed promise, the mechanical testing results were disappointing. Unfortunately, the findings suggest that 3D-printed denture base resin is not yet ready for clinical use.
    • Biomechanical behavior related to structure in normal and congenitally disordered elastic arteries

      Beall, Arthur C.; Department of Pharmacology and Toxicology (Augusta University, 1992-12)
    • Bionanofabrication: engineering biomaterials for in situ remodeling and drug delivery

      Batt, Carl A.; Cornell University (2016-02-26)
      The bionanofabrication of smart materials presents opportunities in fields as far ranging as food science and medicine. The tools of molecular biology allow for the in vivo and in vitro production of unique biomolecules enabling not only the direct(ed) creation of novel proteins but also catalysts that can then produce other non-protein polymers. An example is the biodegradable polymer, polyhydroxyalkanoate (PHA), which is normally produced by a number of different bacteria. It is synthesized through a series of three enzymes but only one, polyhydroxalkanoate synthetase (PHAC) is required for the conversion of a soluble CoA-substrate into an insoluble hydrophobic polymer. Our laboratory has pioneered the in situ formation of PHA by engineering PHAC and targeting it toward fabricated and native substrates. Once on-site polymer formation can be initiated by introducing the substrate. Alternatively polymers can be formed in vitro and then delivered to the target site. Beyond the localized impact by the introduction of significant quantities of a highly hydrophobic polymer, PHA can also be used as a vehicle for the delivery of therapeutic drugs and once there release their cargo through its normal degradation process. Applications to cancer therapy and in situ engineering of microvasculature will be presented.
    • Biosynthesis and Modification of Helicobacter pylori Lipid A

      Stead, Christopher Michael; Department of Biochemistry and Molecular Biology (2010-05)
      The secondary acylation steps of Helicobacter pylori lipid A biosynthesis are poorly understood because H. pylori only has one homolog (Jhp0265) to the Escherichia coli secondary acyl transferases LpxL and LpxM. Jhp0265 was shown to be responsible for the transfer of a secondary C18 acyl chain to the 2′-linked acyl chain of lipid A, making Jhp0265 homologous to LpxL. An activity was also demonstrated for the addition of a secondary acyl chain to the 3′-linked acyl chain of H. pylori lipid A, although the enzyme responsible for the transfer remains unknown. After synthesis, H. pylori lipid A is modified by the action of five enzymes. Mutation of the candidate modification enzyme Jhp0634 demonstrated that the enzyme catalyzes the removal of the 3′-linked acyl chains of H. pylori lipid A, producing a tetra-acylated lipid A species. Continuing with the characterization of H. pylori lipid A modification enzymes, we were also able to demonstrate an activity for a Kdo trimming enzyme in vitro. Requirement for a Kdo hydrolase in vivo was confirmed after the Kdo transferase of H. pylori was shown to be bifunctional despite the presence of only one Kdo sugar in H. pylori lipopolysaccharide. Attempted identification of the Kdo hydrolase revealed that both Hp0579 and Hp0580 were required for the removal of the Kdo sugar, which occurred in the periplasm. A Kdo hydrolase mutant revealed two unexpected phenotypes related to interaction with the innate immune system. The first was an increased sensitivity to cationic antimicrobial peptides, which was explained by a downstream effect on modification to the 4′- phosphate group of lipid A. The second phenotype related to the expression of Oantigen on the bacterial cell surface. The Kdo hydrolase mutants produced a reduced amount of fully extended lipopolysaccharide and conversely, an increased amount of core-lipid A. The type of O-antigen epitope displayed was also affected by a Kdo hydrolase mutation, in a strain specific manner.
    • Biosynthesis of the Vibrio cholerae Kdo-lipid A Domain and its Role in Pathogenesis

