PubMed Health⌕ Search

Biomedical subjects

M J Powers

Publications and source records attributed to M J Powers.

At least 19 recordsLinked to original sources
PubMed2001

Regulation of parasympathetic neurons by mast cells and histamine in the guinea pig heart.

The potential interaction between the immune system and the autonomic nervous system was examined in the cardiac ganglia of guinea pigs. Intracellular voltage recordings were used to determine the effects of mast cell degranulation on the membrane properties of parasympathetic neurons in animals actively sensitized to ovalbumin. Stimulation of mast cell degranulation by perfusion with ovalbumin (10 micrograms/ml) produced a depolarization and increase in the excitability of intracardiac neurons. These effects could be mimicked by histamine application, either by perfusion (10 microM) or by local pressure application (100 microM, 1-2 s application). In either case, histamine application resulted in a similar membrane depolarization and increase in excitability. Immunohistochemical experiments demonstrated that histamine-immunoreactive mast cells are located in close proximity to parasympathetic postganglionic neurons. The histamine response was not due to release of other neurotransmitters from adjacent nerve terminals and both the depolarization and increase in excitability were inhibited by the H1 antagonist, pyrilamine (300 nM), and were unaffected by the H2 antagonist cimetidine (5 microM). Incubation of cardiac ganglion preparations from sensitized animals with pyrilamine prior to ovalbumin perfusion resulted in the inhibition of both the depolarization and increase in excitability. These results demonstrate that mast cell degranulation, and the subsequent release of histamine, results in the stimulation of intracardiac neurons via the activation of H1 receptors. Thus, local inflammatory reactions in the cardiac tissue can lead to the rapid activation of parasympathetic neurons, thereby altering cardiac function.

Action Potentials↗
PubMed1998

Adhesion-guided in vitro morphogenesis in pure and mixed cell cultures.

The ability to understand and control the morphogenesis of mammalian cells is a fundamental objective of cell and developmental biology and tissue engineering research. Numerous processes, both biochemical and biophysical in nature, have been studied in an attempt to elucidate the mechanisms underlying this behavior. We focus here on the contributions of biophysical phenomena to the morphogenetic behavior of pure and mixed cell populations on solid surfaces in vitro. These principles are illustrated using characteristic liver tissue cells as a model system. The studies discussed demonstrate that cell-substratum and cell-cell adhesive forces are critical determinants of the ultimate morphology, cytoarchitecture, and organization achieved by these cells in vitro.

Animals↗
PubMed1997

In vitro organogenesis of liver tissue.

The high metabolic rate of hepatocytes severely limits the mass of cells which can be transplanted without a vascular supply. We are developing an alternative approach in which vascularized tissue is grown ex vivo for anastamosis into the portal vein. Here, we discuss the key design issues for in vitro organogenesis of vascularized hepatic tissue, describe a fabrication approach for making complex degradable polymer scaffolds to organize cells in three dimensions on the scale of hundreds of microns, and demonstrate the feasibility of using these scaffolds for in vitro tissue organization in mixed-cell cultures.

Animals↗
PubMed1993

Quality of life of hemodialysis patients.

The purpose of this study was to assess the quality of life of hemodialysis patients. The sample (n = 349) was selected randomly from the adult, inunit hemodialysis patient population of 90% of the counties of Illinois, with the exception of those dialyzed by the Veterans Administration. The findings indicate that the patients in this study were satisfied with their lives in general. Nevertheless, the results also indicated that continued efforts are needed to improve the health and financial independence of hemodialysis patients.

Adult↗
PubMed1992

Psychometric assessment of the Quality of Life Index.

