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Biomedical subjects

E W Peterson

Publications and source records attributed to E W Peterson.

At least 19 recordsLinked to original sources
PubMed2001

Developing meaningful Fear of Falling Measures for community dwelling elderly.

OBJECTIVE: The objective of this study is to demonstrate how a Rasch analytic approach can be used to create fear of falling measures that remain connected to the meaningful descriptions provided by the instrument items. DESIGN: The University of Illinois at Chicago Fear of Falling Measure was developed using focus groups and consists of 19 common activities designed to represent an increasing level of concern about falling among older adults. RESULTS: Rasch analysis of responses from 106 community dwelling elderly revealed that the two middle rating scale categories (a little worried and moderately worried) were not being used in the expected fashion. After modification of the rating scale, Rasch analysis showed that the three items causing the least worry (get dressed, get on/off toilet, and get in/out of bed) were statistically erratic. CONCLUSION: Final analysis demonstrated that the remaining 16 items represented a unidimensional construct that, in general, supported the original expected item difficulty hierarchy. Because person and item measures were calibrated on the same linear scale person measures are translatable to item descriptions. This connection provides meaning to the numeric values obtained from the instrument and provides a basis for setting clinically relevant criteria for interventions.

Accidental Falls↗
PubMed1998

Fear of falling and activity restriction: the survey of activities and fear of falling in the elderly (SAFE).

A new instrument was developed to assess the role of fear of falling in activity restriction. The instrument assesses fear of falling during performance of 11 activities, and gathers information about participation in these activities as well as the extent to which fear is a source of activity restriction. The instrument demonstrated good internal consistency reliability and showed convergent validity with other fear of falling measures. Concurrent (empirical) validity was demonstrated in that the scale was effective in differentiating among those who were expected to be afraid vs. not afraid of falling. Criterion validity was examined in relation to quality of life variables. Fear of falling was shown to be related to lower quality of life, even when controlling for related background factors. One advantage of this measure over existing measures is the possibility for differentiating fear of falling that leads to activity restriction from fear of falling that accompanies activity. This may provide useful information for those interested in treating fear of falling of promoting activity among the elderly.

Accidental Falls↗
PubMed1998

Covariates of fear of falling and associated activity curtailment.

With a sample survey (N = 266) of elderly adults residing in six housing developments in Massachusetts, we used logistic regression to: (a) identify covariates of fear of falling among all subjects and (b) identify covariates of activity curtailment among the subset of subjects who were afraid of falling. Fifty-five percent of respondents were afraid of falling; of those who were afraid, 56% had curtailed activity due to this fear. Factors associated with fear of falling were: being female, having had previous falls, and having fewer social contacts. Factors associated with activity curtailment among those who were afraid were: not communicating about falls; having less social support; and knowing someone who had fallen. Falls history appears an important contributor to fear of falling, whereas the impact of this fear on activities appears more a function of social support. These findings suggest different strategies for the primary and secondary prevention of fear of falling.

Accidental Falls↗
PubMed1997

Patients with Alzheimer's disease who cannot perform some motor skills show normal learning of other motor skills.

Previous researchers have claimed that patients with Alzheimer's disease (AD) learn new motor skills normally, although many AD patients cannot perform the tasks and must be eliminated from the analysis. Excluding them assumes that they have a deficit of motor performance (competence to perform the task), but not of motor learning (ability to improve performance). The present study administered 4 motor tasks to 20 AD patients and 20 controls. The results showed that the ability to complete 1 task (performance) did not predict the rate of improvement (learning) on another task, which indicates that AD patients do indeed have a performance deficit and not a general deficit of motor skill learning. Dementia ratings predicted the ability to perform tasks but not the ability to learn them. It is concluded that it is defensible to claim that AD patients learn a motor skill normally, even if some of the patients are unable to perform the task.

Aged↗
PubMed1996

Predicting radon testing among university employees.

To determine covariates of radon testing behavior, we surveyed by mail a random sample of all Boston University employees (N = 915) six to nine months after they had been informed of the availability of radon testing services through the University's medical center. The response rate was 58%. Analysis suggests blue collar workers were underrepresented within the response rate. Slightly more than half of the respondents (51%) were men. The majority (69%) were under the age of 45. Twenty-seven percent of the respondents (N = 143) had tested their homes for radon. Bivariate analysis revealed important differences between radon testers and nontesters. Testers were 12 times more likely to be home owners than renters (p = 0.00), and were more knowledgeable about radon's characteristics and testing procedures (p = 0.00). Testers were more likely to view radon as a serious problem (p = 0.00), to consider radon testing efficacious (p = 0.00), and to consider themselves susceptible to exposure (p = 0.00). Testers were also less likely to perceive barriers to radon testing. We used logistic regression to compare the usefulness of the Health Belief Model and the Diffusion of Innovations Model in predicting radon testing. We concluded that the knowledge deficits and barriers to radon testing identified in this study should be targeted in radon educational interventions.

