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Biomedical subjects

J W Davis

Publications and source records attributed to J W Davis.

At least 73 records · Page 4Linked to original sources
PubMed1997

Medical versus surgical management of diverticulitis in patients under age 40.

BACKGROUND: Diverticulitis in patients under age 40 is a distinct entity. We compared the medical versus surgical management of diverticulitis for complications and outcomes in these patients. METHODS: A retrospective review was performed for treatment, hospitalizations, complications, and outpatient visits. Complications included readmission, recurrent symptoms after antibiotic therapy, and postoperative problems. RESULTS: Twenty-nine patients had a radiographic or surgical diagnosis of diverticulitis (18 surgical, 11 medical). Medically managed patients had significantly more emergency department visits (4.7 +/- 6.6 versus 0.3 +/- 0.6, P < or =0.01), and readmissions (7 versus 4, P < or =0.02). Three surgical patients (17%) had a total of 6 complications as compared with 6 medical patients (55%) with 25 complications (chi square, P < or =0.05). All medically treated patients had recurrent symptoms, and 6 required surgery. CONCLUSION: Medically managed patients had significantly more emergency department visits and complications than those managed surgically. Surgery is the indicated treatment for the first episode of diverticulitis in patients under age 40.

Adult↗
PubMed1997

Left ventricular adaptation to aortic regurgitation in conscious dogs.

OBJECTIVE: Cardiac failure as a result of valvular heart disease remains a major clinical problem that frequently leads to ventricular dysfunction, myocardial failure, and even death. The development of irreversible myocardial damage may be especially insidious in volume overload as a result of aortic or mitral regurgitation. METHODS AND RESULTS: Left ventricular wall volume, ventricular function, and myocardial performance were assessed in 10 chronically instrumented conscious dogs before and after creation of aortic regurgitation. Left ventricular wall volume was measured by serial echocardiography. Left ventricular function was assessed by total cardiac output, stroke work, the slope of the Frank-Starling relationship, and the slope of the end-systolic pressure-volume relationship. Myocardial performance was assessed by the slope of the myocardial power output versus end-diastolic strain relationship. End-diastolic wall stress and volume both increased acutely and remained elevated after creation of aortic regurgitation. Peak systolic wall stress increased initially (1 to 3 weeks) from 336 +/- 30 to 369 +/- 55 mm Hg but returned to control values as left ventricular wall volume increased from 78 +/- 13 to 88 +/- 16 ml after development of compensatory hypertrophy. Left ventricular systolic function remained constant or increased and was maintained initially by increased myocardial performance, which returned to baseline levels after the development of compensatory hypertrophy. CONCLUSIONS: Myocardial performance and ventricular function vary independently in aortic regurgitation. Measures of myocardial performance such as the myocardial power output versus end-diastolic strain relationship may be useful in clinical assessment of aortic regurgitation.

Animals↗
PubMed1997

Incidence rates of falls among Japanese men and women living in Hawaii.

Japanese people in both Japan and in Hawaii have a lower incidence of hip fractures than white people in Hawaii or on the mainland of the United States. Hip fractures usually occur after a fall, and differing incidence rates of falls might contribute to the observed differences in hip fracture rates. To investigate this possibility we undertook a prospective study of falls among elderly Japanese men and women living in Hawaii using intensive surveillance methods similar to those used in studies of predominantly white populations. For our Japanese participants, the incidence rates of total falls were 139 per 1000 person years for men and 276 per 1000 person years for women. Age adjusted rate ratios of falls for predominantly white populations compared with our Japanese participants ranged from 1.8 to 2.3 for women and from 2.6 to 4.7 for men. The risk of injuries when they did fall, however, was not lower for our Japanese participants than reported for white participants. For our Japanese population, past falls, female gender, and daytime hours were associated with an increased incidence of falls.

Accidental Falls↗
PubMed1997

Development and validation of a geriatrics knowledge test for primary care residents.

This study reports the development and preliminary validation of an instrument to measure geriatrics knowledge of primary care residents. A 23-item test was developed using questions selected from the American Geriatrics Society's Geriatrics Review Syllabus. Ninety-six internal medicine and family practice residents, 14 geriatrics fellows, and 11 geriatrics faculty members participated in the study. Findings support the reliability (Cronbach's alpha = 0.66) and validity (content and "known groups") of this short test. Predictive validity and sensitivity of the test to changes in knowledge will have to be further explored as residents progress through their training.

Adult↗
PubMed1997

Effect of alcohol on the utility of base deficit in trauma.

