M.S. - Biomedical Sciences (Physiology)

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Now showing 1 - 8 of 8
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    Sex differences in osmotic stimulation of vasopressin release in rats chronically exposed to alcohol
    ([Honolulu] : [University of Hawaii at Manoa], [May 2011], 2011-05) Andaya, January May
    Whether the purported differences in alcohol effects in males and females may be due to alcohol influence on estradiol and progesterone mediation of vasopressin (VP) release was studied in Sprague-Dawley male and female rats exposed to control, moderate alcohol (1.2% ethanol) or high alcohol (6.4-6.7% ethanol) liquid diet for 4-6 weeks. VP response to an osmotic stimulus (5% NaCl i.v. infusion) and pituitary VP stores in relationship to circulating VP were examined. In males, alcohol did not appear to affect VP osmotic stimulation. In females, however, alcohol affected VP osmotic stimulation sensitivity depending on estrous cycle phase, and appeared to alter circulating estradiol and progesterone relationships with VP stores and release. Results thus indicate that females may be more susceptible to alcoholinduced changes in VP regulation of water balance.
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    Using RNAi technology to down-regulate Six2 expression in vitro
    ( 2008) Hynd, Thomas Eugene
    The Brachyrrhine (Br) mutant mouse, which displays frontonasal dysplasia and renal hypoplasia, has previously been described. Linkage analysis mapped the semi-dominant Br mutation close to the homeobox transcription factor Six2, which is normally expressed in the facial and metanephric mesenchyme during embryonic development. The purpose of this study is to evaluate the role of Six2 in craniofacial and renal branching morphogenesis by quantifying its expression level in the facial prominences and using immunohistochemistry to visualize branching of the ureteric bud in Br mice. In addition, an in vitro system utilizing RNA interference (RNAi) technology was developed to determine whether Six2 could be experimentally down-regulated. Medial nasal (MNP), lateral nasal (LNP) and maxillary prominences (MAX) of EII.5 embryos were dissected and Six2 expression was measured with qRT-PCR. Six2 expression was highest in the MNP, with about 2-fold less in the MAX, and 3-fold less in the LNP of wild-type embryos. Our data indicate a haploinsufficient pattern of Six2 expression in each of the three sets of facial prominences. In addition, kidney organ explants were dissected from E13.5 mouse embryos and immunostained to reveal differences in ureteric bud branching patterns between the three genotypes (+1+, Br/+ and Br/Br). We confirmed a down-regulation of Six2 in a cell culture system utilizing five RNAi constructs. These data indicate a lack of Six2 expression may playa role in the development of a median facial cleft and its reduced effect in the kidney may lead to renal hypoplasia Additionally, an in vitro system was established that will allow experimental down-regulation of Six2 to assess effects on morphogenesis.
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    Compensatory glomerulopathy in 3H1 Brachyrrhine mice with genetic renal hypoplasia is exacerbated by salt treatment
    ( 2008) Kim, Jin Seon
    The Brachyrrhine (Br/+) mice displays a mutation that directly affects the six2 gene, and this results in premature development of the kidneys and nephrons. These mice exhibit renal hypoplasia which is characterized by a reduced kidney volume with a fewer number of nephrons. The purpose of this study is to compare the morphological differences between the 3H1 wild-type (Wt) and Br/+ mice subjected to salt loading. The specific aim of this project is to determine whether salt loading results in glomerulopathy in mice with heritable renal hypoplasia A total of 24 3Hl mice, ranging in age from 12 to 20 weeks, were divided into four groups of 6 mice each: (1) Wt, no salt, (2) Wt, salt-treated, (3) Br/+, no salt and (4) Br/+, salt-treated. The salt-treated groups were given 2% NaCl solution as a sole source of their fluid intake for 5 days while the control animals were given distilled water. After the mice were perfusion-fixed at the end of the 5th day, the kidneys were removed and embedded in paraffin in preparation for histological sectioning. The sections were stained using H&E, and relevant sections were photographed using an Olympus BX41light microscope. The sections were analyzed for the various stereological parameters and analyzed statistically. The fina1 results showed significant differences between the Wt and the Br/+ in kidney volume, glomerular density/number, and glomerular surface area The Wt mice were significantly larger in kidney volume, glomerular density, and glomerular number, while the salt-treated Br/+ were significantly larger in glomerular surface area Results indicate that salt treatment worsens glomerulopathy in the Br/+ mice as a result of compensatory hyperfiltration.
