Research Methods in Life Sciences Commons^™

Development Of Periapical Lesions In Immunosuppressed Rats, Phillip A. Waterman Jr.

Loma Linda University Electronic Theses, Dissertations & Projects

The pathogenesis of periapical lesions is the interaction of the oral flora with the existing host defenses. The role of bacteria has been established in endodontic disease but the contribution of the host defenses in periapical lesion formation is less clear. The purpose of this study was to compare periapical lesion development in immunosuppressed rats with that in normal rats. Thirty-five, eight-week old Sprague-Dawley rats were equally divided into seven groups. Groups 1, 2, and 3 were given weekly injections of Cytoxan, an immunosuppressive agent. Groups 4, 5, and 6 received no immunosuppressive therapy. Group 7 served as a control, …

Transforming Growth Factor-Beta 1 Expression In Developing Ovine Teeth As Visualized By In Situ Hybridization, Søren Jepsen

Loma Linda University Electronic Theses, Dissertations & Projects

Recently we demonstrated that human dentin contained relatively high amounts of transforming growth factor beta (TGF-ß) and proposed that dentin TGF-ß originated from odontoblasts. Because of the suggested role of TGF-ß in mediating cellular interactions in dental cell development by paracrine mechanisms, we studied the expression of TGF-ß message in developing teeth by in situ hybridization. 5 µm serial sections of neonatal sheep mandibular third molars that had been fixed in glutaraldehyde and paraffin-embedded were used for in situ analysis. An [³⁵S]-labeled cRNA probe, complementary to TGF-ß1 mRNA, was constructed from human TGF-ß1 cDNA. Northern analysis of total …

New In Vivo And In Vitro Techniques For Quantification Of Lateral Force Levels That Cause Implants To Fail : A Progress Report On Monkey Research, V. Leroy Leggitt

Loma Linda University Electronic Theses, Dissertations & Projects

Two new techniques for quantification of forces generated by an expansion screw apparatus placed between pairs of cylindrical endosseous titanium implants are described, along with preliminary data gained from their use in Macaca rhesus monkeys. Strain gages were bonded to the expansion apparatus and were calibrated either directly by micro load cell, or indirectly by Instron Machine to reflect the applied force.

Immediate loads of up to 6 kilograms have been applied to the implants with no increase in mobility as verified by a Periotest device. No previous studies on the orthodontic uses of implants have evaluated in vivo forces …

Modulation Of Rat Hepatic S9-Dependent Mutagenesis, Dna Binding, And Metabolism Of Aflatoxin B1 And Benzo[A]Pyrene By Four Chinese Medicinal Herbs, Brian Yuen Yau Wong

Loma Linda University Electronic Theses, Dissertations & Projects

Extracts of the herbs Oldenlandia diffusa (OD) and Scutellaria barbata (SB) have been used in traditional Chinese medicine for treating liver, lung and rectal tumors while extracts of Astragalus membranaceus (AM) and Ligustrum lucidum (LL) are often used as adjuncts in cancer therapy. In this study, we determined the effects of aqueous extracts of these four herbs on aflatoxin B₁ (AFB₁) benzo[a]pyrene (BaP), benzo[a]pyrene 7,8-dihydrodiol (BaP 7,8-DHD) and benzo[a]pyrene 7,8-dihydrodiol-9,10-epoxide (BPDE)-induced mutagenesis, mediated by enzymes in rat hepatic 9000 x g supernatant (S9), in Salmonella typhimurium TA100. We also studied the effects of these four herbs on …

Plasticity Of The Gnrh Neuronal System During Sexual Maturation Of The Male Djungarian Hamster, Kevin L. Buchanan

Loma Linda University Electronic Theses, Dissertations & Projects

Onset of puberty in male Djungarian hamsters is characterized by increased pituitary gonadotropin secretion and testes maturation, and is controlled by neurons within the brain which secrete gonadotropin-releasing hormone (GnRH). Puberty is associated with increased numbers of morphologically unipolar, but not bipolar, GnRH neurons in the medial preoptic area (MPOA) and diagonal band of Broca (DBB). To test the hypothesis that delayed sexual maturation arrests this increase, males were exposed to short days or administered melatonin. Males with delayed puberty had significantly fewer unipolar GnRH neuron numbers in the MPOA and DBB comparable to pubertal controls in long days. Unipolar …