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Biomedical subjects

R B Wallace

Publications and source records attributed to R B Wallace.

At least 109 records · Page 6Linked to original sources
PubMed1994

Assessing the health of individuals and populations in surveys of the elderly: some concepts and approaches.

Most health survey research in devoted to assessing the health of individuals in a defined population. Various measures include the prevalence and incidence of diseases, signs and symptoms, functional states, and use of health services. However, assessing individual biologic robustness can be problematic, and some suggestions for testable approaches are offered. Additionally, there are characteristics of the health of populations or communities, not referent to individual constituents, that have been underutilized. These include measures of the physical, social, and health service environment.

Activities of Daily Living↗
PubMed1994

Desmopressin acetate in cardiac surgery: a double-blind, randomized study.

Use of desmopressin acetate (DDAVP) for patients having cardiac surgery is controversial. We did a double-blind, randomized study of 83 patients having cardiac operations at Georgetown University Hospital. The effect of DDAVP on bleeding as compared to placebo was evaluated by blood loss, replacement volume, and laboratory tests. There were no significant differences in baseline and intraoperative data between the DDAVP (n = 40) and placebo (n = 43) groups. Total drainage for the first 24 postoperative hours was 1,214 mL (+/- 78) for the DDAVP group and 1,386 mL (+/- 116) for the placebo group (not significant). There were no significant differences in replacement therapy. In this study, administration of DDAVP did not decrease bleeding.

Blood Loss, Surgical↗
PubMed1994

Association of visual impairment with mobility and physical function.

OBJECTIVE: To examine the association of distant vision and physical function in the population of older adults. DESIGN: Cross-sectional and cohort study. PARTICIPANTS: 5143 older residents of three communities (Established Populations for the Epidemiologic Studies of the Elderly) who were interviewed in 1988-89, including residents of two communities who were re-interviewed 15 months later (n = 3133, 97% of those eligible). MEASURES: Visual acuity screening, self-reported activities of daily living and mobility, and objective physical performance measures of balance, walking, and rising from a chair. RESULTS: Limitations in mobility, activities of daily living, and physical performance were associated with worse visual function. In prospective analyses controlling for potential confounders, participants with severe visual impairment had 3-fold higher odds of incident mobility and activity of daily living limitations than those with acuity of 20/40 or better (P < 0.001). In prospective analyses investigating the relationship of vision with improvement in function, those with poor vision were about half as likely to improve as those with better acuity, but this relationship was only statistically significant for improvement in mobility limitations. CONCLUSIONS: Distant visual function appears to play an important role in physical function, particularly for mobility. An intervention to improve vision in at-risk elders might preserve function and prevent disability; this warrants further investigation.

Activities of Daily Living↗
PubMed1994

Use of laxative medication in older persons and associations with low serum albumin.

OBJECTIVE: To study laxative use among older persons and the association of laxative intake with hypoalbuminemia. DESIGN: Cross-sectional study in a population-based cohort. SETTING: Community and institutions in the Iowa and Washington counties, Iowa site of the Established Populations for Epidemiologic Studies of the Elderly. PARTICIPANTS: Persons aged 71 years or older, who were interviewed at the 6th year of follow-up and for whom drug intake information was obtained (n = 2,529). MAIN OUTCOME MEASURES: Laxative medication use and prevalence of hypoalbuminemia. RESULTS: The prevalence rate of laxative use was 8.8% in the community and 74.6% in nursing homes. Increasing age was independently associated with laxative use (odds ratio [OR] = 1.66, 95% confidence interval [CI] = 1.33 to 2.07 for a 10-year increase), after adjusting for gender, institutionalization, disability in activities of daily living, body mass index, and use of the following drugs: furosemide, benzodiazepines, antidepressants, codeine, and calcium antagonists. Laxative use was independently associated with hypoalbuminemia (OR = 3.17, 95% CI = 1.42 to 7.08) after adjusting for age, gender, anemia, number of comorbid conditions, disability in activities of daily living, body mass index, use of furosemide, and institutionalization status. Compared with those who never used laxatives, those who took laxatives only at the 6th year of follow-up were at increased risk of hypoalbuminemia (OR = 2.65, 95% CI = 1.04 to 6.77), and those who used laxatives at both the 3rd and 6th years of follow-up were at greatest risk (OR = 4.02, 95% CI = 1.53 to 10.06). CONCLUSION: Laxatives are used by large numbers of older persons, and the investigation on unknown adverse effects is important. Prospective studies are needed to confirm the association of laxative use with hypoalbuminemia found in this study and to assess the mechanisms of this association.

