Journal Of Gerontology[JOURNAL]
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200 papers
Genetic and environmental influences on pulmonary function in aging Swedish twins.
McClearn GE, Svartengren M, Pedersen NL … +2 more , Heller DA, Plomin R
J Gerontol · 1994 Nov · PMID 7963289 · Publisher ↗
BACKGROUND: In addition to their value in assessing pulmonary health and disease, spirometric variables have been shown to be powerful predictors of time until death in aging populations. The sources of variability in th...
BACKGROUND: In addition to their value in assessing pulmonary health and disease, spirometric variables have been shown to be powerful predictors of time until death in aging populations. The sources of variability in these spirometric values are consequently of relevance to basic gerontological research, and also of potential value in clinical application. The objective of this study was to estimate genetic and environmental sources of variance in pulmonary function. METHODS: The study involved 230 Swedish twin pairs (mean age = 64.9 years), of which number 37 monozygotic (MZ) pairs and 72 dizygotic (DZ) pairs had been separated and reared apart. Comparing these groups to the 57 MZ and 64 DZ pairs reared together permits stronger interpretation than that of conventional twin studies. Measures of vital capacity (VC) and forced expiratory volume in one second (FEV1) were residualized for height, age, sex, and tobacco consumption in pack-years. RESULTS: Maximum likelihood analyses of VC and FEV1 gave heritability estimates of .48 and .67, respectively. Age effects were explored both by dividing the sample into two cohorts, respectively above and below 65 years, and by moving interval analysis. In the two-cohort analysis, heritabilities were somewhat higher for the older cohort than the younger cohort for FEV1. The opposite was true for VC: heritability was lower in the older cohort, and there was evidence for a shared rearing environmental effect for this group. Moving interval analysis suggests these differences are gradual rather than saltatory. There were no gender differences in parameter estimates. CONCLUSION: Genetic factors account for between one-half and two-thirds of the variability in pulmonary function. There is a suggestion of age differences in the relative importance of genetic and environmental influences.
Sibling support in older age.
Connidis IA
J Gerontol · 1994 Nov · PMID 7963288 · Publisher ↗
Data from a multi-stage quota sample which includes 528 respondents aged 55 and over with at least one living sibling are used to examine instrumental support (financial, help during illness, other) from siblings, the pe...
Data from a multi-stage quota sample which includes 528 respondents aged 55 and over with at least one living sibling are used to examine instrumental support (financial, help during illness, other) from siblings, the perception of siblings as a source of support if needed (in a crisis, long-term illness, coresidence), and the characteristics of respondents and their sibling networks associated with receiving help and perceiving help to be available. A minority of respondents have received sibling support, and a majority perceive siblings to be available in a crisis. Those with two or more siblings are more likely to have received help and to perceive siblings as available than those with one sibling. Significant differences by gender, marital status, parent status, and geographic proximity are discussed with reference to models of support, particularly the functional-specificity of relationships model.
Predisposition to self-health care: who does what for themselves and why?
Kart CS, Engler CA
J Gerontol · 1994 Nov · PMID 7963287 · Publisher ↗
Data collected on a national sample of 714 respondents aged 55 years and over were used to investigate predisposition to self-health care. Three different indicators of self-health care were employed in this work, includ...
Data collected on a national sample of 714 respondents aged 55 years and over were used to investigate predisposition to self-health care. Three different indicators of self-health care were employed in this work, including a measure of actual self-care behavior (ASCB), a behavioral indicator, and two attitudinal indicators, normative self-care response (NSCR) and global self-care. In OLS regression modeling, predisposing characteristics from the health-behavior model yielded levels of variance consistent with those found in the extant literature on health- and social-services utilization among elderly Americans. Age showed limited utility as an explanatory variable; it appeared as a direct effect only on global self-care. Race was the only variable to achieve a statistically significant effect on NSCR, and being female showed direct effects on ASCB and global self-care.
Impact of joint impairment on longitudinal disability in elderly persons.
Hughes SL, Dunlop D, Edelman P … +2 more , Chang RW, Singer RH
J Gerontol · 1994 Nov · PMID 7963286 · Publisher ↗
Recent longitudinal data indicating that arthritis is a major contributor to disability in elderly persons are based on self-reported diagnostic information. This longitudinal study included baseline physical examination...