Behavior↗
PubMed1995

NMR spectroscopy studies of severe hypokalemia in isolated rat hearts.

Effects of acute tissue potassium depletion on cellular energy metabolism are poorly understood. To examine this issue, we performed the following studies in an isovolumic isolated perfused heart preparation. Perfusion of isolated hearts with media lacking potassium (K = 0 mmol/l) for 30 min resulted in ventricular fibrillation, rapid decreases in creatine phosphate (PCr) and ATP, and increases in Pi. During reinstitution of normal perfusate potassium, hearts did not resume normal contractions, and no increases in tissue ATP were observed. However, some normalization of PCr and Pi were noted during reinstitution of normal perfusate. Perfusion with media containing K = 2 mmol/l caused significant but less dramatic decreases in tissue ATP concentrations than perfusion with media containing K = 0 mmol/l. Reduction of perfusate calcium from 1.2 (normal) to 0.6 mmol/l in media containing K = 0 mmol/l attenuated the fall in ATP seen with media containing K = 0 mmol/l. Conversely, increasing perfusate calcium to 2.4 mmol/l in media containing K = 2 mmol/l markedly worsened the fall in tissue ATP seen in media containing K = 2 mmol/l. In this subgroup (K = 2 mmol/l, Ca = 2.4 mmol/l), ventricular fibrillation developed approximately one-half of the time. However, no differences in the rate of ATP fall were observed between those hearts that fibrillated and those that did not. During perfusion with media containing K = 0 mmol/l, nuclear magnetic resonance (NMR)-visible tissue potassium concentrations fell rapidly and dramatically. Significant but less severe reductions in NMR-visible potassium were seen during perfusion with media containing K = 2 mmol/l. With K = 2 mmol/l perfusate, the rate of cellular potassium loss was influenced by perfusate calcium concentration. When cardiac mitochondria were examined after perfusion with media containing K = 0 mmol/l, evidence for calcium loading as well as respiratory dysfunction was noted. These data indicate that reductions in perfusate potassium caused dramatic reductions in tissue ATP and NMR-visible potassium concentrations. The abnormal energy metabolism that results from acute cellular potassium depletion appears to be due, at least in part, to impaired energy production by cardiac mitochondria that become calcium loaded.

Acidosis↗
PubMed1993

Fear of falling among the community-dwelling elderly.

To assess the incidence of falls and the prevalence, intensity, and covariates of fear of falling among community-dwelling elderly, the authors surveyed a random sample of 196 residents (> or = 58 years of age) of housing developments for the elderly in Brookline and Plymouth, Massachusetts. Forty-three percent reported having fallen in recent years, 28% in the last year. Of those who had fallen within the year prior to the interview, 65% reported injury, 44% sought medical attention, and 15% required hospitalization as a consequence of their fall(s). Fear of falling ranked first when compared to other common fears (i.e., fear of robbery, financial fears). Self-rated health status and experience of previous falls were significantly associated with fear of falling. Further analysis suggests that fear of falling may affect social interaction, independent of risks for falling.

Accidental Falls↗
PubMed1988

Multiple noncontiguous fractures of the cervical spine.

Multiple noncontiguous fracture-subluxations of the cervical spine are fractures and subluxations separated by at least one normal intervening cervical vertebra. A review of all 66 consecutive cervical spine fractures treated by the Division of Neurosurgery at the University of Ottawa during 26 consecutive months revealed six such cases (9%). These injuries are more common than previously recognized. Special consideration is required in their treatment because of the presence of a mobile intermediate segment in some of these patients.

Accidents, Traffic↗
PubMed1985

Sub-pial infiltration of blood products following experimental subarachnoid haemorrhage.

The authors studied the trans-pial penetration of blood products into the cerebral cortex of cats within the first hour following subarachnoid hemorrhage (SAH). Twenty-two animals were subjected to SAH by cisternal injection of blood, and 13 were used as controls. The brains were fixed in situ and the histological sections were examined under the fluorescence microscope. The cerebral parenchyma of the control animals displayed a homogeneous greenish autofluorescence. In the animals with SAH, the subarachnoid blood showed a yellow autofluorescence that also penetrated into the superficial cortex. The possible clinical implications of the observation are discussed.

Animals↗
PubMed1984

Pituitary apoplexy: a review.

