• 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.
    • 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.
    • Cellular and Molecular Mechanisms of Retinal Bipolar Regeneration in Zebrafish

      Ariga, Junko; Department of Pediatrics (2012-03)
      Human retinal degenerative diseases are characterized by slow progressive loss of retinal cells which induces reactive gliosis in Muller glia cells. In mammalian systems, this results in scar tissue formation which exacerbates loss of vision. Similar initial responses are observed following injury in highly regenerative species, such as zebrafish. However, Muller glia cells in these systems are capable of regenerating a functional retina. We are interested in determining how the regenerative potential of Muller glia cells is triggered and controlled. Thus, we are studying the cellular and molecular mechanisms governing how zebrafish regenerate specific retinal cell types. Ultimately, we seek to identify factors that could be harnessed to redirect mammalian Muller glia cells into regenerative pathways. Such insights could aid the development of regenerative therapies for degenerative diseases. Despite the relevance to disease, little is known about how the retina responds to loss of discrete cell types. Here, we focused on characterizing this paradigm to study four principle aspects of the regenerative process: 1) endogenous stem cell activation, 2) stem and progenitor cell proliferation, 3) progenitor cell differentiation, and 4) functional recovery. By studying all four of these aspects in relation to each other we were able to reveal fundamental insights into how retinal regeneration is governed. Specifically in Aim 1, we used transgenic and pharmacological techniques to induce ablation of /^-expressing retinal bipolar cell subtypes and asked whether the lost cells were subsequently regenerated in zebrafish larvae. We then sought to identify potential stem cell sources. In Aim 2, lineage tracing of retinal stem cell populations was used to ask whether the extent of bipolar cell loss altered the specificity of the regenerative response. In Aim 3, we manipulated the Wnt pathway to investigate the role of Wnt signaling in bipolar cell regeneration. Finally, in Aim 4 we used visual behavior assays to determine if functional deficits attend the loss of nyx-expressing bipolar cells and, if so, whether functional recovery was evident following their regeneration. In particular, our observations demonstrating opposing roles of the Wnt pathway in regeneration have implications regarding the development of age-appropriate and/or cell-specific regenerative therapies.
    • Characterization of a high-affinity, highly selective tryptophan transport system in the human macrophage and the effects of overexpression of tryptophanyl t-RNA synthetase on Jurkat proliferation

      Seymour, Robert L.; Department of Pediatrics (2004-04)
      Suppression of T cell activation by macrophages/dendritic cells via tryptophan degradation has been shown to play an important role in immunotolerance. Tryptophan degradation is carried out by the enzyme indolamine-2,3-dioxegenase (IDO). This model raises many questions. This study addresses two of these questions. First, how does the macrophage gain access to and degrade tryptophan to a level below 50 nM in culture medium? This is achieved despite the fact that the known high affinity tryptophan transport systems accept other amino acids and have Km values for tryptophan ranging fi-om 10-100 pM. In this study we show that the macrophage possesses a high-affinity, highly selective, and Na-independent tryptophan transport system with a Km for tryptophan of about 300 nM. This would allow the macrophage to have effective access to tryptophan at concentrations in the nanomolar range. We also show T cells do not possess this transport system. Second, how does the T cell sense the level of intracellular free tryptophan? It has been shown in the past that if T cells are stimulated in medium containing less than SOOnM tryptophan that they attempt to activate but arrest in mid-Gl of the cell cycle. The enzyme tryptophanyl t-RNA S5mthetase (WRS) charges tRNA*'^ with tryptophan. This enzjmie has two protein isoforms, with one having a non-canonical N-terminal kinase domain. WRS is also upregulated by interferon gamma (IFNy). These characteristics put WRS in a position to be an intracellular free tryptophan sensor. Here we show that transient transfection of the T cell line, Jurkat, with cDNA encoding the kinase-containing isoform of WRS inhibits proliferation. In addition, to the above we have ereated a subline of Jurkat, which stably arrests in the absence of tryptophan. We also show that this new subline is resistant to the drug G418 but is sensitive to hygromycin. When treated with rapamycin the Jurkat sub line will stably arrest in the presence or absence of tryptophan. Rapamycin is a known immunosuppressive agent, which inhibits T cell proliferation. This leads to the speculation of a possible link between the signaling pathways involved in tryptophan sensing and those involved in the effects of rapamycin.
    • Characterization of the transcriptome profiles related to globin gene switching during in vitro erythroid maturation

