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Biomedical subjects

S A Murrell

Publications and source records attributed to S A Murrell.

At least 19 recordsLinked to original sources
PubMed2005

The vascular depression hypothesis: the influence of age on the relationship between cerebrovascular risk factors and depressive symptoms in community dwelling elders.

The current study examined the moderating effect of age on the relationship between cerebrovascular risk factors (CVRF's) and depressive symptoms. Consistent with the broader vascular depression model, it was hypothesized that CVRF's would demonstrate a stronger link to depressive symptoms in the older age groups than among the younger age groups. Data from 2916 adults from the Resources, Stress, and Older Persons Panel Study were utilized. Path analysis was used to estimate direct and indirect effects (via health related symptoms and limitations) of CVRF's on depressive symptoms. Path analyses were estimated separately on four age groups: 50-64 years old, 65-74 years old, 75-84 years old, and 85 years and older. CVRF's and other comorbid medical conditions were highly predictive of health related symptoms and limitations across the four age groups. Health related symptoms and limitations were strongly linked to depressive symptoms and mediated the influence of medical illnesses (both vascular and nonvascular) on depressive symptoms. However, CVRF's exerted a unique effect on depressive symptoms in the oldest-old group (i.e., 85+). Among those over the age of 85, a greater number of CVRF's was associated with more severe depressive symptoms independent of health related symptoms/limitations and other comorbid medical conditions. Health related symptoms and limitations mediated the relationship between CVRF's and depression in individuals under 85. That is, the influence of vascular burden on depression is predominately indirect via health related limitations. But among those over the age of 85, vascular disease had a unique contribution on depression, even after controlling for other comorbid medical illness and health related limitations. This finding supports the vascular depression hypothesis and is consistent with prior work suggesting vascular disease may exert its greatest effect on depression in the context of increasing frailty.

Age Factors↗
PubMed2001

Contribution of education to health and life satisfaction in older adults mediated by negative affect.

OBJECTIVES: The authors developed a model of relationships between two enduring attributes (educational attainment and negative affect) and two indicators of successful aging (health and life satisfaction). METHODS: A probability sample of 1,177 participants (age 55 and older) were interviewed four times at 6-month intervals. Structural equation models were developed based on the authors' hypothetical model proposing a mediating effect of negative affect between health and successful aging. RESULTS: As predicted, education and negative affect both were directly related to health and life satisfaction. Also, as predicted, negative affect mediated the relationship between education and successful aging indicators. DISCUSSION: Education appears to confer a lifelong advantage for healthy aging. Part of this advantage is accounted for by the relationship between education and trait negative affect. Higher educational attainment is related to lower levels of trait negative affect; lower negative affect results in better health and life satisfaction.

Aged↗
PubMed2000

Longitudinal relationships between depressive symptoms and health in normal older and middle-aged adults.

Comorbidity between health and depression is salient in late life, when risk for physical illness rises. Other community studies have not distinguished between the effects of brief and long-standing depressive symptoms on excess morbidity and mortality. S. Cohen and M. S. Rodriguez's (1995) differential hypothesis of pathways between depression and health was used to examine the relationships between health and depression in a prospective probability sample of 1,479 community-resident middle-aged and older adults. Findings suggest that different durations of depressive symptoms have different relationships to health. Health had an impact on short-term increases in depressive symptoms but depressive symptoms had a weaker impact on health. The reciprocal impact was indistinguishable from the health influence on depression. In contrast, longer term depressive symptoms had a clear impact on health. The results imply that physical illness can affect depressive states; depressive traits but not states can affect illness.

Age Factors↗
PubMed1997

Mental illness in late life: socioeconomic conditions, psychiatric symptoms, and adjustment of long-term sufferers.

The relationships between social and economic conditions and psychiatric disorder among 346 older adults with severe mental illness living in the community are examined in this article. Measures included socioeconomic indexes, symptoms, diagnoses, and adjustment. As expected, socioeconomic and illness factors were interrelated in this sample. Diagnosis was related to both functioning and socioeconomic factors. As a rule, participants were financially impoverished but socially integrated into social networks consisting largely of kin. In spite of impoverishment and presence of significant symptoms, most were maintaining themselves in the community with at least marginal functioning, though they received very little support from the mental health system beyond medication. Compared with the younger cohort, the older cohort was functioning better, had fewer symptoms, and had better global adjustment. Those with coexisting psychotic and affective syndromes were most at risk. Future analyses with this data set will need to develop complex multivariate models to predict the primary influences on functioning and short-term stability.

Adult↗
PubMed1994

Impact of psychological and physical health, stressful events, and social support on subsequent mental health help seeking among older adults.

