abstract: Despite recent strides for awareness, treatment, and control of hypertension, prevalence remains high with estimates suggesting one third of Americans have hypertension. The hypotensive effects of potassium and magnesium have been known and administered in a clinical setting for nearly a century. The purpose of this study was to examine the effectiveness of taking a potassium/magnesium supplement to help reduce blood pressure in individuals with mildly-moderately elevated blood pressure. In this randomized, controlled crossover trial, potassium and magnesium supplementation was explored among healthy adults with mildly elevated blood pressure in Phoenix, Arizona. Subjects (n = 12) were randomly assigned to ingest either the treatment chewy bar (217 mg potassium/day; 70.8 mg magnesium/day) or a placebo chewy bar for four weeks. For the subsequent four weeks, subjects ingested the other corresponding chewy bar. Systolic (SBP), diastolic (DBP), and average blood pressure values were not significantly different between the two groups (p = 0.645, p = 0.464 and p = 0.939, respectively). Baseline mean blood pressure was 121.0/75.7 mm Hg. The 12 subjects (8 females, 4 males) had a mean age of 29.3 years old and a mean BMI of 26.2. After four weeks, the treatment group had a slightly higher SBP (118.3 ± 13.3 mm Hg) than the control group (116.5 ± 17.8 mm Hg); however, DBP was lower in the treatment group (71.7 ± 12.4 mm Hg) than the control group (73.0 ± 10.0 mm Hg). In conclusion, daily supplementation of potassium and magnesium (217.2 mg/day and 70.8 mg/day, respectively) did not significantly lower blood pressure in adults with mildly-moderately elevated blood pressure. / Dissertation/Thesis / Masters Thesis Nutrition 2015

Made available in DSpace on 2014-10-09T12:23:43Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:27Z (GMT). No. of bitstreams: 1 01285.pdf: 1338586 bytes, checksum: 66375650824e982de91454877d67af8a (MD5) / Dissertacao (Mestrado) / IPEN/D / Faculdade de Medicina Veterinaria e Zootecnia, Universidade de Sao Paulo - FMVZ/USP

Orientador: Ricardo de Lima Isaac / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-12T16:05:09Z (GMT). No. of bitstreams: 1 Siqueira_SidneiLima_M.pdf: 1474737 bytes, checksum: 071f5399e0fae4354b4e3c3bccc930ba (MD5) Previous issue date: 2008 / Resumo: Este trabalho consistiu em avaliar a capacidade de remoção da toxina Microcistina-Lr utilizando oxidação por cloro, dióxido de cloro e permanganato de potássio. Os ensaios foram realizados em escala de bancada em jar test simulando o processo de tratamento de água nas ETA's 3 e 4 da SANASA de Campinas. Foram realizados estudos com concentrações de 2.5, 5.0 e 10 µg/L de Mc-Lr quando se utilizou oxidação com cloro e dióxido de cloro e com concentrações de 2.5 e 5.0 µg/ L quando foi utilizado permanganato de potássio como oxidante. Foram feitos testes para verificação da influência da aplicação do oxidante antes e depois do alcalinizante com dosagens de 10µg/L de Mc-Lr. As utilizações do cloro e do permanganato se mostraram eficientes para a remoção da Mc-Lr, enquanto que com a utilização do dióxido de cloro, nenhuma remoção foi alcançada dentro das três horas de testes. Nos testes com aplicação do oxidante antes e depois do alcalinizante, não houve alterações significativas. Quando os testes foram feitos utilizando o tempo, os resultados foram similares para o cloro e permanganato de potássio, com a oxidação ocorrendo durante a primeira hora. Com o dióxido de cloro, a oxidação aconteceu somente durante a sexta hora. / Abstract: This work consisted in evaluate the capacity of removal of Microcystin-Lr toxin using oxidation with chlorine, chlorine dioxide and potassium permanganate. The tests were did using bench -scale tests in jar test equipment to simulated water treatment process of 3 and 4 WTP of SANASA Campinas. Study were did using 2.5, 5.0 and 10 µg/L Mc-Lr concentration when were used chlorine and chlorine dioxide oxidation and 2.5 and 5.0 µg/L Mc-Lr concentration when was used potassium permanganate oxidation. Were did tests to verify the influence of before and after alkali oxidant dosing with 10µg/L Mc-Lr. The chlorine and permanganate uses were efficient to Mc-Lr removal while chlorine dioxide no one removal was obtained with normal quantity used in Convencional Water Drinking Treatment Plant. When the tests were did using time, the results were silimary to chlorine and permanganate with the oxidation happened during the first hour. With chlorine dioxide oxidation, the oxidation happened only during the sixth hour. When the tests were did dosing. / Mestrado / Saneamento e Ambiente / Mestre em Engenharia Civil

