Mitochondrial abnormalities and oxidative imbalance in neurodegenerative disease

An increasing body of evidence now suggests the involvement of mitochondrial abnormalities in the etiology of neurodegenerative diseases, such as Parkinson's disease (PD) and Alzheimer disease. In this Perspective, we describe a recent study that shows that treatment of human patients with the antioxidant coenzyme Q(10'), which functions in concert with certain mitochondrial enzymes, reduced the worsening of symptoms associated with PD. These findings are consistent with the hypothesis that mitochondrial dysfunction plays a role in the pathogenesis of PD and that treatments that target mitochondrial biochemistry might ameliorate the functional decline observed in patients suffering from PD.     

Statistical theory of the analysis of experimental designs

(Abstracts of papers presented at the Annual Meeting of the Statistical Science Association of Canada; May 29, 30, 31, 1975. / R$eAsum$eAs des articles pr$eAsent$eAs au congres annuel; 29, 30, 31 mai 1975; University of Alberta, Edmonton, Alberta.)     

Relationships between muscle strength and multi-channel surface EMG parameters in eighty-eight elderly

Background

Since age-related muscle strength loss cannot be explained solely by muscle atrophy, other determinants would also contribute to muscle strength in elderly. The present study aimed to clarify contribution of neuromuscular activation pattern to muscle strength in elderly group. From 88 elderlies (age: 61~?83 years), multi-channel surface electromyography (EMG) of the vastus lateralis muscle was recorded with two-dimensional 64 electrodes during isometric submaximal ramp-up knee extension to assess neuromuscular activation pattern. Correlation analysis and stepwise regression analysis were performed between muscle strength and the parameters for signal amplitude and spatial distribution pattern, i.e., root mean square (RMS), correlation coefficient, and modified entropy of multi-channel surface EMG.

Results

There was a significant correlation between muscle strength and RMS (r =?0.361, p =?0.001) in the elderly. Muscle thickness (r =?0.519, p <?0.001), RMS (r =?0.288, p?=?0.001), and normalized RMS (r =?0.177, p =?0.047) were selected as major determinants of muscle strength in stepwise regression analysis (r?=?0.664 in the selected model).

Conclusion

These results suggest that inter-individual difference in muscle strength in elderly can be partly explained by surface EMG amplitude. We concluded that neuromuscular activation pattern is also major determinants of muscle strength on elderly in addition to indicator of muscle volume.

     

Values and fertility change in Japan

This paper analyses how value change and economic and social change have jointly affected fertility in Japan since 1950, and especially since 1973 when fertility resumed declining after some 15 years at near-replacement level. The resumption of fertility decline since 1973 has been driven primarily by underlying economic and social changes. Value change has tended to lag behind fertility change, and this lag has tended to be larger in Japan than in other advanced nations, primarily because underlying economic and social conditions have evolved more rapidly in Japan, and because it takes time for values to adjust to changes in underlying conditions. Because of Japan's high degree of cultural homogeneity, values tend to be widely and quickly shared, so that under certain conditions value change tends to occur in spurts. In Japan, many of the more important value changes affecting fertility in recent decades are bound up with major educational and job gains by women, which have led to greater economic independence and more emphasis on values of individualism and equality between the sexes.     

Income earning opportunity and work performance affect donating behavior: Evidence from dictator game experiments

Using dictator game experiments, the authors investigate the effect on donation of the dictator and/or recipient working prior to the dictator donating. We focus on two issues that previous studies have not considered. First, we examine the impact on donating behavior of a difference in endowment caused by the dictator's work performance. Second, we explore donation behavior when the recipient's work does not yield income or affect the dictator's endowment, but the recipient's work performance is made known to the dictator. Experimental results indicate that donating behavior is affected not only by the dictator working, but also by the recipient working. In addition, donating behavior is affected by income level, as determined by the dictator's work performance, and is influenced by the recipient's work performance, two findings not previously reported.     

