Life Table Data Research Articles

Establishing appropriate measures for monitoring aging in birds: comparing short and long lived species

In order to reveal patterns of reproductive aging in birds we focus on a short lived species, the Japanese quail and the American kestrel, which has a life span of medium length. Quail have been studied extensively in the laboratory as models for understanding avian endocrinology and behavior, and as a subject for toxicological research and testing. In the lab, Japanese quail show age-related deterioration in endocrine, behavioral, and sensory system responses; the American kestrel is relatively long lived and shows moderate evidence of senescence in the oldest birds. Using data collected from captive kestrels at the Patuxent Wildlife Research Center, a database was designed to document selected parameters over the life cycle of the kestrels. Life table data collated from many species indicate that longer lived species of birds show senescence in survival ability but this pattern has not been established for reproductive function. We suggest that useful comparisons among species can be made by identifying stages in reproductive life history, organized on a relative time scale. Preliminary data from quail and kestrels, admittedly only two species, do not yet indicate a pattern of greater reproductive senescence in longer-lived birds.

Pharmacomechanical thrombolysis of natural vein fistulas: reduced dose of TPA and long-term follow-up.

Twenty-five episodes of pharmacomechanical thrombolysis of 20 clotted arteriovenous fistulas (AVFs) are reported. The technique presented utilizes the local instillation of tissue plasminogen activator (TPA) in small doses together with manual maceration to dissolve clot and balloon angioplasty to correct the underlying stenoses. Since the minimum dose of TPA necessary to successfully perform thrombolysis of a natural vein fistula had never been determined, an attempt to use as minimal a dose of TPA as possible was made. Five procedures were performed in fistulas which had previously undergone a thrombolysis procedure with TPA. The procedures were successful in 92% of cases with an average dose of TPA required of 2.3 +/- 0.32 mg/procedure. In addition to the 20 accesses in this article, we offer follow-up life table data on 15 fistulas that were previously reported for a total of 35 accesses salvaged with pharmacomechanical thrombolysis. Primary patency was 11.2 months and secondary patency was 25 months. Fifty-five percent of fistulas required repeat angioplasty procedures at an average of 3.6-month intervals. In addition, more than half of the fistulas that presented with clotting required repeat interventions for continued patency. This report demonstrates the effectiveness of small doses of TPA in successful pharmacomechanical thrombolysis of clotted fistulas.

Reported family history of cancer in the prostate, lung, colorectal, and ovarian cancer screening trial.

The authors analyzed data from almost 150,000 subjects aged 55-74 years enrolled in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial who completed a self-administered baseline questionnaire (1993-2001) that included items about family history of cancer. Male respondents reported significantly less family history of cancer than females. The relative underreporting by male respondents relative to females was greater for female family members (28% lower for sisters and 21% lower for mothers) than for male family members (13% lower for brothers and 9% lower for fathers). Black, Hispanic, and Asian respondents reported significantly less family history of cancer than Whites. Reported family history prevalences for parents decreased with respondents' age, while those for siblings increased with respondents' age. The four most commonly reported cancers in families were breast (11.8%), lung (10.1%), colorectal (9.4%), and prostate (7.3%) cancer. Expected prevalences in family members of history of cancer overall and history of specific types of cancer were calculated using incidence rates and life table data obtained from the Surveillance, Epidemiology, and End Results Program. Overall, the ratio of reported cancer rates to expected cancer rates in family members was approximately 0.7. Liver, bone, stomach, and brain cancer had greater-than-average reported:expected ratios, while lymphoma, bladder cancer, melanoma, and testicular cancer had lower-than-average ratios.

Analysis Of 435 Screw-Vent Dental Implants Placed in 161 Patients: Software Enhancement Of Clinical Evaluation

This paper demonstrates how a computer software program was utilized in a private practice to supplement the clinical evaluation of one implant system. Clinical data were entered into a computer database at the time of implant placement and up to 13 years for follow-up appointments. Data were divided into two groups and subjected to lifetable analyses. The focus group consisted of a machined-titanium, screw-type implant with an internal abutment connection from one manufacturer. The residual database consisted of mixed implant designs with a variety of abutment connections and surfaces from several other manufacturers. Lifetable survival data between the two groups were generated. Cumulative survival rates from 0 to 13 years were 94.2% (n = 435) for the focus group and 90.1% (n = 2339) for the reference group. There were 25 implants lost in the focus group and 11 other implants were deemed "at risk." Survival results from other lifetable analyses are also presented for the two groups. Documentation of empirical clinical data in a computer software database over a period of time can help private practice clinicians better evaluate the dental implant systems used in their practices.