OBJECTIVE: Base deficit (BD) is an indicator of metabolic acidosis and is used as an index of shock and resuscitation for trauma patients. Ethanol causes an increase in lactate production and may cause metabolic acidosis in otherwise normal patients. The effects of alcohol on BD have not been investigated. This study was performed to determine the effects of ethanol on the utility of BD for assessing shock and resuscitation among trauma patients. DESIGN: Retrospective review of trauma registry, blood bank, and medical records data. METHODS: Data were collected for trauma patients admitted to the University Medical Center Level I trauma service from July 1990 through August 1995 with an arterial blood gas and blood alcohol level obtained within 1 hour of admission. MEASUREMENTS AND MAIN RESULTS: The Trauma Score and the Revised Trauma Score were slightly higher (p < 0.001), and the Injury Severity Score was significantly lower (p < 0.001) in the presence of alcohol. These changes were present until patients reached the severe BD category (< or = -10), at which point there were no significant differences across all blood alcohol levels. In spite of these changes, there was no difference in intensive care unit or hospital length of stay in any BD or blood alcohol group. In patients with a BD < or = -6, there was a decreased requirement for transfusion in the presence of alcohol (57 vs. 78%; p < 0.001, chi2), but the majority of patients in both groups required blood transfusion. CONCLUSION: Ethanol can contribute significantly to metabolic acidosis among trauma patients and may confound the utility of BD to some degree. There was no difference in intensive care unit or overall length of stay, however, regardless of ethanol level, and the majority of patients with a BD < or = -6 still required transfusion. Even in the presence of ethanol, a BD < or = -6 remains a powerful indicator of major injury, increased length of stay, and transfusion requirement.

Acidosis↗
PubMed1997

The effects of smoking on bone mass and the rates of bone loss among elderly Japanese-American men.

Bone density and bone loss rates were examined among Japanese-American men categorized as current cigarette smokers, past smokers, and nonsmokers. The design included a retrospective study of smoking and bone density and a prospective study of current smoking and bone loss rates. The mean length of follow-up was 5 years; the setting was the island of Oahu. The subjects included 1303 men in the Hawaii Osteoporosis Study, 51-82 years old at their initial examination. Twenty percent were current smokers, 45% past smokers, and 35% had never smoked. Their bone density was measured at the distal and proximal radius and calcaneus using single photon absorptiometry. Compared with never smokers, current and past smokers had significantly lower bone density, especially in the predominantly cancellous calcaneus (4.8 and 4.3% lower, respectively) and partially trabecular distal radius (1.8 and 3.3% lower, respectively). The magnitude of the smoking effect was linked strongly to the duration of smoking and also to the number of cigarettes smoked. Bone loss rates subsequent to the initial measurement were greater in the current smokers than the never smokers (20.5, 27.2, and 9.7% greater at the calcaneus, distal, and proximal radius, respectively) but the differences did not achieve significance. Smokers of more than one pack per day had 32.0, 77.6, and 30.7% greater loss rates than never smokers in these same sites; the difference achieved significance at the distal radius. The results from the distal radius suggest that these smokers may increase their fracture risk 10-30% per decade of smoking. The adverse effects of smoking appeared to be greater in cancellous than cortical bone.

Aged↗
PubMed1996

Observations on serum uric acid levels and the risk of idiopathic Parkinson's disease.

Uric acid, an antioxidant found in high concentrations in serum and in the brain, has been hypothesized to protect against oxidative damage and cell death in Parkinson's disease. The authors tested this hypothesis among men participating in a 30-year prospective study known as the Honolulu Heart Program. Serum uric acid was measured in 7,968 men at the baseline examination held from 1965 to 1968. Of these men, 92 subsequently developed idiopathic Parkinson's disease (IPD). In analyses adjusted for age and smoking, men with uric acid concentrations above the median at enrollment had a 40% reduction in IPD incidence (rate ratio (RR) = 0.6; 95% confidence interval (CI) 0.4-1.0). Reduced IPD incidence rates persisted in analyses restricted to nonsmokers (RR = 0.5; 95% CI 0.3-1.0) and cases younger than age 75 years (RR = 0.5; 95% CI 0.3-0.9). Incidence rates were not notably affected when analyses were restricted to cases that occurred more than 5 years after uric acid measurement (RR = 0.6; 95% CI 0.4-1.0). Inclusion of known or computed correlates of uric acid in regression models did not substantially change risk of IPD. This study provides prospective evidence of an association between uric acid and reduced occurrence of IPD and indicates that further investigations of this association are warranted.

Aged↗
PubMed1996

Evidence against the operation of selective mortality in explaining the association between cigarette smoking and reduced occurrence of idiopathic Parkinson disease.