Economic implications of Japan's aging population: a macro-economic demographic modeling approach

This paper utilizes a macroeconomic demographic model to analyze the probable impact of population aging on various public programs in Japan. Rapid fertility decline aided by mortality decline has caused the proportion of the Japanese population aged 65 and over to increase from 4.9% in 1950 to 9.0% in 1980. A population projection based on the 1975 population census assumes a recovery of fertility from a total fertility rate (TFR) of 1.9 in 1976 to 2.16 in 1980 and a gradual decline to 2.1 by 1987, while an alternative projection assumes a continuing fertility decline to a TFR of 1.65 in 2025. According to these assumptions, in 2025 18.12% to 21.29% of the total population would be aged 65 or over and 38.66% to 43.80% of the working age population would be aged 45-64. A macroeconomic neoclassical growth model with some Keynesian features was formulated to evaluate the future impact of population aging on social security programs. Population changes are transmitted to economic variables in the model through the supply of labor, level of savings, public health care plans, and old-age pension schemes. The simulation experiments included the 2 population projections and 2 alternative production functions, 1 with the quality of labor incorporated and 1 without. The results indicated that, regardless of the population projection and production function used, the growth of the economy is likely to slow to 1 or 0% in the beginning of the next century due to decreased growth of the labor force and a change in its quality due to age-compositional variations. Public health insurance schemes and pension plans will require increasing financial resources as a result of accelerated population aging; depending on the choice of benefit levels, the proportion of national income allocated to them is expected to range from 14%-40% in the year 2010. Per capita gross national product will continue to grow despite decreased economic growth, but savings might be adversely affected if the provision of social insurance benefits continued to increase monotonically. Possible palliative measures would be to change present employment practices or to upgrade the quality of the labor force through vocational training programs for older workers.     

Multivariate analysis of parity progression—based measures of the total fertility rate and its components

This article describes a methodology for applying a discrete-time survival model—the complementary log-log model—to estimate effects of socioeconomic variables on (1) the total fertility rate and its components and (2) trends in the total fertility rate and its components. For the methodology to be applicable, the total fertility rate (TFR) must be calculated from parity progression ratios (PPRs). The components of the TFR are PPRs, the total marital fertility rate (TMFR), and the TFR itself as measures of the quantum of fertility, and mean and median ages at first marriage and mean and median closed birth intervals by birth order as measures of the tempo or timing of fertility. The focus is on effects of predictor variables on these measures rather than on coefficients, which are often difficult to interpret in the complex models that are considered. The methodology is applicable to both period and cohort data. It is illustrated by application to data from the 1993, 1998, and 2003 Demographic and Health Surveys (DHS) in the Philippines.     

Age at motherhood in Japan

The paper analyzes factors influencing the age of motherhood in Japan, using both cross-sectional and time-series data. Both hazard rate and time series analyses support the hypothesis that better women's earning opportunities, as indicated by their educational attainments and relative pay, encourage Japanese women to marry and become mothers later in their lives. But both these analyses indicate that the trend toward later marriage and motherhood in Japan cannot be fully accounted for by improvements in women's educational attainments and earning opportunities, and the hazard analysis indicates that the strength of the trend increases with a woman's educational attainment.We are grateful to Shigemi Kono, former Director-General of the Institute of Population Problems, for providing us the aggregate data on the first birth probability, and the Population Problems Research Council of the Mainichi Newspapers for permitting us to use their survey data. We also thank Robert D. Retherford and two anonymous referees for helpful comments on earlier versions of the paper, Kazuichiro Iizuka and Rikiya Matsukura for their research assistance, and the American Family Life Assurance Company of Japan for its financial support for the research.     

Estimation of distribution parameters in time mortality trials: An example of time mortality analysis

In this paper we are primarily concerned with the effectiveness of a particular insecticide on beetles. The statistical problem is the comparison of results calculated by the standard probit method adapted to the time-mortality curve and those calculated by a suitably selected set of sample quantiles.     

Randomization in a complete block design with few blocks

It is known that the distributions of statistics commonly used in experimental design (notably the F statistic) involve certain nuisance parameters which depend on the model and the design. Raudomization was a technique introduced by R.A. Fisher to eliminate some of these parameter and produce a usable distribution function. We will show that there is a close relationship between the analytical properties of the non-randomized distribution and the more combinatorial properties of the nuisance parameters. This relationship allows us to determine theoretically, and practically in some cases, how good an approximation the central F distribution is to the randomized distribution.