Activities of Daily Living↗
PubMed1994

Disability and severe gastrointestinal hemorrhage. A prospective study of community-dwelling older persons.

OBJECTIVE: To describe the occurrence of severe gastrointestinal bleeding in community-dwelling older persons and to examine whether disability is a risk factor for this life-threatening condition independent of other known predictors. DESIGN: Prospective cohort survey. SETTING: Three communities of the Established Populations for Epidemiologic Studies of the Elderly (EPESE). PARTICIPANTS: 8205 persons age > or = 68 years. MEASUREMENTS: The hospital discharge diagnoses provided by the Medicare Provider Analysis and Review files and the death certificates were prospectively surveyed for 3 years. Those with at least 1 discharge diagnosis of gastrointestinal bleeding and who received a blood transfusion or died were identified as cases of severe gastrointestinal hemorrhage. Physical disability, cognitive function, smoking and alcohol intake habits, body mass index, blood pressure, chronic conditions, number of hospital admissions in past year and medications taken were assessed at baseline. RESULTS: The occurrence rate of severe gastrointestinal bleeding was 10.8 per 1000 person-years (241 events/22,277 person-years). In proportional hazards regression models, compared with no disability, > or = 1 disabilities in the Rosow-Breslau scale (RR = 2.1, 95% CI = 1.5-2.9), and > or = 1 ADLs limitations (RR = 3.1, 95% CI = 2.1-4.6) independently predicted gastrointestinal hemorrhage after adjusting for age, gender, body mass index, comorbidity, number of hospital admissions, blood pressure, intake of coumarin, corticosteroids, aspirin and other nonsteroidal anti-inflammatory drugs. CONCLUSIONS: In this prospective analysis, disability is an independent predictor of gastrointestinal hemorrhage. Further studies are needed to explain the mechanisms by which disability may cause gastrointestinal hemorrhage. Because physical disability is potentially modifiable, strategies to lower the risk of gastrointestinal bleeding should be evaluated.

Aged↗
PubMed1994

Pulmonary hydraulic impedance responses to hypoxia and hypercapnia in newborn pigs.

The purpose of this study was to determine the cumulative effects of brief intervals of hypoxia and hypercapnia on the pulsatile characteristics of the pulmonary arterial circulation of 48-h-old compared with 2-wk-old open-chest Yorkshire pigs while using two different anesthetic regimens: 1) azaperone and ketamine (4 and 12 mg/kg im, respectively) and 2) thiopental sodium (25 mg/kg i.v.). Animals 48 h old were randomly allocated to undergo mild hypoxia (inspired O2 fraction = 0.15), severe hypoxia (inspired O2 fraction = 0.05), or hypercapnia (inspired CO2 fraction = 0.20), whereas animals 2 wk old underwent severe hypoxia or hypercapnia. With use of Fourier analysis, characteristic impedance (Zo), mean input impedance (Zm), impedance moduli, and phase angles were determined. In 48-h-old pigs anesthetized with azaperone-ketamine, neither mild nor severe hypoxia altered Zo, Zm, or pulmonary vascular resistance (PVR), whereas hypercapnia increased Zo by 22% (P < 0.001), which persisted despite a return to normocapnia. In 48-h-old animals anesthetized with thiopental, baseline control Zo and Zm were lower than those in same-age pigs anesthetized with azaperone-ketamine. In thiopental-anesthetized 48-h-old pigs, both severe hypoxia and hypercapnia increased Zm and PVR but Zo was unaltered. In 2-wk-old pigs anesthetized with thiopental, severe hypoxia but not hypercapnia elevated Zm and PVR, whereas Zo was not changed with either stress. Results indicate age- and anesthetic-dependent responses of Zo, Zm, and PVR to severe hypoxia and hypercapnia. The persistent elevation in Zo caused by hypercapnia indicates a prolonged decrease in arterial compliance or a reduction in effective proximal pulmonary arterial radius.

Airway Resistance↗
PubMed1994

Type II diabetes and cognitive function. A population-based study of Native Americans.

