New modalities of brain stimulation for stroke rehabilitation.

Stroke is a leading cause of disability, and the number of stroke survivors continues to rise. Traditional neurorehabilitation strategies aimed at restoring function to weakened limbs provide only modest benefit. New brain stimulation techniques designed to augment traditional neurorehabilitation hold promise for reducing the burden of stroke-related disability. Investigators discovered that repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and epidural cortical stimulation (ECS) can enhance neural plasticity in the motor cortex post-stroke. Improved outcomes may be obtained with activity-dependent stimulation, in which brain stimulation is contingent on neural or muscular activity during normal behavior. We review the evidence for improved motor function in stroke patients treated with rTMS, tDCS, and ECS and discuss the mediating physiological mechanisms. We compare these techniques to activity-dependent stimulation, discuss the advantages of this newer strategy for stroke rehabilitation, and suggest future applications for activity-dependent brain stimulation.

Extraordinary long life spans in fruit-feeding butterflies can provide window on evolution of life span and aging.

Information on the life span of organisms in the field is essential for elucidating the evolution of life span and aging. We present mark-recapture data (>30,000 marked individuals, >4000 recaptured at least once) on 47 species of fruit-feeding butterflies in a tropical forest in Uganda. The data reveal adult life spans in the field for several species that are significantly longer than previously recorded in Lepidoptera (butterflies and moths). Longevity records for species of which more than 100 individuals were recaptured ranged from 67 (Bicyclus auricruda) to 293 days (Euphaedra medon). In contrast to the majority of Lepidoptera which are short-lived, these all show exceptionally long life spans, and may thus help to better identify factors that affect aging, particularly when combined with information on temporal patterns in reproduction, strategies to avoid predation, and nutritional ecology. These key traits are readily measurable in butterflies and thus studies on fruit-feeding butterflies have much potential for gaining insight into the evolution of life span and aging, especially given the tradition of field-research on butterflies.

The ecology and biodemography of Caenorhabditis elegans.

The nematode Caenorhabditis elegans is a well-known model organism for research on aging and life span, but very little is known about its ecology and natural history. The strain N2 is the standard wild-type C. elegans and arose from the progeny of a single hermaphrodite. Since N2 has passed through laboratory culture, the influence of inadvertent selection and genetic drift on C. elegans strains kept in culture is unclear. Because it seems that other wild-type strains have also been subject to lengthy laboratory culture, the life span and biodemography of wild-caught C. elegans is of interest. We recovered C. elegans from snails (Helix aspersa) in ca. 50% of the California locations where we made collections. In experiments with one of the wild-caught isolates, it differed in important demographic properties, mortality, fertility, fitness, and activity patterns, from the standard N2 strain, when both strains were evaluated in a common laboratory environment. The differences were not only statistically significant; they were also large enough to be biologically important. The differences are consistent with the hypothesis that N2 has adapted to laboratory conditions.

Muscle fiber orientation in muscles commonly injected with botulinum toxin: an anatomical pilot study.

The endplate zone is assumed to be at about the midpoint of a muscle fiber. This study was designed to locate the middle of the muscle fibers of commonly injected muscles, thus identifying the endplate zone of these muscles. The proximal and distal musculotendinous junctions in muscles of the upper and lower extremities were identified. Orientation of muscle fibers was determined. Measurements using common surface landmarks were used to determine the relationship of these muscles with the landmarks (e.g., biceps muscle bulk extends from the upper fourth to the lower fourth of the humerus). Figures were developed using these measurements so as to be able to extrapolate these measurements to other patients of varying sizes. Illustrations of muscle fiber orientation were done and the assumed location of motor endplate bands marked. Color illustrations will be shown. With the thought that the endplate zone is at the middle of the muscle fiber, this detailed study of muscle fibers helps identify assumed location of motor endplates of specific muscles, thereby improving technique and efficacy of botulinum toxin injections.

Revising the standard wisdom of C. elegans natural history: ecology of longevity.

Here, we consider that most of the research concerning Caenorhabditis elegans has been laboratory focused and that only limited research has directly considered the worm's biology relative to its natural history in the wild. We describe that, although the worm has traditionally been considered a soil nematode, we could not find it in soil but frequently recovered it from snails. Finally, we discuss how a better understanding of the natural history of C. elegans may enhance its usefulness as a model organism for studying aging and other phenomena.

[A model of resource reallocation during physiological adaptation in Mediterranean fruit fly females]. / Model' pereraspredeleniia resursa v khode fiziologicheskoi adaptatsii samok sredizemnomorskoi fruktovoi mukhi Ceratitis capitata.