A antecipação de potássio (K) do milho segunda safra na cultura da soja é um sistema de adubação que pode apresentar aproveitamento do K-fertilizante pela sucessão soja - milho similar ao parcelamento de potássio para cada cultura, sem alterar o desempenho da sucessão soja - milho em região de Cerrado. A viabilidade da antecipação do K de base e cobertura do milho na cultura da soja se dá pela aplicação a lanço, que reduz o tempo de reabastecimento da semeadora durante o plantio. Isto permite rápida semeadura do milho para garantir seu desenvolvimento em época de precipitação pluviométrica adequada. O objetivo desta tese foi avaliar o desempenho da sucessão soja - milho, assim como o aproveitamento de K-fertilizante (acúmulo e recuperação), em razão da aplicação de doses de potássio feitas a lanço em dois sistemas de adubação (antecipação e parcelamento). Os estudos de campo foram feitos nas safras 2014/15 e 2015/16 no estado do Tocantins. Os tratamentos foram as doses 0, 60, 120 e 180 kg ha-1 de K2O com aplicação parcelada (40% - soja e 60% - milho) e antecipada, uma única vez na soja. As avaliações foram acúmulo de biomassa, potássio e magnésio (Mg) na parte aérea das plantas, a concentração K e Mg na folha diagnóstica, e a produtividade de soja e milho. Foram quantificados também, o acúmulo e a recuperação de potássio proveniente do fertilizante por meio de rubídio como traçador de potássio. Os resultados mostraram que antecipação de potássio não alterou a produtividade de grãos das culturas de soja e milho. No entanto, as doses de potássio mostraram efeito positivo na nutrição de K e negativo na de Mg, independente do sistema de adubação. O aproveitamento de K-fertilizante pela sucessão soja-milho foi similiar e até superior (22%) para a antecipação de potássio. Portanto, justifica-se ao produtor fazer a aplicação de potássio uma única vez, por ganhar agilidade durante a semeadura do milho. / Early application is a practice that brings potassium (K) fertilizer from corn to soybean in the soybean - corn succession. Recovery of K-fertilizer by these crops might be similar between early (to soybean) and split (soybean and corn) application, without change crops performance at Cerrado\'s region. Broadcast application allow these practices because planter stops is reduced: avoiding recharges of fertilizer during corn sowing and ensure a good plant development until the end of rainy season. So, the aim of this dissertation was assess crop`s performance, and uptake and recovery of K from fertilizer in the soybean - corn affected by potassim application at two practices (split application and early). Field study was conducted in the rainy season 2014/15 and 2015/16 at Tocantins State, Brazil. Treatments are rates 0, 60, 120 e 180 kg ha-1of K2O with two practices: spplit application (40% - soja e 60% - milho) and early application (once in soybean). Evaluations were aboveground biomass, potassium and magnesium (Mg) accumulation, and leaf K and Mg content, and yield of soybean and corn. Potassium uptake and recovery from fertilizer was meseuared by rubidium as a tracr of potassium. Results showed that early application did not change grain yield for soybean and corn. However, regardless practice, the rate of potassium showed positive effect on K plant nutrition, whilst negative effect was observed on Mg. Overall, K recovery from fertilizer by soybean - corn succession was similar and higher (22%) for early application. Therefore, farmers can do early application for improve corn sowing.

Potassium ions are the most abundant cation and potassium transport is essential in maintaining cellular homeostasis through the regulation of cell turgor and cytoplasmic pH. It allows bacteria to grow and survive, therefore, the potassium pool needs to be strictly controlled, which is mainly performed by transport systems that contain a KTN domain. The potassium efflux system, Kef, is such a KTN-bearing system and it is widespread among Gram negative bacteria. The system provides protection against harmful electrophiles through cytoplasmic acidification. Kef is a glutathione-regulated protein: it is inhibited by glutathione (GSH), but it becomes activated by binding glutathione-S-conjugates (GSX), that are formed in the presence of electrophiles. GSH or GSX are bound in the same pocket that is located in a cytosolic regulatory domain which controls the K+ flux. Previous studies already showed that bacterial growth is inhibited when the gating of Kef is manipulated, which makes Kef a potential target for developing novel antibacterial drugs. Structure-Function studies have already lead to a better understanding of the regulation of potassium efflux activity, but no quantitative analyses had been performed until now. A simplified model Kef system (SdKef) is presented and a novel assay was developed that provided new insights into the structural components necessary for the gating of Kef. This assay makes the search for modulators of Kef, and therefore potential novel antibacterial drugs, more easily accessible. Another objective was to identify the nucleotide(s) bound and to determine its role in controlling the Kef system. This nucleotide was identified as AMP which is essential for stability of the Kef system.

