Comparison of stress responses between mental tasks and white noise exposure

The purpose of this study was to compare the cardiovascular responses to different types of mental stress. Ten healthy males performed a mental arithmetic task (MA) on one day and were exposed to white noise (WN, 80dB) on another day. Both the MA and the WN were composed of four 5-min consecutive periods with a 3-min rest between them. On each day, the systolic and diastolic blood pressure (SBP and DBP), mean arterial pressure (MAP), cardiac output (CO), and total peripheral resistance (TPR) were measured continually during the entire experimental period. The changes from the baseline (Delta) in all periods were calculated for both mental stresses. As for the results, the DeltaMAP, DeltaCO, DeltaHR, and DeltaTPR in the MA did not significantly change during the task periods. However, in the WN, the DeltaMAP and DeltaTPR showed significant increases over the time of the consecutive periods. In addition, we discuss the response patterns for the two mental stresses. We examine three hemodynamic reactivity patterns: a cardiac pattern characterized by increased CO and decreased TPR, a mixed pattern characterized by a moderate increase in both CO and TPR, and a vascular pattern characterized by increased TPR and decreased CO. The results show that throughout all task/exposure periods, the response pattern remained the same for six subjects in each stress. Furthermore, of these six subjects, half showed the same response pattern in both the MA and the WN. In conclusion, compared to the MA task, consecutive WN exposure showed an accumulation of stress responses. A change in TPR contributed to a gradual increase in MAP in the WN. It is also possible that among the subjects there were different types of response to the MA and WN.     

Effects of object color stimuli on human brain activities in perception and attention referred to EEG alpha band response

This study was designed to investigate the physiological effects of color in terms of blood pressure and the results of electroencephalogram (EEG) as subjects looked at the sheets of paper of various colors. A questionnaire was also used to assess psychological effects. Three colors (red, green, blue) were shown to each subject in randomized order. The various colors showed distinctly different effects on the mean power of the alpha band, theta band, and on the total power in the theta-beta EEG bandwidth and alpha attenuation coefficient (AAC). Scores of the subjective evaluations concerning heavy, excited, and warm feelings also indicated significant differences between red and blue conditions. Against to our prediction, blue elicited stronger arousal than did red as expressed by the results of AAC and the mean power of the alpha band, which conflicted with the results of the subjective evaluations scores. This phenomenon might be caused by bluish light's biological activating effect. The powers of the alpha band, and the theta band, and the total power of the theta-beta bandwidth as measured by EEG showed larger values while the subjects looked at red paper than while they looked at blue paper. This indicated that red possibly elicited an anxiety state and therefore caused a higher level of brain activity in the areas of perception and attention than did the color blue. Red paper's effect to activate the central cortical region with regard to perception and attention was considerably more distinguishable than was the biological activating effect of bluish light in our study.     

Mechanism of activation of branched-chain alpha-keto acid dehydrogenase complex by exercise

Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex catalyzes the committed step of branched-chain amino acid catabolism, and its activity is regulated by the phosphorylation-dephosphorylation cycle. BCKDH kinase is responsible for inactivation of the complex by phosphorylation. In the present study, we examined acute exercise on the activity state of the complex as well as the amounts of bound and free forms of the kinase in rat liver and skeletal muscle. Acute exercise activated the complex in association with a decrease in the bound form of kinase in both liver and muscle. The free form of kinase in both tissues was slightly increased but the total amount of the kinase was not affected by acute exercise. The protein amount ratio of bound kinase to E1beta component of the complex was much higher in muscle than in the liver of rats, reflecting the low activity state of the complex in muscle. These results suggest that the amount of the bound kinase plays an important role in regulation of the activity state of the complex. We propose that the alteration in the amount of bound BCKDH kinase is a short-term regulatory mechanism for determining the activity of BCKDH complex.     

Phenanthropyran derivatives from Phalaenopsis equestris

Two phenanthropyran derivatives, 3-methoxy-2,7-dihydroxy-5H-phenanthro[4,5-bcd]pyran and 2,3,7-trihydroxy-5H-phenanthro[4,5-bcd]pyran were isolated from the orchid Phalaenopsis equestri. Their chemical structures were elucidated from spectroscopic (NMR, MS etc.) analyses.     

