The roles of ERK1/2 and PI3K in abnormal vascular functions in angiotensin II-infused hypertensive rats

Background: Ang II plays a major role in cardiovascular regulation. Recently, it has become apparent that vascular superoxide anion may play an important role in hypertension development. Treatment with antisense NAD(P)H oxidase or SOD decreased BP in Ang II-infused rats. Wang et al recently reported mice which lack one of the subunits of NAD(P)H oxidase developed hypertension at a much lower extent when compared to the wild type animals infused with Ang II, indicating that superoxide anion contributes to elevation in BP in the Ang II-infused hypertensive model. In the Ang II-infused hypertensive model, altered reactivity of blood vessels is often associated with the elevation of systolic blood pressure. We have observed abnormal tension development and impaired endothelium-dependent relaxation in the isolated aorta of Ang II-infused and DOCA-salt hypertensive rats. Recently, several other cellular signal molecules, including ERK1I2 and PI3K, have been determined to play important roles in the regulation of smooth muscle contraction and relaxation. ERKl/2 and PI3K pathways are also reported to contribute to Ang II induced cell growth, hypertrophy, remodeling and contraction. Moreover, these signaling pathways have shown ROS-sensitive properties. Therefore, the aim of the present study is to investigate the roles of ERKl12 and PI3K in vascular oxidative stress, spontaneous tone and impaired endothelium relaxation in Ang II-infused hypertensive model. Hypothesis: We hypothesize that the activation of ERKl12 and PI3K are elevated in response to an Ang II infusion for 6 days. The elevated activation of phospho-ERKl/2 and PI3K mediated the increased level of vascular superoxide anion, the abnormal vascular contraction and impaired endothelium-dependent vascular relaxation in Ang II-infused hypertensive rats. Methods: Vascular superoxide anion level is measured by lucigenin chemiluminescence. Spontaneous tone and ACh-induced endothelium-dependent relaxation was measured by isometric tension recording in organ chamber. The activity of ERK pathway will be measured by its Western blot of phosphorylation of ERK. PI3K activity was evaluated indirectly by Western blot of the phosphorylation of PDKl, a downstream protein of PI3K signaling pathway. The role of each pathway was also addressed via comparing the responses to the specific inhibitors. Results: Superoxide anion was markedly increased in the isolated thoracic aorta from Ang II-infused rats. There was spontaneous tone developed in rings from Ang II-induced hypertensive but not sham-operated normotensive rats. ACh-induced endothelium-dependent relaxation function is impaired in Ang II-infused hypertensive rats. Superoxide dismutase and NAD(P)H oxidase inhibitor, apocynin, inhibited the abnormal spontaneous tone and ameliorated impaired endothelium-dependent relaxation. The expression of phopho-ERKII2 was enhanced in Ang II-infused rats, indicating the activity of ERK1I2 could be increased. MEK1I2 inhibitors, PD98059 and U126, but not their inactive analogues, SB203580 and U124, significantly reduced the vascular superoxide anion in aortas from Ang II-infused rats. The MEK1I2 inhibitors reduced the spontaneous tone and improved the impaired endothelium-dependent relaxation in aorta of hypertension. These findings supported the role of ERKII2 signaling pathway in vascular oxidative stress, spontaneous tone and impaired endothelium-dependent relaxation in Ang II-infused hypertensive rats. The amount of phospho-PDK, a downstream protein of PI3K was increased in Ang II rats indicating the activity of PI3K activity was elevated. Strikingly, PI3K significantly inhibited the increase of superoxide anion level, abnormal spontaneous tone and restored endothelium-dependent relaxation in Ang II-infused hypertensive rats. These findings indicated the important role of PI3K in Ang II-infused hypertensive rats. Conclusion: ERKII2 and PI3K signaling pathways are sustained activated in Ang II-infused hypertensive rats. The activated ERKII2 and PI3K mediate the increase of vascular superoxide anion level, vascular abnormal spontaneous tone and impaired endothelium-dependent relaxation.

