Reliable measurement methods for the isovolumic relaxation time: comparisons of dual gate Doppler and seven other methods.

PURPOSE: Isovolumic relaxation time (IVRT) is a useful indicator of diastolic dysfunction. However, a measurement method for IVRT has not been established. The Dual Gate Doppler method, which can record two separate pulse-wave Doppler signals simultaneously using two sample gates, may be ideal for measuring IVRT. This study aimed to evaluate the accuracy of IVRT measured using conventional methods versus that measured using the Dual Gate Doppler method. METHODS: A total of 104 patients (mean age 58 ± 21 years, 48 women) were examined using ultrasound equipment with Dual Gate Doppler at our hospital. In addition to Dual Gate Doppler method, IVRTs were measured using seven different methods: pulsed Doppler (PW method), continuous wave Doppler (CW method), and other methods. The IVRT values obtained using the Dual Gate Doppler method were compared with those measured using other methods. RESULTS: All IVRTs measured using conventional methods showed a strong correlation with the that measured using the Dual Gate Doppler method. However, there were slight deifferences among the IVRTs depending on the method. The PW method and the PW time difference method using only the PW showed small statistical bias and were not complicated. The IVRT measured using the CW method was significantly longer than that measured using the Dual Gate Doppler method. CONCLUSIONS: Among the conventional methods, the PW method was the simplest and most practical method for measuring the IVRT in any conditions as arrhythmias. It is important to recognize the characteristics of IVRTs based on the measurement method.

Egg White Protein Feeding Facilitates Skeletal Muscle Gain in Young Rats with/without Clenbuterol Treatment.

Based on the Digestible Indispensable Amino Acid Score (DIAAS), egg white protein (EGG) has an excellent score, comparable to that of whey protein but with a lower amount of leucine. We examined the effect of EGG feeding on rat skeletal muscle gain in comparison to that of two common animal-derived protein sources: casein (CAS) and whey (WHE). To explore the full potential of EGG, this was examined in clenbuterol-treated young rats. Furthermore, we focused on leucine-associated anabolic signaling in response to EGG after single-dose ingestion and chronic ingestion, as well as clenbuterol treatment. Because EGG is an arginine-rich protein source, a portion of the experiment was repeated with diets containing equal amounts of arginine. We demonstrated that EGG feeding accelerates skeletal muscle gain under anabolism-dominant conditions more efficiently than CAS and WHE and this stronger effect with EGG is not dependent on the arginine-rich composition of the protein source. We also demonstrated that the plausible mechanism of the stronger muscle-gain effect with EGG is not detectable in the mechanistic target of rapamycin (mTOR) or insulin signaling under our experimental conditions. We conclude that EGG may have a superior efficiency in muscle gain compared to other common animal-based proteins.

Effect of Quercetin Treatment on Mitochondrial Biogenesis and Exercise-Induced AMP-Activated Protein Kinase Activation in Rat Skeletal Muscle.

The purpose of this study was to evaluate the effect of chronic quercetin treatment on mitochondrial biogenesis, endurance exercise performance and activation levels of AMP-activated protein kinase (AMPK) in rat skeletal muscle. Rats were assigned to a control or quercetin group and were fed for 7 days. Rats treated with quercetin showed no changes in the protein levels of citrate synthase or cytochrome C oxidase IV or those of sirtuin 1, peroxisome proliferator-activated receptor gamma coactivator-1α or phosphorylated AMPK. After endurance swimming exercise, quercetin-treated rats demonstrated no differences in blood and muscle lactate levels or glycogen utilization speed compared to control rats. These results indicate that quercetin treatment does not stimulate mitochondrial biogenesis in skeletal muscle and does not influence metabolism in a way that might enhance endurance exercise capacity. On the other hand, the AMPK phosphorylation level immediately after exercise was significantly lower in quercetin-treated muscles, suggesting that quercetin treatment might provide a disadvantage to muscle adaptation when administered with exercise training. The molecular results of this study indicate that quercetin treatment may not be advantageous for improving endurance exercise performance, at least after high-dose and short-term therapy.

Late Pleistocene climate change and population dynamics of Japanese Myodes voles inferred from mitochondrial cytochrome b sequences.

The Japanese archipelago is comprised of four main islands-Hokkaido, Honshu, Shikoku, and Kyushu-which contain high mountainous areas that likely allowed for lineage differentiation and population genetic structuring during the climatic changes of the late Pleistocene. Here, we assess the historical background of the evolutionary dynamics of herbivorous red-backed voles (Myodes) in Japan, examining the evolutionary trends of mitochondrial cytochrome b gene (Cytb) sequence variation. Four apparent signals from rapid expansion events were detected in three species, M. rufocanus and M. rutilus from Hokkaido and M. smithii from central Honshu. Taken together with results from previous studies on Japanese wood mice (Apodemus spp.), three of the expansion events were considered to be associated with predicted bottleneck events at the marine isotope stage (MIS) 4 period, in which glaciers are thought to have expanded extensively, especially at higher elevations. In the late Pleistocene, the possible candidates are transitions MIS 6/5, MIS 4/3, and MIS 2/1, which can be characterized by the cold periods of the penultimate glacial maximum, MIS 4, and the last glacial maximum, respectively. Our data further reveal the genetic footprints of repeated range expansion and contraction in the northern and southern lineages of the vole species currently found in central Honshu, namely M. andersoni and M. smithii, in response to climatic oscillation during the late Pleistocene. The time-dependent evolutionary rates of the mitochondrial Cytb presented here would provide a possible way for assessing population dynamics of cricetid rodents responding to the late Pleistocene environmental fluctuation.