Recent longitudinal data indicating that arthritis is a major contributor to disability in elderly persons are based on self-reported diagnostic information. This longitudinal study included baseline physical examinations of joints of 541 persons over age 60. Previous results from a cross-sectional multivariate model of disability in this sample found that joint impairment (and, its absence, arthritis pain) explained a significant proportion of variance in overall disability. We have retested this model using generalized estimation equations (GEE) analysis to estimate the effect of joint impairment and arthritis pain on baseline and Year 2 disability. Findings indicate that baseline joint impairment contributes substantially to longitudinal disability. If direct measures of baseline joint impairment are unavailable, concurrent self-reported arthritis pain also predicts longitudinal disability well. These findings indicate that longitudinal studies should monitor arthritis pain and that symptomatic arthritis is a risk factor for future disability.
Aging and fatal accidents in male and female drivers.
Hakamies-Blomqvist L
J Gerontol · 1994 Nov · PMID 7963285
The effect of aging on fatal accident characteristics of male and female drivers was investigated using Finnish fatal-accident case study material from the period 1984-1990. Age-bound changes in accident characteristics...
The effect of aging on fatal accident characteristics of male and female drivers was investigated using Finnish fatal-accident case study material from the period 1984-1990. Age-bound changes in accident characteristics (e.g., increase of at-fault accidents and of collisions in intersections) appeared in both sexes but seemed to affect female drivers at an earlier age and to a higher degree. When the sexes differed in accident characteristics, those of female drivers were more like the ones typically found in older drivers. The female drivers were also both quantitatively and qualitatively less experienced as drivers than their male counterparts. Thus, the lower resistance of women to the effects of aging on driving may be explained by their lower skill level. In future cohorts of old drivers, decrease of sex differences in experience will presumably attenuate the sex differences in accident characteristics.
Multiple roles and psychological well-being in a national sample of older adults.
Adelmann PK
J Gerontol · 1994 Nov · PMID 7963284 · Publisher ↗
Activity theory and the role enhancement hypothesis predict that multiple role involvement in late life is linked to greater psychological well-being, but the disengagement hypothesis and the role change hypothesis antic...
Activity theory and the role enhancement hypothesis predict that multiple role involvement in late life is linked to greater psychological well-being, but the disengagement hypothesis and the role change hypothesis anticipate a negative association between these variables. In this study, the association between multiple roles and psychological well-being is tested among adults age 60 and over from a national sample. Three measures of well-being are regressed on background variables, number of roles (from among employee, spouse, parent, volunteer, homemaker, grandparent, caregiver, and student), and interaction terms. Multiple roles are associated with higher life satisfaction and self-efficacy and lower depressive symptoms. A significant interaction shows larger regression coefficients for roles among men than women on life satisfaction, and a three-way interaction indicates a stronger association of roles with self-efficacy for Black men than the other three gender-ethnicity combinations. Findings support the role enhancement hypothesis and the activity perspective among older adults.
Remembering to remember: adult age differences in prospective memory.
Mäntylä T
J Gerontol · 1994 Nov · PMID 7963283 · Publisher ↗
Age-related differences in prospective memory were examined in a laboratory-based task in which younger and older adults performed different actions whenever a semantically defined target word occurred in the context of...
Age-related differences in prospective memory were examined in a laboratory-based task in which younger and older adults performed different actions whenever a semantically defined target word occurred in the context of a free-association task. Requirements for self-initiated retrieval operations were manipulated by presenting target words that were typical or atypical instances (e.g., milk vs ink) of a given semantic category (liquid). The results showed that age differences in prospective memory were accentuated when atypical items were used as targets, but reduced when highly typical targets were presented. Furthermore, age differences were not limited to remembering when to perform action, but young subjects also showed better performance in remembering what was to be done. These findings indicate that the magnitude of age difference in prospective memory interacts with task complexity, and support the view that prospective memory failures are accentuated in tasks with high resource demands on self-initiated retrieval operations.
Aging and episodic memory: are elderly adults less likely to make connections between target and contextual information?
Denney NW, Larsen JE
J Gerontol · 1994 Nov · PMID 7963282 · Publisher ↗
The hypothesis that elderly individuals are less likely than young adults to connect target and contextual information was tested. Young and elderly adults were presented with a number of slides, each of which contained...