Cytosolic calcium levels and stress induced y-amino butyrate synthesis in asparagus mesophyll cells

Numerous investigations have demonstrated large increases in y-amino butyrate (GABA) levels in response to a variety of stresses such as touch or cold shock (Wallace et ale 1984) Circumstantial evidence indicating a role of Ca2 + in these increases includes elevated Ca2+ levels in response to touch and cold shock (Knight et ale 1991), and the demonstration of a calmodulin binding domain on glutamate decarboxylase (GAD), the enzyme responsible for GABA synthesis (Baum et al 1993) In the present study the possible role of Ca2+ and calmodulin in stimulation of GAD and subsequent GABA accumulation was examined using asparagus mesophyll cells. Images of cells loaded with the Ca2+ indicator Fluo-3 revealed a rapid and transient increase in cytosolic Ca2+ in response to cold shock. GABA levels increased by 106% within 15 min. of cold shock. This increase was inhibited 70% by the calmodulin antagonist W7, and 42% by the Ca2+ channel blocker La3+.. Artificial elevation of intracellular Ca2+ by the Ca2+ionophore A23187 resulted in an 61% increase in GABA levels. Stimulation of GABA synthesis by ABA resulted in an 83% increase in GABA levels which was inhibited 55% by W7. These results support the hypothesis that cold shock stimulates Ca2+ entry into the cytosol of the cells which results in Ca2+/calmodulin mediated activation of GAD and consequent GABA synthesis.

The relationship between stem-form, stand-closure and site -conditions : the influence of environmental conditions on tree allometry and forest structure in west-central Alberta

Changes in the configuration of a tree stern result insignificant differences in its total volume and in the proportion of that volume that is merchantable timber. Tree allometry, as represented by stem-fo~, is the result of the vertical force of gravity and the horizontal force of wind. The effect of wind force is demonstrated in the relationship between stem-form, standclosure and site-conditions. An increase in wind force on the individual tree due to a decrease in stand density should produce a more tapered tree. The density of the stand is determined by the conditions that the trees are growing under. The ability of the tree to respond to increased wind force may also be a function of these conditions . This stem-form/stand-closure/site-conditions relationship was examined using a pre-existing database from westcentral Alberta. This database consisted of environmental, vegetation, soils and timber data covering a wide range of sites. There were 653 sample trees with 82 variables that formed the basis of the analysis. There were eight tree species consisting of Pinus contorta, Picea mariana, Picea engelmannii x glauca, Abies lasiocarpa, Larix laricina, Populus tremuloides, Betula papyrifera and Populus balsamifera plus a comprehensive all-species data set. As the actual conformation of the stern is very individual, stem-fo~was represented by the diameter at breast height to total height r~tio. The four stand-closure variables, crown closure, total basal area, total volume and total number of stems were reduced to total basal area and total number of stems utilizing a bivariate correlation matrix by species. Site-conditions were subdivided into macro, meso and micro variables and reduced in number 3 using cross-tabulations, bivariate correlation and principal components analysis as screening tools. The stem-fo~/stand-closure relationship was examined using bivariate correlation coefficients for stem-fo~ with total number of stems and stem-fo~ with total basal area. The stem-fo~/site-conditions and the stand-closure/site- conditions relationships were examined using multiple correlation coefficients. The stem-form/stand-closure/site-conditions relationship was examined using multiple correlation coefficients in separate analyses for both total number of stems and total basal area. An increase in stand-closure produced a decrease in stem-form for both total number of stems and total basal area for most species. There was a significant relationship between stem-form and site-conditions and between stand-closure and site-conditions for both total number of stems and total basal area for most species. There was a significant relationship between the stemform and site-conditions, including the stand-closure, for most species; total number of stems was involved independently of the site-conditions in the prediction of stem-form and total basal area was not. Larix laricina and Betula papyrifera were the exceptions to the trends observed with most species. The influence of both stand-closure (total number of stems in particular) and site-conditions (elevation in particular) suggest that forest management practices should include these- ecological parameters in determining appropriate restocking levels.

Phytoplankton species diversity of 27 lakes and ponds of Costa Rica (Central America)

The literature on species diversity of phytoplankton of tropical lakes is scarce, and for the main part comes from studies of the big lakes in Africa, or deep lakes in South America, leaving a gap in the information about small shallow tropical lakes. In the present work the phytoplankton species composition and diversity of 27 shallow lakes and ponds in Costa Rica (Central America) was studied. The species composition was found to agree with other studies of tropical lakes, with a dominance of Chlorophyta, Cyanophyta, or in some cases Bacillariophyta or Euglenophyta; and a general paucity of Chrysophyta and Cryptophyta. Species richness varied considerably among the lakes, and tended to decrease with an increase in lake elevation. A low evenness in the species abundances was found, with one or more species outnumbering the rest by several orders of magnitude. Individual species abundances and species composition was found to vary with time in Rio Cuarto Lake, a meromictic lake situated in a region with low seasonal change in precipitation. In comparison with the phytoplankton of temperate lakes, the phytoplankton of the tropical lakes studied tended to have a lower evenness of species abundances, although species richness may be similar to temperate figures in some cases. Diversity indices sensitive to changes in the abundance of rare species tend to be higher in the tropical lakes studied; diversity indices sensitive to changes in the numbers of abundant species tend to be similar between the temperate and tropical lakes examined.

