Physiology Commons^™

Mechanisms Of Retinal Ganglion Cell Development In The Rhesus Macaque, Thomas C. Steineke

Loma Linda University Electronic Theses, Dissertations & Projects

At present, no effective treatments are known for many common neurological problems. For instance, degenerative diseases and central nervous system injuries are two examples of conditions for which few treatment options exist. Studying how neurons develop, and how they establish and maintain connections may provide important insights into potential treatment modalities. To this end, retinal ganglion cell structural development was studied in the fetal rhesus macaque ranging in age from embryonic day (E)60 to El65 (gestation is 165 ± 2 days). Horse radish peroxidase (HRP) retrograde labeling techniques were used to investigate changes in retinal ganglion cell structure during fetal …

Mechanism Of Action Of Pentobarbital Induced Attenuation Of Vascular Smooth Muscle Contraction, Michael R. Samardzija

Loma Linda University Electronic Theses, Dissertations & Projects

Pentobarbital (PB) vasodilates dog mesenteric and cerebral arteries precontracted with KC1, PGF_2α, caffeine or norepinephrine. It is postulated that PB causes this dilation by reducing Ca²⁺ influx as a non-specific Ca²⁺ channel blocker, or decreasing intracellular Ca²⁺ release. We examined PB effects on intracellular Ca²⁺ release (ICR) and extracellular Ca²⁺ influx (ECI) by stimulating Sprague-Dawley rat tail artery rings with either 100 mM KC1, 50 uM phenylephrine (PE), or two different electrical field stimulation (EES) parameters: tetrodotoxin (TTX; 1 uM) sensitive, or perivascular nerve, (NEFS) stimulation (10 Hz, 0.3 ms, 50 V, 30 …

Short And Long Term Effects Of Proton Microbeam Irradiation : In The Lateral Geniculate Nucleus Of Felis Domesticus, Chad Sherwood Reder

Loma Linda University Electronic Theses, Dissertations & Projects

Little is known of the effects of proton irradiation on neural tissue. A 1.0 mm microbeam was used on the cat lateral geniculate nucleus (LGN) to quantify the short term (< 3 months) and long term (< 9 months) effects of radiation damage. The LGN is a large structure with well defined afferent, efferent, and receptive field properties.

Electrophysiological and histological techniques were used to examine the effects of the microbeam at 60, 40, and 16 Gy, administered as a single bolus. Recordings of light evoked responses in the LGN were obtained using microelectrodes in nine animals within 12 weeks of irradiation, and 6 animals within 36 weeks of irradiation. Receptive fields were mapped onto a tangent screen using standard receptive field techniques. Histological measures included afferent …

An Intramural, Tension-Modulating Reflex In The Rat Caudal Artery, Greg G. Geary

Loma Linda University Electronic Theses, Dissertations & Projects

Electrical field stimulation (EES) of preconstricted arteries causes relaxation. This relaxation is of either neuronal, vascular smooth muscle, and/or endothelial origins. We have shown that EFS-induced relaxation of intact, phenylephrine (PE) preconstricted rat tail artery (RTA) rings was dependent upon the extracellular concentration of Ca++. Inhibiting either nitric oxide (NO) synthesis with N-nitro-L-arginine methyl ester (L-NAME), or the synthesis of cyclic guanosine monophosphate (cGMP) with methylene blue (MB) reduced the EFS-induced relaxation. In addition, inhibition of K_Ca++-dependent hyperpolarization with tetraethylammonium (TEA), or K_ATP hyperpolarization with BaCl₂ or glibenclamide also reduced EFS-induced relaxation. L-arginine reversed the effect …

Inhibition Of Nnk Mutagenesis And Metabolism By Chemopreventive Phytochemicals, Cecil Henry Miller

Loma Linda University Electronic Theses, Dissertations & Projects

Approximately one third of all cancer deaths in the United States can be linked to the use of tobacco products. Cessation of smoking is not always an effective prevention method, especially since nicotine is so addictive. For those individuals who continue to use tobacco products, chemoprevention may be an alternative to reduce their cancer risk. We have investigated the chemopreventive efficacy of five phenolic (catechin, ellagic acid, escletin, esculin and propyl gallate) and five non-phenolic (capsaicin, silymarin, diallyl sulfide, tannic acid, and d-limonene) phytochemicals on tobacco-specific nitrosamine (NNK)-induced mutagenesis and NNK metabolism. In the mutagenesis studies, Salmonella typhimuriumstrain TA1535 …