Regional variation in vertebral bone density and trabecular architecture are influenced by osteoarthritic change and osteoporosis

STUDY DESIGN

The effects of age-related osteoarthritic disease and bone loss on cortical and trabecular bone density in the human spine were analyzed. Changes were quantified by a new method of computed quantitative radiography. Using this method, the relative losses of bone mineral from specific areas and the specific redistribution of bone within vertebrae as a function of age-related bone loss and osteoarthritic change were determined.

OBJECTIVES

To quantify the effects of age-related bone loss and osteoarthritic disease on cortical and trabecular density in the human spine by the use of a new method of computed quantitative radiography.

SUMMARY OF BACKGROUND DATA

To the authors' knowledge, osteoarthritic and age-related changes resulting in the relative loss of bone mineral from specific areas within vertebrae have never been quantitatively studied.

METHODS

Seventy-four vertebrae were obtained from 23 normal, human subjects at autopsy. Vertebral bodies were measured by dual-energy x-ray absorption, and then sectioned for analysis by computerized quantitative radiography. Attention was focused on overall bone density, regional cancellous bone density, and cortical bone density (anterior cortex, superior, and inferior endplates) for both mid-sagittal and para-sagittal sections. One hundred forty sections were so analyzed.

RESULTS

Quantitative radiography demonstrated previously undescribed, well defined patterns of cortical and trabecular architecture and bone density within vertebral bodies that were uniform among vertebrae, but strongly influenced by osteoarthritic change and bone loss. These changes were neither detected nor documented by dual-energy x-ray absorption.

CONCLUSIONS

Understanding the patterns of bone lose, and knowing how osteoarthritic change affects normal bone loss yields insight into the pathophysiology of the aging process and osteoarthritic disorders. Knowledge of the variations in density and microanatomy within vertebrae may improve techniques of internal fixation and designs of spinal implants, and may help to clarify the pathogenesis of clinical problems such as fractures.

Decreasing the prevalence of pressure ulcers using agency standards

Home care patients either have or are at high risk for pressure ulcers. This article describes the outcome of a study that examined the effects of pressure ulcer prevention and treatment standards on the prevalence rate of a home healthcare agency's client caseload. Implications for practice and further research also are discussed.

Development of a multilevel Ecological Classification System for the state of Minnesota

The Minnesota Department of Natural Resources (MNDNR) began development of an Ecological Classification System (ECS) in 1991. The ECS is hierarchically organized into six levels following the United States Forest Service structure. The upper four levels are being developed State-wide by an interdisciplinary group from several agencies. Geographic Information Systems approaches are being used to overlay and integrate existing data. The first two levels (Province and Section) have been completed. The third level (Subsection) is nearly completed, and work on the fourth level (Land Type Association (LTA)) started in January 1995. Classification and inventory for the lowest two levels (Ecological Land Type and Ecological Land Type Phase) was cooperatively undertaken on two Land Type Associations within the Chippewa National Forest. A sample set of management interpretations is being developed and tested for the two lower levels. Workshops demonstrating how ECS can be used for natural resource management began in mid-1995 and will continue for several years, as will development of the lower two levels on LTAs beyond the Chippewa National Forest.

Pitfalls in the measurement of bone mineral density by dual energy x-ray absorptiometry

STUDY DESIGN

Fifty-three human thoracic and lumbar vertebrae were analyzed by dual energy x-ray absorptiomety to obtain projectional (g/cm2) and volumetric (g/cm3) bone mineral density.

OBJECTIVES

To determine the effect of volume on the measurement of bone mineral density by DEXA.

SUMMARY OF BACKGROUND DATA

Despite the widespread use of dual energy x-ray absorptiomety to measure bone mineral density expressed as grams per projectional unit area (g/cm2), the effect of volume has been ignored in many published biomechanical studies.

METHODS

Projectional bone mineral density (g/cm2) of fifty-three human vertebrae was obtained by dual energy x-ray absorptiometry measurement. This was compared to bone mineral density expressed as grams per unit volume.

RESULTS

Many specimens with near equal projectional bone mineral density were demonstrated to have significantly different true densities when measured by dual energy x-ray absorptiomety in grams per unit volume. The difference in true bone mineral density for these specimens ranged from 24.1% to 139%.

CONCLUSION

The effect of volume on bone mineral density data based on projectional areas can cause very significant perturbations of the data in biomechanical studies.