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    Bioinformatic approach for tracking HIV-1 evolution in Vietnam and neighboring southeast Asian countries
    (University of Hawaii at Manoa, 2003-12) Isami, Fumiyuki ; Nerurkar, Vivek R ; Biomedical Sciences (Tropical Medicine - Cell, Mollecular, & Neuro Sciences)
    There is high prevalence of a methionine substitution at the tip of the V3 loop (MGPGQ) among HIV CRF_AE strains from Vietnam. The aim of this study was to identify other molecular markers or ""signature sequences"" for mapping the spread of HIV in Vietnam and in neighboring Southeast Asian countries. Analysis of the sequence diversity and grouping by molecular markers suggested that ET strain initially gained entry in CSW in southern Vietnam. Unique substitutions among ECM and EC- strains in southern Vietnam IDU and CSW suggested independent introduction and spread of HIV among these high-risk groups. Unique and identical amino acid substitutions found in ECV strains from IDU in northern Vietnam and southern China suggested cross-border travel of virus-infected IDU.
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    Control of the Coqui frog, Eleutherodactylus coqui
    (University of Hawaii at Manoa, 2003-12) Hutchinson, Robert B. ; Ako, Harry ; Biomedical Sciences (Physiology)
    Eleutherodactylus coqui is an invasive species whose unchecked population growth is having environmental and social impacts on the Hawaiian islands. One focus was to fine tune doses of possible toxicants to control the frogs. It was found that applied as a spray, a 1% caffeine and 0.01% pyrethrin cocktail yielded complete mortality in a single application. These concentrations could be tested in field trials. Animals treated with the caffeine/pyrethrin cocktail experienced decreases in liver and muscle glycogen and severe hyperglycemia. This is consistent with known phosphodiesterase inhibition triggering enzyme inhibitions that ultimately lead to lethality. IBMX, a caffeine analogue and potent phosphodiesterase inhibitor, when combined with pyrethrin, had a similar effect. Drugs blocking other possible modes of action such as adenosine antagonism and ryanodine receptor opening had no effect. It was therefore suggested that caffeine in combination with pyrethrin might be an effective method for controlling frog populations and the lethality of the treatment may be due to phosphodiesterase inhibition followed by eventual hyperkalemia.
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    Markers of cardiac injury in ultraendurance runners
    (University of Hawaii at Manoa, 2003-05) Caroll, Patricia A. ; Lally, David ; Biomedical Sciences (Physiology)
    Ultraendurance sports, allowing athletes eager to test the limits of their endurance, are becoming increasingly popular in the United States and throughout the world. The numbers of 100 mile running events; Ironman-distance triathlons (2.4 mile swim, 112 mile bike ride, 26.2 mile run); and multi day, multi-sports events such as the Eco Challenge are increasing. To date, few researchers have investigated the effects these ultraendurance events have on the human heart. In the early 1990's William Rowe suggested that permanent cardiac injury could develop in some endurance athletes in the absence of coronary atherosclerosis. Injury to the coronary endothelium as a result of endurance exercise could occur in athletes participating in multiple events if sufficient time is not allowed for endothelial repair. Rowe proposed that high levels of circulating catecholamines produced by endurance exercise might cause acute myocardial ischemia, patchy fibrosis, as well as coronary vasospasm (sudden, transient constriction of blood vessels). The vasospasm then produced high-sheer endothelial turbulence thus injuring the endothelium. These injuries suffered overtime would adversely affect the heart (Rowe 1992; 1993). In a review of catecholamine cardiotoxicity, Rona stated that the release of catecholamines during exercise might deplete the energy reserves of cardiac muscle cells and this depletion could ultimately result in necrosis. Moreover high-circulating levels of catecholamines might increase cardiac-muscle cell-membrane permeability (Rona 1985) Do events that test the upper limits of human endurance in fact have any adverse effects on the heart? If so, what are they? Are these effects transient or permanent? What is the minimum level of effort at which injury is first observed? These questions prompted this study and the results will contribute to the limited but increasing knowledge regarding the cardiac effects and/or side effects of ultraendurance exercise.