OBJECTIVE: To explore the relationship between type II diabetes and cognitive function in older Native Americans and to assess the effects of other selected risk factors for cognitive dysfunction on this relationship. RESEARCH DESIGN AND METHODS: Cognitive function was assessed in 80 diabetic and 81 nondiabetic Native Americans who were 45-76 years of age in a cross-sectional population-based sub-study of the Strong Heart Study. Thirteen cognitive function tests were administered during a personal interview. Information about six other risk factors for cognitive dysfunction, including depressive symptoms, physical function, alcoholism, current alcohol use, hypertension, and myocardial infarction, was ascertained from interviews and from abstraction of medical records. RESULTS: Diabetes was associated with impairment on only two tests of cognitive function: verbal fluency (P = 0.004) and similarities (P = 0.010). Depressive symptoms were related to verbal fluency (P = 0.004), but did not explain the diabetes-related difference in performance. The effects of hypertension, depressive symptoms, and current alcohol use explained the diabetes-related performance difference on similarities. Cognitive function was not related to metabolic control (HbA1c level). CONCLUSIONS: We found little evidence that type II diabetes in this population of Native Americans is associated with decrement in cognitive function. Some of the cognitive impairment previously attributed to diabetes may be related, at least in part, to the influence of other risk factors. This should be considered in the design of future studies in other populations.

Aged↗
PubMed1993

Transfusion history and cancer risk in older women.

OBJECTIVE: To test the hypothesis that history of blood transfusion is associated with an increased incidence of cancer in older women. DESIGN: Prospective cohort study. SETTING: General community in the state of Iowa. PARTICIPANTS: Random sample of 37,337 cancer-free Iowa women ages 55 to 69 years. MEASUREMENTS: Transfusion history was assessed with a mailed questionnaire completed in January 1986. Cancer incidence in 5 years was ascertained by a population-based cancer registry. RESULTS: Women who had ever received a blood transfusion were at an increased risk for non-Hodgkin lymphoma (relative risk (RR) = 2.20; 95% CI, 1.35 to 3.58) and kidney cancer (RR = 2.53; CI, 1.34 to 4.78). The relative risks for these cancers were greater with decreasing time from first transfusion. No increased risk occurred for cancers of the breast, lung, uterine corpus, ovary, pancreas, colon, rectum, skin (melanoma), or for all cancers considered together. CONCLUSION: These findings suggest that previous blood transfusion may be a risk factor for non-Hodgkin lymphoma and kidney cancer but is not associated with the most common neoplasms.

Age Factors↗
PubMed1993

Maintaining mobility in late life. I. Demographic characteristics and chronic conditions.

To assess the role of demographic factors and chronic conditions in maintaining mobility in older persons, this study utilized longitudinal data collected as part of the Established Populations for Epidemiologic Studies of the Elderly between 1981 and 1987 on 6,981 men and women aged 65 years and older in East Boston, Massachusetts; Iowa and Washington counties, Iowa; and New Haven, Connecticut. Results are presented for those who at baseline reported intact mobility, defined as the ability to climb stairs and walk a half mile without help, and who were followed annually for up to 4 years for changes in mobility status. Age, income, education, and chronic conditions present at baseline and occurring during follow-up were evaluated for their association with loss of mobility. Over the follow-up period, 55.1% of subjects maintained mobility, 36.2% lost mobility, and 8.7% died without evidence of mobility loss prior to death. In both men and women, increasing age and lower income levels were associated with increased risk of losing mobility, even after controlling for the presence of chronic conditions at baseline. After adjustment for age, income, and chronic conditions, lower education levels were a significant risk factor for mobility loss in men, but not in women. Baseline reports of previous heart attack, stroke, high blood pressure, diabetes, dyspnea, and exertional leg pain were associated with small but significant risks for mobility loss. There was a stepwise increase in the risk of mobility loss according to the number of chronic conditions present at baseline that was very consistent between men and women. The occurrence during the study of a new heart attack, stroke, cancer, or hip fracture was associated with a substantially greater risk of mobility loss than was associated with the presence of these conditions at baseline.

Activities of Daily Living↗
PubMed1993

Maintaining mobility in late life. II. Smoking, alcohol consumption, physical activity, and body mass index.

