Preventive effects of carvedilol on nitrate tolerance—a randomized, double-blind, placebo-controlled comparative study between carvedilol and arotinolol

AbstractObjectives. This study was designed to compare the preventive effect of nitrate tolerance between carvedilol with antioxidant properties and arotinolol without antioxidant properties.Background. The attenuation of cyclic guanosine monophosphate (cGMP) production due to inactivation of guanylate cyclase by increased superoxide has been reported as a mechanism of nitrate tolerance. Carvedilol has been known to combine alpha- and beta-blockade with antioxidant properties.Methods. To evaluate the preventive effect of nitrate tolerance, 24 patients with untreated hypertension were randomized to receive either carvedilol (10 mg twice a day [carvedilol group, n = 8]), arotinolol (10 mg twice a day [arotinolol group, n = 8]), or placebo (placebo group, n = 8). Vasodilatory response to nitroglycerin (NTG) was assessed with forearm plethysmography by measuring the change in forearm blood flow (FBF) before and 5 min after sublingual administration of 0.3 mg NTG, and at the same time blood samples were taken from veins on the opposite side to measure platelet cGMP. Plethysmography and blood sampling were obtained serially at baseline (day 0), 3 days after carvedilol, arotinolol or placebo administration (day 3) and 3 days after application of a 20 mg/24 h NTG tape concomitantly with carvedilol, arotinolol or placebo (day 6).Results. There was no significant difference in the response of FBF (%FBF) and cGMP (%cGMP) to sublingual administration of NTG on days 0 and 3 among the three groups. On day 6, %FBF and %cGMP were significantly lower in the arotinolol group and the placebo group than days 0 and 3, but these parameters in the carvedilol group were maintained.Conclusions. The results indicated that carvedilol with antioxidant properties may prevent the development of nitrate tolerance during continuous therapy with NTG compared with arotinolol without antioxidant properties

Tribochemical Reactions of Halogen-Free Ionic Liquids on Nascent Steel Surface

Ionic liquids are expected to show applicability as novel lubricants. However, halogen anion-based ionic liquids cause severe corrosive wear. To preclude this, this chapter describes the use of halogen-free anion-based ionic liquids as lubricants. The study investigated the tribological performances and lubricating mechanisms of sulfur, phosphorus, and cyanoanion-based ionic liquids. Sulfur and phosphorus anion-based ionic liquids formed reaction films on worn surfaces; the sulfur- and phosphorus-containing films exhibited low-friction coefficients and specific wear rates, respectively. The steric hindrance of the ionic liquids affected their tribochemical reaction behaviors. Cyanoanion-based ionic liquids also showed low-friction coefficients; however, their values were higher than those of halogen anion-based ionic liquids. To achieve low friction, tribochemical reaction of the ionic liquids and adsorption of anions on the worn surface were required. The stability of the cyanoanion-based ionic liquids against the nascent steel surface was related to the thermal stability. These halogen-free anion-based ionic liquids and formed tribolayer films differ in physical and chemical properties. When these ionic liquids are applied as lubricants in the industry, it is important to choose ionic liquids depending on the sliding conditions

Effects of Alloying Elements on Strength and Thermal Stability of Amorphous Iron-Base Alloys

The effects of alloying elements on hardness and crystallization temperature have been studied for amorphous alloys with the compositions Fe_M_xP_C_7, where M=Ti, V, Cr, Mn, Co, Ni and Cu. As a result, it has been found that the average outer electron concentration has a significant effect on the hardness and crystallization temperature. This suggests that the alloying elements are mainly confined to the bonding character of the outer electrons of the component elements

4-bit Bipolar Triangle Voltage Waveform Generator Using Single-Flux-Quantum Circuit

AbstractSFQ digital-to-analog converters (DACs) are one of the candidates for AC voltage standards. We have proposed SFQ-DACs based on frequency modulation (FM). Bipolar output is required for applications of AC voltage standards, while our previous SFQ-DACs generated only positive voltages. In this paper, we present our design of a 4-bit bipolar triangle voltage waveform generator comprising an SFQ-DAC. The waveform generator has two output ports. Synthesized half-period waveforms are alternately generated in one of the output ports. The bipolar output is realized by observing the differential voltage between the ports. We confirmed a 72-μVPP bipolar triangle voltage waveform at the frequency of 35.7Hz

Differential subcellular recruitment of monoacylglycerol lipase generates spatial specificity of 2-arachidonoyl glycerol signaling during axonal pathfinding

Peer reviewedPublisher PD

Relationship between cognitive function and prevalence of decrease in intrinsic academic motivation in adolescents

<p>Abstract</p> <p>Background</p> <p>Decrease in intrinsic motivation is a common complaint among elementary and junior high school students, and is related to poor academic performance. Since grade-dependent development of cognitive functions also influences academic performance by these students, we examined whether cognitive functions are related to the prevalence of decrease in intrinsic academic motivation.</p> <p>Methods</p> <p>The study group consisted of 134 elementary school students from 4th to 6th grades and 133 junior high school students from 7th to 9th grades. Participants completed a questionnaire on intrinsic academic motivation. They also performed paper-and-pencil and computerized cognitive tests to measure abilities in motor processing, spatial construction, semantic fluency, immediate memory, short-term memory, delayed memory, spatial working memory, and selective, alternative, and divided attention.</p> <p>Results</p> <p>In multivariate logistic regression analyses adjusted for grade and gender, scores of none of the cognitive tests were correlated with the prevalence of decrease in intrinsic academic motivation in elementary school students. However, low digit span forward test score and score for comprehension of the story in the <it>kana </it>pick-out test were positively correlated with the prevalence of decrease in intrinsic academic motivation in junior high school students.</p> <p>Conclusions</p> <p>The present findings suggest that decrease in capacity for verbal memory is associated with the prevalence of decrease in intrinsic academic motivation among junior high school students.</p

Mental fatigue caused by prolonged cognitive load associated with sympathetic hyperactivity

<p>Abstract</p> <p>Background</p> <p>It is known that chronic fatigue is associated with sympathetic hyperactivity. However, the relationship between autonomic function and mental fatigue caused by a prolonged mental load in healthy humans is still unclear. Thus, in order to clarify the mechanisms underlying mental fatigue, we examined the association between mental fatigue and autonomic functions.</p> <p>Methods</p> <p>The study group comprised 10 healthy participants. To induce mental fatigue, participants performed mental tasks, which consisted of the advanced trail making test, <it>kana </it>pick-out test and mirror drawing test, for 8 hr, corresponding to a normal work day. Autonomic functions were measured by accelerated plethysmography before and after the fatigue-inducing mental tasks. As a control, the same participants completed an 8-hr relaxation session 4 weeks before the fatigue session.</p> <p>Results</p> <p>After the 8-hr relaxation session, low-frequency component power (LF), high-frequency component power (HF) and low-frequency component power/high-frequency component power ratio (LF/HF ratio) were not changed from baseline. In contrast, after the fatigue session, the HF and LF/HF ratio were significantly changed from baseline; specifically, the HF was lower and LF/HF ratio was higher as compared to those after the relaxation session.</p> <p>Conclusions</p> <p>Sympathetic hyperactivity based on decreased parasympathetic activity is associated with mental fatigue induced by prolonged cognitive load.</p