Life History of the Whitefly Predator Nephaspis oculatus (Coleoptera: Coccinellidae) at Six Constant Temperatures

Nephaspis oculatus (Blatchley) is a predator of whiteflies including Bemisia tabaci (Gennadius) and B. argentifolii Bellows and Perring. The usefulness of this and other coccinellid predators of whiteflies could be improved by better information on responses to different temperatures experienced in the field. We reared N. oculatus from egg to adult in incubators at six constant temperatures and observed a linear relationship between developmental time and temperature for all preimaginal lifestages through all but the highest temperatures (33°C). Four larval instars were observed, although a significant proportion of third instar larvae molted directly to the pupal stage at 29°C and above. Complete life table data were obtained at all temperatures except 33°C. Survivorship was greatest over all immature stages at 26°C and finite and intrinsic rates of increase were highest at this temperature. Although 26°C appeared to be the optimum temperature for population growth, estimated rates of increase at all temperatures tested above 20°C were within 75% of the maximum, indicating that the beetle can perform well within the temperature range usually found in greenhouses. © 2002 Elsevier Science (USA)

Cost of reproduction in selected species of zooplankton (rotifers and cladocerans)

Reproduction is an energetically costly biological process. Among the freshwater zooplankton, rotifers and cladocerans reproduce parthenogenetically and the cost of reproduction can be estimated using the life table data from demographic studies. Reduced probability of future survival or future reproduction as a result of current investment in offspring production (trade-off) is the central theme of the cost hypothesis. Correlations using present reproduction vs. future reproduction (called the reproductive costs) or future survival (called the survival costs) can be used to evaluate the cost hypothesis. In this work sets of correlations were made: (1) between present reproduction (mx) vs. future survival (lx+1, lx+2, lx+3 etc. for the entire lifespan) (survival costs), and (2) present reproduction (mx) vs. future reproduction (mx+1, mx+2, mx+3 etc. for the entire reproductive span) (reproductive costs). These correlations were plotted against the cohort age-classes in order to quantify survival and reproductive costs in rotifers (Asplanchna girodi, Brachionus macracanthus, B. variabilis and Platyias quadricornis) and cladocerans (Ceriodaphnia cornuta – one strain maintained on Chlorella and another strain adapted to Microcystis), Daphnia carinata, D. laevis, Moina macrocopa, Pleuroxus aduncus, Scapholeberis kingi and Simocephalus vetulus). All the tested rotifer species showed negative tendency in correlation coefficients (when the data of current reproduction vs. future reproduction and future survival were plotted) for both reproductive and survival costs. However, from the total survival and reproductive costs derived, 84% of the former and 42% of the latter were statistically significant. In cladocerans about 80% of the costs (correlations between current reproduction vs. future survival or future reproduction) were negative suggesting that present reproduction had negatively affected both the further survival and reproduction of test populations. In terms of statistically significant survival costs, the cladocerans showed a trend slightly lower (72%) but comparable to rotifers. The reproductive costs were significant in 45% cases. In our study, the simple statistical correlations detected the trade-offs between reproduction and survival. Thus, in more than 60% cases of both survival and reproductive costs in zooplankton were negative, and our data supported the cost hypothesis, in the majority of cases where reproduction by zooplankton of a given age class caused reduced survival and reproduction of the next age class.

