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Age Related Changes In The Activity And The Responsiveness Of The Renin-Angiotensin System In The 15 Month Old Rat, Michele Mckee Thompson

Dissertations and Theses

Progressive deterioration of renal function is one consequence of aging. Glomerular maladaptation is one aspect of this and includes increased glomerular capillary hypertension and a reduced ultrafiltration coefficient, which can lead to glomerular sclerosis and proteinuria. In the aging rat, angiotensin converting enzyme inhibitors (CEI) lower proteinuria (U_protV) and decrease glomerular sclerosis (2, 18, 24, 45). Accordingly, alterations in the circulating and renal renin-angiotensin system (RAS) are hypothesized to play a role in the pathogenesis of renal disease in the aging rat. Previous studies using rat models have demonstrated a lower responsiveness to converting enzyme inhibitor treatment in …

Whole Body I=In Vivo Vascular Compliance In Two Amphibians, Bufo Marinus And Rana Cate, Todd Micheal Hoagland

Dissertations and Theses

The mean circulatory filling pressure (MCFP), vascular compliance (C) and unstressed volume (USV) were measured in Bufo marinus and Rana catesbeiana, using an in vivo preparation. Capacitance curves were constructed by varying total vascular volume and then measuring MCFP. These capacitance curves enable the extrapolation of USV and the measurement of vascular compliance. The MCFP, C, and USV were 8.6 ± 0.2 (mmHg), 3.7 (ml· mmHg-1 · kg- 1 ) and 2.5 (ml), respectively, in B. marinus. The MCFP, C, and USV were 9.5 ± 0.1 (mmHg), 2.2 (ml· mmHg-1 · kg- 1 ) and 14.2 (ml), respectively, …

Human Trampling In The Upper Rocky Intertidal: Trampling And Recovery In Barnacle Mediated Succession, Timothy Lawrence Grubba

Dissertations and Theses

Marine intertidal ecosystems are vulnerable to human interference,

because trampling can be a significant problem. I studied the impacts of

trampling on community patterns and succession in a rocky intertidal

habitats. This study was divided into two phases: ( 1) a trampling phase and

(2) a recovery phase. Both phases are focused on two barnacles, Balanus

glandula and Chthamalus dalli, and on fucoid and red algae. The trampling

phase tested the effects of trampling on these organisms. The effects of

herbivores, primarily limpets (Collisella digitalis) were also tested to

determine whether anthropogenic (trampling) and natural (herbivory and

limpet bulldozing) disturbances …

Whole Body In Vitro Hydraulic Conductivity And Transcapillary Filtration In Two Amphibians, Bufo Marinus And Rana Catesbeiana, Thomas Vincent Hancock

Dissertations and Theses

The capillary filtration coefficient (CFC) and isovolumetric capillary pressure (P_ci) were measured in Bufo marinus and Rana catesbeiana, using a gravimetric technique on an in vitro preparation while perfusing with Ringers and 0.1 g·100 ml^-1 bovine serum albumin Estimates of pre- and post-capillary resistance were obtained from Bufo; the post- to pre-capillary resistance ratio was found to be 0.18, which was used to estimate capillary pressure. CFC was found to be 6.68 ± 0.51 and 5.07 ± 0.23 ml·min^-1·kg^-1·mmHg^-1 and P_ci was found to be 7.4 and 6.3 mmHg in …

The Effect Of Lymph Sac Pressure On Lymph Heart Pressure Development In The Toad Bufo Marinus, Michael Georgitsis

Dissertations and Theses

Lymph hearts play an important role in blood volume regulation in anurans by controlling the movement of fluid from the lymphatic spaces to the vasculature. The anatomical continuity between lymph sacs and lymph hearts predicts a coupling of pressure between the two structures which may represent a physical basis for lymph heart regulation. The precise relationship between lymph heart pressure and lymph heart output was not examined so that conclusions regarding changes in work performed by the hearts as a result of changing lymph sac pressure could not be made. However, increases in lymph sac pressure led to increases in …

A Pouplation Genetic Study Of Wild Bottlenose Dolphins (Tursiops Truncatus) In Matagorda Bay, Texas, Joel Stephen Lenox

Dissertations and Theses

A long-term photoidentification study was initiated in response to an unusually high incidence of bottlenose dolphin mortality between Corpus Christi and Matagorda Bays, Texas. Blood samples from 36 captured and released animals were analyzed using three genetic techniques; mtDNA haplotyping, nuclear DNA fingerprinting and electrophoretic analysis of hemoglobin. Two Hinf I mtDNA haplotypes previously described in bottlenose dolphins from other locations within the Gulf of Mexico were discovered. Similarity Indices (SI) were calculated based on nuclear DNA fingerprinting data. These SI values were used as a relative measure of relatedness between two individuals run on the same gel. Means of …