The hypothesis that elderly individuals are less likely than young adults to connect target and contextual information was tested. Young and elderly adults were presented with a number of slides, each of which contained a word superimposed in the center of a background picture of a landscape or cityscape. Half of the subjects were told to remember the words and half were told to remember the word-and-background pairs. All subjects were then tested for their recognition memory of the word-and-background pairs. The results indicate that elderly adults have greater difficulty than young adults remembering the connections between words and background pictures but that this occurs whether the pictures are target information or contextual information. Therefore, the results of this study provide no support for the notion that elderly adults have a specific contextual encoding deficit.
Effects of a music therapy strategy on depressed older adults.
Hanser SB, Thompson LW
J Gerontol · 1994 Nov · PMID 7963281 · Publisher ↗
A music-facilitated psychoeducational strategy was developed as a cost-effective and accessible intervention for older adults experiencing symptoms of depression, distress, and anxiety. Thirty older adults who had been d...
A music-facilitated psychoeducational strategy was developed as a cost-effective and accessible intervention for older adults experiencing symptoms of depression, distress, and anxiety. Thirty older adults who had been diagnosed with major or minor depressive disorder were randomly assigned to one of three 8-week conditions: (1) a home-based program where participants learned music listening stress reduction techniques at weekly home visits by a music therapist; (2) a self-administered program where participants applied these same techniques with moderate therapist intervention (a weekly telephone call); or (3) a wait list control. Participants in both music conditions performed significantly better than the controls on standardized tests of depression, distress, self-esteem, and mood. These improvements were clinically significant and maintained over a 9-month follow-up period. The potential for this type of intervention with homebound elders and others who have limited access to services is discussed.
Age differences in the symptoms of depression: a latent trait analysis.
Gallo JJ, Anthony JC, Muthén BO
J Gerontol · 1994 Nov · PMID 7963280 · Publisher ↗
Our hypothesis was that older adults are less likely than younger adults to acknowledge dysphoria or anhedonia even at the same level of depression. Study subjects were 3,141 participants in Baltimore, Maryland, and 3,46...
Our hypothesis was that older adults are less likely than younger adults to acknowledge dysphoria or anhedonia even at the same level of depression. Study subjects were 3,141 participants in Baltimore, Maryland, and 3,469 participants in the Durham-Piedmont region of North Carolina who had complete data on symptoms of depression active in the one month prior to interview, as well as several covariates thought to be related to depression. The effect of age on the endorsement of the dysphoria/anhedonia stem question from the section on Major Depression in the Diagnostic Interview Schedule was estimated in the two independently gathered samples employing structural equations with a measurement model. The results indicate that, even accounting for differences due to overall level of depressive symptoms, as well as gender, minority status, educational attainment, marital status, employment status, and cognitive impairment, dysphoria was less likely to be endorsed by persons 65 years of age and older. This bias against older adults may account in part for the low rates of Major Depression reported for older persons from epidemiologic studies employing the standard diagnostic criteria.
Risk factor change in older persons, a perspective from Hong Kong: weight change and mortality.
Ho SC, Woo J, Sham A
J Gerontol · 1994 Nov · PMID 7963279 · Publisher ↗
BACKGROUND: The influence of anthropometric measurements on mortality and longevity has been of interest to a number of investigators. However, although such measurements are not stable over time, few studies have attemp...
BACKGROUND: The influence of anthropometric measurements on mortality and longevity has been of interest to a number of investigators. However, although such measurements are not stable over time, few studies have attempted to account for such changes in longitudinal studies. The present study attempts to examine the relationship between weight change and mortality outcome. METHODS: The research was based on a longitudinal study of a cohort of 1,056 Hong Kong Chinese men and women aged 70 and above. Among the 476 nonsmoking women at baseline, 374 with weight measurements both at baseline and at 24 months follow-up were included in the study. Proportional hazards analysis with adjustments for age and other physical and social factors was used to estimate the relative risk of mortality of the higher body mass index groups in relation to the lowest body mass index group and between the weight change groups. RESULTS: Women belonging to the middle tertile of body mass index distribution had the lowest mortality. Those with a weight loss of more than 2 kg over the first 24 months follow-up had five times the risk of mortality at 40 months, even after adjusting for health and social conditions and baseline body mass index. CONCLUSION: The results suggest that both the initial body weight and weight change during the follow-up period are important considerations in the study of the association between body weight and mortality.
Functional base of support decreases with age.
King MB, Judge JO, Wolfson L
J Gerontol · 1994 Nov · PMID 7963278 · Publisher ↗
BACKGROUND: Poor balance in older persons increases the risk of injurious falls during daily activities. Functional base of support (FBOS), the anterior-posterior proportion of foot length used in maximal sustained forwa...