Mortality rates of feral ferrets (Mustela furo) in New Zealand

Life-table data from feral ferret populations in New Zealand were analysed to estimate their mortality rates, and to test for any additive effect of Mycobacterium bovis infection on observed mortality rates. The observed instantaneous mortality rate was best estimated by modelling mortality as a 2-phase step model with different rates for juveniles (μ1 = 1.45 year–1, 95% C.I. 1.2–1.7 year–1) and adults (μ2 = 0.55 year–1, 95% C.I. 0.4–0.9 year–1). This corresponds to a survival probability of 0.25 during the first year of life, rising to 0.55 year–1 thereafter, and a life expectancy of 0.95 years. At a population level, no additional mortality due to M. bovis infection was observed, suggesting either that the rate of disease-induced mortality was negligible, or that it was compensatory with natural mortality.

Using matrix models to explore the influence of temperature on population growth of arthropod pests

Abstract1 Population growth of four arthropod pests on agricultural crops, the pea aphid, the bird‐cherry oat aphid, the Mediterranean fruit fly, and the two‐spotted spider mite, was modelled using stage matrix models.2 Temperature was included as a variable in the model, affecting fecundity, mortality and growth rate. Linear temperature dependence was used to describe fecundity and individual growth rate in the matrix model. Life table data collected at various constant experimental temperatures were used to parameterize the model.3 Sensitivity analysis identified the most influential demographic parameters determining the growth rate of the population at different temperature regimes. Mortality of young adults and immature stages were found to be the most important parameters in determining population growth for all species presented. However, high temperatures increased the relative impact of individual growth rates and fecundity on the growth of the population.

Factors associated with mortality in patients with early-onset Alzheimer's disease: a five-year longitudinal study.

To identify neuropsychiatric and somatic factors related to survival in early-onset Alzheimer's disease, we longitudinally studied 108 patients (35 male, 73 female) with early-onset Alzheimer's disease who were 46 to 64 years old at onset and 50 to 69 years old when diagnosed at our institution. A five-year follow-up, 30 patients had died. Pneumonia was the most common cause (73%), followed by malignancy (20%) and heart disease (7%). Kaplan-Meier survival curves showed a lower survival rate in patients with early-onset Alzheimer's disease than in age- and sex-matched life-table data in Japan. In Cox proportional hazards analysis, male gender, early disease onset, concurrent physical illness at time of diagnosis, and a low mini-mental state examination score increased the likelihood of death in patients with early-onset Alzheimer's disease. Our study confirmed that these patients have considerable excess mortality and a different pattern of cause of death than in the general population. Gender, age at onset, physical illness, and cognitive function strongly influenced survival. These factors may be predictors of mortality in patients with early-onset Alzheimer's disease that are useful in counseling patients and their families.

Influence of Temperature on Exotic Daphnia lumholtzi and Implications for Invasion Success

We investigated the effects of water temperature on the exotic cladoceran Daphnia lumholtzi in a eutrophic Kansas reservoir (USA) and under laboratory conditions. Daphnia lumholtzi demonstrated a distinct late summer appearance in the reservoir at temperatures between 26 and 31 °C, which corresponded with steep declines in the densities of native Daphnia spp. Laboratory life-table experiments confirmed that D. lumholtzi performs well at elevated water temperatures. The intrinsic rate of increase (r), net reproductive rate (R q ) age at first reproduction, survivorship (l x ) and molting rates all demonstrate that D. lumholtzi has a high temperature optimum between 20 and 30°C. A comparison of literature-reported r-values indicates that the reproductive rate of D. lumholtzi is comparable with other Daphnia spp. between 20 and 25°C, but also implies that D. lumholtzi may out-perform some Daphnia spp. at temperatures >25°C. Collectively, these results suggest that D. lumholtzi may be taking advantage of a late summer thermal niche, and that this invader may continue to colonize lakes and reservoirs in the southern US. However, life table data also indicate that D. lumholtzi performs poorly at temperatures < 10°C, which may inhibit the range expansion of this invader into northern waters.

