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Structural And Functional Analysis Of Secondary Structure Block To Mrna Utilization, Juan Lin

Loma Linda University Electronic Theses, Dissertations & Projects

Experimentally introduced secondary structure, formed by a cis-targeted hammerhead ribozyme in exon 2 two nucleotides dowstream of the 3' splice site of a yeast ACT-E. coli lacZ fusion gene, virtually abolishes splicing in vivo and inhibits B-galactosidase production. This is the first demonstration of the splicing inhibitory effect of secondary structures occurring in exons in the absence of splice site sequestration. Our goal is to understand the mechanism by which utilization of this splice site is impeded. Two cis - and one trans-acting mutations that alleviate the splicing blockage were obtained by screening for restoration of B-galactosidase activity. Both cis …

Diseased Thyrocytes Have Aberrant Communication And Tnf Receptor Secretion, Mary Labue

Loma Linda University Electronic Theses, Dissertations & Projects

Autoimmune diseases are a world-wide health concern and are an intense area of investigation. However, one area of research has been largely ignored. This involves the contribution of the target tissue to the disease process. We hypothesized that cell-cell communication is disrupted by lymphocytic infiltration and advancing fibrosis and this disruption results in altered target cell responses to immune components produced at the site of inflammation, including Tumor Necrosis Factor-alpha (TNF- α).

We have used thyroiditis as our model of autoimmunity and have documented the development of spontaneous thyroiditis in MRL-lpr/lpr mice. We have found aberrant connexin expression in …

Aberrant Communication And Protein Kinase C In Experimental Autoimmune Thyroiditis, Joyce P. Lazarus

Loma Linda University Electronic Theses, Dissertations & Projects

Autoimmune diseases are a worldwide healthcare concern. Research has focused mainly on the role of the immune system and genetic susceptibility to autoimmune disease. However, this study investigates altered target tissue properties and their contributions to the pathogenesis of induced autoimmune thyroiditis in Lewis rats. Our hypothesis was; inflammation-induced lymphocytic infiltration and subsequent fibrosis results in physical disruption of gap junctional communication in the target tissue contributing to the disease process. Our study of intercellular communication in experimentally-induced autoimmune thyroiditis (EAT) in Lewis rats revealed a deficiency in connexin expression, connexin assembly and dye transfer [(results corroborated in murine model …

An Animal Model For Development Of Pulpal Inflammation, John W. Masters

Loma Linda University Electronic Theses, Dissertations & Projects

Several animal models have been proposed to develop pulpal inflammation. Procedures recommended in these models have many variables and have not produced consistent results. The purpose of this study was to create pulpal inflammation using the Nd:YAG laser.

Forty-five cuspids of 12-18 month old beagle dogs were lased at 5, 7.5, and 10 watts (W) for 20 seconds with a 600 micron contact probe. Five cuspids were not lased but were used as controls. Following laser application, the teeth were extracted at intervals of 3, 7, and 30 days. They were then fixed in 10% formalin, decalcified, sectioned, and stained …

The Effects Of Zinc On Skeletal Alkaline Phosphatase Activity And Skeletal Tissues, Susan L. Hall

Loma Linda University Electronic Theses, Dissertations & Projects

Zinc is essential for normal growth, however, very little is known about the mechanisms by which zinc influences growth. ALP, an ectoenzyme expressed in high levels in osteoblasts, is a zinc-containing metalloenzyme and is important in bone formation. Preliminary studies showed that low levels of zinc could increase ALP specific activity in human osteosarcoma, SaOS-2 cells. Current studies were designed to characterize this zinc effect, test possible mechanisms, and determine whether the effect is physiologically relevant. Incubation with zinc resulted in a time and dose dependent increase in ALP specific activity in the extracts and conditioned media of SaOS-2 cells, …

Molecular Studies Of Restriction Genes In Enteric Bacteria, Obed B. Rutebuka

Loma Linda University Electronic Theses, Dissertations & Projects

Bacterial cells contain various restriction-modification (R-M) systems to protect themselves from incoming foreign DNA. Most bacteria have at least one such system. In this study, the restriction genes and the location of the genes on the chromosome were examined in three enteric bacteria. Salmonella typhimurium LT2, Klebsiella pneumoniae GM 236, and Klebsiella pneumoniae M5al. The 98 minute region of the Salmonella typhimurium LT2 chromosome comprises at least two R-M systems. From genetic data this region was previously thought to be only one minute in length but was found to be larger than two minutes using a physical mapping technique, pulsed …

In Vitro Plaque Formation On Orthodontic Resin Sealants, Leland W. Pack

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of this study was to examine in vitro plaque formation on sealant coated enamel. The plaque growth on different types of sealants placed on enamel was compared to each other and to an unsealed enamel control. The antimicrobial properties of sealants were also studied.

