Age-related changes in the metabolism of cholesterol in rat liver microsomes

The effects of aging on the hepatic metabolism of cholesterol were studied in 1-, 6- and 24-month-old male Sprague-Dawley rats. Microsomal 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity, which regulates cholesterol biosynthesis, decreased from 835±144 (SEM) pmol/min/mg protein in the youngest group to 219±34 and 205±53 pmol/min/mg protein (p<0.001) in the 6- and 24-month-old groups, respectively. Cholesterol 7α-hydroxylase activity, which governs bile acid synthesis, was gradually reduced from 70±14 pmol/min/mg protein in the 1-month-old group to 32±7 and 16±3 pmol/min/mg protein (p<0.05) in the 6- and 24-month-old groups, respectively. Acyl coenzyme A:cholesterol acyltransferase activity, which catalyzes the esterification of cholesterol, averaged 431±47 and 452 ±48 pmol/min/mg protein in the 1- and 6-month-old groups, respectively, and was increased to 585±55 pmol/min/mg protein (p<0.05) in the 24-month-old group. The level of total cholesterol showed an age-related increase from 1.56±0.16 mg/g liver in the 1-month-old group to 1.70±0.15 and 2.20±0.19 mg/g liver (p<0.05) in the 6- and 24-month-old groups, respectively. The increase was mainly caused by an accumulation of esterified cholesterol. We conclude that a marked decrease in HMG-CoA reductase occurs between 1 and 6 months of age; thereafter the enzyme activity stays unchanged. The activity of cholesterol 7α-hydroxylase decreases progressively and drastically with age, whereas the capacity for esterifying cholesterol increases slightly. We speculate that the reduced conversion of cholesterol to bile acids may be one explanation of the age-related increase of plasma cholesterol seen in rats.     

Reaktion von Hydroperoxiden mit Radikalen

2,4,6-Tri-tert.-butyl-phenoxyl was reacted with tert.-butyl hydroperoxide (BHPO), cumene hydroperoxide (CHPO) and tri-phenylmethyl hydroperoxide (TPMHPO). Main reaction products are 2,4,6-tri-tert.-butyl phenol and substituted 4-cyclo-hexadienoneperoxides. Only by reacting TPMHPO a 2-cyclohexadienoneperoxide was isolated but by reacting BHPO and CHPO 3,5-di-tert.-butyl-o-quinone, isobutene and tert.-butanol or dimethylphenylcarbinole, resp., were formed. The products show the phenoxyradical attacking the peroxidic H-atom and a combination of formed peroxyradicals with phenoxyradicals. ESR-measurements demonstrate a first order radical decay, the reaction rate varies linear with hydroperoxide concentration. Hexaphenylethane (triphenylmethyl) reacts with BHPO under formation of triphenylmethylcarbinole, benzophenone, p-tert.-butoxy-triphenyl methane and little triphenylmethane. From these reaction products is to conclude that this radical attacks predominantly the peroxidic oxygen-oxygen bond.     

Bruchmechanische Überprüfung der Integrität des Primärkühlmittel-Eintrittsstutzens eines Druckwasser-Reaktordruckbehälters unter Zugrundelegung eines Kühlmittelverlust-Störfalles

Sicherheitstechnische Beurteilung eines Primärkühlmittel-Eintrittsstutzens mit Oberflächenrissen bei Eintritt eines Kühlmittelverlust-Störfalles. Voraussagen über kritische Rißgrößen während der Einspeisung von Kühlwasser. Bruchmechanische Berechnung unter Zugrundelegung des wahren Spannungsprofils sowie eines kontinuierlichen Umfangsrisses. Berücksichtigung der Bruchzähigkeit K_1c des Werkstoffes entsprechend dem Temperaturgradienten über die Wanddicke. Ermittlung von K_l-Faktoren mit Hilfe eines Computerprogrammes für verschiedene Stutzenquerschnitte in Abhängigkeit von der Rißtiefe und mit den für bestimmte Zeitintervalle erhaltenen Spannungsprofilen. Vergleich des Verlaufs der K-Faktoren mit dem Verlauf der Bruchzähigkeit.     

