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Biomedical subjects

J R Carey

Publications and source records attributed to J R Carey.

At least 19 recordsLinked to original sources
PubMed2001

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.

Animals↗
PubMed2001

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.

Animals↗
PubMed2001

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?

Animals↗
PubMed2001

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.

Animals↗
PubMed2001

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.

Animals↗
PubMed2001

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.

Computers↗
PubMed2000

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.

Aged↗
PubMed1999

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.

Adaptation, Physiological↗
PubMed1998

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.

Aging↗
PubMed1998

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.

Aging↗
PubMed1998

Tracking control in the nonparetic hand of subjects with stroke.

OBJECTIVE: To examine in subjects with stroke using their nonparetic side how different levels of stimulus-response (S-R) compatibility, which require different levels of information processing, affect manual tracking control. DESIGN: Descriptive study comparing finger movement tracking performance under S-R-compatible and S-R-incompatible conditions between subjects with stroke and healthy controls. Four two-factor analysis of variance tests with one independent factor (group, gender, laterality, or order) and one repeated measures factor (position) comprised the data analysis. SETTING: University-based research setting. PATIENTS: Forty subjects with chronic stroke: 20 right hemiplegia (average age, 65.2+/-2.3 yrs); 20 left hemiplegia (average age, 68.6+/-2.3 yrs). Fifty-one healthy controls: 24 using nondominant hand (average age, 68.6+/-2.1 yrs); 27 using dominant hand (average age, 68.7+/-2.0 yrs). All were right-handed. MAIN OUTCOME MEASURE: Tracking accuracy index (AI), based on root-mean-square error normalized to scale of each subject's tracking target. RESULTS: In S-R-incompatible condition, AI of subjects with stroke was not significantly different from controls (F[1, 89]=1.73, p=.19). In S-R-compatible condition, AI of control subjects was significantly better than subjects with stroke (F[1, 89]=14.3, p=.0003). CONCLUSION: Manual tracking is impaired in nonparetic hand of subjects with stroke, suggesting that information processing, distinctly separate from motor weakness, may be an underestimated problem impairing controlled movements in individuals with stroke.

Adult↗
PubMed1997

Early mortality surge in protein-deprived females causes reversal of sex differential of life expectancy in Mediterranean fruit flies.

Experiments based on over 400,000 medflies revealed that females maintained on a normal diet (sucrose plus protein) have a higher life expectancy than males maintained on a normal diet, with a difference of 1.30 +/- 0.27 days in favor of females. However, this sex differential reverses under protein deprivation, with a difference of 2.24 +/- 0.18 days in favor of males. The reversal of the male-female life expectancy differential is caused by a sustained surge in early female mortality under protein deprivation that is tied to egg-laying and physiological processes. In contrast, male mortality and life expectancy are only mildly affected by protein deprivation. The surge in early mortality for female medfly cohorts is an instance of a vulnerable period. These vulnerable periods are linked with patterns in hazard rates.

Aging↗
PubMed1997

What demographers can learn from fruit fly actuarial models and biology.

Historically demographers have viewed the results of actuarial studies of nonhuman species, particularly those on invertebrates such as fruit flies, as largely irrelevant to investigations on human populations. In this paper I present life table data from large scale studies on the Mediterranean fruit fly, and show that they provide important insights into fundamental aspects of mortality relevant to human populations: the trajectory of mortality at older ages, sex mortality differentials, the concept of maximal life span, and demographic heterogeneity and selection. An overriding theme of the paper is the need for demographers to acquire a heightened awareness of new developments in biology including areas such as evolutionary ecology, experimental demography, and molecular medicine.

Age Distribution↗
PubMed1996

Lumbar lordosis and pelvic inclination of asymptomatic adults.