      Hankins, Jessica V.; Department of Biochemistry and Molecular Biology (2011-05)
      Bacteria assemble remarkable surface structures that interface with their surrounding environment. One such structure is the glycolipid lipopolysaccharide (LPS) that covers the surface of Gram-negative bacteria. LPS is anchored to the bacterial cell by its lipid anchor known as lipid A. Since lipid A is the bioactive component of LPS, modulation of its structure can have a profound impact on disease by altering the host immune response. Additionally, LPS structure directly impacts the outer membrane permeability barrier and bacterial resistance to host antimicrobial peptides. Although the lipid A domain of Escherichia coli has been well characterized, the Vibrio cholerae lipid A biosynthetic pathway has received little attention. The late stages of lipid A biosynthesis include the transfer of the 3-deoxy-Dmanno- octulosonic acid (Kdo) sugars and the secondary acyl chains to the lipid A backbone. Here, the V. cholerae Kdo transferase (Vc0233) was shown to be monofunctional, transferring one Kdo residue to the lipid A precursor, lipid IVA. V. cholerae encode a Kdo kinase (Vc0227) responsible for the phosphorylation of the Kdo residue. The functionality of Vc0227 was shown to be required for the activity of the V. cholerae lipid A LpxL homologue, Vc0213. Interestingly, the addition of the phosphate group on the Kdo sugar was shown to be essential for lipid A secondary acylation in Haemophilus influenzae and Bordetella pertussis. Vc0213 was shown to catalyze the transfer of a myristate (C14:0) to the 2′-position of the V. cholerae phosphorylated Kdolipid A domain. A second protein, Vc0212, acts as an LpxM homologue and transfers 3- hydroxylaurate (3-OH C12:0) to the 3′-position creating hexa-acylated V. cholerae lipid A domain. Although lipid A secondary acyltransferases have been characterized among various Gram-negative bacteria, this is the first report of a lipid A secondary hydroxyacyltransferase. Further, the transfer of 3-hydroxylaurate (3-OH C12:0) was demonstrated to be essential for antimicrobial peptide resistance in V. cholerae and required for activation of the innate immune receptor TLR4.
    • Bisphenol A (BPA) Contamination in Yellow-Bellied Sliders (Trachemys scripta scripta)

      McDavid, Kayla; Department of Biological Sciences (Augusta University, 2017-05)
      Bisphenol A, also known as BPA, is a chemical that is recognized for being in a variety of consumer products, particularly to make plastic food containers and drink bottles (Makinwa, 2015). It was estimated in 2011 that about 5.5 million metric tons of BPA have been consumed globally (Flint, 2011). This is cause for alarm because it is classified as moderately toxic to aquatic life by the Environmental Protection Agency (EPA) (Flint, 2011). BPA can negatively affect gene expression and hormone pathways. It is also known for triggering sex changes during embryonic stages in turtles and caiman (Flint, 2011). A major source of BPA is littering of plastics, which enter ponds and wetlands and may become incorporated into the food web of aquatic species (Campani, 2013). When plastic products degrade, BPA is leached into the soil and can potentially flow into neighboring waterways (Makinwa, 2015). Animals acquire BPA through direct ingestion of plastic particles or through consuming plants or animals that have accumulated BPA. Previous research has shown that Bisphenol A acts as an endocrine disruptor on painted turtles, caiman, fish, and amphibians (Jandegian, 2015). It mimics the hormone estrogen, which at sufficient concentrations, may cause developing male embryos to produce female reproductive tissue. Snails have been observed to undergo “superfeminization” when exposed to about 1 μg/L (Flint, 2011). This superfeminization caused “additional female organs, enlarged sex organs, and oviduct deformities” (Flint, 2011). There is evidence that Bisphenol A causes feminization in most animals that have been studied, although the mechanism has yet to be found (Krüger, 2005). Turtles are often used as environmental indicators because they are omnivorous and tend to be long-lived. Their longevity makes them more likely than short-lived species to bioaccumulate toxins.If BPA concentrations are high in turtles, then it is likely that humans have absorbed a certain amount that may contribute to unknown biological consequences. Research has shown that there are links between this contaminant and the rates of cancer development, obesity, and the probability of a child developing neurological problem when exposed. According to the analysis of 315 urine samples “93% of people had detectable levels of BPA” (Kinch, 2015). The objective of my research was to quantify BPA concentrations in Yellow-bellied sliders (Trachemys scripta scripta) and their habitat. Blood samples were collected from the subcarapacial or dorsal coccygeal vein of each turtle captured. Additionally, soil samples were taken at the edge of the water. Study Areas Blood samples were collected from 9 turtles trapped at Reed Creek Park. Additional samples were collected from 22 turtles from Brick Pond Park. Reed Creek Park is in Martinez, Georgia (33.53375598, -82.08555523) (Google maps, 2016). Brick Pond Park is in North Augusta, South Carolina (33.4874273, -81.9786814) (Google maps, 2016). Ten soil samples were collected at each location. The soil samples were analyzed for BPA quantities and compared with the amounts of BPA that were recorded from the blood samples taken from the captured turtles. [Introduction]
    • Bisphosphonate-Related Osteonecrosis of the Jaw: From Mechanism to Treatment