The authors present a critical review of the literature on the hemorrhagic complications of pituitary adenomas, especially those leading to apoplexy. They emphasize the distinction between pituitary apoplexy, hemorrhages leading to sudden endocrine alterations, and asymptomatic hemorrhages. Moreover, they speculate upon the possible pathophysiology of pituitary apoplexy and its predisposing factors. The clinical presentation, natural history, radiological findings, and differential diagnosis are also discussed. Finally, the historical evolution of the treatment of pituitary apoplexy is reviewed, with emphasis on the surgical treatment.

Adenoma↗
PubMed1983

Pituitary apoplexy and vasospasm.

Two cases of pituitary apoplexy complicated by cerebral vasospasm are described. They emphasize the importance of angiography in the investigation of a protracted clinical course after pituitary apoplexy. The pathophysiology of postapoplectic vasospasm is discussed.

Adult↗
PubMed1983

The blood-brain barrier following experimental subarachnoid hemorrhage. Part 1: Response to insult caused by arterial hypertension.

In three groups of cats, the authors studied the effect of subarachnoid hemorrhage (SAH) on the permeability of the blood-brain barrier (BBB) to the penetration of Evans blue-protein complex. One group received arterial hypertension alone, one group SAH alone, and one group SAH followed by arterial hypertension. Animals subjected to arterial hypertension alone showed areas of BBB breakdown. However, when cats were rendered hypertensive after SAH, there were no demonstrable BBB lesions. The SAH was produced by intracisternal injection of whole blood and hypertension by the intravenous injection of metaraminol. The preservation of the BBB after SAH is discussed. Vasospasm is considered as a possible hemodynamic variable responsible for the protection of the BBB from hypertensive damage. The need for a new model is proposed to further investigate the state of the BBB after SAH.

Animals↗
PubMed1983

The blood-brain barrier following experimental subarachnoid hemorrhage. Part 2: Response to mercuric chloride infusion.

Under controlled physiological conditions, fresh blood was injected into the cisterna magna of 10 adult cats to produce subarachnoid hemorrhage (SAH). Damage to the blood-brain barrier (BBB) was induced 30 minutes after SAH by the intracarotid injection of a 6 x 10(-5)M solution of mercuric chloride (HgCl2). A control series of five cats received the same injection of HgCl2. Intravenously injected Evans blue dye was used to indicate areas of BBB damage. The lesions were confirmed by fluorescence microscopy. All control animals showed BBB damage in the hemisphere injected with HgCl2. Of the animals in the test group with SAH, 90% were free from lesions. When lesions were present, the distribution differed from that in the control group. These results bear a similarity to the reported absence of HgCl2 lesions during the acute stages after total cerebral ischemia. This suggests that the cellular components of the BBB participate in a general metabolic inhibition following SAH.

Animals↗
PubMed1981

Mixed-function oxidases of 25-hydroxycholecalciferol in isolated chick kidney glomeruli: evidence for nuclear localization.

Pure chick kidney glomeruli and proximal tubular fragments have been isolated by graded sieving through nylon screens. Electron micrographs revealed that, in distinct contrast to proximal epithelial cells, the glomerular epithelial and endothelial cells are essentially devoid of mitochondria. Glomeruli as well as proximal tubular fragments contain the 1 alpha- and 24R-hydroxylases of 25-hydroxycholecalciferol. The level of 1 alpha-hydroxylase activity was the same in both segments of the nephron. However, the tubular fragments contained twice the 24R-hydroxylase activity found in glomeruli. Glomerular nuclei were purified by sucrose gradient sedimentation and used to confirm the association of the 1 alpha-hydroxylase with this kidney organelle. Almost all of the glomerular 1 alpha-hydroxylase activity was found in the nuclear fraction. Two metabolites, which are produced predominantly by the nuclei, are designated N-1 and N-2. Their structural identity remains unknown. The novel presence of the 1 alpha-hydroxylase in the glomerulus may be important in defining the etiology of bone diseases in patients with glomerulonephritis and similar disorders.

24,25-Dihydroxyvitamin D 3↗
PubMed1976

A theory of the mechanism of cerebral vasospasm and its reversal, the role of calcium and cyclic AMP.

It is proposed that the basic mechanism of vasospasm which sometimes follows subarachnoid hemorrhage is dependent on increased free intracellular calcium ion produced by spasmogens from closely applied extravasated blood. Relaxation of this spasm occurs when the intracellular cyclic AMP levels are raised, resulting in sequestration of calcium ion by the vascular smooth muscle cell sarcoplasmic reticulum.

Blood Platelets↗