While positive health behaviors have been shown to extend life, their association with extending active life has not been well investigated. In this report, several health behaviors were investigated in relation to maintaining mobility during 4 years of follow-up among 6,981 men and women aged 65 years and older with intact mobility at baseline between 1981 and 1983 who lived in one of three communities: East Boston, Massachusetts; Iowa and Washington counties, Iowa; and New Haven, Connecticut. Intact mobility, defined as the ability to climb up and down stairs and walk a half mile, was determined annually by interview, and study subjects were classified into one of three categories at the end of 4 years of follow-up: 1) maintained mobility (55.1%); 2) lost mobility (36.2%); or 3) died without evidence of having lost mobility prior to death (8.7%). After adjustment for age and all of the health behaviors, risk of losing mobility was significantly associated with current smoking, not consuming alcohol compared with small-to-moderate amounts of alcohol consumption, high (> 80th percentile) compared with moderate (21-80th percentiles) body mass index, and low physical activity levels in both men and women. These findings suggest that positive health behaviors can not only extend longevity but also reduce the risk of losing mobility and independence in later life.

Activities of Daily Living↗
PubMed1993

Predictors of decline in social relationships in the rural elderly.

Prospective evidence for predictors of decline in social relationships over a 3-year follow-up period in an elderly cohort are presented. The cohort consisted of men (n = 903) and women (n = 1,673) over age 65 years in two rural Iowa counties who were interviewed in 1982 and again in 1985. Three separate measures of social relationships were dichotomized into lower and higher levels and included the number of close friends and relatives (less than three vs. three or more), church attendance (less than once per month or not at all vs. once per month or more), and membership in a group (nonmember vs. member). Those with higher social relationship levels at both interviews were compared with those who had higher levels at baseline but lower levels at follow-up (i.e., a decline in social relationship level) using logistic regression. In multivariate analysis, important baseline predictors of decline in social relationship levels included greater age, lower educational level, lower memory test score, the presence of physical disabilities, and a higher level of depressive symptoms. Marital status and lower self-perceived health status were less consistent predictors, and having any living children, history of major illness, and continence status were generally not important predictors of decline in social relationship levels. These findings underscore the multifactorial and complex influences on changes in social relationships, but they also identify factors for possible prevention and intervention strategies.

Aged↗
PubMed1993

Characterization of a new allele of the human ERBB2 gene by allele-specific competition hybridization.

Nucleotide sequence analysis of the ERBB2 proton-oncogene in human breast tumors revealed a sequence variation at codons 654 and 655, corresponding to the transmembrane region of the protein. To investigate this polymorphism, genotyping of 340 unrelated individuals was conducted by allele-specific oligonucleotide (ASO) hybridization of DNA amplified from the ERBB2 transmembrane region. ASO hybridization under competition conditions allowed rapid and unambiguous assignment of alleles and revealed the occurrence of a new allele, B3, encoding Val-Val. The sensitivity and the specificity of the ASO competition hybridization technique indicate that the method is generally applicable to the analysis of polymorphisms in the human genome.

Alleles↗
PubMed1993

Body size, estrogen use and thiazide diuretic use affect 5-year radial bone loss in postmenopausal women.

Understanding factors associated with more rapid bone mineral loss among aging women is important for establishing preventive strategies for intervention. This study reports factors associated with the 5-year change in radial bone mineral density (BMD) determined prospectively in 435 women aged 55-80 years at baseline. The baseline study included measurement of radial BMD (gm/cm2) by single photon densitometry and personal interview. The baseline protocol was replicated 5 years later in a follow-up study. Women with a lower baseline weight or Quetelet index, smaller triceps skinfold and less arm muscle area had significantly greater 5-year bone loss (p = 0.001). Current users of estrogens had less radial bone loss (2.8% vs 7.3%, p = 0.0005) than women not currently using estrogens. Current users of estrogen had significantly less 5-year loss if use had been for 5 years or longer (-1.0% vs -6.9%, p = 0.05). Current users of the thiazide class of medications had less 5-year radial bone loss (5.0% vs 7.4%, p = 0.0035) than women without current thiazide use. Baseline dietary calcium, alcohol consumption and smoking were not associated with BMD change. This suggests that greater body size, and current use of estrogens or thiazide antihypertensives are associated with less radial bone mass loss in a 5-year period among postmenopausal women.

Absorptiometry, Photon↗
PubMed1993

Established populations for epidemiologic studies of the elderly: study design and methodology.