Comparative biology of aging in birds: an update

The long life spans and slow aging rates of birds relative to mammals are paradoxical in view of birds' high metabolic rates, body temperatures and blood glucose levels, all of which are predicted to be liabilities by current biochemical theories of aging. Available avian life-table data show that most birds undergo rapid to slow "gradual" senescence. Some seabird species exhibit extremely slow age-related declines in both survival and reproductive output, and even increase reproductive success as they get older. Slow avian senescence is thought to be coupled evolutionarily with delayed maturity and low annual fecundity. Recent research in our lab and others supports the hypothesis that birds have special adaptations for preventing age-related tissue damage caused by reactive oxygen species (ROS) and advanced glycosylation endproducts, or AGEs, as well as an unusual capacity for neurogeneration in brain. Much of this work is in its early stages, however, and reliable biomarkers for comparing avian and mammalian aging need more thorough development.

Partial Life-Cycle Analysis: A Model for Birth-Pulse Populations

Matrix population models have become standard tools for the demographic analysis of age- or stage-structured populations. Although age-classified (Leslie) matrix models make maximum use of age-specific demographic data, age at first reproduction, which has been suggested to be an important life-history variable, does not appear as an explicit parameter in these models. Consequently, the sensitivity of population growth rate to changes in age at first reproduction cannot be calculated using standard techniques. Age-specific demographic data to parameterize age-structured models are difficult to collect, and models that can be parameterized with partial demographic data (“partial life-cycle models”) have been developed. Partial life-cycle models are based on life-history stages, and these models can also be used to calculate sensitivity of population growth rate to changes in various life-history variables, including ages at first and last reproduction. Here, we present a partial life-cycle model appropriate for situations where demographic data are collected immediately after the birth pulse (post-breeding census). We present methods of parameterizing the partial life-cycle model, and derive formulas for calculating the sensitivity of the population growth rate to changes in model parameters, including ages at first and last reproduction. We analyzed life-table data for several species of mammals using the partial life-cycle model and found that results of our partial life-cycle model compare favorably with those obtained from the corresponding age-classified models.

PARTIAL LIFE-CYCLE ANALYSIS: A MODEL FOR BIRTH-PULSE POPULATIONS

Matrix population models have become standard tools for the demographic analysis of age- or stage-structured populations. Although age-classified (Leslie) matrix models make maximum use of age-specific demographic data, age at first reproduction, which has been suggested to be an important life-history variable, does not appear as an explicit parameter in these models. Consequently, the sensitivity of population growth rate to changes in age at first reproduction cannot be calculated using standard techniques. Age-specific demographic data to parameterize age-structured models are difficult to collect, and models that can be parameterized with partial demographic data (“partial life-cycle models”) have been developed. Partial life-cycle models are based on life-history stages, and these models can also be used to calculate sensitivity of population growth rate to changes in various life-history variables, including ages at first and last reproduction. Here, we present a partial life-cycle model appropriate for situations where demographic data are collected immediately after the birth pulse (post-breeding census). We present methods of parameterizing the partial life-cycle model, and derive formulas for calculating the sensitivity of the population growth rate to changes in model parameters, including ages at first and last reproduction. We analyzed life-table data for several species of mammals using the partial life-cycle model and found that results of our partial life-cycle model compare favorably with those obtained from the corresponding age-classified models.

Implications of host mortality on the economics of Fopius arisanus (Hymenoptera: Braconidae) mass rearing

Fopius (= Biosteres) arisanus (Sonan) (= Opius oophilus Fullaway) is an egg-pupal parasitoid of tephritid fruit flies. Our breakthrough in the development of a laboratory-adapted strain of F. arisanus facilitated insectary rearing of parasitoids in large numbers. First colonized in captivity in 1989, F. arisanus has been reared routinely on the oriental fruit fly, Bactrocera (= Dacus) dorsalis (Hendel), its natural host. Parasitization by F. arisanus results in the latent death of developing hosts. Host mortality data are presented in a life table to estimate cost of parasitization on the economics of F. arisanus mass rearing. Percent kills of 10, 32, and 76% exerted by F. arisanus on the egg, larval, and pupal stages of the rearing hosts, respectively, resulted in a mean parasitoid recovery of 23.6%. The production cost was estimated by integrating life table data with the costs of rearing supplies and materials and personnel-hours requirements. Production of 1 million parasitoid adults requires the exposure of 4.2 million B. dorsalis eggs (= propagation hosts). We estimated the cost of producing 1 million parasitoids to be $2,363.30 and identified the most expensive aspects of F. arisanus rearing. Recommendations for streamlining the rearing process to reduce costs are provided.