Analysis of experimental data on longevity and fertility of females of Mediterranean fruit fly Ceratitis capitata demonstrates that flies lay fewer eggs on the average as the average life-span increases. At the same time, the values of individual life-span and the number of eggs laid are positively correlated. To explain these results, a resource model describing the allocation and reallocation of resources between two basic functions, reproduction and maintenance, was proposed. The reallocation of resources, is triggered by changes in environmental conditions such as diet changes, and the parameters of reallocation depend on the current environmental conditions. Modeling demonstrated that the results of experiments are greatly influenced by population selection and heterogeneity.

The impact of diet switching on resource allocation to reproduction and longevity in Mediterranean fruitflies.

Understanding the factors that determine the allocation and utilization of organism resources may provide an insight into the mechanisms of adaptation, ageing and reproduction. Resource allocation, which is regarded as a method of adaptation, increases fitness and is genetically controlled. Experiments with variable diet feeding of female Mediterranean fruitflies (Ceratitis capitata) demonstrated that the feeding regime dramatically influences lifespan, mortality and the reproduction of flies. An analysis of experimental data and numerical experiments reveals that resource allocation could explain lifespan increase when females are switched from a sugar-only to a protein-containing diet. The heterogeneity of the initial female cohort in terms of the total amount of resources and its allocation to the processes of maintenance and reproduction plays a significant role in this.

How an individual fecundity pattern looks in Drosophila and medflies.

Reproduction usually is characterized by a mean-population fecundity pattern. Such a pattern has a maximum at earlier ages and a subsequent gradual decline in egg production. It is shown that individual fecundity trajectories do not follow such a pattern. In particular, the regular individual fecundity pattern has no maximum so that experimentally observed maximums are average-related artifacts. The three-stage description of individual fecundity, which includes maturation, maturity, and reproductive senescence, is more appropriate. Data are presented for Drosophila and Mediterranean fruitfly females that clearly confirm this hypothesis. A systematic error between egg-laying scores and the regular individual pattern allows for evaluation of how close the random scores are to the pattern. The first finding of the analysis of the systematic errors is that they are consistent with the three-stage hypothesis and do not contradict the absence of the maximum in the regular individual pattern. The other finding is the existence of obvious dynamic properties of the systematic error. The slow decrease in egg-laying at the maturity stage might be the result of a cost of mating. It can also be a consequence of "structural" senescence, that is, a slow rate accumulation of oxidative damage in the gonads.

Effect of aerobic exercise on tracking performance in elderly people: a pilot study.

BACKGROUND AND PURPOSE: Although much is known about the benefits of aerobic exercise on cardiovascular health, little research has been done on the effect of aerobic exercise on motor performance. This study examined whether aerobic exercise has an effect on visuospatial information processing during finger-movement tracking in elderly subjects. SUBJECTS: Fifteen elderly subjects (mean age=83.2 years, SD=5.7, range=72-91) from a senior housing complex were randomly assigned to a control group or an experimental (exercise) group. Twelve subjects completed the study, and data obtained for 10 subjects were used for data analysis (2 control subjects were eliminated to allow for matched-pairs analysis between the experimental and control groups). The control group (n=5) had a mean age of 80.2 years (SD=7.8). Subjects in the experimental group (n=5) had a mean age of 84.8 years (SD=2.5). METHODS: The intervention consisted of group exercise 3 times a week for 8 consecutive weeks, and included calisthenics (eg, marching in place, side stepping, mock boxing), stationary bicycling, and walking. A finger-movement tracking test and submaximal graded exercise tolerance step tests were performed before and after training to determine changes in finger-movement tracking and any aerobic training effects. RESULTS: Matched-pairs t tests showed a difference in tracking from pretest to posttest in the experimental group compared with the control group. Step test performance did not differ between the 2 groups. DISCUSSION AND CONCLUSION: The results of this small-scale study with a limited number of subjects indicate that, for elderly people, finger-movement tracking performance can improve with aerobic exercise, despite the absence of an aerobic training effect. Possible mechanisms for the treatment effect on information processing are discussed.

Early detection and population monitoring of Ceratitis capitata (Diptera: Tephritidae) in a mixed-fruit orchard in northern Greece.