To investigate the association between idiopathic Parkinson disease (IPD) and reduced frequency of prior cigarette smoking, the authors compared the 29-year follow-up mortality rates and IPD incidence rates of men who were either cigarette smokers or nonsmokers at the time of enrollment in the Honolulu Heart Study (1965-1968). Based on IPD cases detected up to June 30, 1994, the age-adjusted incidence rate in smokers was less than half that in nonsmokers: 34.4 versus 94.2 cases per 100,000 person-years of pre-illness follow-up, respectively. When data were stratified by 5-year age group, lower IPD incidence in smokers was observed at all ages between 50 and 90 years. Age-specific mortality trends for smokers and nonsmokers with and without IPD suggested that increased mortality in IPD patients was mostly associated with IPD itself and not with smoking. The slight excess mortality in smokers without IPD, versus nonsmokers without IPD, appeared insufficient to account for the "missing" incident IPD cases in smokers. These IPD incidence and mortality data are not highly consistent with the "selective mortality" hypothesis, which attributes reduced prior smoking frequency, typically reported by persons with IPD, to accelerated mortality in undiagnosed IPD-affected persons who smoke. The "protective" association of cigarette smoking with IPD occurrence may thus be real, suggesting the need for further study of biologic mechanisms of protection.

Age Distribution↗
PubMed1996

Postdischarge geriatric assessment of hospitalized frail elderly patients.

BACKGROUND: The diffusion of comprehensive geriatric assessment services has been rather limited in North America partly because of reimbursement and organizational constraints. OBJECTIVE: To evaluate the impact of a comprehensive geriatric assessment intervention for frail older patients that is started before hospital discharge and is continued at home. METHODS: Patients older than 65 years were selected who had either unstable medical problems, recent functional limitations, or potentially reversible geriatric clinical problems. Patients (n = 354) were randomly assigned to either the intervention group or a control group. Information on survival, readmissions, nursing home placement, medication use, and health status was collected at 30 and 60 days after hospital discharge. RESULTS: No differences were observed between the two treatment groups in survival, hospital readmission, or nursing home placement by 60 days. After adjustment for baseline characteristics, no significant differences were observed between the two groups on measures of physical functioning, social functioning, role limitations, health perceptions, pain, mental health, energy and/or fatigue, health change, or overall well-being. CONCLUSIONS: Although efficacy has been demonstrated for some forms of comprehensive geriatric assessment, the types of services that are easier to establish (inpatient consultation services and ambulatory assessment) have not been shown to improve outcomes. Our results indicate that outcomes are unaffected by a limited form of comprehensive geriatric assessment begun in the hospital and completed at home. Further efforts are needed to develop and to evaluate realistic approaches to comprehensive geriatric assessment.

Aged↗
PubMed1996

Contributions of vertebral fractures to stature loss among elderly Japanese-American women in Hawaii.

Loss of stature is a typical feature of osteoporosis and associated vertebral fractures. However, there have been few prospective population-based studies to estimate the magnitude of this association. Further, the separate contributions of different types of vertebral fractures to stature loss have not been evaluated using prospective data. In this study we investigated the extent to which stature loss could be explained by the number of different types of vertebral fractures (wedge, endplate, and crush fractures) after adjusting for other covariates. Longitudinal data on stature loss and vertebral fractures were collected among 504 postmenopausal Japanese-American women living in Hawaii with mean age 73.4 (SD 4.9) years. During an average of 7.7 years of follow-up, women with at least one incident vertebral fracture had an average of 2.1 cm of stature loss while the average stature loss among those without incident fractures was only 0.4 cm. The mean rate of stature loss was very slight (< 1 mm/year) for those without incident vertebral fractures even after age 80. Our analyses suggest that both the number of wedge and the number of crush fractures are strong predictors of stature loss. After adjusting for age and total height loss in the anterior dimension over T3-L5, the estimated stature loss resulting from each wedge and crush fracture was 0.86 and 1.08 cm, respectively. Endplate fractures did not show significant contributions to stature loss.

Adult↗
PubMed1996

The in vivo quantification of myocardial performance in rabbits: a model for evaluation of cardiac gene therapy.

