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Biomedical subjects

M D Hayward

Publications and source records attributed to M D Hayward.

At least 37 records · Page 2Linked to original sources
PubMed1994

The relationship between retirement life cycle changes and older men's labor force participation rates.

This study probes the utility of older men's labor force participation rates (LFPRs) as indicators of the work-to-retirement transition. Specific attention is directed at how shifts in the retirement life cycle are related to LFPRs. Based on Current Population Survey data for the 1970s, a life table modeling approach showed that LFPRs are relatively weak indicators of the work-to-retirement transition. This was demonstrated by the relative stability in older men's age profiles of LFPRs despite significant changes in the timing and "organization" of the work-to-retirement transition. The 1970s evidenced a contraction of the main career and the expansion of both post-retirement work activity and retirement, yet none of these changes substantially altered the age profiles of older men's labor force participation rates.

Aged↗
PubMed1994

Changing mortality and morbidity rates and the health status and life expectancy of the older population.

This paper demonstrates the consequences of changes in mortality and health transition rates for changes in both health status life expectancy and the prevalence of health problems in the older population. A five-state multistate life table for the mid-1980s provides the baseline for estimating the effect of differing mortality and morbidity schedules. Results show that improving mortality alone implies increases in both the years and the proportion of dependent life; improving morbidity alone reduces both the years and the proportion of dependent life. Improving mortality alone leads to a higher prevalence of dependent individuals in the life table population; improving morbidity alone leads to a lower percentage of individuals with problems in functioning.

Activities of Daily Living↗
PubMed1993

Induction of immediate early genes by cyclic AMP in primary cultures of neurons from rat cerebral cortex.

In this paper, we tested whether physiological activators of the cAMP second messenger pathway in primary cultures of neurons from rat cerebral cortex directly induce c-fos and other immediate early gene (IEG) transcription factors. We have found that brief (30 s to 2 min) stimulation of neurons with vasoactive intestinal peptide (VIP) and SKF-38393, a D1-dopaminergic receptor agonist, potently increased mRNA levels for the IEGs c-fos, jun-B, and NGFI-A, with weaker increases for c-jun. This action was mimicked by forskolin and dibutyryl cAMP. IEG induction by VIP and dibutyryl cAMP was not blocked by excitatory amino acid receptor antagonists or by blockers of dihydropyridine-sensitive calcium channels. Moreover, calcium-free medium did not modify IEG induction by dibutyryl cAMP, suggesting that cAMP can directly regulate IEG expression in differentiated neurons independently of calcium.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1992

Differential induction of immediate early genes by excitatory amino acid receptor types in primary cultures of cortical and striatal neurons.

In primary cultures of neurons from cerebral cortex and striatum, 30 s stimulation with the excitatory amino acid glutamate elicited a 5 to 9-fold increase in immediate early gene (IEG) mRNAs. Glutamate increased c-fos, c-jun, jun-B, and NGFI-A (zif/268) mRNAs by binding to both alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptor types, and increased c-fos, jun-B, and NGFI-A mRNAs by binding to the metabotropic receptor. NMDA receptor activation elicited IEG expression by a transmembrane calcium influx; AMPA receptor-induced depolarization played a permissive role for the opening of the NMDA receptor channel. The protein kinase C (PKC) inhibitor H-7 (but not inhibitors of cyclic nucleotide-dependent and calcium/calmodulin-dependent protein kinases) partially blocked IEG expression induced by glutamate.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Induction of the c-fos proto-oncogene in rat amygdala during unconditioned and conditioned fear.

Induction of the nuclear proto-oncogene c-fos in rat amygdala was investigated 30-40 min following the presentation of mild footshocks (unconditioned fear) or of contextual cues associated with similar footshocks 24 h earlier (conditioned fear). Initially, it was found that handling rats for the first time elevated c-fos mRNA levels, but this response could be blocked completely by repeated handling. Unconditioned and conditioned fear both elevated amygdala c-fos mRNA dramatically above control levels.

