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Hydrolytic Polymerization of Chromium (III) Hydroxides in the Aquatic Environment (open access)

Hydrolytic Polymerization of Chromium (III) Hydroxides in the Aquatic Environment

Products of hydrolytic polymerization of Cr(III) hydroxide were investigated in Milli-Q water and in natural water matrices. Products were first fractionated on Sephadex column using eluents of increasing strength. Ion chromatography (IC) with UV detection at 436 nm was then used to separate the ionic species.
Date: December 1991
Creator: Mbamalu, Godwin E.
System: The UNT Digital Library
Adenosine and Down-Regulation of Myocardial Oxygen Demand (open access)

Adenosine and Down-Regulation of Myocardial Oxygen Demand

This investigation studied the physiological means by which myocardium can survive and function properly when oxygen supply is limited and cannot initially match oxygen demand. The effects of isoproterenol (ISO) stimulations during low coronary perfusion pressure or hypoxemia on myocardial oxygen demand, work, and oxygen utilization efficiency were investigated.
Date: December 1991
Creator: Lee, Shang Chiun
System: The UNT Digital Library
Characterization of Pyrimidine Biosynthesis in Pseudomonas putida Using Mutant and Wild Type Strains (open access)

Characterization of Pyrimidine Biosynthesis in Pseudomonas putida Using Mutant and Wild Type Strains

The biosynthesis of pyrimidines in Pseudomonas putida was investigated. In this study, pyrimidine requiring mutants were isolated by conventional mutagenesis and enrichment. The strains required exogenously supplied pyrimidines for growth and were found by enzyme assays to be deficient for the product of the pyrB gene encoding the enzyme aspartate transcarbamoylase. None of the intermediates of the pathway could supply the auxotrophic requirement of the strain; only preformed pyrimidines, metabolized via salvage pathways could suffice. Pyrimidine limitation in the mutant caused a slight but significant fifty per cent increase in expression of all the de novo biosynthetic enzymes. Pyrimidine starvation's effect on nucleotide pool levels was examined in the mutant and caused a marked swelling of the purine nucleotide pools.
Date: August 1991
Creator: Chang, Mingren
System: The UNT Digital Library
Physiological Effects of Ascaris Suum Intestinal Microflora on 5-Hydroxytryptamine Level and Binding Sites in the Intestinal Epithelial Cells (open access)

Physiological Effects of Ascaris Suum Intestinal Microflora on 5-Hydroxytryptamine Level and Binding Sites in the Intestinal Epithelial Cells

Serotonin (5-hydroxytryptamine, 5-HT) has been shown to activate carbohydrate metabolism in adult female Ascaris suum. Serotonin may be either absorbed directly from the environment or synthesized de novo from the absorbed L-tryptophan in adult female A. suum. The enzymes necessary for the synthesis of 5-HT have been identified in both intestine and muscle tissues. The serotonin absorbed from the environment is obtained either from the host's gastrointestinal contents or from the 5-HT producing bacteria in the intestine of A. suum. Numerous 5-HT producing bacteria were identified in the intestinal microflora. The physiological contributions of 5-HT producing bacteria to the 5-HT level, turnover and binding sites in the intestinal tissue of A. suum were investigated.
Date: December 1991
Creator: Shahkolahi, Akbar Mohammadpour
System: The UNT Digital Library
Pyrimidine Metabolism in Bacteria: Physiological Properties of Nucleoside Hydrolase and Uridine Kinase (open access)

Pyrimidine Metabolism in Bacteria: Physiological Properties of Nucleoside Hydrolase and Uridine Kinase

In this study, high-performance liquid chromatography (HPLC) was employed to detect and quantify pyrimidine salvage enzymes by monitoring the disappearance of substrates or formation of products.
Date: December 1991
Creator: Lee, Yick-Shun
System: The UNT Digital Library