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    The Effect of Heavy Metals on the Uptake of L-Histidine by the Polychaete Nereis Succinea
    (University of Hawaii at Manoa, 2002-12) Peppler, Jessica Elise ; Whitow, Causey G ; Biomedical Sciences (Physiology)
    Integumentary uptake of 3H-L-Histidine by Nereis succinea was measured in the presence and absence of selected heavy metals and inhibitors in 60% artificial seawater (ASW). At low concentrations of L-Histidine (10 uM), metals stimulated L-Histidine uptake from ASW. Higher concentrations of metal inhibited L-Histidine uptake. In amino acid kinetic experiments, 0.5 uM Zn2+ significantly (P < 0.003) increased both L-Histidine influx Jmax (control: 4.7 ± 0.4; treatment: 15.3 ± 1.7 nmol/g dry weight x 15 min), and Km (control: 23.8 ± 5.1; treatment: 44.0 ± 8.8 uM). Fe3+ (0.5 uM) stimulated influx of 10 uM L-Histidine (Jmax = 6.9 ± 0.4 nmol/g dry wt x 15 min; Km = 86.7 ± 12.3 uM), but neither Ag+ nor Al3+ significantly (P > 0.05) altered amino acid influx. L-Leucine (25 uM) reduced Zn2+ -stimulated L-Histidine influx, suggesting a possible role of the Na-independent L-transport system in metal-stimulated L-Histidine transport by worm integument.
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    The Effect of Zinc on the Transmural Transport of L-H-Histidine in the Intestinal Epithelium of the American Lobster, Homarus Americanus
    (University of Hawaii at Manoa, 2002-12) Forry, Erin Patricia ; Lally, David A ; Biomedical Sciences (Physiology)
    It has been demonstrated that in rat erythrocytes, L-histidine enhances the transport of zinc (Aiken et al., 1992). These experiments also indicated that histidine uptake in rat erythrocyte is partially sodium dependent and shows inhibition by leucine. These observations suggest the involvement of the L-system carrier which is capable of transporting histidine with the participation of sodium ions. Similar effects have been shown to occur in the rat intestine (Wapnir et al., 1983). Other work has been conducted testing zinc absorption in rats and the effects of amino acids (histidine, cysteine, tryptophan and proline) on this process (Wapnir & Stiel, 1986). This study determined that histidine assisted in the transport of zinc in the jejunem and ileum of the rat. Further evidence shows that metals stimulate amino acid transport in crustacean hepatopancreatic cells. Monteilh-Zoller, Zonno, Storelli, and Ahearn (1999) showed that zinc doubled the transmembrane transfer of L-proline in lobster hepatopancreatic brush border membrane vesicles. The enhanced uptake of the amino acid in the presence of the metal was found to be due to increased 3H-L-proline maximal transport velocity (i.e. Jmax), rather than due to a change in binding affinity (i.e. Kt) induced by the metal. The L-proline transport occurred by way of a specific transport protein, the IMINO system. These studies indicate that zinc and histidine form a complex that is transported together. It is thus postulated that zinc enhances the transport of histidine. In this study, the effect of zinc on the transmural flux of L-histidine across the intestine of the Atlantic lobster (Homarus americanus) was investigated. Previous studies of amino acid transport involved alanine, a non-essential amino acid, which was largely metabolized by the tissue (Wyban, Ahearn & Maginniss, 1980). However, in this study, L-histidine, an essential amino acid for the growth of lobsters and other crustaceans, was the nutrient considered (Factor, 1995). Experiments support the hypothesis that the uptake of L-histidine is increased in the presence of zinc (Ahearn, H.R.H. et al, 2000; Liou & Ellory, 1990). The first portion of this project determined the net transmural flux of 3H-L-histidine at five different concentrations, in the presence and absence of a defined zinc concentration. Unidirectional transepithelial transport was measured across the intestine as a function of time. These measurements established that transport is likely carrier-mediated, as a saturation of a carrier molecule will limit transport. The second portion of the described research studied the influence of varying the concentration of zinc at a constant concentration of 100 µM L-histidine. The concentrations of zinc ranged from 5 µM to 250 µM. The optimal concentrations of zinc, which produced maximal carrier-mediated activation, were determined to be between 25 µM and 50 µM.