世居及移居高原青少年最大有氧能力的特征

本文报道海拔３４１７ｍ和４２８０ｍ地区世居藏族和移居汉族青少年运动状态下心肺功能的对比研究。结果显示：３４１７ｍ和４２８０ｍ世居藏族的最大氧耗量、无氧阈值及最大心输出量都明显大于汉族,血氧饱和度（Ｓａｏ２）随运动负荷的增加而降低。海拔３４１７ｍ藏、汉族的△Ｓａｏ２分别为７．４６％和１０．０３％,４２８０ｍ处为８．５７％和１３．７５％,最大心率随海拔升高而下降。研究提示,藏族青少年有较高的最大有氧能力,反映了他们对低氧环境的适应优势。     

The phylogeny of the ant tribe Formicini (Hymenoptera: Formicidae) with the description of a new genus

Abstract. The holarctic ant tribe Formicini is revised, the new genus Bajcaridris described, and possible phylogenetic relationships are discussed. The subgenus Iberoformica is synonymized with Formica. A synopsis, diagnosis and keys to the genera are provided.     

Theory for designing mechanically stable single- and double-walled SiGe nanopeapods

Journal of Molecular Modeling - The adsorption and inhibition mechanism of chain length increase and group substitution of imidazole tetrafluoroborate derivatives for the corrosion inhibition of...     

Ancistrolikokine D,a 5,8'-coupled naphthylisoquinoline alkaloid,and related natural products from Ancistrocladus likoko

A new naphthylisoquinoline alkaloid, ancistrolikokine D, and the likewise 5,8'-coupled alkaloid ancistroealaine A, as well as two further, biosynthetically related, but nitrogen-free natural products, ancistronaphthoic acid B and cis-isoshinanolone, have been isolated from Ancistrocladus likoko J. LEACUTE;ONARD (Ancistrocladaceae). The 5,8'-coupling of the new alkaloids and of the alkaloids isolated earlier hints at a close phylogenetic relationship of A. likoko to other Central African Ancistrocladus species. The compounds show moderate activities against Leishmania donovani, Trypanosoma cruzi, and Trypanosoma brucei rhodesiense.     

Making Activity Recognition Robust against Deceptive Behavior

Healthcare services increasingly use the activity recognition technology to track the daily activities of individuals. In some cases, this is used to provide incentives. For example, some health insurance companies offer discount to customers who are physically active, based on the data collected from their activity tracking devices. Therefore, there is an increasing motivation for individuals to cheat, by making activity trackers detect activities that increase their benefits rather than the ones they actually do. In this study, we used a novel method to make activity recognition robust against deceptive behavior. We asked 14 subjects to attempt to trick our smartphone-based activity classifier by making it detect an activity other than the one they actually performed, for example by shaking the phone while seated to make the classifier detect walking. If they succeeded, we used their motion data to retrain the classifier, and asked them to try to trick it again. The experiment ended when subjects could no longer cheat. We found that some subjects were not able to trick the classifier at all, while others required five rounds of retraining. While classifiers trained on normal activity data predicted true activity with ~38% accuracy, training on the data gathered during the deceptive behavior increased their accuracy to ~84%. We conclude that learning the deceptive behavior of one individual helps to detect the deceptive behavior of others. Thus, we can make current activity recognition robust to deception by including deceptive activity data from a few individuals.     

Sex differences in the rate of fatigue development and recovery

Background

Many musculoskeltal injuries in the workplace have been attributed to the repetitive loading of muscle and soft tissues. It is not disputed that muscular fatigue is a risk factor for musculoskeltal injury, however the disparity between gender with respect to muscular fatigability and rate of recovery is not well understood. Current health and safety guidelines do not account for sex differences in fatiguability and may be predisposing one gender to greater risk. The purpose of this study was to quantify the sex differences in fatigue development and recovery rate of lower and upper body musculature after repeated bouts of sustained isometric contractions.

