Differential gene expression in cultured osteoblasts and bone marrow stromal cells from patients with Paget's disease of bone.

Paget's disease is a focal condition of bone. To study changes in cells within pagetic lesions, we cultured osteoblasts and stromal cells from 22 patients and compared gene expression in these cells to cells from healthy bone. We identified several differentially regulated genes, and we suggest that these changes could lead to the formation of the lesions. INTRODUCTION: Paget's disease is a focal condition of bone of unknown cause. Although it is regarded as primarily an osteoclast disorder, the tight coupling of the activity of osteoclasts and osteoblasts suggests that the osteoblast could play a key role in its pathogenesis. The aim of the study was to identify possible changes in pagetic osteoblasts and stromal cells that might contribute to the development of pagetic lesions. MATERIALS AND METHODS: Candidate genes were identified based on known bone cell regulators, supplemented with microarray analysis. Gene expression was determined by real-time PCR in primary cultures of osteoblasts and bone marrow stromal cells from pagetic patients and control subjects. Concentrations of secreted proteins were determined by ELISA. RESULTS: Dickkopf1 mRNA and protein levels were increased in both pagetic osteoblast and stromal cell cultures, and interleukin (IL)-1 and IL-6 were overexpressed in pagetic osteoblasts. These changes parallel recent findings in myeloma bone disease, which shares some clinical similarities with Paget's disease. Alkaline phosphatase was overexpressed, and bone sialoprotein and osteocalcin were underexpressed in pagetic osteoblasts, consistent with their circulating levels in pagetic patients. It is hypothesized that overexpression of Dickkopf1, IL-1, and IL-6 would result in stimulation of osteoclast proliferation and inhibition of osteoblast growth, leading to the development of the characteristic lytic bone lesions. By stimulating osteoblast differentiation, Dickkopf1 and IL-6 may also promote mineralization, leading to the conversion of lytic lesions to sclerotic. CONCLUSIONS: These findings suggest that dysregulated gene expression in pagetic osteoblasts could cause the changes in bone cell number and function characteristic of Paget's disease.     

Cognitive and neuroimaging predictors of instrumental activities of daily living.

Impaired ability to conduct daily activities is a diagnostic criterion for dementia and a determinant of healthcare services utilization and caregiver burden. What predicts decline in instrumental activities of daily living (IADLs) is not well understood. This study examined measures of episodic memory, executive function, and MRI brain volumes in relation to baseline IADLs and as predictors of rate of IADL change. Participants were 124 elderly persons with cognitive function between normal and moderate dementia both with and without significant small vessel cerebrovascular disease. Random effects modeling showed that baseline memory and executive function (EXEC) were associated with baseline IADL scores, but only EXEC was independently associated with rate of change in IADLs. Whereas hippocampal and cortical gray matter volumes were significantly associated with baseline IADL scores, only hippocampal volume was associated with IADL change. In a model including cognitive and neuroimaging predictors, only EXEC independently predicted rate of decline in IADL scores. These findings indicate that greater executive dysfunction at initial assessment is associated with more rapid decline in IADLs. Perhaps executive function is particularly important with respect to maintaining IADLs. Alternatively, executive dysfunction may be a sentinel event indicating widespread cortical involvement and poor prognosis.     

142Effects of Low‐Frequency Ultrasound Applied In Vitro to Highly Antibiotic‐Resistant Acinetobacter Isolates Recovered From Soldiers Returning From Iraq

Abstract  Brooke Army Medical Center isolated 25 highly antibiotic‐resistant Acinetobacter ssp . (primarily A. baumannii ) from wounded soldiers returning from Iraq. Concern about effective treatment of these organisms led our institution to begin investigating low‐frequency ultrasound (LFU) as a method of increasing the effectiveness of antibiotics on A.baumannii in wound management. Studies have suggested that LFU applied in conjunction with antibiotics may increase their overall effectiveness. We hypothesize that combining antibiotics with LFU may be an effective method of wound management and that this combination may be synergistic in its overall effect. In this initial work, we wanted to determine if sonocation would have an effect on our organism of interest, A. baumannii . We selected several organisms, both gram positive and gram negative, that have been shown to be killed by sonocation ( E. coli, S. aureus , and S. pyogenes ) and added three highly resistant A. baumannii isolates. Bacterial death was measured by both colony counts after 24 hours of growth and acridine orange staining using a standard protocol.
Colony counts were significantly reduced by sonocation. Furthermore, A.'baumannii colony counts were also greatly reduced by sonocation. Actual cell destruction was also visualized using acridine orange staining. Our data support the assertion that sonocation has an antibacterial effect on some bacteria, including A. baumannii . Our next step is to add antimicrobial agents and determine if their effectiveness can be increased by sonocation.     

The effects of altering time delays of coupled pacing during acute atrial fibrillation

BACKGROUND: Coupled pacing (CP), which consists of delivering a premature electrical stimulation to the heart after the effective refractory period of ventricular activation, is a novel method for controlling ventricular rate during atrial fibrillation (AF). It also has been established that CP improves pump function by enhancing external cardiac work and myocardial efficiency. OBJECTIVE: The purpose of the present study was to determine if two time delays for CP (short and long) would result in similar improvements in ventricular function. METHODS: In a canine model, we applied CP at two time delays (CP-S and CP-L) during two stages: sinus rhythm (SR) and acute AF. The cardiac responses to CP during SR served as the nontachycardic and nondepressed control. During both rhythms, we shortened the coupling interval until we obtained maximal contractility, designated CP-S. Next, we increased the delay until we started to see a measurable secondary contraction (left ventricular pressure development of approximately 20 mmHg). These longer delays were designated CP-L. RESULTS: Our results showed that the ventricular rate of intrinsic activation (VRIA) remained decreased despite prolongation of the time delay of CP during both AF and SR. Also, both delays of CP increased left ventricular systolic pressure (LVSP) and dLVP/dt, which are indices of myocardial contractility. In contrast, CP increased external cardiac work only during AF. Prolonging this time delay did not markedly decrease the improvement in external cardiac work. Myocardial O(2) consumption (MVO(2)) did not significantly change as the result of CP during either SR or AF. Finally, myocardial efficiency improved during AF as the result of CP at both time delays. CONCLUSIONS: In conclusion, shorter time delays for CP increased contractile strength during both SR and AF. However, extending the time delay of CP had minimal effects on diminishing the improved ventricular pump function and energetics that resulted from CP during AF. Thus, the maximal enhancement of myocardial contractility via CP-S was not needed to maintain the improved ventricular function during acute AF when CP is applied.