      Howie, Rebecca; Department of Cellular Biology and Anatomy (2015-04-20)
      With 55 million prescriptions issued each year, bisphosphonates are the second most prescribed class of drug in the United States. They are widely used to treat diseases with excessive osteoclastic resorption, including post-menopausal osteoporosis, Paget’s disease, and tumor metastasis to bone. Unfortunately, with long term intravenous administration of nitrogen-containing bisphosphonates some patients develop bisphosphonate-related osteonecrosis of the jaw (BRONJ). This debilitating disease has limited treatment options once it has manifested and no mechanism for its development has been elucidated. This dissertation explores the novel concept that bisphosphonates cause osteonecrosis of the jaw by impairing osteocyte-induced osteoclastogenesis and, through the physical accumulation of bisphosphonates in bone, impairing the ability of recruited osteoclasts to attach thereby arresting bone healing. Furthermore, it explores the possibility that chelating agents can be used for the removal of bisphosphonate attachment from bone systemically and locally during extractions, potentially leading to a future preventive treatment. It was found that 13 weeks of 80µg/kg intravenous tail vein injections of Zoledronate followed by two mandibular molar extractions caused the clinical presentation of BRONJ as analyzed by the gross, radiographic, and histological methods. Bone dynamic parameters and TRAP staining suggested an impaired ability for the bone to remodel and defective osteoclast attachment in treated groups that persisted eight weeks after the cessation of treatment. Additionally, it was found through the use of a fluorescently tagged bisphosphonate, that the decalcifying agents cadmium, EDTA, and citric acid all had the ability to cause the significant release of bound bisphosphonate from bone. Finally, this dissertation showed that the migration of monocytes treated with low doses of Zoledronate had increased migration, while their migration to conditioned media of osteocytes treated with Zoledronate was impaired. Collectively, these data suggest that invasive trauma by itself consistently precipitated massive bone necrosis in Zoledronate treated animals, possibly through a bisphosphonate driven alteration of monocyte migration and that the use of decalcifying agents could acutely remove bisphosphonate from bone both systemically and locally. This study establishes and effective rodent model for BRONJ and a possible preventive strategy for the side-effects of bisphosphonates during high-risk situations.
    • Blinding Crystals: Monosodium Urate Crystals and Diabetic Retinopathy

      Amanamba, Udochukwu; Department of Psychological Sciences (Augusta University, 2020-12)
      Diabetic retinopathy (DR) is a common complication of diabetes and the main cause of blindness among adults of working age. Previous studies have established that high blood glucose levels (hyperglycemia) promote chronic sub-clinical inflammation which in turn causes retinal tissue injury and development of DR. It has also been shown that increased levels of uric acid, a by-product of the purine metabolism, generates crystals of monosodium urate (MSU) which could contribute to retinal inflammation and to the development of DR. My honors thesis project focused on investigating the molecular basis of inflammation in diabetic retinopathy (DR), specifically how MSU stimulates sterile inflammation in retinal blood vessels cells and in other retinal cells through the induction of the NLRP3-inflammasome. Human retinal endothelial (HuREC) and Human retinal epithelial cells (HuRPE) were treated with clinically relevant doses of MSU (6mg/dL) or high glucose (HG 25mM) or a combination of both. The expression of NLRP3 inflammasome constituents such as IL-1, NLRP3 protein, Toll-like receptor (TLR4), Gasdermin D (GSDMD) and Thioredoxin-interacting protein (TXNIP) were monitored using Western blotting analysis and ELISA assay. Morphometric analysis and ANOVA statistical approaches were employed to analyze the data. The results obtained showed that HuREC are more responsive to MSU alone than HuRPE. However, in all conditions, MSU significantly potentiated the production of inflammatory constituents of the NLRP3 inflammasome. Overall, the results of my studies support MSU as a contributing factor to the pathogenesis of DR. This suggests that uricemia should be monitored in diabetic patients and hypouricemic drugs could be helpful in combating DR and vision loss in diabetic patients.
    • Blood lead level and risk of asthma.