The voltage-gated K+ channel Kv2.1 has been intimately linked with neuronal apoptosis. After ischemic, oxidative, or inflammatory insults, Kv2.1 mediates a pronounced, delayed enhancement of K+ efflux, generating an optimal intracellular environment for caspase and nuclease activity, key components of programmed cell death. This apoptosis-enabling mechanism is initiated via Zn2+-dependent dual phosphorylation of Kv2.1, increasing the interaction between the channel's intracellular C-terminus domain and the SNARE(soluble N-ethylmaleimide-sensitive factor activating protein receptor) protein syntaxin 1A. Subsequently, an upregulation of de novo channel insertion into the plasma membrane leads to the critical enhancement of K+ efflux in damaged neurons. Here, we investigated whether a strategy designed to interfere with the cell death-facilitating properties of Kv2.1, specifically its interaction with syntaxin 1A, could lead to neuroprotection following ischemic injury in vivo. The minimal syntaxin 1A-binding sequence of Kv2.1 C terminus (C1aB) was first identified via a far-Western peptide screen and used to create a protherapeutic product by conjugating C1aB to a cell-penetrating domain. The resulting peptide (TAT-C1aB) suppressed enhanced whole-cell K+ currents produced by a mutated form of Kv2.1 mimicking apoptosis in a mammalian expression system, and protected cortical neurons from slow excitotoxic injury in vitro, without influencing NMDA-induced intracellular calcium responses. Importantly, intraperitoneal administration of TAT-C1aB in mice following transient middle cerebral artery occlusion significantly reduced ischemic stroke damage and improved neurological outcome. These results provide strong evidence that targeting the proapoptotic function of Kv2.1 is an effective and highly promising neuroprotective strategy.

No description available.

The radioactive isotope K⁴² was used to measure the rate of potassium exchange in muscle from 129 strain mice. The results followed an unique course if plotted as K⁴² uptake versus (external potassium concentration ∙ time) [superscript ½], and corresponded to the result predicted for K⁴² uptake mediated by an ion-exchange compartment in the muscle. Variations in external potassium concentration did not affect the uptake rate if plotted this way, but sodium ion exerted some effect on the rate. Dystrophic mouse tissue accumulated K⁴² more rapidly than did normal tissue, and the effect of varying the external potassium concentration did not alter this rate. The effects of sodium variation were more pronounced than in normal tissue. Inulin space of muscle was measured in vivo as well as in vitro, to enable a correction for K⁴² in the extracellular space to be made. The inulin space was found to decrease with increasing muscle size, and this was thought to be related to the development of the muscle. Dystrophic muscle exhibited more of a dependance of inulin space on muscle size than did normal muscle. The suggestion was made that the dystrophic muscle membrane might be abnormally permeable to inulin. Muscles were excised and assayed by flame photometry for sodium and potassium content. They were assayed when freshly excised, and also following incubation in a variant of Locke’s solution. The muscle cations were stable for the first two hours of incubation, but after this time, intracellular sodium rose and potassium fell. Fresh dystrophic mouse muscle had lower potassium and higher sodium content than normal fresh muscle. The cation changes following incubation resembled those found for normal muscle. The changes in intracellular cations were correlated with the K⁴² uptake results, and discussed in some detail. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