Amygdala↗
PubMed1990

Induction of the c-fos proto-oncogene during opiate withdrawal in the locus coeruleus and other regions of rat brain.

Opiate regulation of the nuclear proto-oncogene c-fos was studied in the locus coeruleus (LC) and other regions of rat brain by immunoblotting, northern blotting, and in situ hybridization procedures. Precipitation of opiate withdrawal in rats, which is known to increase LC firing rates 4-fold, led to a two- to three-fold increase in levels of mRNA and protein for c-fos in the LC 1-2 h after initiation of withdrawal. In contrast, levels of c-fos expression were decreased in LC from rats treated acutely or chronically with morphine but not experiencing withdrawal, conditions under which LC firing rates are depressed. Similar regulation of c-fos expression during opiate withdrawal was found in the amygdala, ventral tegmentum, nucleus accumbens, neostriatum, and cerebral cortex, but not in a number of other brain regions studied, which included the hippocampus, dorsal raphe, periaqueductal gray, and paragigantocellularis. In the LC and some other brain regions, induction of c-fos during opiate withdrawal was associated with a parallel induction of c-jun, another nuclear proto-oncogene, which, like c-fos, is expressed rapidly in brain in response to certain extracellular stimuli. The results demonstrate a novel use of c-fos in neuropharmacology, namely to map neuronal pathways and neuronal cell types activated in response to acute and chronic opiate administration and during opiate withdrawal, as well as in response to other psychotropic drug treatments.

Animals↗
PubMed1990

Chronic electroconvulsive seizures down-regulate expression of the immediate-early genes c-fos and c-jun in rat cerebral cortex.

Acute seizures and other stimuli that increase neuronal activity cause a rapid induction of the immediate-early genes c-fos and c-jun, also referred to as nuclear proto-oncogenes, in the nervous system. In the present study, rats were administered one or more electroconvulsive seizures (ECS) and the responsiveness of c-fos and c-jun to an acute, "test" seizure was examined. Four hours after a single ECS, the induction of c-fos mRNA by a test seizure was blocked, in agreement with earlier findings, but by 18 h the levels of c-fos mRNA could be reinduced by the test seizure, suggesting that 1 day is sufficient to "reset" the responsiveness of this system. However, it was found that chronic, daily ECS treatments resulted in a time-dependent decrease in the expression of c-fos mRNA in response to a test seizure administered 18 h after the last daily ECS; this effect was maximal after 8-10 days of treatment, at which time the induction of c-fos mRNA by the test seizure was blocked dramatically. Chronic ECS also blocked the induction of c-jun in response to an acute, test seizure. The effect of chronic ECS on levels of Fos protein was also investigated. It was found that basal levels of Fos protein were reduced after chronic (10 days) ECS and were not induced by a test seizure. Because levels of Fos protein remain elevated 4 h after a single seizure this finding suggests that the mechanisms by which acute (4 h) and chronic (8-10 days) ECS block the induction of c-fos may differ.

Animals↗
PubMed1990

Occupational careers and mortality of elderly men.

This article presents findings from an analysis of occupational differentials in mortality among a cohort of males aged 55 years and older in the United States for the period 1966-1983. Using the National Longitudinal Survey of Mature Men, we construct event histories for 3,080 respondents who reach the exact age of 55. The dynamics that characterize socioeconomic differentials in mortality are analyzed by evaluating the differential effects of occupation over the career cycle. Maximum likelihood estimates of hazard-model parameters show that the mortality of current or last occupation differs substantially from that of longest occupation, controlling for education, income, health status, and other sociodemographic factors. In particular, the rate of mortality is reduced by the substantive complexity of the longest occupation while social skills and physical and environmental demands of the latest occupation lower mortality.

Aged↗
PubMed1990

Work and retirement among a cohort of older men in the United States, 1966-1983.