A project initiated by the intramural Epidemiology, Demography and Biometry Program of the National Institute on Aging, entitled "Established Populations for Epidemiologic Studies of the Elderly" (EPESE), has developed information on death, chronic conditions, disabilities, and institutionalization for representative samples of elderly people living in communities. The EPESE consists of prospective epidemiologic studies of approximately 14,000 persons 65 years of age and older in four different communities: East Boston, Massachusetts; two rural counties in Iowa; New Haven, Connecticut; and segments of five counties in the north-central Piedmont area of North Carolina. The study design includes an initial baseline household interview followed by continued surveillance of morbidity and mortality. Participants are re-contacted annually in conjunction with the collection of data on cause of death and factors related to hospitalization and nursing home admissions. Concurrently, the investigators developed substudies focused on specific problems of the elderly. The value of this research lies in the longitudinal design which allows for analyses aimed at identifying risk factors of diseases, disabilities, hospitalizations, institutionalization, and mortality.

Aged↗
PubMed1993

Long-term follow-up and resection of a postoperative false aortic aneurysm.

This report describes the course and operative findings in a 66-year-old man with a densely calcified false aneurysm of his ascending aorta 19 years after replacement of a severely stenosed bicuspid aortic valve with a McGovern-Chromie prosthesis. This report emphasizes the need to consider this possibility, even in patients with a very remote prior operation.

Aneurysm, False↗
PubMed1993

Human cryopreserved homografts: electron microscopic analysis of cellular injury.

Twenty-five human cryopreserved valves with harvest-related warm ischemic times (WITs) ranging from 0 to 20 hours were studied using transmission electron microscopy to characterize the effects of harvesting and preservation on leaflet matrix cells. The valves were divided into seven groups on the basis of WIT and processed using standard transmission electron microscopic methods. Each cell (528 micrographs) was graded for reversible and irreversible cellular injury and subjected to a Cochran-Mantel-Haenszel trend analysis. Our results demonstrated a progression in cellular injury with increasing WIT. During the first 12 hours of warm ischemia, reversible cellular injury predominated (0.0%, 30.0%, 51.2%, 31.3%, 35.1%, 45.1%, and 40.0% at WITs of 0, 1, 2, 8, 12, 16, and 20 hours, respectively). A positive correlation (p < 0.0001) between increasing WIT and reversible cellular injury through the first 12 hours was observed. Minimal morphologic evidence of irreversible injury was noted in valves harvested with less than 12 hours of warm ischemia; however, after 12 hours there was a marked increase (0.0%, 0.0%, 4.7%, 2.4%, 2.7%, 31.4%, and 40.0% at WITs of 0, 1, 2, 8, 12, 16, and 20 hours, respectively) in irreversible cellular injury (p < 0.001 between 12 and 20 hours WIT). These data demonstrate a progression in cellular injury with increasing WIT. There was virtually no morphologic injury in valves with harvest-related WITs less than 2 hours and minimal irreversible cellular injury observed in valves exposed to 12 hours or less of warm ischemia. If cellular viability is critical to homograft durability then harvest-related warm ischemia may need to be restricted to 12 hours.

Aortic Valve↗
PubMed1993

Reduction of conjugated dienes in lung transplantation: effect of BN 52021.

Oxygen-derived free radicals have been identified as the mediators of tissue injury during reperfusion in organ transplantation. Lipid peroxidation of cell membrane polyunsaturated fatty acids, generating conjugated dienes (CD), is a toxicity of oxygen-derived free radicals. The CD structure in fatty acyl moieties was measured by high-pressure liquid chromatography in samples of inferior pulmonary venous blood and pulmonary tissue to assess reperfusion injury and oxygen-derived free radical-mediated damage in a canine model of left lung allotransplantation. The cold ischemic preservation interval was 6 hours and the posttransplantation monitoring period was 6 hours. Twenty-eight size- and weight-matched adult male dogs underwent left lung allotransplantation and were randomized to receive pulmonary artery flush of modified Euro-Collins (EC) (40 mL/kg) or University of Wisconsin (UW) (40 mL/kg) solutions alone or with the addition of the platelet-activating factor antagonist BN 52021 (10 mg/kg). When employed, BN 52021 was administered to donors 30 minutes before harvest and recipients 30 minutes before reperfusion. Left and right inferior pulmonary venous blood samples were obtained at baseline before transplantation and at 1, 2, 4, and 6 hours after transplantation; tissue samples were obtained after euthanasia. Serum and tissue CD levels are expressed as mean fraction of the total hydroperoxide sample +/- standard error of the mean. At 6 hours after transplantation, the EC group's (n = 7) CD fraction was 0.28 +/- 0.03, whereas that of the EC + BN 52021 group (n = 7) was 0.12 +/- 0.03 (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