States

Echocardiographic Assessment of the Left Ventricle in the Spinal Cord Injured Patient (open access)

Echocardiographic Assessment of the Left Ventricle in the Spinal Cord Injured Patient

Ten caucasian male quadriplegics were compared with eight sedentary caucasian male controls in regards to left ventricular dimensions and mass obtained from echocardiograrns. The interventricular septum (IVS), left ventricular posterior wall (LVPW) and left ventricular internal diameter (LVII) were within normal limits for both groups. However, the INS in the SCI were significantly thicker than controls (p <0.05). Myocardial thickness was larger in SCI subjects (p <0.05). Absolute left ventricular mass (LVM) and total left ventricular volume was not different ( p > 0.05), but SCI subjects had significantly greater LVM to lean body mass ratios. Echocardiographically, SCI patients demonstrate concentric hypertrophy. This suggests adaptive response to chronic increase in afterload pressure secondary to their daily activities and muscle spasticity.
Date: May 1989
Creator: Nock, Bonnie J. (Bonnie Jean)
System: The UNT Digital Library
Exoprotease Production by Aeromonas hydrophila in a Chemically Defined Medium (open access)

Exoprotease Production by Aeromonas hydrophila in a Chemically Defined Medium

Wretlind, Heden, and Wadstrom found ammonium sulfate to be inhibitory for the formation of extracellular protease in Aeromonas hydrophila grown in Brain Heart Infusion medium. They demonstrated by manipulating the iron and zinc content within their medium that it is possible to differentially affect the accumulation of hemolysin and protease by A. hydrophila grown in batch culture. Further manipulation of the composition of this medium was done in the present study to determine the effect of other components on the production of protease. The purpose of this study was to determine the factors affecting the level of A. hydrophila protease produced in a chemically defined medium.
Date: May 1985
Creator: Anderson, Paulette S. (Paulette Sue), 1952-
System: The UNT Digital Library
Serotonin, Norepinephrine, and the Hypothalamic Ventromedial Nucleus: a Proposed Mechanism Mediating Hyperphagia and Obesity (open access)

Serotonin, Norepinephrine, and the Hypothalamic Ventromedial Nucleus: a Proposed Mechanism Mediating Hyperphagia and Obesity

Serotonin has been implicated as a modulator of feeding behavior. This experiment was designed to alter brain serotonin levels through dietary means in hypothalamic ventromedial-lesioned and unlesioned rats. Daily food, water, and animal weights were measured. The purpose was to determine if VMH lesions altered the feeding pattern found in unlesioned rats. Although food intake for tryptophanenriched diets and tryptophan-deficient diets did not differ from their respective control groups, in some cases gross animal weights did differ significantly between experimental and control groups and between lesioned and unlesioned groups. A proposed model explains how a "low" energy signal and a "high" protein signal cycles amino acids through gluconeogenesis to comPensate for an energy deficit.
Date: May 1981
Creator: McDermott, Kathy Howard
System: The UNT Digital Library
Mast Cells in the Brains of Mice of Different Genotypes: A Histological Study (open access)

Mast Cells in the Brains of Mice of Different Genotypes: A Histological Study

Histamine is present in the central nervous system and is believed to be derived from neurons (50 percent) and mast cells (50 percent). This experiment was designed to analyze histologically the numbers and distribution of brain-associated mast cells in normal (+/+), mast cell deficient (W/W^v) and heterozygote (W/+, W^v/+) mice of the WBB6F_1 /J strain. Significant variations in the number and distribution of mast cells between the various genotypes were found. Based on the results, a hypothesis is proposed to account for the observed genotypical differences in mast cell numbers and distribution. Based on the total number of mast cells and the content of histamine in a typical mast cell, it is apparent that the mast cell is not a major source of brain histamine, suggesting that another non-neuronal pool of histamine must be present in the brain.
Date: May 1983
Creator: Dolce, Angela Kay
System: The UNT Digital Library
Tolerance to the Behavioral Effects of Methylphenidate (open access)

Tolerance to the Behavioral Effects of Methylphenidate

Thirty-one rats were trained on a differential reinforcement of low rate schedule. After responding had stabilized, animals were injected with methylphenidate, twice weekly, presession. Methylphenidate produced dose-dependent increases in response rates and decreases in reinforcements. Repetition of these doses produced a reduced drug effect, and a third administration of the 10 mg/kg dose further reduced the drug effect. Subsequently, the effects of daily and intermittent administration were determined for this dose. Daily methylphenidate, pre-session, produced tolerance to the behavioral effects of methylphenidate and cross-tolerance to the amphetamines. Twice-weekly methylphenidate, pre-session, produced partial tolerance to methylphenidate and partial cross-tolerance to the amphetamines. Thus, periodic exposure to the behaviorally disruptive effects of a drug of the amphetamine class reduces the effects of subsequent exposure.
Date: May 1979
Creator: Brewin, Anne M.
System: The UNT Digital Library
Partial Purification and Some Properties of Lipase From Pseudomonas Aeruginosa (open access)

Partial Purification and Some Properties of Lipase From Pseudomonas Aeruginosa

Purification of lipase from Pseudomonas aeruginosa (from both a washed cell suspension and crude culture supernatant as the enzyme source) was performed utilizing affinity chromatography. Affinity chromatography was carried out using n-dodecylamine bound to Sepharose 4B. Chromatography of the concentrated crude culture supernatant resulted in a 65 to 95 fold purification with 5.8% recovery. Washed cells collected from a ten hour culture suspended in water also produced enzyme. Activity of the washed cell suspension supernatant was found to be 4.5 fold higher than the activity of the culture supernatant. A thirty percent recovery was obtained using the washed cell suspension supernatant. The washed cell suspension provides a cleaner preparation for use with the dodecylamine-agarose chromatography in purifying the enzyme.
Date: May 1979
Creator: Morrison, Linda Kay
System: The UNT Digital Library