      Joseph, Christine L.M.; Havstad, Suzanne L; Ownby, Dennis R; Peterson, Edward L; Maliarik, Mary; McCabe, Michael J; Barone, Charles; Johnson, Christine Cole; Department of Pediatrics (2005-07-08)
      Asthma and lead poisoning are prevalent among urban children in the United States. Lead exposure may be associated with excessive production of immunoglobulin E, possibly increasing asthma risk and contributing to racial disparities. The objective of this study was to examine racial differences in the association of blood lead level (BLL) to risk of developing asthma. We established and followed a cohort prospectively to determine asthma onset, using patient encounters and drug claims obtained from hospital databases. Participants were managed care enrollees with BLL measured and documented at 1-3 years of age. We used multiple variable analysis techniques to determine the relationship of BLL to period prevalent and incident asthma. Of the 4,634 children screened for lead from 1995 through 1998, 69.5% were African American, 50.5% were male, and mean age was 1.2 years. Among African Americans, BLL > or = 5 and BLL > or = 10 microg/dL were not associated with asthma. The association of BLL > or = 5 microg/dL with asthma among Caucasians was slightly elevated, but not significant [adjusted hazard ratio (adjHR) = 1.4; 95% confidence interval (CI), 0.7-2.9; p = 0.40]. Despite the small number of Caucasians with high BLL, the adjHR increased to 2.7 (95% CI, 0.9-8.1; p = 0.09) when more stringent criteria for asthma were used. When compared with Caucasians with BLL < 5 microg/dL, African Americans were at a significantly increased risk of asthma regardless of BLL (adjHR = 1.4-3.0). We conclude that an effect of BLL on risk of asthma for African Americans was not observed. These results demonstrate the need for further exploration of the complex interrelationships between race, asthma phenotype, genetic susceptibilities, and socioenvironmental exposures, including lead.
    • Blood pressure impacts the renal T cell profile of male and female spontaneously hypertensive rats

      Tipton, Ashlee J.; Department of Physiology (2014-03)
      Of the 68 million Americans with hypertension, fewer than 46% have their blood pressure (BP) adequately controlled and women are more likely than men to have uncontrolled hypertension. This underscores the critical need for new treatment options; however, this is a challenge due to our lack of knowledge regarding the mechanism(s) driving essential hypertension. T cells have been implicated in hypertension in males. Prior to our work, the role of T cells in hypertensive females had been unexplored. We demonstrate that female spontaneously hypertensive rats (SHR) have a decrease in BP in response to an immunosuppressant, supporting an immune component to their hypertension. We further defined a sex difference in the renal T cell and cytokine profile in SHR. Female SHR have a more anti-inflammatory immune profile in their kidneys than males. To gain insight into the mechanisms mediating sex differences in the immune profile, male and female SHR were gonadectomized. Gonadectomy increased pro-inflammatory markers in both sexes and attenuated anti-inflammatory markers particularly in females. Therefore, while both male and female sex hormones promote an anti-inflammatory immune profile, female ii sex hormones contribute greater to their more anti-inflammatory profile, but do not explain the sex difference. To determine the impact of hypertension on the renal immune profile, experiments measured renal T cells and cytokines in hypertensive male and female SHR, normotensive Wistar Kyoto rats (WKY), and SHR treated with antihypertensive therapy. All T cells and cytokines measured were higher in SHR compared to the same sex WKY. Moreover, antihypertensive therapy decreased renal Tregs only in female SHR. These data suggest that increased BP in both sexes is associated with an increase in renal inflammation; however female SHR have a compensatory increase in renal Tregs in response to increases in BP. TGF-β is a key cytokine regulating Treg and Th17 differentiation and we found that female SHR express more TGF-β than males. Experiments assessed if female SHR possessed a sex hormone or BP-mediated increase in renal TGF- β corresponding with increases in Tregs. We determined that loss of female sex hormones and increased BP in female SHR increase renal TGF-β expression. We conclude that BP status drive sex differences in the renal T cell and cytokine profile of SHR.
    • Blurred Lines within the Music Industry: A Different Perspective of Copyright Law and Sampling in the Digital Age

      Wingate, Montrel; Department of History, Anthropology & Philosophy; Turner, Wendy; VanTuyll, Debra; VanTuyll, Hubert; Augusta University (2019-02-13)
      This thesis focuses on the relationship of music and law. Throughout, the debated question is: should the laws of copyright be redefined? The case Williams v. Bridgeport Music, Inc., which focuses on the songs "Blurred Lines" by Robin Thicke and "Got to Give It Up" by Marvin Gaye is the trial central to this thesis. Following a brief history of sampling, Williams v. Bridgeport Music, Inc. is reexamined, challenging the substantiality of the evidence presented. The court proved that the songs have similarities on the surface, yet there is a notable structural difference among the songs. A proposed solution is given, advocating a revision of copyright laws and a substantive similarity test with emphasis on the expert listener rather than the lay listener.
    • Blurred Lines within the Music Industry: A Different Perspective ofCopyright Law and Sampling in the Digital Age