Population monitoring of the Mediterranean fruit fly,Ceratitis capitata (Wiedemann), was studied in 1998 in a mixed-fruit orchard in northern Greece, using International Pheromone McPhail traps (IPMT) baited with the female targeted attractants ammonium acetate, putrescine, and trimethylamine, and Jackson traps baited with the male specific parapheromone trimedlure. Special emphasis was placed on detecting the low initial adult population resulting from surviving overwintering larvae as early as possible in the spring and early summer. Traps were suspended on various host trees, using trap grid densities of either 15 or 1.5 traps per hectare. The first adults detected were females captured on 24 June in IPMT traps suspended on apricot trees, which are among the earliest maturing hosts in the area. From the end of July, the most effective trap was the IPMT trap placed on peaches, which followed apricots in the fruit ripening sequence. IPMT traps captured predominately females (approximately 80% of the total captures) and by far outperformed Jackson traps in early detection (the first males in Jackson traps were captured in August) as well as in total captures until mid-October. After mid-October, however, more flies were captured in Jackson traps. Comparing the performance of two trap grid densities on apple trees (the common host in the two grids), we found that in the high-density trap grid the first adults were detected 1 wk earlier than in the low-density trap grid. Our findings for this locality suggest that trap type and plant species on which traps are suspended are of key importance in early detection and population monitoring of C. capitata.

Finger movement tracking control in 8- and 9-year-old males and females in stimulus-response compatible and non-compatible hand positions.

This study examined whether differences exist between 8-9 year-old males and females in two finger movement tracking tasks with different degrees of stimulus-response (S-R) compatibility. Sixteen males and 20 females performed finger extension and flexion movements to track a computer screen cursor along a sine wave target in two different hand positions. Subjects had control of cursor movement only in the vertical plane as the cursor moved automatically from left to right across the target. In the compatible position, the hand was pronated so that finger motion occurred in the vertical plane. In the non-compatible position, the hand was neutral between pronation and supination so that finger motion occurred in the horizontal plane. The results showed that males tracked significantly more accurately than females in both the compatible and non-compatible positions. Also, an S-R compatibility effect was found in females but not in males. These results are consistent with other reports of higher information processing performance in adult males compared to females during visual-spatial tasks. The results are discussed as a possible manifestation of hormonally induced brain organization differences between males and females.

Reproductive potential predicts longevity of female Mediterranean fruitflies.

Reproduction exacts a price in terms of decreased survival. Our analysis of the interplay between age patterns of fecundity and mortality for individual female medflies (Ceratitis capitata) revealed that individual mortality is associated with the time-dynamics of the egg-laying trajectory. In a sample of 531 medflies, we found that each individual has a characteristic rate of decline in egg laying with age. This defines an individual's rate of reproductive exhaustion. This rate was shown to predict subsequent mortality The larger the remaining reproductive potential, the lower the subsequent mortality An increased mortality risk was seen in flies for which egg production declined rapidly early on, irrespective of the level of egg production. Thus, reproductive potential and lifetime are coupled in such a way that those flies which are able to profit most from an extended life span in terms of increased egg output are indeed likely to live longer.

Demographic mechanisms for the evolution of long life in social insects.

One of the most remarkable life history traits of many species of eusocial insects is the extraordinary longevity of their queens, with the recorded life span of some individuals exceeding 30 years. Surprisingly, little research has been conducted on either the proximate or ultimate questions concerning what factors favor the evolution of the long life spans in social insects. The broad objective of this paper is to address four sets of questions: (1) What are the similarities and differences in the longevity patterns among species in the four main groups of social insects - bees, wasps, ants and termites? (2) What is the evolutionary association of longevity and sociality in insects? (3) Are there biodemographic principles that can be derived from studies on longevity in social insects? and (4) What are the general implications for longevity in vertebrates, including humans?

Comparative demography of isogenic populations of Caenorhabditis elegans.

Demographic characteristics of the bacterial-feeding nematode Caenorhabditis elegans were determined in two long-lived mutant strains, TJ1052 (age-1), CB4876 (clk-1), and a wild-type strain, N2. Within each strain, there was little correlation between longevity and reproduction for individuals that lived longer than 10days. Long-lived mutant strains produced fewer eggs than the wild type. Mean total life spans were 13.2days for the wild type, 21.9days for age-1, and 15.8days for clk-1; maximum life spans were 24days for the wild type, 47days for age-1, and 32days for clk-1. Differences in total life span resulted primarily from longer post-reproductive survival. The mean post-reproductive life spans were longer than the wild type by 183% in age-1 and 60% in clk-1. We conclude that (i) post-reproductive survival is not correlated with egg production within isogenic populations of C. elegans, and (ii) the relationship between reproduction and longevity differs among isogenic populations with specific longevity genes.

Female sensitivity to diet and irradiation treatments underlies sex-mortality differentials in the Mediterranean fruit fly.

