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Irtokartta

Development of the insulin secretion mechanism in fetal and neonatal rat pancreatic B-cells: response to glucose, K+, theophylline, and carbamylcholine

We studied the development of the insulin secretion mechanism in the pancreas of fetal (19- and 21-day-old), neonatal (3-day-old), and adult (90-day-old) rats in response to stimulation with 8.3 or 16.7 mM glucose, 30 mM K+, 5 mM theophylline (Theo) and 200 µM carbamylcholine (Cch). No effect of glucose or high K+ was observed on the pancreas from 19-day-old fetuses, whereas Theo and Cch significantly increased insulin secretion at this age (82 and 127% above basal levels, respectively). High K+ also failed to alter the insulin secretion in the pancreas from 21-day-old fetuses, whereas 8.3 mM and 16.7 mM glucose significantly stimulated insulin release by 41 and 54% above basal levels, respectively. Similar results were obtained with Theo and Cch. A more marked effect of glucose on insulin secretion was observed in the pancreas of 3-day-old rats, reaching 84 and 179% above basal levels with 8.3 mM and 16.7 mM glucose, respectively. At this age, both Theo and Cch increased insulin secretion to close to two-times basal levels. In islets from adult rats, 8.3 mM and 16.7 mM glucose, Theo, and Cch increased the insulin release by 104, 193, 318 and 396% above basal levels, respectively. These data indicate that pancreatic B-cells from 19-day-old fetuses were already sensitive to stimuli that use either cAMP or IP3 and DAG as second messengers, but insensitive to stimuli such as glucose and high K+ that induce membrane depolarization. The greater effect of glucose on insulin secretion during the neonatal period indicates that this period is crucial for the maturation of the glucose-sensing mechanism in B-cells.

Èkspedicìi k" ust'âm" Eniseâ 1875 i 1876 godov": so stat'eû ad"ûnkt" professora zoologìi Upsal'skago universiteta G. Tèlâ o plavanìi ego po Eniseû v" 1876 godu i dvu'mâ kartami plavanìâ

Perevod s" sÌŒvedskago.

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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

K-liitoksen epäkeskeisen tuennan aiheuttaman sekundäärisen momentin määritys

Työssä on tutkittu laboratoriokokeen ja elementtimenetelmän avulla eri geometrioiden vaikutusta sekundääriseen momentin syntymiseen K-liitoksella. Kokeen liitos on tehty S700-lujuusluokan Ruukin Optim 700 plus MH nelikulmaisista rakenneputkista (RHS). Elementtimalleissa on käytetty geometrista ja materiaalista epälineaarisuutta ennustamaan liitoksen muodonmuutoskykyä ja laskennallista kestävyyttä. Liitoksen elementtimalleissa muutettavia geometrioita ovat: vapaaväli, uumasauvan ja paarteen välinen kulma, paarteen seinämän paksuus, liitoksen eksentrisyys ja uumasauvan ja paarteen leveyden suhde. Laboratoriokokeen liitoksen vetouumasauvassa vaikuttava sekundäärisen momentin aiheuttama jännitys on noin 25 % vetouumasauvan myötörajasta. Suurin sekundäärinen momentti syntyy, kun vapaaväliä pienennetään ja uumasauvaa kavennetaan paarteeseen nähden. Eurocode 3:n mitoitusohjeita voidaan elementtimallien perusteella soveltaa tietyille geometrioille turvallisesti.

In vivo and in vitro effect of imipramine and fluoxetine on Na+,K+-ATPase activity in synaptic plasma membranes from the cerebral cortex of rats

The effects of in vivo chronic treatment and in vitro addition of imipramine, a tricyclic antidepressant, or fluoxetine, a selective serotonin reuptake inhibitor, on the cortical membrane-bound Na+,K+-ATPase activity were studied. Adult Wistar rats received daily intraperitoneal injections of 10 mg/kg of imipramine or fluoxetine for 14 days. Twelve hours after the last injection rats were decapitated and synaptic plasma membranes (SPM) from cerebral cortex were prepared to determine Na+,K+-ATPase activity. There was a significant decrease (10%) in enzyme activity after imipramine but fluoxetine treatment caused a significant increase (27%) in Na+,K+-ATPase activity compared to control (P<0.05, ANOVA; N = 7 for each group). When assayed in vitro, the addition of both drugs to SPM of naive rats caused a dose-dependent decrease in enzyme activity, with the maximal inhibition (60-80%) occurring at 0.5 mM. We suggest that a) imipramine might decrease Na+,K+-ATPase activity by altering membrane fluidity, as previously proposed, and b) stimulation of this enzyme might contribute to the therapeutic efficacy of fluoxetine, since brain Na+,K+-ATPase activity is decreased in bipolar patients.