Multivariate increment-decrement working life tables are estimated for a cohort of older men in the United States for the period 1966-1983. The approach taken allows multiple processes to be simultaneously incorporated into a single model, resulting in a more realistic portrayal of a cohort's late-life labor force behavior. In addition, because the life table model is developed from multivariate hazard equations, we identify the effects of sociodemographic characteristics on the potentially complex process by which the labor force career is ended. In contrast to the assumed homogeneity of previous working life table analyses, the present study shows marked differences in labor force mobility and working and nonworking life expectancy according to occupation, class of worker, education, race, and marital status. We briefly discuss the implications of these findings for inequities of access to retirement, private and public pension consumption, and future changes in the retirement process.

Aged↗
PubMed1989

Contraceptive switching among currently married women in the United States.

This study examines contraceptive method switching among married women in the US. It enquires first into the effect of method type and women's socioeconomic characteristics on the risk of switching to each of six methods, including no method, and secondly into the previous methods used by women who adopt specific contraceptive means. The results indicate a great deal of circulation among all method types and of movement to unprotected intercourse. The adoption of sterilization is greatest among women not previously using any contraceptive method.

Adult↗
PubMed1989

Occupational influences on retirement, disability, and death.

This research examines the alternative mechanisms by which occupations influence the nature and timing of older men's labor force withdrawal. We specifically assess the extent to which occupational factors operate directly and indirectly on exiting events and whether occupations constrain traditional determinants of labor force participation. Based on a discrete-time hazard modeling approach, the results substantiate that the occupational task activities--substantive complexity and physical demands--are key elements of the work environment that are evaluated against nonwork alternatives. In the case of retirement, these aspects of occupational attractiveness function as a dominant and direct force in retirement decision making. With regard to disability, the occupational attribute of substantive complexity operates as an indirect advantage (through higher wages) by reducing the risk of disability. Indicators of career continuity also influence retirement among older workers. Finally, the results suggest that financial characteristics and health problems are central to the distribution of older workers across the alternative destination statuses of retirement, disability, and death.

Aged↗
PubMed1988

Recent changes in mortality and labor force behavior among older Americans: consequences for nonworking life expectancy.

Increment-decrement working life tables for 1972 and 1980 are used to assess the relative impact of recent changes in mortality and labor force behavior on the number of years older men and women can expect to spend out of the labor force (nonworking life expectancy). The life tables are based on data from the Current Population Surveys and pertain to the population aged 55 and older for the two observation points. The results indicate that nonworking life expectancy increased dramatically between 1972 and 1980 for both men and women. Although labor force behavior changed markedly for both population groups during the observation period, the results clearly identify that changes in mortality were responsible for the increases in nonworking life expectancy. Implications of the findings for social policy are briefly discussed.

Actuarial Analysis↗
PubMed1988

Changes in the retirement process among older men in the United States: 1972-1980.

Recent changes in older men's retirement patterns are investigated for the United States. The results show that labor force incumbents, particularly those in secondary occupations, experienced increases in the volume of both retirement and reentry to the labor force. In addition, although working life expectancy remained relatively stable across occupations, men in secondary occupations spent increasingly greater portions of their work lives in postretirement jobs. Finally, large increases in nonworking life expectancy occurred because of substantial increases in life expectancy. In several occupations, however, declines in working life expectancy were major contributors to increases in nonworking life expectancy.

Actuarial Analysis↗
PubMedDate not supplied

Contraceptive discontinuation among married women in the United States.

Using data from the 1982 National Survey of Family Growth (NSFG), this analysis reports differentials in contraceptive discontinuation among married women aged 15-44 years in the United States. The total discontinuation rate is broken down into change to no method (termination) or to a different method (a method switch), and rates are obtained for specific methods. In addition, sociodemographic differences in risks associated with each type of discontinuation are shown. Discontinuation rates are compared to use-failure rates to provide a more comprehensive understanding of the implications of discontinuation for contraceptive efficacy.

Actuarial Analysis↗