Sealant coated bovine enamel disks were immersed in a S. mutans culture medium for four days. The amount of bacterial plaque formation was quantified by removing the deposit, suspending it in solution with subsequent serial dilution. Aliquots of the dilutions were then spread on blood agar plates and incubated for 48 hours. The number …

Progesterone Regulation Of Insulin Like-Growth Factor : Binding Protein-5 Gene Transcription In Human Osteoblasts, Viroj Boonyaratanakornicit

Loma Linda University Electronic Theses, Dissertations & Projects

Insulin-like growth factor binding protein-5 (IGFBP-5) is produced by osteoblasts and potentiates IGF mitogenic actions in osteoblast cultures. Progesterone (PG) increases osteoblast proliferation and increases osteoblast IGFBP-5 expression. Mechanisms underlying PG induction of IGFI3P-5 expression were investigated in U2 human osteosarcoma cells. In nuclear run-on analyses, PG increased IGF)3P-5 gene transcription to 400% of control. To define the underlying mechanisms, the human IGF13P-5 gene proximal promoter was cloned and sequenced. The proximal 500 bp of this region contains TATA and CAAT boxes, five putative PG response element (PRE) half-sites and two tandem CACCC boxes. Chloramphenicol acetyltransferase (CAT) reporter constructs containing …

Expression Of The Human Milk Protein, Beta-Casein : In Transgenic Potato Plants, Wendy Roberts

Loma Linda University Electronic Theses, Dissertations & Projects

Mother’s milk is recommended by the nutritional and pediatric communities as the best food for suckling infants. For non breast-fed infants, bovine milk-based formulas have been regarded as a suitable substitute. In the early 1900's, physicians found that foreign proteins in cow milk were responsible for gastrointestinal disease and even digestive collapse of the newborn fed a cow milk-based diet¹⁶. The allergenicity of cow milk for the human infant appears to be caused predominantly by p-casein¹⁷. In this research, the cDNA encoding human p-casein was introduced into potato cells under the control of the bidirectional, auxin-inducible …

The Effects Of Lowering Cholesterol On Vasodilation, Maria Christi Hardt

Loma Linda University Electronic Theses, Dissertations & Projects

Endothelial dysfunction has been found prior to any signs of atherosclerotic plaque formation in patients with a variety of risk factors for atherosclerosis. Elevated serum cholesterol has repeatedly been associated with endothelial dysfunction as demonstrated by impaired vasoreactivity to vasodilating stimuli.

The aim of this research was to determine whether short term lowering of serum cholesterol levels by life style changes or by cholesterol lowering medication could reverse or reduce the endothelial dysfunction. The brachial artery diameter was measured by high-resolution ultrasound at rest and during reactive hyperemia pre and postintervention. Fifty-three subjects with cholesterol levels above 240 mg/dl were …

An Avian Botulism Epizootic Affecting A Nesting Site Population Of Presbyornis : On A Carbonate Mudflat Shoreline Of Eocene Fossil Lake, V. Leroy Leggitt

Loma Linda University Electronic Theses, Dissertations & Projects

The shorebird-duck mosaic bird, Presbyornis, is best known from the Eocene Green River Formation where it often occurs in local monospecific bonebeds, suggestive of mass mortality events. The sedimentology, paleontology, taphonomy, XRD mineralogy, and the carbonate stable isotope signature (δ¹⁸O) of one of these bonebeds was studied on the southern margin of Eocene Fossil Lake.

A series of 408 standardized radiographs were used to construct the first large scale radiograph aided taphonomic map of a vertebrate fossil quarry (3,874 bones were recorded in 11.5 m²). A small group of 100 bones (including a complete skull …

The Effect Of Guidor™ And Hop-1 On Hard Tissue Healing : Following Periradicular Surgery In Cats, Hugh Maguire

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of this study was to evaluate the effects of the resorbable membrane Guidor™ and the osteogenic protein hOP-1 on hard tissue healing following periradicular surgery in cats.

Surgical endodontic therapy was performed on the maxillary canine teeth of twelve cats. After orthograde root canal therapy, flap reflection, osteotomy, resection of the root end, root end cavity preparation and the placement of a root end filling, eight of the surgical sites were treated with Guidor™ and eight with hOP-1. The remaining eight sites received no further treatment and served as controls.