Factors that influence mental health help seeking among adults 55+ years were examined prospectively. A discriminant analysis significantly differentiated between 120 older adults needing and seeking services and a comparison group of 120 older adults not needing services. Prior to having sought help, help seekers demonstrated poorer psychological well-being, reported more physical health problems, reported a higher level of unpleasant stressful events, and perceived greater deficits in the amount of social support available to them in time of need. The vast majority of these older help seekers sought help for their mental health problems from a medical doctor rather than from a mental health center or clinic or from a minister. Significantly more help seekers than nonseekers experienced stressful events involving bereavement, social and economic loss, and new physical illness.

Activities of Daily Living↗
PubMed1994

Service providers in the social networks of clients with severe mental illness.

The social networks of 27 severely mentally ill (SMI) clients of two community mental health centers were compared with those of 19 clients who had less severe disorders. The networks of the SMI clients were smaller and less reciprocal and contained fewer family members. SMI clients' networks were also more likely to include social service providers, such as group home staff and caseworkers. These social service providers gave direct advice and medical, food, and financial assistance in addition to emotional support, but the relationships were nonreciprocal. Clients with the fewest indigenous supports had the most social service links. These findings suggest that mental health services for SMI persons may provide substitute social supports that serve a broader function than more traditional emotional therapy.

Adult↗
PubMed1992

Functional versus structural social support, desirable events, and positive affect in older adults.

The independent contributions of structural social support versus functional support to positive affect in older adults were compared in this prospective design. Four social support models were translated from the stress-symptoms literature into promotional models for positive mental health and for relationships to desirable challenge events. A total of 1,031 older adults were interviewed 5 times at 6-month intervals, and events were measured across the middle 18-month period. The 2 support variables made quite different contributions. Functional support was directly related to positive affect 2 years later, independent of events; structural support had more transitory direct effects. Structural support, but not functional support, was related to the subsequent occurrence of challenge events and in turn was strengthened by challenge events, suggesting a dynamic interplay between the social network and desirable events.

Adaptation, Psychological↗
PubMed1991

Differential social support and life change as contributors to the social class-distress relationship in older adults.

Four hypotheses previously put forth to explain the strong association between social class and mental health in the general population were examined in 1,326 older adults (55 years and older). Respondents were interviewed 3 times at 6-month intervals. Lower class was associated with more past life changes (occurring before Wave 1) and more subsequent life events (occurring between Waves 1 and 3); these changes were predictive of distress, supporting the differential exposure hypothesis. Lower class was associated with weaker social support (embeddedness), which was related to distress, supporting the resource deterrent hypothesis. There was little evidence that people of the lower classes were more vulnerable to stress or that their status was due to their weaker social support; thus, the differential vulnerability and applied buffering hypotheses were not consistently supported. Social support does appear to be a versatile resource for older adults. A significant portion of the class-distress relationship was not accounted for by life change, social support, or the interaction between these factors.

Adaptation, Psychological↗
PubMed1991

Protective functions of health and self-esteem against depression in older adults facing illness or bereavement.

Four functions were examined by which health and self-esteem could ward off depression over time in older adults. Adults (N = 1,074)--55 years and older--were interviewed 5 times at 6-month intervals. Demographic and prevent depression controls were included. Neither health nor self-esteem served as an interactive buffer. Both had direct negative effects on depression, independent of events, over 2 years. Neither illnesses nor bereavements had direct effects on depression; both had indirect effects through other events; illness also had indirect effects by weakening health. Health had stronger preventive effect on illnesses but was more vulnerable to undesirable events than was self-esteem. There was little support for the specificity hypothesis that a close match between event and resource would increase resource effects.

Adaptation, Psychological↗
PubMed1990

Social support, life events, and stress as modifiers of adjustment to bereavement by older adults.

As part of a larger panel study, interviews were obtained from 3 samples of older adults: 45 persons who had recently lost a spouse, 40 who had lost a parent or child, and 45 who were not bereaved. Assessments were conducted before and after the deaths. In the widowed sample, health remained quite stable, but depression increased sharply, then remained elevated. Changes were minimal in the sample who had lost a parent or child and in the nonbereaved sample. Multiple regression procedures were used to identify factors that contribute to depression and health 9 months after the spouse's death. Postbereavement depression was associated with higher prebereavement depression, higher financial pressures, higher global stress, fewer new interests, and lower social support. Health was a function of prebereavement health, new interests, financial pressures, and global stress. In general, life events and resources had stronger effects in the widowed sample than in the comparison samples.

Adaptation, Psychological↗
PubMed1989

Effects of attachment bereavement and pre-event conditions on subsequent depressive symptoms in older adults.

A sample of 1,411 older adults (age 55+) who had been interviewed both prior to and after bereavement were studied, allowing for pre-event controls. Those who had lost a parent, spouse, or child had the strongest depressive reactions, as predicted by an attachment-bonding hypothesis; however, material losses were also related to depression. Although bereavement/loss events were clearly related to subsequent depression even after pre-event depression, resources, and events were controlled, certain pre-event characteristics were predictive of the bereavement/loss events, including prior undesirable events, age, and urban/rural residency. A further analysis of 1,007 persons with two post-event interviews (at 6-month to 1-year follow-up) revealed an initial depressive reaction to a bereavement/loss event, which then dissipated completely within 1 year's time. Generally, bereavement appeared to have limited etiologic importance.