      Li, Biaoru; Ding, Lianghao; Li, Wei; Story, Michael D; Pace, Betty S.; Department of Pediatrics (2012-04-26)
      Background: The fetal and adult globin genes in the human b-globin cluster on chromosome 11 are sequentially expressed to achieve normal hemoglobin switching during human development. The pharmacological induction of fetal g-globin (HBG) to replace abnormal adult sickle bS-globin is a successful strategy to treat sickle cell disease; however the molecular mechanism of g-gene silencing after birth is not fully understood. Therefore, we performed global gene expression profiling using primary erythroid progenitors grown from human peripheral blood mononuclear cells to characterize gene expression patterns during the g-globin to b-globin (g/b) switch observed throughout in vitro erythroid differentiation
    • Comparison of early-, late-, and non-participants in a school-based asthma management program for urban high school students

      Joseph, Christine L.M.; Saltzgaber, Jacquelyn; Havstad, Suzanne L; Johnson, Christine Cole; Johnson, Dayna; Peterson, Edward L; Alexander, Gwen; Couper, Mick P; Ownby, Dennis R; Department of Pediatrics (2011-06-6)
      Background: To assess bias and generalizability of results in randomized controlled trials (RCT), investigators compare participants to non-participants or early- to late-participants. Comparisons can also inform the recruitment approach, especially when working with challenging populations, such as urban adolescents. In this paper, we describe characteristics by participant status of urban teens eligible to participate in a RCT of a school-based, web-based asthma management program.
    • Disordered Eating Behavior in Individuals With Diabetes

      Young-Hyman, Deborah L.; Davis, Catherine L.; Department of Pediatrics; Georgia Institute for Prevention of Human Diseases and Accidents (2010-03)
    • FK228 Analogues Induce Fetal Hemoglobin in Human Erythroid Progenitors

      Makala, Levi HC; Di Maro, Salvatore; Lou, Tzu-Fang; Sivanand, Sharanya; Ahn, Jung-Mo; Pace, Betty S.; Department of Pediatrics (2012-05-14)
      Fetal hemoglobin (HbF) improves the clinical severity of sickle cell disease (SCD), therefore, research to identify HbF-inducing agents for treatment purposes is desirable. The focus of our study is to investigate the ability of FK228 analogues to induce HbF using a novel KU812 dual-luciferase reporter system. Molecular modeling studies showed that the structure of twenty FK228 analogues with isosteric substitutions did not disturb the global structure of the molecule. Using the dual-luciferase system, a subgroup of FK228 analogues was shown to be inducers of HbF at nanomolar concentrations. To determine the physiological relevance of these compounds, studies in primary erythroid progenitors confirmed that JMA26 and JMA33 activated HbF synthesis at levels comparable to FK228 with low cellular toxicity. These data support our lead compounds as potential therapeutic agents for further development in the treatment of SCD.
    • Healthy aging and disease: role for telomere biology?

      Zhu, Haidong; Belcher, Matthew; van der Harst, Pim; Department of Pediatrics; Georgia Institute for Prevention of Human Diseases and Accidents (2011-05-1)
      Aging is a biological process that affects most cells, organisms and species. Human aging is associated with increased susceptibility to a variety of chronic diseases, including cardiovascular disease, Type 2 diabetes, neurological diseases and cancer. Despite the remarkable progress made during the last two decades, our understanding of the biology of aging remains incomplete. Telomere biology has recently emerged as an important player in the aging and disease process.
    • Hybrid palliation of interrupted aortic arch in a high-risk neonate.

      Karimi, Mohsen; Farouk, Ahmed; Golden, Alex; Gilkeson, Robert; Department of Pediatrics (2010-09-03)
      We report a case of a high-risk neonate with interrupted aortic arch (IAA) and ventricular septal defect who underwent a successful hybrid palliative procedure using a ductal stent and bilateral branch pulmonary artery banding. This case represents not only a successful use of hybrid approach in high-risk neonates with IAA, but also introduces an alternative and safe access for ductal stent insertion through the right ventricular infundibulum.
    • Modulation of Tumor Tolerance in Primary Central Nervous System Malignancies