An ellagic compound and iridoids from Cornus capitata root cultures.

An ellagic acid derivative, 3,3'-di-O-methylellagic acid 4-(5"-acetyl)-alpha-L-arabinofuranoside, and two iridoid glucosides, 6alpha-dihydrocornic acid and 6beta-dihydrocornic acid, were isolated from Cornus capitata adventitious roots cultured in Murashige-Skoog (Murashige, T., Skoog, F., 1962. A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol. Plant. 15, 473-487) liquid medium containing 10 microM CuSO(4). Three known related metabolites, i.e. stenophyllin H1, dihydrocornin and cornin were also produced in the root cultures. The chemical structures were characterized by analysis of spectroscopic data.     

Comparison of phosphodiesterase isozymes in rodent parotid glands

We investigated phosphodiesterase (PDE) isozymes, which hydrolyze cAMP, in rodent parotid glands (mouse, hamster and guinea pig) in order to clarify the effects of cGMP and Ca/calmodulin on the regulation of cellular cAMP and compared them with those of the rat. More than 80% of the activities were in the supernatant fractions except for the hamster. The isozymes were fractionated using Mono Q ion-exchange column. The mouse parotid PDEs consisted of PDE1 (Ca/calmodulin-dependent), PDE2 (cGMP-stimulated), PDE3 (cGMP-inhibited) and PDE4 (cAMP-specific) similar to those of the rat. PDE3 was not detected in the hamster, and PDE4 was not detected in the guinea pig. PDE activities in the supernatant of the mouse and the hamster were stimulated by cGMP, and that of the guinea pig was stimulated by Ca/calmodulin. These results suggest that various PDE isozymes are present in the parotid gland of several species of order Rodentia. There seems to be differences among the species with regard to the PDE isozymes.     

Super agonist actions of clothianidin and related compounds on the SAD beta 2 nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes

To compare the actions of clothianidin, a neonicotinoid acting on insect nicotinic acetylcholine receptors, and related compounds with that of imidacloprid, the compounds were tested on the Drosophila SAD-chicken beta2 nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes using two-electrode voltage-clamp electrophysiology. The maximum response of the SAD beta 2 nicotinic receptor to clothianidin was larger than that observed for acetylcholine. Ring breakage of the imidazolidine ring of imidacloprid resulting in the generation of a guanidine group was critical for this super agonist action.     

Sex- and lineage-specific inheritance of depression-like behavior in the rat

The Wistar–Kyoto (WKY) rat exhibits physiological and behavioral similarities to endophenotypes of human depression. In the forced swim test (FST), a well-characterized antidepressant-reversible test for behavioral despair in rodents, WKYs express characteristics of behavioral despair; increased immobility, and decreased climbing. To map genetic loci linked to behavior in the FST, we conducted a quantitative trait loci (QTL) analysis of the segregating F2 generation of a WKY × Fisher 344 (F344) reciprocal intercross. Using linear-model-based genome scans to include covariate (sex or lineage)-by-QTL interaction effects, four significant QTL influencing climbing behavior were identified. In addition, we identified three, seven, and two suggestive QTL for climbing, immobility, and swimming, respectively. One of these loci was pleiotropic, affecting both immobility and climbing. As found in human linkage studies, several of these QTL showed sex- and/or lineage-dependent effects. A simultaneous search strategy identified three epistatic locus pairs for climbing. Multiple regression analysis was employed to characterize the joint contributions of these QTL and to clarify the sex- and lineage-dependent effects. As expected for complex traits, FST behavior is influenced by multiple QTL of small effect, each contributing 5%–10%, accounting for a total 10%–30% of the phenotypic variance. A number of loci mapped in this study share overlapping candidate regions with previously identified emotionality QTL in mice as well as with susceptibility loci recognized by linkage or genome scan analyses for major depression or bipolar disorder in humans. The presence of these loci across species suggests that these QTL may represent universal genetic factors contributing to mood disorders.