BACKGROUND: Poor balance in older persons increases the risk of injurious falls during daily activities. Functional base of support (FBOS), the anterior-posterior proportion of foot length used in maximal sustained forward and backward leaning, tests controlled center of mass movement, a component of balance required in daily activities. The purpose of this study was to examine the relationship between FBOS and age and establish the reliability of this measure. METHODS: Subjects were 113 community-dwelling men and women, ages 20 to 91. FBOS, measured on a force platform, is the difference between mean center of pressure location during sustained forward and backward leaning, divided by foot length. Forward lean (FL), backward lean (BL), and average sway distance during normal standing (STAND SWAY) and while leaning (FBOS SWAY) were also measured. RESULTS: Mean FBOS was .60 +/- .07 in subjects under age 60, and .42 +/- .12 in subjects 60 and older. FBOS remained constant in younger subjects; beyond age 60, FBOS declined about 16% per decade and was more variable. FL and BL also declined with age, remaining 66% and 34% of FBOS, respectively. STAND SWAY and FBOS SWAY were significantly correlated with each other, but not with FBOS. CONCLUSIONS: FBOS is a reliable measure and is decreased on average in older persons. This decrease is not related to increased sway while standing or leaning. FBOS is a simple force platform test that has potential as a measure of change in this dimension of balance and as a predictor of falls risk in older persons.
Determinants of change in total cholesterol and HDL-C with age: the Framingham Study.
Wilson PW, Anderson KM, Harris T … +2 more , Kannel WB, Castelli WP
J Gerontol · 1994 Nov · PMID 7963277 · Publisher ↗
OBJECTIVE: The purpose of the study was to assess the determinants of change of total cholesterol and high density lipoprotein cholesterol (HDL-C) change in an adult population. METHODS: The prospective cohort was examin...
OBJECTIVE: The purpose of the study was to assess the determinants of change of total cholesterol and high density lipoprotein cholesterol (HDL-C) change in an adult population. METHODS: The prospective cohort was examined at baseline and eight years later. A total of 2,222 men and 2,677 women age 20-79 years at baseline were included. Analyses were performed in 15-year age groups, and persons with cardiovascular disease or cancer during the observation period were excluded. RESULTS: In longitudinal analyses, body mass index (BMI) and plasma total cholesterol levels of each rose in concert among younger age groups, whereas levels declined in older individuals. Mean levels of BMI and total cholesterol peaked at a later age in women than in men. The corresponding changes in HDL-C were negative at all ages, and greater declines were seen in the elderly. A decrease in plasma total cholesterol was highly associated with greater age and a decrease in body mass index over the study interval, whereas the decline in HDL-C was proportional to change in body mass index. These changes remained significant after adjustment for baseline age and change in alcohol intake, cigarette consumption, diuretic use, and oral estrogen use. CONCLUSIONS: The rise in plasma total cholesterol among apparently healthy young men and women and its fall in the elderly are significantly associated with similar trends for obesity. The key determinants of a decline in HDL-C are an increase in obesity and advancing age itself. A decline in total cholesterol and in HDL-C is particularly common among the elderly, and it can be expected to occur without specific dietary or pharmacologic intervention.
Predictors of mortality in outpatient geriatric evaluation and management clinic patients.
Keller BK, Potter JF
J Gerontol · 1994 Nov · PMID 7963276 · Publisher ↗
BACKGROUND: This study describes characteristics and predictors of survival in an outpatient Geriatric Evaluation and Management (GEM) population. METHODS: Prospective evaluation and longitudinal follow-up of consecutive...
BACKGROUND: This study describes characteristics and predictors of survival in an outpatient Geriatric Evaluation and Management (GEM) population. METHODS: Prospective evaluation and longitudinal follow-up of consecutive patients (N = 636) seen in a GEM Clinic between January 1986 and September 1991. RESULTS: The typical patient was 78.4 years of age, White, female (73%), unmarried (66%), and living with a spouse or relative (47%). Although two-thirds were demented, most were independent in Activities of Daily Living (ADL) and partially dependent in Instrumental Activities of Daily Living (IADL). Subjects were followed for an average of 25 months. In bivariate analysis, IADL was the strongest predictor of survival (O.R. = 4.4). Higher ADL, better cognitive status, lower comorbid illness, and lack of recent hospitalization were also predictive of survival. In stepwise logistic regression, only IADL (O.R. = 4.2) and comorbid illness (O.R. = 1.5) predicted survival. In Kaplan-Meier Lifetable Analysis, survival at two years was 91% in the least dependent IADL group while survival was 75% in the most dependent group. Comorbid illness was the only factor that improved prediction of survival above that seen with IADL alone. When subjects are stratified by both function and illness, mortality was 36% in the ill and disabled group and 8% in those of high function and limited illness. CONCLUSIONS: IADL and comorbid illness scores offer a means of stratifying subjects for risk of death and may be useful in evaluating and comparing mortality experience in outpatient GEM and control populations. Stratification may increase the likelihood that studies aimed at improving survival will detect a difference resulting from the intervention.