Solubilization of Na,K-ATPase from rabbit kidney outer medulla using only C12E8

SDS, C12E8, CHAPS or CHAPSO or a combination of two of these detergents is generally used for the solubilization of Na,K-ATPase and other ATPases. Our method using only C12E8 has the advantage of considerable reduction of the time for enzyme purification, with rapid solubilization and purification in a single chromatographic step. Na,K-ATPase-rich membrane fragments of rabbit kidney outer medulla were obtained without adding SDS. Optimum conditions for solubilization were obtained at 4ºC after rapid mixing of 1 mg of membrane Na,K-ATPase with 1 mg of C12E8/ml, yielding 98% recovery of the activity. The solubilized enzyme was purified by gel filtration on a Sepharose 6B column at 4ºC. Non-denaturing PAGE revealed a single protein band with phosphomonohydrolase activity. The molecular mass of the purified enzyme estimated by gel filtration chromatography was 320 kDa. The optimum apparent pH obtained for the purified enzyme was 7.5 for both PNPP and ATP. The dependence of ATPase activity on ATP concentration showed high (K0.5 = 4.0 µM) and low (K0.5 = 1.4 mM) affinity sites for ATP, with negative cooperativity. Ouabain (5 mM), oligomycin (1 µg/ml) and sodium vanadate (3 µM) inhibited the ATPase activity of C12E8-solubilized and purified Na,K-ATPase by 99, 81 and 98.5%, respectively. We have shown that Na,K-ATPase solubilized only with C12E8 can be purified and retains its activity. The activity is consistent with the form of (alphaß)2 association.

Low pH and calcium effects on net Na+ and K+ fluxes in two catfish species from the Amazon River (Corydoras: Callichthyidae)

The present study analyzes Na+ and K+ disturbances caused by low pH in two catfish species from the Amazon River. Corydoras adolfoi inhabits ion-poor, black-stained, low pH (3.5-4.0) waters, while C. schwartzi is native to ion-rich waters at circumneutral pH. Fish were exposed to pH 3.5 Ca2+-free, and Ca2+-enriched (~500 µmol/l) water to determine the protective effects of calcium. Net Na+ and K+ fluxes were measured in the water collected from the fish experimental chambers. C. adolfoi was unable to control the Na+ efflux at low pH, exhibiting Na+ loss up to -594 ± 84 nmol g-1 h-1 during the first hour. After 3 and 6 h, net Na+ flux increased by 7- and 23-fold, respectively. In C. schwartzi, at pH 3.5, the initial high Na+ loss (-1,063 ± 73 nmol g-1 h-1) was gradually attenuated. A K+ loss occurred in both species, but remained relatively constant throughout exposure. High [Ca2+] affected ion losses in both species. C. adolfoi had 70% loss attenuation, indicating incapacity to control Na+ efflux. In C. schwartzi, elevated [Ca2+] completely prevented the Na+ losses caused by exposure to low pH. Rather different patterns were seen for K+ fluxes, with C. adolfoi showing no K+ disruption when exposed to low pH/high [Ca2+]. Thus, C. adolfoi loses Na+ during acid exposure, but has the ability to control K+ loss, while C. schwartzi controls diffusive Na+ loss but exhibits a slightly higher K+ loss. Ion balance was influenced by [Ca2+] at low pH in C. schwartzi but not in C. adolfoi.

