Morphology-Dependent Coherent Acoustic Phonon Vibrations and Phonon Beat of Au Nanopolyhedrons.

Coherent acoustic phonon vibrations of Au nanopolyhedrons, including nanocubes, nano-octahedrons, and nanocuboctahedrons, in aqueous solutions and poly(vinyl alcohol) (PVA) films, were investigated using transient absorption (TA) spectroscopy combined with finite element analysis based on continuum elastic theory. In each type of nanopolyhedron, two vibrational modes with similar quality factors (Qs) and phases were observed, suggesting that both were induced by thermal expansion. The low-frequency vibrational mode represents a tip-to-tip displacement in each nanopolyhedron, whereas the high-frequency mode is the breathing vibration of the whole particle and reveals morphology dependence, displaying a face-to-face displacement in nanocuboctahedrons, an edge-to-edge displacement in nano-octahedrons, and a combination of face-to-face and edge-to-edge displacements in nanocubes. Moreover, a clear phonon beat was identified in the two vibrational modes of the nanocuboctahedrons. Our experimental results provide a possible application of morphology-controllable metal nanoresonators.

Effects of inducing exercise on growing mice by means of three-dimensional structure in rearing environment.

We reared ICR mice during a growth period (3 to 10 weeks of age) and examined the effect of exercise induction, by enriching the rearing environment with obstacles such as ladders, compared to the standard environment. Environmental enrichment significantly increased the amount of exercise in both sexes (P<0.01). Enriched exercise mice had higher body weight than control mice at 6 to 9 weeks of age in males and 8 weeks of age in females (P<0.05). The sexual maturation of female enriched exercise mice was significantly advanced compared to the control (P<0.001). Enriched exercise mice showed decreased anxiety-like behavior in the open field test and lower plasma corticosterone levels in both sexes compared to the control, and differences were statistically significant in males (P<0.05). In both sexes, enriched exercise appeared to increase natural killer cells in blood compared to the control, but no statistical differences was detected. In conclusion, we confirmed that daily low-stress exercise could be induced using a three-dimensional rearing environment in growing mice. In addition, we suggest that exercise has beneficial effects on physical growth, sexual maturation and anxiety-like behavior. Furthermore, environmental enrichment might be more effective in male than female in group-housed mice.

[Causative factors of esmolol-induced reduction in arterial blood pressure differ in accordance with its doses].

BACKGROUND: Because the causative factors responsible for hypotension by esmolol remain to be fully elucidated, this study investigated whether different doses of esmolol may be different in causing esmolol-induced hypotension in dogs anaesthetized with sevoflurane. METHODS: The ES 25, ES 100 and ES 400 groups (n = 8, each) randomly received esmolol that was infused at a constant rate at 25, 100, or 400 microg x kg(-1) x min(-1) during a 60 min-infusion period, respectively. RESULTS: Esmolol produced dose-dependent decreases in mean arterial pressure (MAP) which were not associated with any changes in heart rate. With the ES 25 group, the hypotensive effect was caused by significant reductions in systemic vascular resistance (SVR) without any changes in cardiac index (CI). In contrast, the hypotensive effect in the ES 400 group was due to the significant decrease in CI resulting from significant reductions in cardiac contractility without any changes in SVR. Hypotension in the ES 100 group resulted in the significant reductions in both SVR and cardiac contractility. CONCLUSIONS: These findings suggest that a low dose of esmolol might induce the vasodilating effect resulting in changes in the resistance of vessels and thus may provide a cardiac safety during perioperative periods.

[Responses of hemodynamics and splanchnic organ blood flow to esmolol during inhalation of volatile anesthetics in dogs].

BACKGROUND: Because the hemodynamic alterations due to sympathetic suppression by the interaction of esmolol with volatile anesthetics may alter the blood flow to the splanchnic organs, this study was designed to investigate whether esmolol might modify the hemodynamics and splanchnic organ blood flow in anesthetized dogs. METHODS: Anesthesia was maintained with 0.9% halothane, 1.3% isoflurane or 2.4% sevoflurane (1MAC, n=8, each) in oxygen. Esmolol was infused at a constant rate of 400 microg * kg(-1) x min(-1) during a 60 min-infusion period. The renal, hepatic, and pancreatic blood flows (RBF, HBF, and PBF) were measured by using the hydrogen clearance method. RESULTS: Mean arterial pressure in all three groups decreased without any changes in heart rate or systemic vascular resistance. Cardiac index in all three groups decreased with reductions in cardiac contractility. The RBF, HBF, and PBF in all three groups were reduced during the esmolol infusion. CONCLUSIONS: The splanchnic organ blood flow reductions caused by esmolol may be due to cardiac depression, whereas there appears to be no differences in there change regarding the kind of the volatile anesthetics. These findings suggest that hypotension induced by esmolol may impair the maintenance of splanchnic organ blood flow during anesthesia by volatile agents.

Laterality of flipper rubbing behaviour in wild bottlenose dolphins (Tursiops aduncus): caused by asymmetry of eye use?