The animals were sacrificed at twelve weeks following …

Periodontal Repair In Dogs : Effect Of Recombinant Human Transforming Growth Factor Beta-1 On Guided Tissue Regeneration, Saghi Shayan Razi

Loma Linda University Electronic Theses, Dissertations & Projects

The objective of this study was to evaluate bone and cementum regeneration in the critical size, supraalveolar, periodontal defect model following surgical implantation of recombinant human transforming growth factor beta-1 (rhTGFß-1) in conjunction with guided tissue regeneration (GTR). Five male beagle dogs were used in a split-mouth design. Alternate jaw quadrants in consecutive animals received GTR with rhTGFß-1 in a resorbable calcium carbonate carrier. Contralateral jaw quadrants received GTR with carrier only (control). The healing interval was 4 weeks. Clinical healing was generally uneventful, however, minor membrane exposures were observed for both treatments with limited gingival inflammation. All defects with …

Myocardial Contractility In Fetal Sheep Exposed To Long-Term Hypoxia At High Altitude : Activator Calcium And Beta-Adrenergic Receptor Function, Vaughn A. Browne

Loma Linda University Electronic Theses, Dissertations & Projects

We studied myocardial contractility in fetal sheep exposed to ~112 days of hypoxia at high-altitude (3,820 m). We recorded left and right ventricular wet weight, and measured the inotropic responses to extracellular calcium [Ca²⁺]_o (0.2-10 mM), ryanodine (10^-10-10^-4 M), isoproterenol (10^-10-10^-6 M), and forskolin (0.01-10 uM) in isometrically contracting papillary muscles. In addition, we quantified dihydropyridine (DHPR), ryanodine (RyR), and β-adrenergic receptor densities, and measured basal and stimulated intracellular cAMP levels. In hypoxic fetuses, left ventricular wet weight was unchanged, but right ventricular weight was ~20% lower than controls. Curves describing …

Bone Morphogenetic Proteins And Periodontal Repair, Michael B. Lee

Loma Linda University Electronic Theses, Dissertations & Projects

For over thirty years now, research has been carried out to isolate and purify bone morphogenetic protein (BMP), a substance which has been shown to induce heterotopic bone formation in various animal species. Recent advances in the fields of developmental biology, molecular biology and genetics, have shown that the BMPs not only are responsible for postfetal bone induction (including normal bone remodeling, healing and repair), but are also critical during embryogenesis - not only in regards to the skeletal system, but quite possibly in the morphogenesis and pattern formation of other tissues and organs as well.

Due to their bone …

Inhibitory Effects Of Isothiocyanates On The Mutagenicity And Metabolism Of Environmental Carcinogens, Solomon M. Hamilton

Loma Linda University Electronic Theses, Dissertations & Projects

The inhibitory effects of the two naturally occuning isothiocyanates, benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC) on the metabolism and mutagenicity of 4-(methylnitrosamino)-l-(3-pyridyl)-lbutanone (NNK) and benzo[a]pyrene (BaP) by F344 rat and male Syrian golden hamster liver microsomes were investigated. In addition, the alkyl chain-length effects of BITC and PEITC, together with phenyl isothiocyanate (PITC) and phenylpropyl isothiocyanate (PPITC) on the metabolism and mutagenicity of NNK, and on the metabolism of testosterone were determined. Further, the effects of all four homologues of isothiocyanates on the mutagenicity of five heterocyclic amines (HCAs) IQ, MelQx, Trp-P-2, Glu-P-2 and PhIP and on the dealkylation …

Association Between Nutrient Intake And Risk Of Coronary Heart Disease In California Seventh-Day Adventists, Peter Pribiš

Loma Linda University Electronic Theses, Dissertations & Projects

Dietary habits are believed to be major determinants of risk of coronary heart disease (CHD). Studies of high and low risk populations have suggested several nutrients to be protective or hazardous against CHD. Most published work since 1984 on diet and CHD in the Adventist Health Study (AHS) population examined either foods or food groups. This study investigated ten nutrients as exposure variables and their relationship to CHD risk. A cohort of 23,616 nonsmoking, non-Hispanic white California Seventh-day Adventists was followed for six years beginning in 1976. Extensive dietary information was collected at baseline, as well as values of traditional …

Regulation Of Human Osteosarcoma Cell Differentiation By Transforming Growth Factor B1 (Tgfb And 1a,25- Dihydroxyvitamin D3 : The Mechanism Of Tgfb1 Potentiation Of 1,25d3-Induced Alkaline Phosphatase Activity In Human Mg63 Osteosarcoma Cell, Xinde Song

Loma Linda University Electronic Theses, Dissertations & Projects

Transforming growth factor β₁ (TGFβ₁) is a pluripotent cytokine that works in conjunction with other cytokines to modulate their effects on cell function. Our previous work demonstrated that the combination of TGFβ₁ and 1α,25-dihydroxyvitamin D₃ had a synergistic effect on alkaline phosphatase induction (500 to 700%) in human osteoblastic osteosarcoma cells (MG63). The current studies focused on the molecular basis of alkaline phosphatase induction, including the regulation of the signal transduction and modification of 1α,25-dihydroxyvitamin D₃ receptors (VDR). We demonstrated that alkaline phosphatase activity was regulated at the transcription level. TGFβ₁ at 1 …