Karta öfver Sverige upptagande jernvägar och diligens-leder samt språk-djur-och trädgränser m.m. : på föranstaltande af brukegaren Emil Ericsson : norra delen

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

Karta öfver Sverige upptagande jernvägar och diligens-leder samt språk-djur-och trädgränser m.m. : på föranstaltande af brukegaren Emil Ericsson : södra delen

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

Henkilö- ja talousriskin yhteys t&k-projektin onnistumiseen

Tämän pro gradu-tutkielman tarkoituksena oli tarkastella henkilö- ja talousriskin yhteyttä tutkimus- ja kehitysprojektin onnistumiseen. Tutkimus toteutettiin toimeksiantona Innovaatiorahoituskeskus Tekesille. Tutkielman teoreettisessa osuudessa tarkasteltiin t&k-projektien ja uuden tuotteen kehitysprojektien onnistumisen määritelmää sekä onnistumis- ja epäonnistumistekijöitä. Teoriaosuus pohjautui aikaisempaan tutkimukseen ja sen pohjalta oli tavoitteena muodostaa käsitys siitä, millaisiin tekijöihin projektin alkuvaiheessa kannattaa kiinnittää huomiota ja kuinka eri tekijät voivat ennakoida projektien onnistumista tai epäonnistumista. Tutkimuksen empiirinen osuus toteutettiin kvantitatiivisena tutkimuksena. Aineisto koostui 4755 mikro- ja pk-yritysten t&k-projektista. Empiirisen osuuden päätarkoituksena oli selvittää, onko projektin henkilö- ja talousriskitasolla vaikutusta siihen, kuinka hyvin projekti onnistuu. Tutkimuksessa selvitettiin myös riskien taustalla vaikuttavien tekijöiden yhteyttä projektin onnistumiseen ja tarkasteltiin yleisimpiä syitä projektien epäonnistumiseen. Tutkimuksen tuloksena havaittiin seuraavaa. Yleisimpiä syitä epäonnistuneisiin hankkeisiin olivat teknologiasyyt, muut syyt sekä henkilö- ja taloussyyt. Tarkasteltaessa talousriskin vaikutusta onnistumiseen hyödynnettiin kolmea erilaista onnistumisen mittaria. Tuloksena havaittiin, että talousriskitason merkittäväkään nousu ei vaikuttanut valtavasti siihen, kuinka hyvin projektit onnistuivat. Sillä, perustuiko kohonnut talousriski hakijan omaan rahoitukseen, ulkopuoliseen rahoitukseen, vai molempiin rahoituksen muotoihin ei ollut suurta vaikutusta projektin onnistumiseen. Hyvin pieni vaikutus näkyi siten, että parhaiten onnistuvien hankkeiden osuus oli hieman suurempi sellaisten hankkeiden joukossa, jossa riski hajaantui molempiin rahoituksen muotoihin. Henkilöriskitasolla havaittiin olevan hieman vaikutusta siihen, kuinka hyvin hanke onnistui, sillä korkeimmassa riskiluokassa havaittiin suhteellisesti enemmän epäonnistuneita projekteja kuin matalammissa riskiluokissa. Erot olivat kuitenkin maltillisia. Tutkimuksessa havaittiin lisäksi, että valittu onnistumisen mittari ja sen moniportaisuus vaikuttivat tulosten tulkintaan, joten on tärkeää tiedostaa, millaista onnistumista projektilla tavoitellaan.

Erythrocytes may contain a ouabain-insensitive K+-ATPase which plays a role in internal K+ balance

Erythrocytes are useful in evaluating K+ transport pathways involved in internal K+ balance. Several forms of H+,K+-ATPase have been described in nephron segments active in K+ transport. Furthermore, the activity of a ouabain-insensitive isoform of H+,K+-ATPase expressed in collecting duct cells may be modulated by acid-base status. Various assays were performed to determine if a ouabain-insensitive K+-ATPase is present in rat erythrocytes and, if so, whether it plays a role in internal K+ balance. Kinetic studies demonstrated that maximal stimulation of enzyme activity was achieved with 2.5 mM K+ at pH 7.4. Subsequent experiments were performed on erythrocyte membranes collected from animals submitted to varying degrees of K+ homeostasis: control rats, K+-depleted rats, K+-loaded rats, and rats rendered hyperkalemic due to acute renal failure. As observed in the collecting duct cell studies, there was a significant decrease in the activity of ouabain-insensitive K+-ATPase in the erythrocytes of both K+-loaded and metabolically alkalotic K+-depleted rats. However, this enzyme activity in erythrocyte membranes of rats with metabolic acidosis-related hyperkalemia was similar to that of control animals. This finding may be interpreted as resulting from two potentially modulating factors: the stimulating effect that metabolic acidosis has on K+-ATPase and the counteracting effect that hyperkalemia and uremia have on metabolic acidosis. In summary, we present evidence of a ouabain-insensitive K+-ATPase in erythrocytes, whose activity is modulated by acid-base status and K+ levels.