To determine whether wild Indo-Pacific bottlenose dolphins (Tursiops aduncus) at Mikura Island, Japan, show asymmetry of eye or flipper use during a social behaviour, we investigated the laterality of flipper-to-body (F-B) rubbing, in which one dolphin ("rubber") rubs the body of another ("rubbee") with its flipper. We analysed 382 episodes of video-recorded F-B rubbings performed by identified individuals (N=111 rubbers). F-B rubbing was conducted significantly more frequently with the left flipper than with the right flipper. The duration of F-B rubbings was also significantly longer with the left flipper than with the right flipper. Of 20 dolphins, nine individuals showed significant left-side bias as the rubber in this behaviour, whereas no dolphins showed significant right-side bias. The results indicate a population-level left-side bias of the rubber in F-B rubbing. An analysis of the swimming configurations during this behaviour suggests that the asymmetry in F-B rubbing was caused not only by the laterality of the rubber, but by a preference for use of the left eye in both dolphins during this behaviour. Dolphins used the left eye significantly more frequently than the right eye during the inquisitive behaviour, while they showed no significant bias in flipper use during the object-carrying behaviour. These facts also suggest that the asymmetry of F-B rubbing is caused by the preference for using the left eye. Significant left-side bias was observed only in F-B rubbings initiated by the rubbee, in which the rubbee determined its position during this behaviour. This suggests that this behavioural asymmetry was enhanced by the rubbees choosing the left side of the rubber to ensure better and longer rubs.

Esmolol attenuates hepatic blood flow responses during sodium nitroprusside-induced hypotension in dogs.

PURPOSE: The hemodynamic responses secondary to sympathetic suppression by esmolol may alter blood flow to splanchnic organs. We investigated whether esmolol might modify splanchnic organ blood flow responses during sodium nitroprusside (SNP)-induced hypotension in dogs anesthetized with sevoflurane. METHODS: The control group (n = 10) received SNP (SNP group). The ES25 and ES100 groups (n = 10, each) received SNP combined with esmolol infused at a constant rate of 25 and 100 micro g*kg(-1)*min(-1) during the hypotensive period after a mean arterial pressure (MAP) of 60 mmHg was attained by the infusion of a 0.03% SNP solution, respectively. The renal, hepatic, and pancreatic blood flows (RBF, HBF, and PBF) were measured by using the hydrogen clearance method. RESULTS: Cardiac index in the SNP group increased (P < 0.01), but in the ES groups it decreased (P < 0.01). Left ventricular dP/dtmax in the SNP group remained unchanged, but in the ES groups it decreased (P < 0.01, each) during the hypotensive period. Except for HBF in the SNP group, the splanchnic blood flow in all groups decreased (P < 0.01, each). The HBF in the ES groups was lower than that in the SNP group (SNP vs ES25, ES100; 70 +/- 1 vs 64 +/- 5, 6 3 +/- 3 mL*min(-1)*100 g(-1)). CONCLUSIONS: This study shows that the differences in HBF between SNP-induced hypotension with or without esmolol may be due to the changes in cardiac output caused by alterations of cardiac contractility. These findings suggest that a small dose of esmolol may impair the maintenance of HBF during SNP-induced hypotension.

Effects of KRN2391-induced hypotension on the endocrine system and carbohydrate metabolism in halothane-anesthetized dogs.

PURPOSE: The hemodynamic profiles of KRN2391-induced hypotension have been reported to be a hyperdynamic state. However, the endocrine effects of KRN2391-induced hypotension remain to be elucidated. We investigated the endocrine and metabolic effects of KRN2391-induced hypotension on the plasma concentrations of catecholamines, aldosterone, cortisol, glucose, and lactic acid and on plasma renin activity. METHODS: Eight dogs were anesthetized with 087% halothane in oxygen. After a baseline period, mean arterial pressure (MAP) was lowered to 60 mmHg for 60min by the infusion of KRN2391. RESULTS: KRN2391-induced hypotension resulted in a 50% decrease (P<0.01) in MAP due to a 80% reduction (P<0.01) in systemic vascular resistance associated with a 224% increase (P<0.01) in cardiac index. Plasma norepinephrine concentrations increased (P<0.01) after 60 min of hypotension. Plasma epinephrine concentrations and plasma renin activity both increased (P<0.05) during the hypotensive period. Plasma aldosterone concentrations remained unchanged during the hypotensive period, but then increased (P<0.05) after termination of KRN2391. Plasma cortisol concentrations remained unchanged throughout the observation period. Plasma glucose concentrations increased (P<0.01) during the hypotensive period. Plasma lactic acid concentrations increased (P<0.01) throughout the observation period. CONCLUSION: KRN2391-induced hypotension activates the sympathetic nervous system and consequently may modulate the renin-angiotensin-aldosterone axis and carbohydrate metabolism.

The effect of CGRP-induced hypotension on organ blood flow during halothane anesthesia in dogs: a comparison with trimetaphan.