Ambulatory blood pressure and heart rate responses to the stress of work and caregiving in older women.
King AC, Oka RK, Young DR
J Gerontol · 1994 Nov · PMID 7963275 · Publisher ↗
BACKGROUND: Although the informal caregiving role is associated with a range of stressors that are both chronic and severe, little is known concerning the acute physical and psychological effects of caregiving in the nat...
BACKGROUND: Although the informal caregiving role is associated with a range of stressors that are both chronic and severe, little is known concerning the acute physical and psychological effects of caregiving in the natural setting. This study evaluated the hemodynamic and psychological responses of five women identified as family caregivers who also worked outside the home and five matched working noncaregivers. METHODS: Subjects wore an ambulatory blood pressure monitor that recorded blood pressure and heart rate on an hourly basis throughout a one- to two-day period. They also completed hourly logs evaluating psychological, physical, and health-related variables through use of a preprogrammed pocket computer. Within- and between-group responses were compared in clinical, work, and postwork settings. RESULTS: Caregivers and noncaregivers showed comparable ambulatory blood pressure levels in the clinic and work settings. However, in contrast to noncaregivers, who showed the expected decrease in blood pressure level upon leaving the work setting (p values < .03), caregivers demonstrated a significant increase in systolic blood pressure levels following work when they were in the presence of the care recipient (p < .0002). The differences observed in blood pressure responses between the two groups were similarly reflected in the patterns of affective response recorded in the work and postwork settings. CONCLUSIONS: The results provide initial evidence of the acute iatrogenic effects of caregiving on physiological as well as psychological response systems.
Effects of exercise training on alpha-adrenergic mediated pressor responses and baroreflex function in older subjects.
Spina RJ, Bourey RE, Ogawa T … +1 more , Ehsani AA
J Gerontol · 1994 Nov · PMID 7963274 · Publisher ↗
Endurance exercise training increases maximal O2 uptake (VO2max) in older subjects, and training also improves cardiac function in older men. Although the effects of training on beta-adrenergic responses have been invest...
Endurance exercise training increases maximal O2 uptake (VO2max) in older subjects, and training also improves cardiac function in older men. Although the effects of training on beta-adrenergic responses have been investigated, little information is available regarding the effects of alpha-adrenergic responses and baroreflex function in older men and women. The purpose of the study was to determine whether endurance exercise training can affect alpha-adrenergic responses and baroreflex function in the elderly. We studied 13 men and women, 63 +/- 4 yrs old (mean +/- SE). VO2max was determined during treadmill exercise. Baroreflex function was determined from the change in heart rate (HR) relative to the change in systolic blood pressure (delta HR/delta SBP) during infusion of phenylephrine. VO2max was increased by 23% (1.9 +/- 0.16 vs 2.34 +/- 0.20 l/min; p < .01) in response to training. Maximal heart rate did not change, but HR during submaximal exercise at the same absolute exercise intensity was 17% lower after training. Resting heart rate was slower in the trained state. During alpha-adrenergic stimulation induced by graded doses of phenylephrine infusion, heart rate was lower after training because of training-induced bradycardia at rest. However, the elevation in systolic blood pressure (delta SBP) and mean blood pressure (delta MBP) from basal levels in response to a given dose of phenylephrine were significantly larger (delta SBP:18 +/- 3 vs 26 +/- 3 mmHg, p < .01; and delta MBP 10 +/- 2 vs 15 +/- 3 mmHg, p < .01) after than before training.(ABSTRACT TRUNCATED AT 250 WORDS)
Thermotolerance of a long-lived mutant of Caenorhabditis elegans.
