The Effects of Electrochemical Therapy on Colon-25 Tumors in Balb-C Mice (open access)

The Effects of Electrochemical Therapy on Colon-25 Tumors in Balb-C Mice

The purpose of the research was to treat immunodeficient mice, implanted with colon-25 tumors, with continuous and interrupted electrochemical therapy (ECT). ECT involves the placement of two electrodes, an anode near the center of the tumor and a cathode into the tumor periphery. A constant voltage is applied across the electrodes for a given period of time. The data showed that the interrupted and continuous ECT resulted in a decrease in mean tumor growth as compared to that of the sham controls. The histology of both ECT groups showed an increase presence of large vacuoles, randomly distributed tumor cells as well as the presence of "crevicing" in the medullary tissue. The differential leukocyte counts showed a distinct neutrophilia and lymphopenia in all groups at day 20 post tumor implantation. The results from the experimental groups appeared to support the findings of previous investigators.
Date: December 2000
Creator: Gillen, Aric
System: The UNT Digital Library
Establishment and Competitive Ability of Nelumbo Lutea in Relation to Myriophyllum Spicatum (open access)

Establishment and Competitive Ability of Nelumbo Lutea in Relation to Myriophyllum Spicatum

Limitations from reduced light and increasing water depth on Nelumbo lutea seedlings were determined in tank experiments. Survival was high in all tested light levels. Total biomass increased significantly with increasing light. Biomass allocation shifted significantly to root production between 3 and 6 weeks in the 10 and 24% levels. Survival decreased with increasing planting depth, and biomass of survivors reduced significantly between 0.5, 1.0, and 1.5 m depths. Nelumbo lutea and Myriophyllum spicatum populations were monitored for one season in a 0.7 ha pond to track changes in species dominance. Myriophyllum spicatum dominated early, and N. lutea dominated from July through October, suppressing M. spicatum at all depths. Competitive interactions between N. lutea and M. spicatum were investigated for two seasons in a container experiment situated within a pond. Where established, N. lutea dominated in the presence of M. spicatum. However, N. lutea could not be established in depths greater than 1 meter.
Date: December 2000
Creator: Snow, Joe R.
System: The UNT Digital Library
Head Trauma Release of Histamine from Dural Mast Cells Alters Blood-Brain Barrier: Attenuation with Zolantidine (open access)

Head Trauma Release of Histamine from Dural Mast Cells Alters Blood-Brain Barrier: Attenuation with Zolantidine

This study employed a new model of mild-to-moderate head trauma to specifically identify the role of dural mast cell (MC) histamine in trauma-induced increased permeability in the blood-brain barrier (BBB). A single line was scored partially through the left dorsal parietal skull. Immediately following the trauma, degranulation was seen in 39% of the MCs on the left and in 2% on the right. After a 20 min survival period, left duras showed 55% with MC degranulation (fewer with complete degranulation) compared to 34% on the right. In the other experiments two parallel lines were scored following the injection of Evan's blue. Histamine assay showed histamine increased in the left cortex to 154% at 5 min, 174% at 10 min, and 151% at 20 min. Fluorescent quantitation of extravasated Evan's blue at 20 min following the trauma gave an increase of 1385% over the value measured for the right cortex. Zolantidine, a selective histamine H2 receptor antagonist, administered at 10- and 20- mg/kg 30 min before the trauma blocked 65% of the Evan's blue extravasation compared with the control and 2.5 mg group.
Date: December 2000
Creator: Laufer, Susan R.
System: The UNT Digital Library
Aspartate Transcarbamoylase of Aeromonas Hydrophila (open access)

Aspartate Transcarbamoylase of Aeromonas Hydrophila

This study focused on the enzyme, aspartate transcarbamoylase (ATCase) from A. hydrophila, a Gram-negative bacterium found in fresh water. The molecular mass of the ATCase holoenzyme from A. hydrophila is 310 kDa. The enzyme is likely composed of 6 catalytic polypeptides of 34 kDa each and 6 regulatory polypeptides of 17 kDa each. The velocity-substrate curve for A. hydrophila ATCase is sigmoidal for both aspartate and carbamoylphosphate. The Km for aspartate was the highest to date for an enteric bacterium at 97.18 mM. The Km for carbamoylphosphate was 1.18 mM. When heated to 60 ºC, the specific activity of the enzyme dropped by more than 50 %. When heated to 100 ºC, the enzyme showed no activity. The enzyme's activity was inhibited by ATP, CTP or UTP.
Date: December 2000
Creator: Higginbotham, Leah
System: The UNT Digital Library