      Wingate, Montrel; Department of History, Anthropology, & Philosophy (Augusta University, 2019-05)
      This thesis focuses on the relationship of music and law. Throughout, the debated question is: should the laws of copyright be redefined? The case Williams v. Bridgeport Music, Inc., which focuses on the songs "Blurred Lines" by Robin Thicke and "Got to Give It Up" by Marvin Gaye is the trial central to this thesis. Following a brief history of sampling, Williams v. Bridgeport Music, Inc. is reexamined, challenging the substantiality of the evidence presented. The court proved that the songs have similarities on the surface, yet there is a notable structural difference among the songs. A proposed solution is given, advocating a revision of copyright laws and a substantive similarity test with emphasis on the expert listener rather than the lay listener.
    • Boobi: An Eight-Part Teleplay

      Garcia, Jasmine; Department of Communications (Augusta University, 2017-12)
    • Bound Relativistic Motion in One Dimension

      Dains-McGahee, Sydney; Department of Mathematics (Augusta University, 2021-05)
      This project is a mathematical study of the relativistic dynamics of particles in one dimension moving under forces derivable from a potential. These motions and their nonrelativistic counterparts are described by Hamiltonian systems of differential equations. These Hamiltonian systems are in general nonlinear. Linear algebraic and differential equations are quite easy to solve – their solutions can be determined exactly – although the same cannot be said for nonlinear equations whose solutions can only be approximated (most of the time, with certain exceptions). We use numeric approximations to explore the relativistic and nonrelativistic simple harmonic oscillator and find that, unlike in the nonrelativistic case, the relativistic simple harmonic oscillator is not isochronous. We further study what happens to the period as the energy increases and then extend to exploring and comparing relativistic and nonrelativistic motions and periods for systems with forces given by power law potentials.
    • BrdU-positive cells in the neonatal mouse hippocampus following hypoxic-ischemic brain injury.

      Bartley, John H; Soltau, Thomas; Wimborne, Hereward J. C.; Kim, Sunjun; Martin-Studdard, Angeline; Hess, David C.; Hill, William D; Waller, Jennifer L.; Carroll, James E; Department of Pediatrics; et al. (2005-03-24)
      BACKGROUND: Mechanisms that affect recovery from fetal and neonatal hypoxic-ischemic (H-I) brain injury have not been fully elucidated. The incidence of intrapartum asphyxia is approximately 2.5%, but the occurrence of adverse clinical outcome is much lower. One of the factors which may account for this relatively good outcome is the process of neurogenesis, which has been described in adult animals. We used a neonatal mouse model to assess new cells in the hippocampus after H-I injury. RESULTS: Neonatal mice underwent permanent unilateral carotid ligation on the seventh postnatal day followed by exposure to 8% hypoxia for 75 minutes. The presence of new cells was determined by bromodeoxyuridine (BrdU) incorporation into cells with sacrifice of the animals at intervals. Brain sections were stained for BrdU in combination with neuronal, glial, endothelial and microglial stains. We found a significant increase in BrdU-positive cells in the neonatal mouse hippocampus in the injured area compared to the non-injured area, most prominent in the dentate gyrus (DG) (154.5 +/- 59.6 v. 92.9 +/- 32.7 at 3 days after injury; 68.9 +/- 23.4 v. 52.4 +/- 17.1 at 35 days after injury, p < 0.0011). Among the cells which showed differentiation, those which were stained as either microglial or endothelial cells showed a peak increase at three days after the injury in the DG, injured versus non-injured side (30.5 +/- 17.8 v. 2.7 +/- 2.6, p < 0.0002). As in the adult animal, neurogenesis was significantly increased in the DG with injury (15.0 +/- 4.6 v. 5.2 +/- 1.6 at 35 days after injury, p < 0.0002), and this increase was subsequent to the appearance of the other dividing cells. Numbers of new oligodendrocytes were significantly higher in the DG on the non-injured side (7.0 +/- 24.2 v. 0.1 +/- 0.3, p < 0.0002), suggesting that oligodendrocyte synthesis was reduced in the injured hippocampus. CONCLUSION: These findings demonstrate that the neonatal animal responds to brain injury with neurogenesis, much like the adult animal. In addition, H-I insult leads to more neurogenesis than hypoxia alone. This process may play a role in the recovery of the neonatal animal from H-I insult, and if so, enhancement of the process may improve recovery.
    • The c-MYC oncogene deregulates global DNA methylation and hydroxymethylation to control genome-wide gene expression for tumor maintenance in leukemia/lymphoma