Population Decline of the American Eel: Implications for Research and Management

Abstract We present evidence for a decline in the population of the American eel (Anguilla rostrata) from several widely distributed regions of North America from 1984 to 1995. Trends in population indices from commercial catch data, upstream passage counts, and seine, trawl, and electrofishing surveys were analyzed and found to be either not significant or significantly negative. Explanations for this decline, whether natural or anthropogenic, are unknown, due to variation and incompleteness in abundance data, and incomplete knowledge of eel life history, ecology, and population dynamics. A number of potential factors may be contributing to the decline, including (in alphabetical order): barriers to migration, habitat loss and alteration, hydro turbine mortality, oceanic conditions, over-fishing, parasitism, and pollution. The paucity of life table data associated with the unconventional life history characteristics of anguillid eels (catadromy, panmixis, semelparity, high age at maturity, wide geographi...

Long-term mortality trends in patients with traumatic brain injury

Comparison of long-term mortality rates between patients with traumatic brain injury (TBI) and the general population has not been adequately investigated. This project aimed to obtain information on the long-term mortality rate of patients with TBI. Using a rehabilitation database of a major teaching hospital, the search identified 476 patients, of whom 27 were deceased. This mortality rate (5.7%) was compared with the expected mortality rate for an equivalent population without TBI (1.5%) using Australian Life Table data. It was found that patients with TBI had a significantly higher mortality rate than the general population (chi2 = 12.2, p < 0.001). Possible reasons for this finding are discussed.

Modelling the cumulative risk for a false-positive under repeated screening events.

Screening examinations are widely utilized in detecting the presence of medical disorders, for instance, screening mammograms and clinical breast examinations for detection of breast cancer. Such procedures are invaluable in enabling early treatment but produce the possibilities of false-positive and false-negative diagnoses. Focusing on false-positive results, with increasing number of screening events, it is clear that the risk of a false-positive increases. The objective of this paper is to quantify the cumulative risk associated with repeated screening. We provide a very general framework within which to investigate this risk, both at the population and the individual level. The latter allows incorporation of evolving patient medical history to permit individualized assessment of risk. We model cumulative risk in terms of the number of screening events until first false-positive. We develop models which are essentially familiar actuarial models for life table data adding a Cox regression to enable individual level modelling. Because it offers several advantages, we employ a Bayesian inference framework and apply our modelling to the analysis of 9773 screening mammograms collected from 2227 women at an HMO serving nearly 300000 adults in and around Boston, MA.

Empirical laws of survival and evolution: their universality and implications.

Presented analysis of human and fly life tables proves that with the specified accuracy their entire survival and mortality curves are uniquely determined by a single point (e.g., by the birth mortality q(0)), according to the law, which is universal for species as remote as humans and flies. Mortality at any age decreases with the birth mortality q(0). According to life tables, in the narrow vicinity of a certain q(0) value (which is the same for all animals of a given species, independent of their living conditions), the curves change very rapidly and nearly simultaneously for an entire population of different ages. The change is the largest in old age. Because probability to survive to the mean reproductive age quantifies biological fitness and evolution, its universal rapid change with q(0) (which changes with living conditions) manifests a new kind of an evolutionary spurt of an entire population. Agreement between theoretical and life table data is explicitly seen in the figures. Analysis of the data on basic metabolism reduces it to the maximal mean lifespan (for animals from invertebrates to mammals), or to the maximal mean fission time (for bacteria), and universally scales them with the total number of body atoms only. Phenomenological origin of this unification and universality of metabolism, survival, and evolution is suggested. Their implications and challenges are discussed.

“Combining Life Table Data”, Gilbert W. Fellingham and H. Dennis Tolley, July, 1999

“Combining Life Table Data”, Gilbert W. Fellingham and H. Dennis Tolley, July, 1999

“Combining Life Table Data”, Gilbert W. Fellingham and H. Dennis Tolley, July, 1999

“Combining Life Table Data”, Gilbert W. Fellingham and H. Dennis Tolley, July, 1999