Large-scale experiments on medflies that were subjected to sterilizing doses of ionizing radiation (plus intact controls) and maintained on either sugar-only or full, protein-enriched diets revealed that, whereas the mortality trajectories of both intact and irradiated male cohorts maintained on both diets are similar, the mortality patterns of females are highly variable. Mean mortality rates at 35 days in male cohorts ranged from 0.2 to 0.3 but in female cohorts ranged from 0.09 to 0.35, depending on treatment. The study reports three main influences: (a) qualitative differences exist in the sex-mortality response of medflies subjected to dietary manipulations and irradiation; (b) the female mortality response is linked to increased vulnerability due to the nutritional demands of reproduction; and (c) female sensitivity to environmental changes underlies the dynamics of the sex-mortality differential.

Insect biodemography.

Biodemography is an emerging subdiscipline of classical demography that brings life table techniques, mortality models, experimental systems, and comparative methods to bear on questions concerned with the fundamental determinants of mortality, longevity, aging, and life span. It is important to entomology because it provides a secure and comprehensive actuarial foundation for life table and mortality analysis, it suggests new possibilities for the use of model insect systems in the study of aging and mortality dynamics, and it integrates an interdisciplinary perspective on demographic concepts and actuarial techniques into the entomological literature. This paper describes the major life table formulae and mortality models used to analyze the actuarial properties of insects; summarizes the literature on adult insect life span, including a discussion of basic concepts; identifies the major correlates of extended longevity; and suggests new ideas for using demographic concepts in both basic and applied entomology.

Postreproductive life predicted by primate patterns.

Regression analyses of primate life spans on recently revised female body and brain masses of Old World primates predict a human life span of between 72 years and 91 years-estimates that exceed the age of human menopause (and prior estimates) by well over 20 years. The life spans predicted from body and brain sizes in the early Homo suggest that postreproductive life spans predate Homo sapiens Among anthropoid primates, residual longevity after body and brain effects are controlled is greatest for Homo and for the New World monkeys of the genus Cebus. Body and brain masses predict a 25-year life span for Cebus, although recorded life spans exceed 50 years. Cebus are geographically widespread, have a female-bonded social organization convergent with Old World monkeys, and are primarily frugivorous, though the diet is heavily supplemented with vertebrate prey. Regressions of phylogenetically independent contrasts indicate that body mass and brain mass relationships to longevity remain significant when phylogeny is controlled and that brain mass is a more robust predictor than body mass. These data are new in terms of the completeness of species representation, more reliable body masses, presentation of various comparison group regressions, and control for phylogenetic independence.

Mortality oscillations induced by periodic starvation alter sex-mortality differentials in Mediterranean fruit flies.

Sex-specific mortality rates of medflies were monitored in cages containing individuals of both sexes and with food (either sugar-only or full diet) removed every 2nd, 3rd, or 4th day (plus ad libitum controls). The general finding is that periodic starvation led to marked oscillations in raw mortality rates. The specific findings are as follows: (i) female medflies live longer than male medflies when they are subjected to periodic starvation; (ii) male medflies maintained on a full diet experience a catastrophic increase in mortality (40%) on the first day food is removed. This mortality surge was not observed for females on either diet or for males maintained on a sugar-only diet; (ii) life expectancy is inversely related to the amplitude of mortality oscillations caused by food deprivation; and (iv) the large perturbations in mortality at younger ages caused by periodic starvation has little effect on the amplitude of mortality at older ages. In general, our data shed new light on the complexity of the mortality response of medflies to both the type and availability of food and thus provide a complimentary perspective to findings from dietary restriction studies on both vertebrate and invertebrate systems.

Dual modes of aging in Mediterranean fruit fly females.

The life history of medflies is characterized by two physiological modes with different demographic schedules of fertility and survival: a waiting mode in which both mortality and reproduction are low and a reproductive mode in which mortality is very low at the onset of egg laying but accelerates as eggs are laid. Medflies stay in waiting mode when they are fed only sugar. When fed protein, a scarce resource in the wild, medflies switch to reproductive mode. Medflies that switch from waiting to reproductive mode survive longer than medflies kept in either mode exclusively. An understanding of the physiological shift that occurs between the waiting and reproductive modes may yield information about the fundamental processes that determine longevity.

Biodemographic trajectories of longevity.

Old-age survival has increased substantially since 1950. Death rates decelerate with age for insects, worms, and yeast, as well as humans. This evidence of extended postreproductive survival is puzzling. Three biodemographic insights--concerning the correlation of death rates across age, individual differences in survival chances, and induced alterations in age patterns of fertility and mortality--offer clues and suggest research on the failure of complicated systems, on new demographic equations for evolutionary theory, and on fertility-longevity interactions. Nongenetic changes account for increases in human life-spans to date. Explication of these causes and the genetic license for extended survival, as well as discovery of genes and other survival attributes affecting longevity, will lead to even longer lives.