      Poole, Candace Jean; Biomedical Sciences (Augusta University, 2019-05)
      Aberrant DNA methylation is a characteristic feature of tumor cells. However, our knowledge of how DNA methylation patterns are established and maintained to contribute to tumorigenesis is limited. Inactivation of the c-MYC oncogene triggers tumor regression in T-cell acute lymphoblastic leukemia (T-ALL) resulting in dramatic changes to the chromatin landscape including DNA methylation. In this study, I investigated how MYC regulates DNA methylation and hydroxymethylation patterns to contribute to gene expression programs important for tumor maintenance in T-ALL and Burkitt lymphoma. I report that MYC maintains 5-methylcytosine (5mC) and 5-hydroxy-methylcytosine (5hmC) patterns by regulating the DNA methylation machinery, which is important for gene expression in T-ALL. DNA methyltransferases (DNMTs) initiate 5mC marks, while Ten-eleven translocation methylcytosine dioxygenases (TETs) oxidize 5mC to produce 5hmC as an intermediate modification, ultimately leading to active DNA de-methylation. I demonstrated that DNMT1 and DNMT3B are MYC target genes and that their expression is dependent on high MYC levels. Knockdown of DNMT3B in T-ALL reduced cell proliferation through cell cycle arrest and caused the reactivation of gene transcription through reversing promoter/CpG island methylation. Furthermore, I demonstrated that TET1 and TET2 expression is MYC-dependent, as high TET1 and low TET2 levels depend on oncogenic MYC. Knockdown of TET1 in T-ALL reduced cell proliferation through cell cycle arrest and caused genome-wide changes in 5mC and 5hmC corresponding to changes in gene programs important for ribosomal biosynthesis and protein synthesis. In contrast, ectopic expression of TET2 reduced tumor cell proliferation through apoptosis/necrosis and caused genome-wide changes in 5mC and 5hmC corresponding to changes in transcriptional regulatory gene programs. My finding that a coordinated interplay between components of the DNA methylation machinery is necessary for MYC-driven tumor maintenance highlights the potential of targeting specific DNMT or TET proteins for therapeutic strategies.
    • Calpain-2 Activates Akt via the TGF~ 1-mTORC2 Pathway in Pulmonary Artery Smooth Muscle Cells

      Abeyrathna, Prasanna; Deparment of Pharmacology and Toxicology (8/23/2016)
      Calpain is a family of calcium-dependent nonlysosomal neutral cysteine endopeptidases. Akt is a serine/threonine kinase that belongs to the AGC kinases and plays important roles in cell survival, growth, proliferation, angiogenesis, and cell metabolism. Both calpain and Akt are downstream signaling molecules of platelet-derived growth factor (PDGF) and mediate PDGF-induced collagen synthesis and proliferation of pulmonary artery smooth muscle cells (PASMCs) in pulmonary vascular remodeling. We found that inhibition of calpain-2 using the calpain inhibitor MDL28170 and calpain-2 siRNA attenuated Akt phosphorylation at serine-473 (S473) and threonine-308 (T308) as well as collagen synthesis and cell proliferation ofPASMCs induced by PDGF. Overexpression of calpain-2 in PASMCs induced dramatic increases in Akt phosphorylation at S4 73 and T308. Moreover, knockout of calpain attenuated Akt phosphorylation at S473 and T308 in smooth muscle of pulmonary arterioles of mice with chronic hypoxic pulmonary hypertension. The cell-permeable specific TGF~ receptor inhibitor SB431542 attenuated Akt phosphorylation at both S473 and T308 induced by PDGF and overexpressed calpain- 2 in PASMCs. Moreover, SB-431452 and knock down of ALK5 significantly reduced PDGF-induced collagen synthesis and cell proliferation of PASMCs. Nevertheless, neutralizing extracellular TGF~l using a cell-impermeable TGF~l neutralizing antibody did not affect PDGF-induced Akt phosphorylation at S473 and T308. Further, inhibition of mTORC2 by knocking down its component protein Rictor prevented Akt phosphorylation at S473 and T308 induced by PDGF and overexpressed calpain-2. These data provide the first evidence supporting that calpain-2 up-regulates PDGF-induced Akt phosphorylation via an intracrine TGF~ 1/mTORC2 mechanism.