Evaluation of pressure ulcer prevalence rates for hospice patients post-implementation of pressure ulcer protocols

Hospice patients may be particularly at risk for pressure ulcer development due to several factors. Identifying populations at risk for pressure ulcer development, such as hospice patients, and providing prevention and risk protocols for these populations can substantially reduce the prevalence and incidence of pressure ulcers. However, are hospice patients prone for skin breakdown despite prevention and treatment efforts? This study examines the prevalence of pressure ulcers in hospice patients following the implementation of pressure ulcer prevention and treatment protocols. Levine's theory of conservation of structural integrity formed the theoretical framework for this descriptive study. A midwestern hospital-based hospice agency was the site for this study. All patients 18 years of age and older were included in the study. Pressure ulcer prevalence audits were done at four, eight, 12, and 18 months after protocols were outlined by the hospice staff. Results of the audits revealed prevalence rates of 14.8 percent, 8.5 percent, 13.6 percent, and 23.8 percent, at each of the aforementioned audits. 10 of 15 patients who were pressure ulcer positive were males; the sacral location was most common (seven of 19 ulcers occurred sacrally) with the ischial location being the next common (six of 19 ulcers were ischially located). No ulcers occurred above the waist or in patients below 51 years of age. Recommendations from this study urge that particular prevention attention be given to protocols which address "sitting," due to the predominance of ulcers located in the sacral and ischial regions. In addition, the author concludes that perhaps, pressure ulcers may occur in this population despite the best of efforts to prevent them.

Effects of lovastatin and chenodiol on bile acid synthesis, bile lipid composition, and biliary lipid secretion in healthy human subjects

To assess the relationship between cholesterol synthesis and feedback inhibition of bile acid synthesis, we studied seven normal human subjects taking three different doses of chenodiol, 0, 5, and 15 mg/kg per day: once while taking no lovastatin and again while taking lovastatin 80 mg/day. Lovastatin and both doses of chenodiol significantly lowered bile acid synthesis measured by the 14CO2 method, but there was no significant interaction between the perturbations. Both also lowered cholesterol saturation index of gallbladder bile without appreciable interaction, and the combination was distinctly more effective than either medication alone. Lovastatin and low-dose chenodiol both lowered biliary cholesterol secretion without affecting bile acid secretion. Increasing the dose of chenodiol did not further lower cholesterol secretion, but did further reduce saturation index because of an increase in secretion of bile acid and phospholipid. These studies indicate that there is no interaction between cholesterol synthesis and feedback return of bile acid in the enterohepatic circulation with respect to either bile acid synthesis or biliary lipid secretion; that the combination of chenodiol and lovastatin is better than either alone for improving biliary cholesterol saturation; and that the mechanism by which chenodiol lowers cholesterol saturation is dose-dependent.

Innovative therapies in hematology and oncology

As one can see, there are a number of new and exciting advances in the prevention, detection, and treatment of various malignancies. We anxiously await the future to see the exact integration of the tremendous advances taking place in the cellular and molecular biopsy of disease and its application to the therapy of patients.

Field evaluation of alternative HIV testing strategy with a rapid immunobinding assay and an agglutination assay

A rapid immunobinding assay ('HIVCHEK', Ortho) and an agglutination assay ('Serodia-HIV', Fujirebio) were evaluated as an alternative to enzyme-linked immunosorbent assay (ELISA) and western blot under field conditions in Africa for detection of antibody to human immunodeficiency virus (HIV). 7106 specimens were tested at 25 laboratories in Kenya, Ghana, Senegal, and Zaire. HIVCHEK was used as a screening test, and serodia-HIV as a supplemental test to evaluate these assays in an alternative testing strategy to the standard ELISA/western blot testing procedure. In each country, HIVCHEK was more sensitive and specific than ELISA when compared with western blot. The sensitivity of HIVCHEK ranged from 87.0 to 96.3% and the specificity from 99.0 to 100%. The sensitivity and specificity of serodia-HIV ranged from 85 to 98% and from 88 to 98%, respectively. The sensitivity and specificity were affected by the presence of HIV-2 in Ghana and Senegal. Overall, with an HIV-1 prevalence of 14.8% in Kenya and 22.5% in Zaire, the sensitivities of the alternative strategy were 96.4% and 91.4%, the specificities 99.6% and 100%, the positive predictive values 97.6% and 100%, and the negative predictive values 99.3% and 97.9% for Kenya and Zaire, respectively. With this testing format there was an estimated average cost saving of up to 82% over the conventional strategy with ELISA/western blot. This procedure constitutes a reasonable alternative to the standard ELISA/western blot combination.