The renin-angiotensin system plays a central role in the maintenance of blood pressure. Angiotensin II, the main effector of this system, results from the action of angiotensin-converting enzyme (ACE) on angiotensin I. Angiotensin II, maintains vasomotor tone via its vasoconstrictor action, and also increases salt and water retention by stimulating the release of aldosterone. ACE inhibitors, such as captopril, enalapril and lisinopril, are highly effective in the treatment of hypertension and congestive cardiac failure. Previous studies have suggested that angiotensin converting enzyme (ACE) production may be enhanced during pharmacological inhibition of the enzyme. Little is known, however about the mechanism of this induction. After demonstrating increases in circulating ACE protein in cardiac failure patients receiving the ACE inhibitor captopril, a rat model was used to study this effect. A sensitive enzyme linked immunosorbent assay for rat ACE was developed and a partial cDNA for rat ACE cloned to enable examination of ACE mRNA and protein expression during enzyme inhibition with enalapril. Rat lung ACE mRNA increased by 156% (p<0.05) and ACE protein doubled within 3 hours of administering a single dose of enalapril. Testicular ACE mRNA also increased by 300% (p<0.05) within 2 hours and returned to pretreatment levels by 6 hours. The angiotensin II antagonist saralasin similarly caused a significant (p<0.0001) 800% enhancement of mRNA expression. Aldosterone pretreatment of rats prior to enalapril administration was found to abolish this mRNA induction. These findings indicate that increased ACE expression during inhibition results from reduced levels of angiotensin II with consequent reduced stimulation of the angiotensin 11 receptor and its effects, such as aldosterone release. This suggests that ACE levels are regulated by a negative feedback loop involving the distal components of the renin-angiotensin system, namely angiotensin II and aldosterone. In situ hybridisation and immunohistochemical techniques were employed to localise the site of this inductive response in rat tissue sections. It was found that lung macrophages were markedly induced to produce ACE, as was ACE in seminiferous tubules. ACE induction was also noted in the expected sites of renal tubular epithelium and glomerular tissue. Interestingly, ACE expression was also enhanced in cardiac valves. In these studies it has been conclusively demonstrated that new ACE expression is induced by enzyme inhibitor therapy. A variety of techniques have been developed that will allow futher study of ACE in rat tissues.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In recent years we have seen an increase in the use of MIL-STD-1553 buses and other asynchronous data sources used in new missile and launcher designs. The application of multiplexed asynchronous buses in missiles and launchers is very common today. With increasing application of asynchronous data sources into very complex systems the need to acquire, analyze, and present one hundred percent of the bus traffic in real time or near real time has become especially important during testing and diagnostic operations. This paper discusses ways of converting asynchronous data, including MIL-STD-1553, into a telemetry format that is suitable for encryption, telemetering, recording, and presenting with Inter Range Instrumentation Group (IRIG) compatible off-the-shelf hardware. The importance of these designs is to provide the capability to conserve data bandwidth and to maximize the use of existing hardware. In addition, this paper will discuss a unique decode and time tagging design that conserves data storage when compared to the methods in IRIG Standard 106-96 and still maintains a very accurate time tag.

published_or_final_version / abstract / Biological Sciences / Master / Master of Philosophy

The effect of iron absorption on subsequent hemoglobin regeneration was investigated by repletion and subsequent analysis of an anemic weanling rat model. Primary assay procedure in these studies was the Regeneration Efficiency method. As repletion or curative assay techniques form the central body of investigative research in iron utilization, the first subject of inquiry was the effect of repletion interval and degree of depletion upon the animals as monitored by physical indicators such as blood volume, growth and hematinic response. Percent blood volume is a particularly useful figure in the calculation of the amount of hemoglobin iron but was found to be relatively constant in a preliminary experiment. Accordingly, the effects of growth and anemia on hemoglobin response and blood volume were examined in 122 weanling male rats which had been depleted for seven days by low iron diet and phlebotomy, then repleted by feeding iron rich diet (47.1 ppm) for zero, five, 10 and 15 days. Percent blood volume proved to be rather constant at 7.5 in these pre-pubescent animals. The most severely depleted animals appeared to regenerate hemoglobin initially rather than replenish tissue iron. Regeneration Efficiency and AOAC assay methods were compared in a study involving the relative potency of two iron salts, ferrous sulfate and ferric orthophosphate, and three commercial cereal sources containing electrolytically reduced, hydrogen reduced or ferric orthophosphate supplements. These two assays utilized 202 albino male weanling rats. The superior availability of ferrous sulfate was evident in both regeneration efficiency and AOAC assays, as was the relative similarity of the dietary iron sources, yet the commercial sources in general provided more available iron in comparison to the reference ferrous sulfate than expected, possibly due to the influence of dietary components and processing variables. Bioavailability based on dietary iron concentration response correlated highly (r = 0.94) between animal groups analyzed using the Regeneration Efficiency and AOAC methods. Stress may have been a factor in animals assayed by the AOAC technique which used a 28 day depletion interval followed by a two week repletion. The Regeneration Efficiency method, which utilizes shorter depletion and repletion intervals also offered sufficient amounts of dietary iron for normal growth. The calculation of iron bioavailability also is dependent on such pertinent variables as dietary intake amount, body weight gain and percent blood volume.

Thesis (M.S. in food science)--Washington State University, December 2007. / Includes bibliographical references.

The renin¡Vangiotensin system (RAS) plays a role in the pathogenesis of obesity. Angiotensin-converting enzyme (ACE), the component of the RAS system, has recently been found to be completely expressed in human adipose tissue. Angiotensin II, the active component of RAS, may affect adipogenesis and adipocyte metabolism. Among ACE polymorphism, the gene DD genotype has shown to be regulated with a higher agiotensin- converting enzyme level in plasma. Hence, the purpose of this research is to investigate the correlation of ACE gene polymorphism to body mass index (BMI) between aborigines and Han non-aborigines. The relationship of race and ACE insertion (I)/ deletion (D) polymorphism was also analyzed.The results showed a higher value of ACE DD genotype appeared in aborigines (35.7 %) than that in Han population (10.8 %)(p < 0.0001). BMI in aborigines was 26.4¡Ó4.6 kg/m2, while in Han population was 24.4¡Ó3.6 kg/m2 (P<0.0001). A higher waist circumference value was also found among females aborigines than that found among female in Han population (86.9¡Ó10.7 vs 84.3¡Ó9.7 cm, P<0.0001). Simple and multiple linear regression analyses showed that both race and ACE gene polymorphism are closely correlated to BMI in all subjects. By discussion on the cases for the Han and aborigines population separately, it was found that the ACE gene polymorphism is associated with BMI in Han population it is not significant in aborigines. In aborigines, life style in culture is associated with BMI. In conclusion, ACE gene polymorphism and race were independent factors correlated to BMI, but differences could be found between race and ACE gene polymorphism.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.)--Brown University, 2008. / Vita. Advisor: Kate L. Lapane. Includes bibliographical references (leaves 64-70).

published_or_final_version / Zoology / Master / Master of Philosophy