Lithgow GJ, White TM, Hinerfeld DA … +1 more , Johnson TE
J Gerontol · 1994 Nov · PMID 7963273 · Publisher ↗
Age-synchronous cohorts of Caenorhabditis elegans were grown at 20 degrees C, then stressed at 30 degrees C or 35 degrees C. Intrinsic thermotolerance of wild type and age-1 mutant strains was assessed by measuring eithe...
Age-synchronous cohorts of Caenorhabditis elegans were grown at 20 degrees C, then stressed at 30 degrees C or 35 degrees C. Intrinsic thermotolerance of wild type and age-1 mutant strains was assessed by measuring either progeny production or survival. In addition to increased life span (Age), mutation of age-1 results in a highly significant increased intrinsic thermotolerance (Itt) as measured by survival at 35 degrees C. Mean survival of Age strains is approximately 45% longer than that of non-Age strains for both sterile and nonsterile worms. Thermotolerance declines across the life span of both Age and non-Age strains, but Itt was observed at almost all ages. Unstressed age-1 animals showed a consistent and significant fertility deficit. Short thermal stresses can cause a dramatic reduction in progeny production for both Age and non-Age genotypes. Mutants of age-1 showed a small but consistent increased thermotolerance as measured by fertility. We propose that the enhanced ability of Age strains to cope with environmental stress may be mechanistically related to their lower age-specific mortality rates.
Molecular genetic characterization of the senescence-accelerated mouse (SAM) strains.
Kitado H, Higuchi K, Takeda T
J Gerontol · 1994 Nov · PMID 7963272 · Publisher ↗
Senescence-Accelerated Mouse (SAM) is a murine model of accelerated senescence, which consists of the senescence-prone P series and the senescence-resistant R series of strains. In order to characterize these SAM strains...
Senescence-Accelerated Mouse (SAM) is a murine model of accelerated senescence, which consists of the senescence-prone P series and the senescence-resistant R series of strains. In order to characterize these SAM strains molecular genetically, we have performed a series of Southern hybridization experiments using oligonucleotide probes designed to recognize the endogenous mouse retrovirus sequences. The repertoires of endogenous retroviruses in different SAM strains indicated that each SAM strain is distinct. Comparisons of the SAM strains with the parental AKR/J strain revealed significant differences between them, suggesting the involvement of other strains in the course of the development of SAM. While some of the endogenous retroviruses were found in all of the SAM strains, others were found to be distributed uniquely, indicating their potential usefulness as genetic markers in the analysis of strain-specific phenotypes, and possibly of the phenomenon of accelerated senescence itself.
Potential misinterpretations using models of accelerated aging.
Harrison DE
J Gerontol · 1994 Nov · PMID 7963271 · Publisher ↗
Abstract loading — click title to view on PubMed.
Utilization of a fos-lacZ plasmid to investigate the activation of c-fos during cellular senescence and okadaic acid-induced apoptosis.
Afshari CA, Bivins HM, Barrett JC
J Gerontol · 1994 Nov · PMID 7525690 · Publisher ↗
C-fos is an immediate-early gene that is induced by external stimuli and is possibly involved in initiation of DNA synthesis by such stimuli. In these studies, we used the murine c-fos promoter coupled to a lacZ reporter...
C-fos is an immediate-early gene that is induced by external stimuli and is possibly involved in initiation of DNA synthesis by such stimuli. In these studies, we used the murine c-fos promoter coupled to a lacZ reporter gene to study fos induction in senescent and quiescent cells. In transfected, quiescent, immortal Syrian hamster embryo (SHE) cells (10W), serum stimulation induced the expression of the fos construct to the same extent that DNA synthesis was stimulated. In contrast, in transfected normal cells that have a finite life span, we observed that the cells failed to display upregulation of fos-lacZ in response to serum in individual cells as they senesced. High doses of the phosphatase inhibitor okadaic acid (160-1000 nM) also induced fos-lacZ expression in quiescent immortal cells; however, induction of DNA synthesis and expression of fos-lacZ were not coordinately induced as a function of okadaic acid concentration. Low concentrations of okadaic acid (0.16 nM) induced DNA synthesis but not fos-lacZ expression, indicating that induction of DNA synthesis by phosphatase inhibitors may bypass, at least quantitatively, the requirement for c-fos induction. At the levels of okadaic acid that induced fos-lacZ expression, cell death, rather than DNA synthesis, was observed. The cells died by apoptosis, thereby implicating a signaling pathway that includes c-fos induction in this process.
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