Rißwachstumsverhalten der austenitischen Stähle X 6 CrNi 18 11 und X 6 CrNiMo 1713 unter den Beanspruchungsbedingungen in natriumgekühlten Brutreaktoren

Mathematische Beschreibung des Rißwachstumsverhaltens der Stähle X 6 CrNi 18 11 mit rd. 0,06% C, 18% Cr und 11% Ni sowie X 6 CrNiMo17 13 mit rd. 0,06% C, 17% Cr, 2,5% Mo und 13% Ni an Luft bei Temperaturen bis 646°C und Lastspielfrequenzen von 8,3·10^?-2 bis 4 · 10³ Lastspielen/min. Einfluß von Carbidausscheidungen. Vergleich der Wirkung thermischer und schneller Neutronen. Frequenzabhängigkeit der Rißausbreitungsgeschwindigkeit. Verzögerte Rißausbreitung in der Umgebung von Schweißnähten. Rißwachstum unter Vakuum und in flüssigem Natrium zwischen 427 und 538°C.     

Linguistic intergroup bias: Differential expectancies or in-group protection?

The linguistic intergroup bias describes the tendency to communicate positive in-group and negative out-group behaviors more abstractly than negative in-group and positive out-group behaviors. This article investigated whether this bias is driven by differential expectancies or by in-group protective motives. In Exp 1, northern and southern Italian participants (N?=?151) described positive and negative behaviors of northern or southern protagonists that were either congruent or incongruent with stereotypic expectancies. Regardless of valence, expectancy-congruent behaviors were described more abstractly than incongruent ones. Exp 2 (N?=?40) showed that language is used in an equally biased fashion for individuals as previously demonstrated for groups. Exp 3 (N?=?192) induced expectancies experimentally and found greater abstraction for expectancy-congruent behaviors regardless of valence. All experiments confirmed the differential expectancy approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Einfluβ der hochtemperaturthermomechanischen Behandlung (HTMB) auf das Ausscheidungsverhalten und die mechanischen Eigenschaften des Martensits im unteren Anlaβtemperaturbereich

Untersuchung des Ausscheidungsverhaltens von hochtemperaturthermomechanisch und konventionell wärmebehandelten Stählen. Ermittlung von Korrelationen zwischen Ausscheidungsparametern und mechanischen Kenngröβen bei einachsiger Zugverformung in Abhängigkeit von der vorangegangenen Behandlung. Deutung der strukturellen Ursachen der Duktilitätssteigerung des niedrigangelassenen hochfesten Martensits durch HTMB.     

Digital shinrin-yoku: do nature experiences in virtual reality reduce stress and increase well-being as strongly as similar experiences in a physical forest?

Virtual Reality - Shinrin-yoku or forest bathing refers to a therapeutic, immersive nature experience that aids to improve well-being. The goal of the current research was to compare the effects of...     

When autocratic leaders become an option—Uncertainty and self-esteem predict implicit leadership preferences.

We investigated the impact of uncertainty on leadership preferences and propose that the conjunction of self-esteem level and stability is an important moderator in this regard. Self-threatening uncertainty is aversive and activates the motivation to regain control. People with high and stable self-esteem should be confident of achieving this goal by self-determined amelioration of the situation and should therefore show a stronger preference for democratic leadership under conditions of uncertainty. By contrast, people with low and unstable self-esteem should place their trust and hope in the abilities of powerful others, resulting in a preference for autocratic leadership. Studies 1a and 1b validate explicit and implicit leadership measures and demonstrate a general prodemocratic default attitude under conditions of certainty. Studies 2 and 3 reveal a democratic reaction for individuals with stable high self-esteem and a submissive reaction for individuals with unstable low self-esteem under conditions of uncertainty. In Study 4, this pattern is cancelled out when individuals evaluate leadership styles from a leader instead of a follower perspective. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Oxidative doping renders graphene hydrophilic, facilitating its use as a support in biological TEM

Graphene represents the first practical realization of crystalline supports in biological transmission electron microscopy (TEM) since their introduction over 30 years ago. The high transparency, minimal inelastic cross-section, and electrical conductivity of graphene are highly desirable characteristics for a TEM support. However, without a suitable method for rendering graphene supports, hydrophilic applications are limited. This work describes the in situ functionalization of graphene with minimal structural degradation, rendering TEM supports sufficiently hydrophilic for the mounting of biological samples.