Adjustment Disorders↗
PubMed1988

ADP-ribosylation of dinitrogenase reductase from Clostridium pasteurianum prevents its inhibition of nitrogenase from Azotobacter vinelandii.

The effect of ADP-ribosylation of dinitrogenase reductase on its binding to dinitrogenase was investigated. Dinitrogenase reductase from Clostridium pasteurianum (Cp2) was a substrate for the ADP-ribosyltransferase and the dinitrogenase-reductase-activating glycohydrolase from Rhodospirillum rubrum. ADP-ribosylation inactivated Cp2 and prevented its formation of a tight complex with dinitrogenase from Azotobacter vinelandii (Av1). The complex between Cp2 and Av1 could not be ADP-ribosylated once it formed.

Adenosine Diphosphate Ribose↗
PubMed1988

Prior experience as a moderator of disaster impact on anxiety symptoms in older adults.

As participants in a panel study, 234 older adults were interviewed before, as well as after, serious flooding occurred in southeastern Kentucky. Floods are not uncommon in this area, but these were more widespread than most, and resulted in both previously exposed and newly exposed subsamples of disaster victims. Flood impact was measured at both personal and community levels. With preflood symptoms controlled, there were modest flood effects on both trait anxiety and weather-specific distress in older adults without prior flood experience, but no flood effects in older adults who had been in floods before. Thus, the study provides support for the "inoculation hypothesis" and other conceptualizations that emphasize the advantage of being familiar or experienced with a stressor that is at hand. An implication is that "experienced" victims could be a valuable resource in prevention efforts.

Aged↗
PubMed1988

Effects of bereavement/loss and pre-event status on subsequent physical health in older adults.

Males and females aged fifty-five and older were interviewed before and after three types of bereavement/loss: attachment bereavement (child, spouse, parent), nonattachment bereavement (sibling, grandchild, close friend), and other losses (nonbereavements). Five measures of health were used. Before pre-event health was accounted for on self-report measures of health status and medical conditions, pre-event measures of environmental factors and impact measures of bereavement/loss events had significant but modest effects on post-event health. However, after pre-event health was taken into account, the effects of bereavement and other losses were pale in comparison. Bereavement/loss events were not related to subsequent deaths, health events, or the use of medical services. Environmental factors were modestly predictive of nonattachment bereavements and other losses. An unexpected finding was that other losses had stronger effects on health than bereavements. Trend analysis over eighteen months showed a modest decline in health status immediately after a loss event, followed by an improvement in health. In general, this older adult sample handled bereavements and other losses with minimal morbidity and mortality.

Aged↗
PubMed1987

Older adult family stress and adaptation before and after bereavement.

As a part of a larger study, interviews were obtained from 63 older adults who had experienced the death of a spouse, parent, or child, and from 387 older adults who had not been bereaved. Three interviews were conducted before the death, one after. The study found that: (a) Bereavement itself did not affect health; (b) family stress increased as the time of death approached but diminished thereafter; (c) before the death, family stress was associated with worsening health; (d) after the death, health worsened if there had been no family stress preceding the death, but otherwise it improved; (e) after the death, however, psychological distress increased sharply, regardless of the level of prebereavement stress. Implications of the study for conceptualizations of grief and for understanding the life experiences of older adults are discussed.

Adaptation, Psychological↗
PubMed1986

Studies on the activating enzyme for iron protein of nitrogenase from Rhodospirillum rubrum.

Removal of ADP-ribose from the iron protein of nitrogenase by activating enzyme resulted in the activation of the inactive iron protein. A radioassay that directly measured the initial velocity of the activation was developed using iron protein radiolabeled with either [8-3H]- or [G-32P]ADP-ribose. The release of radiolabeled ADP-ribose by activating enzyme was linearly correlated with the increase in the specific activity of the iron protein as measured by acetylene reduction. Both ATP and MnCl2 were required for the activation of inactive iron protein. The optimal ratio of [MnCl2]/[ATP] in the radioassay was 2:1, and the optimal concentrations were 4 mM and 2 mM for [MnCl2] and [ATP], respectively. The Km for inactive iron protein was 74 microM and the Vmax was 628 pmol of [32P] ADP-ribose released min-1 microgram of activating enzyme-1. Adenosine, cytidine, guanosine, or uridine mono-, di-, or triphosphates did not substitute for ATP in the activation of native iron protein. Activating enzyme removed ADP-ribose from oxygen-denatured iron protein in the absence of ATP. ADP, ADP-ribose, pyrophosphate, and high concentrations of NaCl inhibited activating enzyme activity.

Adenosine Diphosphate Ribose↗