A study of the potassium status of some Lower Fraser Valley soils was undertaken in order to supply data which would aid in the interpretation of fertility experiments and chemical tests for available soil potassium. Since the rapid chemical tests for available potassium now used in the Lower Fraser Valley leave much to be desired, several promising methods were studied and compared to a standard ammonium acetate extraction gravimetric analysis method for determining exchangeable potassium. The Morgan and Spurway rapid methods for available potassium estimation were not found precise or accurate enough for the purposes of the study. A technique described by Peech and English, which involves extraction of available potassium with normal sodium acetate of pH4.8 and subsequent precipitation of potassium as the di-potassium sodium cobaltinitrite in formaldehyde-isopropyl alcohol solution was tested. A modification of this method was adapted to estimation by the photometer and results for exchangeable potassium, although lower, correlated well with those of the standard determination. A technique which is more rapid and better adapted to studies in which potassium is the only cation to be tested is that described by Bray, who recommends extraction with sodium nitrate and precipitation of potassium with sodium cobaltinitrite in ethyl alcohol solution and subsequent photometric determination. This method extracted slightly more potassium than that of Peech but also showed a high correlation with the standard method used. Both and Bray and Peech procedures were found adaptable to line chart estimation for routine soil testing work. The Bray method was compared to the standard ammonium acetate-gravimetric procedure in potassium fixation and release studies in limed and unlimed soils. Two upland soils and three recent alluvial soils, on which fertility experiments with oats had been conducted, were studied. A greenhouse experiment using lettuce was designed to indicate any existing relation between chemical studies and plant response. In the laboratory fixation was induced by alternately wetting and drying the soils at 110⁰ C. All soils were found to have high fixing potentials when measured by both extraction methods, although the fixation was higher when determined by the standard method. The effect of lime on fixation in both the laboratory and greenhouse soils was determined. The soils generally showed an apparent release of potassium when measured by the ammonium acetate-gravimetric method and a fixation by the sodium nitrate technique. These differences were considered to be due to the relative replacing powers of Na+ and NH+ when Ca++ or H+ dominate the exchange complex. Thus the extraction of potassium by Na+ may be inhibited when calcium is the complementary ion on the colloid. The potassium status of the upland soils was less affected by lime than the lowland soils when fixation or release due to lime was measured by either method. The soils studied failed to release any potassium from the fixed form when leached of their exchangeable potassium and stored for three months in a moist condition, or when wetted and dried at 110 C. No relation was found to exist between exchangeable potassium or the relative potassium fixing and supplying powers of the soils, and oat response to potassium in the field or lettuce growth in the greenhouse. / Land and Food Systems, Faculty of / Graduate

The cellular mechanism and regulation of KC1 reabsorption across the rectum of the desert locust Schistocerca gregaria has been studied using tracer fluxes, ion-sensitive microelectrodes, and electrophysiological techniques. Serosal addition of 1 mM cAMP stimulates transepithelial short- circuit current (I[sub=SC]) and net Cl absorption (J[sub=net;sup=Cl] ) 10-fold, increases transepithelial potential (V[sub=t]) 4-fold, and reduces transepithelial resistance (R[sub=T]) by 40-65%. The properties of locust Cl transport are not consistent with NaCl cotransport models proposed in other epithelia: i) Cl is absorbed from nominally Na-free saline, ii) there is no correlation between trace amounts of Na contamination and the rate of Cl transport, iii) exposure to cAMP increases ³⁶Cl influx across the apical border into rectal tissue without affecting ²²Na influx, iv) Cl-dependent I[sub=SC] is not inhibited by 1 mM ouabain (2 h) or 1 mN furosemide (1 h), v) J[sub=net;sub=Cl] is not affected when the apical Na electrochemical gradient is reduced by 85%, and vi) there is no relationship between Na and Cl net electrochemical gradients across the apical membrane. Cl/HCO₃ exchange is also unlikely since i) Cl-transport is electrogenic, ii) J[sub=net;sub=Cl] is insensitive to CO₂⁻ and HCO₃⁻ removal, and iii) Cl-dependent I[sub=SC] is not inhibited by 1 mM SITS or 1 mM acetazolamide after 1 h exposure. The cAMP-stimulated system is Cl-selective: Cl >> Br >> I,F,SCN,P0₄,SO₄.C₂H₃O₂,urate. The halide sequence suggests a site having high field strength. Cl-dependent I[sub=SC] is inhibited by low mucosal pH and high osmotic pressure. J[sub=net;sub=Cl] obeys Michaelis-Menten-type kinetics. Mucosal K increases both the K[sub=m] and V[sub=max] of transepithelial Cl absorption (K[sub=a] = 5.3 mM K). The active step in J[sub=net;sub=Cl] is at the apical membrane because net entry of Cl occurs against a large, unfavourable electrochemical gradient. Serosal cAMP and mucosal K directly stimulate the active step since both of these agents cause simultaneous increases in J[sub=net;sub=Cl] and the electrochemical potential opposing CI entry. Passive K transport in the mucosa-to-serosa direction is favoured across apical and basal membranes. Most K absorption (~84%) is electrically coupled to active CI transport under open-circuit conditions, however a small active component is apparent during exposure to cAMP. The response of V[sub=T] to transepithelial salt gradients depends strongly on the direction of the gradients, suggesting that locust rectum is a "tight" epithelium. Intracellular current and fluorescent dye injections reveal strong coupling between rectal cells. Flat-sheet cable analysis indicates that locust rectum becomes "tighter" during cAMP exposure, when transcellular conductance increases from 60 to 95% of the total tissue conductance. cAMP increases apical membrane K conductance and basal membrane CI conductance. K permeability is inhibited by high (physiological) K and osmotic concentrations. The driving force of CI transport is calculated by two independent methods and the results are interpreted in terms of an equivalent electrical circuit model for KCl reabsorption across locust rectum. / Science, Faculty of / Zoology, Department of / Graduate