Physiological effect

Serotonin (5-HT) is a neurotransmitter in the central nervous system. Decrease in the brain 5-HT level could induce depression, showing a state of low mood, aversion to motion and feeling of worthlessness. About 12 million adults in the United States have depression. Antidepressants, such as monoamine oxidase inhibitors and selective serotonin reuptake inhibitors, can alleviate the depressive mood by increasing the brain's 5-HT activity, however they can also induce a potentially life-threatening side effect, namely 5-HT syndrome. This syndrome is manifested by neuromuscular hyperactivities, mental disorders and autonomic dysfunctions. Clinical studies have demonstrated that 5-HT2A receptor antagonists could effectively block severe symptoms of patients with the 5-HT syndrome. To understand the underlying mechanisms, in this study we examined the activity of the 5-HT2A receptor in rats with the 5-HT syndrome evoked by a combined injection of clorgyline, a monoamine oxidase inhibitor , and paroxetine, a selective 5-HT reuptake inhibitor. The major findings from my study were that: (1) Chronic clorgyline treatment significantly exacerbated 5-HT2A receptor-mediated symptoms of the 5-HT syndrome animals; (2) The 5-HT2A receptor-mediated symptoms were also aggravated when the 5-HT syndrome animals were housed in warm (32 ÀC) ambient temperature; (3) Blocking 5-HT2A receptors in the medial prefrontal cortex alleviated the 5-HT syndrome through a circuit between raphe serotonergic neurons and medial prefrontal cortex glutamatergic neurons. Taken together, my data demonstrate that the activity of 5-HT2A receptors may be enhanced by chronic antidepressant treatment and warm environmental temperature.

Small conductance calcium-activated potassium (SK) channels are found ubiquitously throughout the brain and modulate the encoding of learning and memory. Systemic injection of 1-ethyl-2-benzimidalzolinoe (EBIO), a SK channel activator, impairs the encoding of novel object memory and locomotion but spares fear memory encoding in C57BL/6NHsd mice. The memory impairments discovered were not due to non-cognitive performance confounds such as ataxia, anxiety, attention or analgesia. Further investigation with intra-hippocampal application of EBIO revealed SK channels in dorsal CA1 contribute to the encoding deficits seen systemically, but do not account for the full extent of the impairment. Concentrated activation of dorsal CA1 SK channels do not influence fear memory encoding or locomotor impairments. Taken together, these data indicate SK channels, especially in the dorsal hippocampus, have a modulatory role on novel object memory encoding, but not retrieval; however, pharmacological activation of hippocampal SK channels does not appear to influence fear memory encoding.

Prostate cancer is the most common form of non-skin cancer and the second leading cause of cancer deaths within the United States. The five year survival rate has increased from 69% to 99% over the last 25 years for the local and regional disease, but has remained fairly low (approximately 34%) for the advanced disease. Therefore, current research is aimed at finding complementary or alternative treatments that will specifically target components of the signal transduction, cell-cycle and apoptosis pathways to induce cell death, with little or no toxic side effects to the patient. In this study we investigated the effect of genistein on expression levels of genes involved in these pathways. Genistein is a (4 , 5 , 7-trihydroxyisoflavone) is a major isoflavone constituent of soy that has been shown to inhibit growth proliferation and induce apoptosis in cancer cells. The mechanism of genistein-induced cell death and potential molecular targets for genistein in LNCaP prostate cancer c ells was investigated using several techniques. The chemosensitivity of genistein towards the prostate cancer cells was investigated using the ATP and MTS assays and apoptosis induction was determined using apoptosis and caspase assays. Several molecular targets were also identified using cDNA microarray and RT-PCR analysis. Our results revealed that genistein induces cell death in a time and dose-dependent manner and regulates expression levels of several genes involved in carcinogenesis and immunogenicity. Several cell cycle genes were down-regulated, including the mitotic kinesins, cyclins and cyclin dependent kinases, indicating that genistein is able to halt cell cycle progression through the regulation of genes involved in this process.

The purpose of this study was to determine the acute effects of caffeine supplementation on strength and muscular endurance in resistance-trained women. In a randomized manner, 15 women consumed caffeine (6 mg/kg) or placebo (PL) seven days apart. Sixty minutes following supplementation, participants performed a one repetition maximum (1RM) barbell bench press test and repetitions to failure at 60% of 1RM. Heart rate and blood pressure were assessed at rest, 60 minutes post-consumption, and immediately following completion of repetitions to failure. Repeated measures ANOVA indicated a significantly greater bench press maximum with caffeine (p<0.05) (52.9 « 11.1 kg vs. 52.1 « 11.7 kg) with no significant differences between conditions in 60% 1RM repetitions (p=0.81). Systolic blood pressure was significantly greater post-exercise, with caffeine (p<0.05) (116.8 « 5.3 mmHg vs. 112.9 « 4.9 mmHg). Our findings indicate a moderate dose of caffeine may be sufficient for enhancing strength performance in resistance-trained women.