PURPOSE: Calcitonin gene-related peptide (CGRP) is an endogenous 37-amino-acid peptide which is a powerful vasodilator of the splanchnic circulation. To elucidate the effects of CGRP-induced hypotension on the organ blood flow, we compared the renal, hepatic, and pancreatic organ flows of CGRP-induced hypotension with those of trimetaphan (TMP) in halothane-anesthetized dogs. METHODS: Systemic hemodynamics and organ blood flow were determined in 18 mongrel dogs allocated to one of two groups: CGRP group (n=10) and TMP group (n=8). CGRP of TMP was infused at a rate sufficient to decrease the mean arterial pressure (MAP) to near 60 mmHg from the baseline values for a 60 min-hypotensive period. Organ blood flow was measured using the hydrogen clearance technique. RESULTS: The decrease in MAP was approximately 50% of baseline values (P<0.01). The hypotension induced by either CGRP or TMP was associated with a reduction (P<0.01) in systemic vascular resistance in both groups. Cardiac index (CI) in the CGRP group did not change significantly throughout the experiment. On the other hand, CI decreased at 30 min (P<0.01) and 60 min (P<0.01) during the hypotensive period in the TMP group. No changes were observed in renal, hepatic, and pancreatic blood flows in the CGRP group. Renal blood flow in the TMP group did not change significantly throughout the experiment. In contrast, hepatic blood flow resulted in a significant decrease (P<0.01) during TMP-induced hypotension. Pancreatic blood flow decreased during the hypotensive period (P<0.01) and at 30 min (P<0.05) after termination of TMP. CONCLUSION: These findings show that CGRP does not adversely affect renal, hepatic, and pancreatic organ blood flows even in the presence of profound hypotension in halothane-anesthetized dogs. The results of this study suggest that CGRP may preserve organ blood flow during induced hypotension.

Comparative hemodynamic effects of hypotension induced by diadenosine tetraphosphate (AP4A) and ATP in dogs.

ATP and diadenosine tetraphosphate (AP4A) have been shown to produce vasodilation mediated by P1- and P2-purinoceptor, respectively. The differing mechanisms involved in this vasodilating activity may induce different systemic hemodynamic changes. We compared the hemodynamic effects of AP4A-induced hypotension with those induced by ATP. Fourteen mongrel dogs were anesthetized with 0.87% halothane in oxygen (1 MAC). After the baseline period, mean arterial pressure was reduced to 60 mmHg for 60 min by the infusion of AP4A or ATP. The ATP- and AP4A-induced hypotension resulted in a maximum reduction in systemic vascular resistance of 43% and 46%, respectively (P<0.01), associated with a significant increase in stroke volume index. With ATP, a 20% of maximum increase (P<0.05) in cardiac index (CI) was observed during the induced hypotension. In contrast, AP4A-induced hypotension did not result in any changes in CI throughout the observation period. The varying results concerning CI during the ATP- and AP4A-induced hypotension were probably due to differences in ventricular filling pressure, since AP4A-induced hypotension was associated with decreases (P<0.01) in both right atrial and pulmonary capillary wedge pressures, whereas neither of these variables significantly changed with ATP. The hypotension induced by either ATP or AP4A was associated with a significant decrease in heart rate (HR). However, both the magnitude and duration of decreases in HR due to ATP-induced hypotension were more pronounced than those seen with AP4A. In conclusion, while both drugs were equally capable of inducing hypotension, our results suggest that AP4A was more suitable for induced hypotension because of its potent vasodilatory action with venodilation and less negative chronotropic action.

Hemodynamic effects of KRN2391 (potassium channel opener) in halothane-anesthetized dogs.

The cardiovascular responses to an infusion of KRN2391, a potassium channel opener, was studied in halothane-anesthetized dogs. Intravenous administration of KRN2391 at 1.0 and 5.0 µg·kg-1·min-1 for 60 min produced dose-dependent decreases in mean arterial pressure (MAP) and systemic vascular resistance (SVR) associated with dose-dependent increases in the cardiac index (CI) and stroke volume index (SVI) but was not accompanied by an increase in heart rate (HR). The maximum decrease in MAP during the infusion of KRN2391 at 1.0 and 5.0 µg·kg-1·min-1 was -13±7% (P<0.01) and -37±10% (P<0.01), respectively. The maximum reduction in SVR after 1.0 and 5.0 µg·kg-1·min-1 was -20±11% (P<0.01) and -60±16% (P<0.01), respectively. A KRN2391 infusion of 1.0 and 5.0 µg·kg-1·min-1 increased Cl a maximum of 11±13% (P<0.05) and 65±33% (P<0.01), respectively. KRN2391 1.0 µg·kg-1·min-1 showed a tendency to increase SVI but this change was not significant, KRN2391 5.0 µg·kg-1·min-1, however, produced a significant increase in SVI. The present results demonstrate that the decrease in MAP and the increases in CI and SVI caused by KRN2391 are due to a reduction in the afterload. Therefore, we conclude that these cardiovascular profiles of KRN2391 may be benificial in perioperative uses including the control of systemic blood pressure and the treatment of hypertension during halothane anesthesia in clinical practice.