The purpose of this study was to examine the psychometric properties of the Quality of Life Index (QLI) (Ferrans & Powers, 1985a). The sample consisted of 349 patients selected randomly from the adult, in-unit hemodialysis patient population of Illinois. Factor analysis was used to examine the underlying factor structure. A four-factors solution best fit the data, indicating that there were four dimensions underlying the QLI: health and functioning, socioeconomic, psychological/spiritual, and family. Factor analysis of the four primary factors revealed one higher order factor, representing quality of life. Construct validity also was supported by the contrasted groups approach. As predicted, it was found that those who had higher incomes had significantly higher quality of life scores on the social and economic subscale. Support for convergent validity was provided by a strong correlation (r = .77) between scores from the QLI and an assessment of life satisfaction. Findings supported the internal consistency reliability of the entire QLI (alpha = .93) and the four subscales (alphas = .87, .82, .90, .77).

Adult↗
PubMed1992

Needs of family members of intensive care unit patients.

To identify important needs of families of critically ill patients, and the degree to which these needs were being met, 64 family members and 58 nurses were asked to complete a modified version of the Critical Care Family Needs Inventory (Molter & Leske, 1983). Family members and nurses identified many similar important needs, such as the need to have questions answered honestly, the need to be called at home about changes in the patient's condition, and the need to know why things were done for the patient. However, family members indicated that some needs were both more important and less satisfactorily met than the nurses perceived: the need to know the occupational identity of staff members, directions as to what to do at the patient's bedside, and having friends for support.

Adaptation, Psychological↗
PubMed1988

Litigation.

Explore the source record for details and available documents.

England↗
PubMed1987

Satisfaction with health care of hemodialysis patients.

The purpose of this study was to assess the satisfaction with care of hemodialysis patients, and to explore the relationships between satisfaction with care, quality of life, and background variables. The sample (n = 416) was randomly selected from the adult, in-unit hemodialysis patient population of a north central state. Overall, patients were satisfied with their care (M = 5.04, range = 1 to 6). An ANOVA demonstrated that patients were most satisfied with physician related aspects of care, followed by nursing/dialysis treatment aspects, and least satisfied with financial/transportation aspects (F(2,830) =28.44. p less than .0001). Overall satisfaction with care was most highly correlated with satisfaction with medical (r = .74) and nursing care (r = .74). Satisfaction with care was moderately correlated with quality of life (r = .42) and satisfaction with health and functioning (r = .42). Somewhat weaker relationships were found between satisfaction with care and socioeconomic aspects of life (r = .31), psychological/spiritual aspects (r = .32), and family (r = .27). Patients who had been on dialysis for a shorter length of time or who had less education were more satisfied with care.

Adult↗
PubMed1986

Influence of weather on osteoarthritics.

This exploratory study examined the effects of selected weather variables on pain and pain-related stress in osteoarthritic subjects. Urban and rural dwelling arthritics who perceived that weather made their symptoms worse and those who did not were surveyed. Some persons with osteoarthritis in urban Chicago were more weather sensitive than their rural counterparts in Grand Forks, North Dakota. Multiple regression analysis showed that precipitation affected degree of pain for urban subjects who identified weather as a pain-generating factor; barometric pressure, relative humidity and sunshine were significant factors influencing pain-related stress. Wind speed correlated with pain and pain-related stress; relative humidity and precipitation correlated with pain-related stress for urban subjects who did not perceive weather as a problem. Specific weather variables were not identified as affecting rural subjects' pain. However, temperature and barometric pressure affected degree of pain-related stress in rural subjects who perceived weather as a problem. Subtle differences between Chicago urban and Grand Forks rural climates are reflected in arthritic subjects' degree of pain and their perception of pain-related stress.

Aged↗
PubMed1985

Life satisfaction, health control orientation, and illness-related factors in persons with osteoarthritis.

The purpose of this study was to assess life satisfaction in osteoarthritics and to explore relationships between that variable and health perception, health locus of control, and illness-related factors. The study group consisted of 160 osteoarthritics from four different types of settings. The osteoarthritics rated their present life satisfaction and recent health as relatively good and were externally controlled in terms of their health beliefs. Present life satisfaction was related to better health perception, internal locus of control, and less joint pain.