An examination of transcriptional and translational regulation of the 70kDa heat shock proteins following amputation of the tail and forelimb in the newt Notophthalmus viridescens

Several stresses to tissues including hyperthermia, ischemia, mechanical trauma and heavy metals have been demonstrated to affect the regulation of a subset of the family of heat shock proteins of70kOa (hsp70). In several organisms following some of these traumas, the levels of hsp70 mRNA and proteins are dramatically upregulated. However, the effects of the stress on limb and tail amputation in the newt Notophthalmus viridescens, involving mechanical tissue damage, have not adequately been examined. In the present study, three techniques were utilized to quantitate the levels of hsp70 mRNA and protein in the tissues of the forelimbs and tails of newts during the early post-traumatic events following surgical resection of these:: appendages. These included quantitative Western blotting of proteins separated by both one and twodimensional SDS-polyacrylamide gel electrophoresis and quantitative Northern blot analysis of total RNA. In tissues of both the limb and tail one hour after amputation, there were no significant differences in the levels of hsp70 protein measured by one-dimensional SOSPAGE followed by Western blotting, when compared to the levels measured in the unamputated limb. A 30 minute heat shock at 35°C failed to elicit an increase in the levels of hsp70 protein in these tissues. Further analysis using the more sensitive 20 PAGE separation of stump tissue proteins revealed that at least some of the five hsp70 isoforms of the newt may be differentially regulated in limbs and tails in response to trauma. It appears also that amputation of the tail and limb tissues leads to slight 3 elevation in the levels of HSP70 mRNA when compared to those of their respective unstressed tissues.

Correlation of Protein Homeostasis With Maximum Lifespans in Endothermic Vertebrates

Cellular stress resistance has been shown to be highly correlated with longevity. However, the mechanisms conferring this stress resistance have yet to be identified. Maintenance of protein homeostasis is a critical component of cellular maintenance and stress resistance. Superior protein homeostasis capacities may thus underlie the greater stress resistance observed in longer-lived animals; however, little vertebrate data have been provided supporting this idea. I used two different experimental approaches to test the associations of protein homeostasis capacities with stress resistance and lifespan: 1) a comparison between a large set of vertebrate species with varying body masses and lifespans and 2) a comparison of long-lived Snell dwarf mice and their normal littermates. Protein homeostasis mechanisms including protein degradation activity, protein repair activity and molecular chaperone levels were examined. These measurements were performed in liver, heart and brain tissues, and isolated myoblasts. My results indicated that neither protein degradation nor protein repair were upregulated in association with enhanced stress resistance and longevity in an inter-species and intraspecies context. Furthermore, my results did show that there is a positive correlation between molecular chaperone levels and maximum lifespan (MLSP). However, there was no elevation of chaperone levels in the long-lived Snell dwarf mouse, indicating there are other mechanisms linked to their increased lifespan. Therefore, these results suggest that molecular chaperones are involved in increasing animal lifespan in an interspecies context.

Report of Loss in Capacity Due to Ice at Rankine Station - April 1934 through April 1937

A report compiled by Canadian Niagara Power Company describes the loss in capacity due to ice. The chart reveals the kilowatts lost and the duration of the outage and the "min. forebay elevation during ice loss period".

Grand Central Hotel Blueprints

Plans are alterations to store fronts and rear elevation.

QUANTIFICATION AND EXTRACTION OF SURFACE FEATURES FROM DIGITAL TERRAIN MODELS

Digital Terrain Models (DTMs) are important in geology and geomorphology, since elevation data contains a lot of information pertaining to geomorphological processes that influence the topography. The first derivative of topography is attitude; the second is curvature. GIS tools were developed for derivation of strike, dip, curvature and curvature orientation from Digital Elevation Models (DEMs). A method for displaying both strike and dip simultaneously as colour-coded visualization (AVA) was implemented. A plug-in for calculating strike and dip via Least Squares Regression was created first using VB.NET. Further research produced a more computationally efficient solution, convolution filtering, which was implemented as Python scripts. These scripts were also used for calculation of curvature and curvature orientation. The application of these tools was demonstrated by performing morphometric studies on datasets from Earth and Mars. The tools show promise, however more work is needed to explore their full potential and possible uses.