      Johnson, Theodore S.; Munn, David H.; Maria, Bernard L.; Department of Pediatrics; Immunotherapy Center; GHSU Cancer Center (2012-01-24)
      Central nervous system tumors take advantage of the unique immunology of the CNS and develop exquisitely complex stromal networks that promote growth despite the presence of antigen-presenting cells and tumor-infiltrating lymphocytes. It is precisely this immunological paradox that is essential to the survival of the tumor. We review the evidence for functional CNS immune privilege and the impact it has on tumor tolerance. In this paper, we place an emphasis on the role of tumor-infiltrating myeloid cells in maintaining stromal and vascular quiescence, and we underscore the importance of indoleamine 2,3-dioxygenase activity as a myeloid-driven tumor tolerance mechanism. Much remains to be discovered regarding the tolerogenic mechanisms by which CNS tumors avoid immune clearance. Thus, it is an open question whether tumor tolerance in the brain is fundamentally different from that of peripheral sites of tumorigenesis or whether it simply stands as a particularly strong example of such tolerance.
    • Non-invasive Biomarkers to Detect Acute Kidney Injury in Premature Infants

      Marin, Terri; Williams, Bryan; Bhatia, Jatinda; Sharma, Ashok; Mundy, Cynthia; Cockfield, Christy; College of Nursing; Department of Pediatrics: Neonatology; Department of Population Health Science; Department of Obstetrics and Gynecology; et al.
    • Novel Therapeutic Approaches to Leishmania Infection

      Makala, Levi HC; Baban, Babak; Department of Pediatrics; Department of Oral Biology (InTech, 2014-03-19)
      Leishmaniasis is a parasitic disease transmitted by phlebotomine sandflies. Approximately 1.2 million cases of cutaneous leishmaniasis (CL) and 500,000 cases of visceral leishmaniasis (VL), which is lethal if untreated, occur annually across the globe as per world health organization (WHO) estimates [1-3]. Current statistics and information relevant to leishmaniasis are summarized in Table 1. Leishmaniasis currently affects about 12 million people and it is estimated that approximately 350 million people live in risk of infection [1-3].The number of cases of leishmaniasis is probably underestimated because only 40 of the 88 countries where diseases frequently occur report them on a regular basis [4]. Leishmaniasis, is caused by several leishmania spp., that are obligate intracellular and unicellular kinetoplastid protozoan flagellate that establish themselves within the phagolysosome of host immune competent cells, especially macrophages and dendritic cells (DCs). In 1903, W.B. Leishman and C. Donovan reported this new parasite at the turn of the century [5,6]. Ronald Ross christened the new genus leishmania and the new species donovani in year 1903 [7]. L. major infection (leishmaniasis) in mice is a widely used model of human infection that has yielded critical insights into the immunobiology of leishmaniasis [8-10]. Leishmaniasis as a parasitic disease manifests itself mainly in 3 clinical forms; visceral leishmaniasis (VL), cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (MCL), of which VL is the most severe form of the disease. VL is lethal if untreated and spontaneous cure is extremely rare. Cutaneous leishmaniasis usually has milder course and often results into a self-healing of ulcers. Resolution of leishmanial infection is dependent on the coordinated interactions between components of cell mediated immune response, specifically the activation of targeted T-cell populations for appropriate cytokine production and activation of macrophages. L. major infection of B6 and BALB/c mouse strains drives predominantly TH1 and TH2 responses, respectively [11-14]. In murine model, the development of Th1 response is associated with control of infection, and Th2 response is associated with disease progression. However, Th1 and Th2 dichotomy in the human system is not as distinct as in mice and the murine model does not strictly apply to human leishmaniasis.
    • Review of Outcome Information in 46,XX Patients with Congenital Adrenal Hyperplasia Assigned/Reared Male: What Does It Say about Gender Assignment?

      Lee, Peter A.; Houk, Christopher Phil; Department of Pediatrics (2010-12-21)
      There is ample historical verification of 46,XX congenital adrenal hyperplasia (CAH) patients being born with essentially male genitaliawhile outcome information is scant. Prior to glucocorticoid therapy, most patients died very young from adrenal insufficiency. Most available reports from laterchildhood, contain little information concerning sexual identity. Reports on older individuals lack adequate information about sexual identity and quality of life. The difficulty in assessing the relative impact of multiple dynamic environmental factors on the development of sexual identity, self- and body esteem and overall adjustment to life is clear. Nevertheless, it remains unclear whether those infants whose masculine genitalia at birth resulted in an initial male assignment would have enjoyed a better adult outcome had they been allowed to remain male rather than the female reassignment that most received. Further, one could ask whether a male sex of rearing should be considered in 46,XX CAH infants with male external genitalia. After reviewing available literature, we conclude that because those extremely virlized 46,XX CAH patients who were reared male with healthy social support demonstrated satisfactory levels of social and sexual function as adults a male sex assignment should be considered in these types of infants when social and cultural environment are supportive.
    • The role of indoleamine 2, 3 dioxygenase in regulating host immunity to leishmania infection