Evaluating cardiac gene therapy in the intact animal requires an index of cardiac function capable of detecting regional differences in contractility in a load-independent fashion. Potentially load-insensitive measures of ventricular performance were therefore evaluated in 10 open- and closed-chested, anesthetized rabbits. LV transmural pressure and myocardial segment length were measured using micromanometry and sonomicrometry during steady-state and transient inferior vena caval occlusion, over a range of inotropic and loading conditions. For each intervention, segmental stroke work was calculated as the area within the left ventricular transmural pressure-length loops at a given end-diastolic segment length during inferior vena caval occlusion; regression analysis was applied to obtain the linear Frank-Starling relationship. In both open- and closed-chested states, these relationships were highly linear (r = 0.97 +/- 0.1) and reproducible. The slope of the linear relationship between segmental stroke work and end-diastolic segment length increased significantly with calcium and epinephrine infusions (P < 0.05 v control) but was not significantly altered by decreased afterload or increased afterload (P > 0.4). The x-intercept was not significantly altered by changes in intropy or afterload (P > 0.4). These data validate the linear Frank-Starling relationship and the slope, MW, as a load-insensitive index of contractility in the intact rabbit. This study presents a novel approach to the quantification of regional cardiac function in smaller animals.

Animals↗
PubMed1996

Alterations in hemodynamics and left ventricular contractility during carbon dioxide pneumoperitoneum.

BACKGROUND: Carbon dioxide (CO2) pneumoperitoneum has been shown to adversely affect hemodynamics in patients. This study specifically examines the potential contribution of altered left ventricular contractility (LVC) to hemodynamic changes observed during CO2 pneumoperitoneum. METHODS: In a canine model, LV volumes, LV pressure, and intrathoracic and central venous pressures were recorded both at basal intra-abdominal pressure (IAP) and after CO2 insufflation to produce IAPs of 5-25 mmHg. RESULTS: At IAPs greater than 15 mmHg, cardiac output and LV end-diastolic volume decreased. Mean arterial pressure and heart rate were unchanged. LVC, quantified using the linear Frank-Starling relationship, was not affected by increases in IAP. CONCLUSIONS: This study is the first to quantify LVC during CO2 pneumoperitoneum and demonstrates no changes in contractility over IAPs from 5 to 25 mmHg. In the dog model, any hemodynamic alterations induced by CO2 pneumoperitoneum are secondary to altered LV preload and not alterations in contractility or LV afterload.

Animals↗
PubMed1996

Factors affecting the biodegradation of toluene in soil.

The biodegradation of toluene in soil microcosms was examined in order to identify the physical, chemical, and biological factors which determine the fate and lifetime of organic chemicals in soils. Toluene degradation rates were proportional to the initial substrate concentration and these rates reached a maximum at a concentration of 200 micrograms/g. No degradation occurred above this concentration presumably due to the toxicity of the hydrocarbon to the soil microorganisms. Small differences were observed in the degradation rates in soils at different moisture content. However, the availability of water in soil appeared to limit toluene degradation only at a very low water content. The lifetime of toluene in soil was also related to the initial level and activity of the soil microorganisms. Toluene was metabolized rapidly in those soils which initially contained high levels of degrading microorganisms. Furthermore, exposure of the soil to toluene resulted in an increase in the number of degrading organisms. The lack of inorganic nutrients such as nitrogen prevented complete degradation of toluene in a clay soil which contained high levels of degrading microorganisms. The biodegradation of organic chemicals in soil is not an intrinsic property of the molecule and cannot be predicted without first delineating the environment in which it is found. The biodegradation of a compound is defined by the biological, physical, and chemical characteristics of the soil environment. The lifetime of a chemical in soil results from a combination of all three of these parameters.

Bacteria↗
PubMed1996

Determinants of vertebral fracture prevalence among native Japanese women and women of Japanese descent living in Hawaii.

Age-adjusted prevalence of vertebral fracture has been reported to be higher among native Japanese women than among women of Japanese descent living in Hawaii. In this cross-sectional population-based study, we examined a variety of potential risk factors for associations with prevalent vertebral fractures and investigated whether these factors could explain the difference in vertebral fracture prevalence between native Japanese and Japanese-American women. Spine radiographs and data on spine bone mineral density (BMD) and other potential risk factors were collected among 802 Japanese women aged 50-88 years living in Hiroshima and 840 Japanese-American women aged 52-88 years living in Hawaii. In logistic regression analysis, BMD was a major predictor of prevalent vertebral fracture. In linear regression models, weight, age, and menstrual history (age at menopause or years between menarche and menopause) were significantly associated with BMD and thus might contribute to fracture risk indirectly through their effects on BMD. However, age and menstrual history provided additional and complementary information about fracture prevalence after adjusting for BMD. These variables together explained much of the difference in vertebral fracture prevalence between the two study populations. We conclude that the observed difference in age-adjusted prevalence of spine fracture between native Japanese and Japanese-American women was accounted for primarily by the differences in BMD, duration of estrogen exposure, and/or duration of estrogen deficiency. Thus, current BMD is a major but not the sole risk factor for vertebral fractures. Age-related and menopause-related mechanisms may also play an important role in spine fracture independent of BMD.

Absorptiometry, Photon↗