BACKGROUND AND PURPOSE: We examined the association between pelvic inclination and lumbar lordosis during relaxed standing and eight variables thought to contribute to lordosis. SUBJECTS: Ninety subjects (45 men, 45 women) without back pain or a history of surgery were examined. The mean age was 54.8 years (SD = 8.5) for male subjects and 58.9 years (SD = 8.8) for female subjects. METHODS: Multiple linear regression modeling was used to assess the association of pelvic inclination and size of lumbar lordosis in a standing position with age, gender, body mass index, physical activity level, back and one-joint hip flexor muscle length, and performance and length of abdominal muscles. RESULTS: Abdominal muscle performance was associated with angle of pelvic inclination for women (R2 = .23), but not for men. Standing lumbar lordosis was associated with abdominal muscle length in women (R2 = .40), but it was multivariately associated with length of abdominal and one-joint hip flexor muscles and physical activity level in men (R2 = .38). No correlation was found between angle of pelvic inclination and depth of lumbar lordosis in a standing position. CONCLUSION AND DISCUSSION: Neither univariate nor multivariate regression models account for variability in the angle of pelvic inclination or size of lumbar lordosis in adults during upright stance; no correlation was found in standing between these two variables. The use of abdominal muscle strengthening exercises or stretching exercises of the back and one-joint hip flexor muscles to correct faulty standing posture should be questioned.

Abdominal Muscles↗
PubMed1995

Sex mortality differentials and selective survival in large medfly cohorts: implications for human sex mortality differentials.

Experimental studies on male-female mortality differences in nonhuman species are important because they provide insights into both the nature of age-specific gender differences and the concept of selective survival--whether one subgroup in a population (e.g., males) is consistently more frail than another subgroup (e.g., females). We found that it was not possible to classify either sex as more robust or longer lived since relative longevity was conditional on age (young or old), cage conditions (solitary confinement or grouped cages), and treatment (starvation, irradiation, or density). Implications of these findings are discussed including selective survival, demographic selection, a framework for male-female mortality differentials, and an evolutionary perspective on gender differences in longevity.

Animals↗
PubMed1995

Stimulus-response compatibility effects in a manual tracking task.

The purpose of this study was to determine whether there are stimulus-response (S-R) compatibility effects in a manual tracking task for male and female subjects of different ages. 20 healthy men and 20 healthy women in each of three different age groups (20 to 39, 40 to 59, and 60 to 79 years) participated (total N = 120). Subjects performed extension and flexion movements of the index finger metacarpophalangeal joint to track a computer-screen cursor along a target sine wave. The hand and forearm were positioned so that the finger movement was either vertical or horizontal, and the computer monitor was positioned so that the voluntary cursor movement was either vertical or horizontal. Each subject performed four different tracking tests corresponding to the four different ensembles of hand-forearm position and monitor position. There were significant differences in tracking performance between test ensembles in both women and men aged 60 to 79 years, and the compatible ensembles showed the superior performance. The results suggest that S-R compatibility effects exist in elderly women and elderly men performing a finger-movement tracking task, and these effects are consistent with impaired information processing in elderly persons. More research is needed on how S-R compatibility affects performance in persons with cerebral lesions.

Adult↗
PubMed1994

Reliability of goniometric measurements of active arm elevation in the scapular plane obtained in a clinical setting.

Our purpose was to determine the intratester and intertester reliability of measurements of both scapular and glenohumeral rotation during active arm elevation in the scapular plane with a new device, the scapulohumeral goniometer (SHG). Ten physical therapists, with 1 to 29 years of clinical experience, obtained repeated measurements on 45 subjects who were 27 to 82 years old. All subjects were tested in a uniform standing position with the handheld SHG, which was positioned over the subject's scapula and posterior shoulder according to operationally defined landmarks. For both scapular and glenohumeral rotation, 50% of the time the first and second measurements made on a patient by the same physical therapist differed by 3 degrees or more. Ten percent of the time, these measurements differed by 8 degrees or more. Measurements of active range of movement of scapular and glenohumeral rotation made by the same physical therapist during arm elevation in the scapular plane are clinically unacceptable when obtained with the current techniques for positioning the SHG. Clinical decisions based on results of active scapular and humeral motion in the scapular plane as measured on a patient by the same therapist with an SHG should be made with caution, because of the variability associated with this procedure.

Adult↗