      Makala, Levi HC; Department of Pediatrics (2012-01-9)
      Pathogen persistence in immune-competent hosts represents an immunological paradox. Increasing evidence suggests that some pathogens, such as, Leishmania major (L. major) have evolved strategies and mechanisms that actively suppress host adaptive immunity. If this notion is correct conventional vaccination therapies may be ineffective in enhancing host immunity, unless natural processes that suppress host immunity are also targeted therapeutically. The key problem is that the basis of pathogen persistence in immune-competent individuals is unknown, despite decades of intense research. This fact, coupled with poor health care and a dearth of effective treatments means that these diseases will remain a scourge on humans unless a better understanding of why the immune system tolerates such infections emerges from research. Indoleamine 2,3-dioxygenase (IDO) has been shown to act as a molecular switch regulating host responses, and IDO inhibitor drugs shown to possess potential in enhancing host immunity to established leishmania infections. It is hoped that this review will help stimulate and help generate critical new knowledge pertaining to the IDO mechanism and how to exploit it to suppress T cell mediated immunity, thus offer an innovative approach to studying the basis of chronic leishmania infection in mice.
    • The role of support groups, advocacy groups, and other interested parties in improving the care of patients with congenital adrenal hyperplasia: pleas and warnings.

      Lee, Peter A.; Houk, Christopher Phil; Department of Pediatrics (2010-07-23)
      In the era of advocacy groups, it seems appropriate to contemplate how best to utilize them for patient benefit in the management of those with disorders of sex development (DSD), including those with congenital adrenal hyperplasia (CAH). Such interactions, to be constructive, require a spirit of cooperation to optimize outcomes. A traditional view of advocacy groups as a type of defender of patients' rights appears outdated and it is time that the benefits of their participation be fully realized. Open dialogue with all patients/families, including those who feel harmed by prior care are paramount. We discuss several recent examples of interactions that illustrate how dialogue in the name of "advocacy" can have a negative impact on developing a framework for ongoing constructive dialogue and actions. Such approaches completely change the dynamics of subsequent interactions. Physicians involved in the care of individuals with DSD, including those with CAH, and patients should be aware of confrontational techniques and legal implications that may be used by some advocacy groups. Hopefully recent efforts to promote a multidisciplinary care approach for patients with DSD/CAH will continue to foster mutual cooperation between team members, where the common goal is improving patient/family outcomes and quality of life.
    • Sickle Cell Disease: Genetics, Cellular and Molecular Mechanisms, and Therapies

      Pace, Betty S.; Ofori-Acquah, Solomon F.; Peterson, Kenneth R.; Department of Pediatrics (2012-08-22)
    • Unnecessary Workup of Asymptomatic Neonates in the Era of Group B Streptococcus Prophylaxis

      Buckler, Brad; Bell, Jason; Sams, Ralph; Cagle, William; Bell, Sue Anne; Allen, Carla; Sutherland, Donald E.; Bhatia, Jatinder; Department of Pediatrics; Department of Pediatrics; et al. (2010-08-22)
      Asymptomatic term neonates born to mothers who are Group B Streptococcus (GBS) unknown or GBS positive but â inadequatelyâ treated prior to delivery do not require invasive laboratory evaluation. We conducted a retrospective cohort study of mother/baby dyads born from January 1, 2005 until September 30, 2007 at the Medical College of Georgia. Their current protocol is to obtain a Complete Blood Count with Differential (CBC with D), Blood Culture (BC), and C-reactive protein (CRP) after birth. Mother/baby dyads (n = 242) that met inclusion criteria were reviewed. Of these 242 babies 25 (10%) were started on antibiotics after the initial lab values were known. None of the blood cultures were positive and the CRP's were normal. The 2002 GBS guidelines call for laboratory evaluation of â at-riskâ neonates, but the workup of these babies is not only costly, it does not provide any advantage over old fashioned clinical observation for the evaluation and treatment of early onset GBS sepsis.