Methods

Twenty-seven healthy males (n = 12) and females (n = 15) underwent bilateral localized fatigue of either the knee extensors (male: n = 8; female: n = 8), elbow flexors (male: n = 8; female: n = 10), or both muscle groups. The fatigue protocol consisted of ten 30-second sub-maximal isometric contractions. The changes in maximum voluntary contraction (MVC), electrically evoked twitches, and motor unit activation (MUA) were assessed along with the ability to control the sustained contractions (SLP) during the fatigue protocol using a mixed four-factor repeated measures ANOVA (gender × side × muscle × time) design with significance set at p < 0.05.

Results

There was a significant loss of MVC, MUA, and evoked twitch amplitude from pre- to post-fatigue in both the arms and legs. Males had greater relative loss of isometric force, a higher rate of fatigue development, and were less capable of maintaining the fatiguing contractions in the legs when compared to the females.

Conclusion

The nature of the induced fatigue was a combination of central and peripheral fatigue that did not fully recover over a 45-minute period. The results appear to reflect sex differences that are peripheral, and partially support the muscle mass hypothesis for explaining differences in muscular fatigue.

     

Chemoprotective effects of carnosine against genotoxicity induced by cyclophosphamide in mice bone marrow cells

The protective effects of carnosine as a natural dipeptide were investigated in mouse bone marrow cells against genotoxicity induced by cyclophosphamide. Mice were injected with solutions of carnosine at three different doses (10, 50 and 100?mg kg(-1) bw) for five consecutive days. On the fifth day of treatment, mice were injected cyclophosphamide and killed after 24?h. The frequency of micronuclei in polychromatic erythrocytes and the ratio of polychromatic erythrocyte/polychromatic erythrocyte?+?normochromatic erythrocyte [PCE/(PCE?+?NCE)] were evaluated by May-Grunwald/Giemsa staining. Histopathology of bone marrow was examined in mice treated with cyclophosphamide and carnosine. Carnosine significantly reduced micronucleated polychromatic erythrocytes (MnPCEs) induced by cyclophosphamide at all three doses. Carnosine at dose of 100?mg kg(-1) bw reduced MnPCEs 3.76-fold and completely normalized the PCE/(PCE?+?NCE) ratio. Administration of carnosine inhibited bone marrow toxicity induced by cyclophosphamide. It appeared that carnosine with protective activity reduced the oxidative stress and genotoxicity induced by cyclophosphamide in bone marrow cells of mice. Copyright ? 2012 John Wiley & Sons, Ltd.     

Cyclic AMP-adenosine binding protein/S-adenosylhomocysteinase from mouse liver. A fraction of adenosine bound is converted to adenine.

1. Adenosine bound to the cyclic AMP-adenosine binding protein/S-adenosylhomocysteinase from mouse liver was partly converted to a product which was identified as adenine in four chromatographic systems. Ribose was formed in equivalent amounts. 2. The time course of the reaction was characterized by an initial burst phase lasting for less than one second followed by a slow progressive phase. The reaction was partly reversed by prolonged incubation, slow denaturation of the protein, dilution of the incubation mixture and removal of adenosine by converting it to inosine by the enzyme adenosine deaminase. 3. Both the ATP-treated (Ueland, P.M. and D?skeland, S.O. (1978) Arch. Biochem. Biophys. 185, 195--203) and the non-treated protein were subjected to polyacrylamide gel electrophoresis at pH 8.8. The adenosine-adenine, the cyclic AMP binding activities and the conversion activity comigrated with the main protein band, indicating that these properties reside on the same protein molecule. 4. Adenine generated by hydrolysis of adenosine was mainly bound to the protein as judged by nearly complete reversion of the conversion upon dilution in the presence of excess unlabelled adenine and by Sephadex G-25 chromatography. 5. The conversion of adenosine to inosine by the enzyme adenosine deaminase was decreased in the presence of the binding protein. 6. Adenine formation could also be demonstrated under condition of enzymic formation of S-adenosylhomocysteine, i.e. in the presence of hymocysteine.