Adult↗
PubMed1985

Quality of life index: development and psychometric properties.

The purpose of the study on which this article is based was to assess the validity and reliability of an instrument designed to measure quality of life. Sixty-four items applicable to both healthy subjects and dialysis patients were tested with graduate students (n = 88); six items relative to dialysis were added, and the instrument was administered to dialysis patients (n = 37). Items were based on literature review, which supported content validity. Correlations between the instrument and an overall satisfaction with life question of 0.75 (graduate students) and 0.65 (dialysis patients) supported criterion-related validity. Support for reliability was provided by test-retest correlations of 0.87 (graduate students) and 0.81 (dialysis patients) and Cronbach's alphas of 0.93 (graduate students) and 0.90 (dialysis patients).

Adult↗
PubMed1984

Health beliefs, adjustment to illness, and control of hypertension.

Health beliefs influencing compliance and psychosocial adjustment to illness were compared in two groups of hypertensive patients. Based upon clinical judgments of physicians, 15 controlled and 15 uncontrolled hypertensives made up the study group. Subjects came from a white middle to upper class suburban community and were demographically homogeneous. There was no significant difference between groups in health beliefs affecting compliance, but significant differences were found in several domains related to psychosocial adjustment to illness. Uncontrolled hypertensives showed less illness-related adjustment. They reported significantly greater difficulties in their domestic environments, more disturbances in extended family relationships, and more psychological distress. Less adjustment to illness was significantly correlated with less compliance and with a more complex medication regimen. No relationships were found between compliance and demographic variables, medication variables, or duration of hypertension; nor between adjustment, demographic variables, or illness duration. Clinical assessment of illness-related adjustment problems may help enhance compliance of hypertensive patients.

Adaptation, Psychological↗
PubMed1984

Nurse practitioner and physician care compared for nonurgent emergency room patients.

This experimental field study compared knowledge, satisfaction and compliance in 62 nonurgent emergency room (ER) patients based on whether they were cared for by a nurse practitioner (experimental group) or a physician (control). Data were collected via structured interviews in the ER, two weeks later by phone and three months later by phone, mail and chart review. No significant differences were found between groups in overall short- and long-term compliance scores, appointment-keeping scores for the three-month study period, number of health recommendations recalled, resolution of health problem or satisfaction ratings of ER care. It was also found that: referrals were the recommendation least complied with; 60 percent of appointments were kept; frequent reasons for noncompliance were inconvenience and lack of perceived need; experimental subjects showed greater comprehension of diagnostic recommendations and therapeutic applications, while controls had better knowledge of medications; 77 percent of experimentals were completely satisfied with NP care, as compared to only 48 percent of the controls with MD care; and reasons for satisfaction centered on the quality of care, while reasons for dissatisfaction focused on unresolved problems and slow care.

Consumer Behavior↗
PubMed1983

Validation of two experimental nursing approaches using content analysis.

The purpose of this study was to analyze and compare the recorded content of two experimental nursing interventions used in a hypertensive-education program. One intervention was characterized as deliberative or high indirect, the other as task-centered or low indirect. A total of 4,149 nurse-patient interaction units was derived from 62 typed interview transcripts, equally representative of both approaches. Two trained coders categorized the interactions, based upon recurring themes of the teaching content; 24 distinct topical categories were identified. Intercoder agreement above chance for all 4,149 interaction units was k = .68, with confidence limits of 99% +/- .03, p less than .0001. A space-time unit for quantifying the relative amounts of time spent on the various categories also was developed, and analyses were conducted for space-time units as well as interaction units. The main findings showed no definable differences in the frequency of categories or the amounts of time spent in their discussion in the two approaches. These results were contrasted to results obtained when the validity of the nursing approaches was tested previously, and differences between the two interventions in attaining social and health goals were interpreted in light of the findings of the content analysis.

Communication↗