Tumor cells interact with basement membrane collagen at the site of extravasation through distinct cellular receptors, including the α2β1 and α3β1integrins. These receptors are known to be differentially expressed in metastatic tumors, relative to the normal cells, depending on tumor type and stage of progression. The binding sites within type IV collagen for the α2β1 andα3β1 integrins have been identified. Since both of the integinspecific sequences possess at least one glycosylated Hyl residue, we questioned whether glycosylation could modulate integrin binding. Triple-helical peptides with and without Lys substituted by glycosylated Hyl for Lys543 and Lys540 from the human a1(IV)531-543 gene sequence (α3β integrin-specific) and Lys393 from the human a1(IV)382-393 gene sequence (α2β1 integrin-specific) were synthesized and utilized in the present study.

Serotonin syndrome (SS) is a drug-induced toxicity caused by an excess of serotonin (5-HT) in the central nervous system (CNS). The symptoms of the disorder range from mild to severe, with the severe state evoking life-threatening hyperthermia. Autonomic dysfunction is controlled in part by serotonin receptors, with the 5-HT2A receptor responsible for increasing core body temperature (Tcor). Our results show that the 5-HT2A receptors on the preoptic/anterior hypothalamus (PO/AH) and prefrontal cortex (PFC), in particular, are sensitive to changes in ambient temperature (Tamb). The toxic increase of 5-HT is postulated to occur due to the temperature-dependent activation of these receptors that promotes a positive feedback mechanism. Our results suggest that changes in Tamb can either exacerbate or alleviate the symptom and that this is mediated by the 5-HT2A receptors. Understanding the mechanism involved in elevating Tcor is imperative in treating and preventing the disorder.

Cardiac ischemia, stroke and some neurodegenerative disorders are all characterized by cell damage and death due to low oxygen levels. Comparative studies show that anoxia tolerant model systems present a unique opportunity to study "survival" instead of death in the complete absence of oxygen. The freshwater turtle (Trachemys scripta elegans) is unique in its ability to survive total oxygen deprivation for hours to days, as well as reoxygenation insult after anoxia. The broad objective of this study is to understand the modulation of key molecular mechanisms involving stress proteins and VEGF that offer neuroprotection and enhance cell survival in the freshwater turtle through anoxia and reoxygenation. In vivo analyses have shown that anoxia induced stress proteins (Hsp72, Hsp60, Grp94, Hsp60, Hsp27, HO-1); modest changes in the Bcl2/Bax ratio and no change in cleaved caspase-3 expression suggesting resistance to neuronal damage. These results were corroborated with immunohistochemical evidence indicating no damage in turtle brain when subjected to the stress of anoxia and A/R. To understand the functional role of Hsp72, siRNA against Hsp72 was utilized to knockdown Hsp72 in vitro (neuronally enriched primary cell cultures established from the turtle). Knockdown cultures were characterized by increased cell death associated with elevated ROS levels. Silencing of Hsp72 knocks down the expression of Bcl2 and increases the expression of Bax, thereby decreasing the Bcl2/Bax ratio. However, there was no increase in cytosolic Cytochrome c or the expression levels of cleaved Caspase-3. Significant increase in AIF was observed in the knockdown cultures that increase through anoxia and reoxygenation, suggesting a caspase independent pathway of cell death.

Atrazine is a popular herbicide used in over 80 countries to inhibit the growth of broadleaf and grassy weeds. Atrazine is a common pollutant in soil and groundwater, and high concentrations of atrazine cause developmental defects in fish, amphibians, and birds. The bacteria Pseudomonas sp. strain ADP (P.ADP) uses atrazine as a nitrogen source by transforming atrazine to ammonia through a number of enzymatic reactions. In this project I measured the growth and atrazine degradation of P.ADP in media with atrazine as the sole nitrogen source. A mutant strain isolated after mutagenesis with UV light showed faster growth and reached higher densities than the control strain. A series of mating experiments were performed to determine whether the growth mutation was on the atrazine degrading plasmid or in the chromosome. The limitations and potential of P.ADP for atrazine degradation are discussed.

Anticancer drugs, including nocodazole and vinblastine, work by disrupting the dynamics of microtubules. Unfortunately, these drugs often produce numerous side effects, including nausea, vomiting, loss of appetite, loss of hair, increased chance of infection, and fatigue. My thesis research evaluated the efficacy of using repeated low doses of microtubule drugs instead of a single high dose, in an attempt to minimize side effects. Using nocodazole and vinblastine, I first established the minimum effective concentration that disrupts the microtubules in normal human cells grown in vitro and treated cells with those concentrations over a period of several days. I found that microtubules were increasingly depolymerized as the days progressed. Next, I tested a combination of nocodazole and vinblastine at low concentrations.

Bioprospecting, the search for useful compounds in nature, has led to the discovery of many important pharmaceuticals. Most current bioprospecting efforts work with chemicals derived from marine invertebrates and terrestrial plants. I looked for useful compounds in a relatively unstudied source, the venom of Crematogaster ants, using Gas Chromatography-Mass Spectroscopy (GC-MS). Further studies can more accurately identify these chemicals using High Pressure Liquid Chromatography (HPLC) and Nuclear Magnetic Resonance (NMR).