Ovarian Steroid Regulation Of Tryptophan Hydroxylase Enzyme Level In The Midbrain Raphe In Ovariectomized Guinea Pigs, Zhidong Lu

Dissertations and Theses

Progesterone stimulates prolactin secretion in estrogen ( estradiol-17-~)primed monkeys and guinea pigs. It is hypothesized that the serotonin neural system plays a pivotol role in mediating the effect of progesterone on prolactin secretion. Indeed, progesterone, but not estrogen, increases serotonin levels in the midbrain raphe in guinea pigs. However, estrogen alone stimulates gene expression of the rate-limiting enzyme for serotonin synthesis, tryptophan hydroxylase (TPH), and progesterone supplement to the estrogen regimen has no additive effect, as indicated by TPH mRNA levels in monkeys. The discrepancy between ovarian steroid effects on the TPH mRNA level and the serotonin level might be …

The Role Of The Hepatic Vagus In The Pathogenesis Of Fever, Christopher Todd Simons

Dissertations and Theses

Recent evidence has suggested a role of vagal afferents in the pathogenesis of fever. Although bilateral truncal subdiaphragmatic vagotomy has been shown to attenuate the febrile response to lipopolysaccharide (LPS) and interleukin-1, no study has yet been able to verify which of the five subdiaphragmatic vagal branches (viz., the anterior and posterior celiac branches, the anterior and posterior gastric branches, and the hepatic branch) is responsible for communicating this signal. The present study tested the hypothesis that the hepatic vagal branch mediates pyrogenic signals from the periphery to the brain. Male Wistar rats underwent one of four selective …

Structural And Successional Analysis Of Woodland Vegetation In Tualatin Hills Nature Park, Christopher J. Dobson

Dissertations and Theses

Tualatin Hills Nature Park is an urban woodland located in Beaverton, Oregon. The park is owned and managed by Tualatin Hills Park & Recreation District. Vegetation in the park is in a state of secondary succession following a long history of disturbance. The site provided an excellent opportunity to study the recovery of a natural woodland in an urban setting in the northern Willamette Valley.

The purpose of this study was to analyze the species composition, structure, and successional trends of the woodland vegetation in Tualatin Hills Nature Park. A secondary purpose was to determine if there were any natural …

The Periphyton Community Of A Second Order Subalpine Stream Following Salmon Carcass Decomposition, Jonathan Micheal Honea

Dissertations and Theses

To protect and manage Pacific Northwest salmonid stocks, sound management programs must be developed that incorporate knowledge of the ecological processes critical to their survival. One such process is the nutrient dynamic in headwater spawning streams. It is essential that we understand the trophic relationships among the spawners, the I to 3 year-old juveniles, the invertebrates, and the primary producers in these streams.

The hypothesis that I tested is that photoautotrophic production increases due to the decomposition of salmon carcasses. Increased primary production would stimulate the production of invertebrates which are an important food resource of juvenile salmonid species. The …

Purification And Characterization Of Catalase From Enterococcus Faecalis, Zhenghong Zhu

Dissertations and Theses

Catalase is an important biological enzyme that most organisms employ during aerobic growth to catalyze the decomposition of hydrogen peroxide, a toxic reduction product of oxygen, into water and molecular oxygen. Traditionally, the bacterium Enterococcus faecal is is considered to have no cytochrome system and to be catalase negative. However, certain strains of E. subsequent studies have shown that faecalis are capable of producing catalase when grown aerobically in a medium containing hematin.

The goals of this study were to purify and characterize catalase from a clinical strain of E. faecalis. The organisms were grown under aerobic conditions in a …

Investigation Of Transactivation Of The Human C-Myc Gene By Herpes Simplex Virus Type 1, Xian Wu

Dissertations and Theses

The purpose of this investigation was to identify the regulatory elements involved in the transactivation of the human c-myc gene by herpes simplex virus type-1 (HSV-1). This study mainly focused on a major c-myc promoter P₂ (Fig. 1). Transient expression assays were carried out with a reporter plasmid, that contained either a wild type (+66wt c-myc) or mutant (+66 mt E2F, +66mt CT -I₂) c-myc promoter fused to the chloramphenicol acetyltransferase (CAT) gene, cotransfected with effector plasmids that contained the HSV-1 immediate early (IE) genes ( encoding IE proteins, ICP4, ICP0, ICP27). The transient expression assays revealed …