Determination of left ventricular mass in dogs with rapid-acquisition cardiac computed tomographic scanning

The development of left ventricular hypertrophy in patients with heart disease often has far-reaching clinical implications with respect to overall morbidity and mortality. Approaches used to assess left ventricular mass include electrocardiography, echocardiography, contrast ventriculography, single photon-emission tomography, and conventional computed tomography. However, all of these modalities suffer from some major draw back that precludes widespread application to all patients. In this study we assessed the accuracy of determinations of left ventricular mass in 22 dogs by rapid-acquisition (50 msec) computed axial tomography (RACAT), an ultrafast computed tomographic (CT) instrument. Electrocardiographically triggered, end-diastolic, short-axis cardiac scans were obtained from apex to base during administration of intravenous iodinated contrast. Myocardial edges were determined for each tomographic scan by two methods: the regional half-contour method (the CT density half way between that of the left ventricular myocardium and adjacent ventricular cavities or lung) and "interactive plateau thresholding" of the cardiac borders. Left ventricular mass by RACAT was calculated as the sum of the mass of each individual scan from apex to base (modified Simpson's rule). Postmortem left ventricular mass ranged from 58 to 160 g. The correlation between true left ventricular mass and tomographically determined mass was excellent (r = .99), with the slope and y intercept not statistically different from 1 and 0, respectively. The standard error of the estimate was 4.1 g. Interobserver and intraobserver variability for determining left ventricular mass demonstrated excellent agreement (r = .99 and r = .99, respectively). We conclude that quantitative assessment of left ventricular mass can be accurately and reproducibly performed in dogs by rapid acquisition CT scanning. It is likely that this technique will be readily transferable to the clinical settings and prove to be an important method for quantifying left ventricular mass in patients.     

Experimental studies of membrane tethers formed from human neutrophils

Membrane tethers (thin, cylindrical pieces of membrane) have been implicated in the rolling of neutrophils along the endothelium. In our studies, these tethers were formed from passive, stimulated (0.1 M fMLP), and osmotically swollen (170–180 mOsm) human neutrophils; as well as neutrophils treated with 0.3 M latrunculin A to disrupt the cytoskeleton. This tether formation was accomplished by micropipette suction of latex beads coated with antibodies to proteins on the neutrophil membrane surface. From plots of force versus velocity for the tether formation process, we calculated adhesion energies per unit area of the lipid membrane to the cytoskeleton and the viscous resistance (effective viscosity) that occurs during the formation of these tethers at finite velocity. Most of the properties of the neutrophil were altered once it had been treated as described above. We were also able to show mechanical reversibility of membrane tethers, as well as an unexpected formation rate at high tether forces. Since membrane tethers have been implicated in the rolling of neutrophils, then the changes in tether formation may ultimately alter how these cells roll. © 2002 Biomedical Engineering Society. PAC2002: 8716Dg     

Human V5/MT+: comparison of functional and cytoarchitectonic data

To date, the delineation of the human visual “motion area” still relies on functional paradigms originally devised to identify monkey area MT. Using fMRI, we have identified putative human area V5/MT+ in normals by modelling the BOLD responses to alternating radially moving and stationary dot patterns. Functional activations were compared with cytoarchitectonic probability maps of its putative correlate area hOc5, which was calculated based upon data from histological sections of ten human post-mortem brains. Bilateral visual cortex activations were seen in the single subject dynamic versus stationary contrasts and in the group random-effects analysis. Comparison of group data with area hOc5 revealed that 19.0%/39.5% of the right/left functional activation was assigned to the right/left hOc5. Conversely, 83.2%/53.5% of the right/left hOc5 was functionally activated. Comparison of functional probability maps (fPM) with area hOc5 showed that 28.6%/18.1% of the fPM was assigned to hOc5. In turn, 84.9%/41.5% of the area hOc5 was covered by the respective fPM. Thus, random-effects data and fPMs yielded similar results. The present study shows for the first time the correspondence between the functionally defined human V5/MT+ and the post-mortem cytoarchitectonic area hOc5.     

Interaction of immunoglobulin with actin

Actin can form specific, direct associations with immunoglobulin resulting in soluble complexes or cross-linked matrices. This interaction can be detected by four in vitro assays using purified components: (1) actin enhances the cytophilic activity of guinea pig IgG2; (2) in solutions of low ionic strength, actin and IgG2 co-precipitate: (3) soluble complexes exist in 0.1 M KCl as revealed by the displacement of actin from its expected sedimentation pattern in a gradient of sucrose when in the presence of IgG 1, IgG2, or IgM; (4) immunoglobulin (IgG1, IgG2, BGG)‡: increases the viscosity of F-actin solutions, presumably by crosslinking F-actin filaments. These data suggest that direct interaction of a cytoskeletal protein with a cell surface receptor is possible.     

A pilot study of recombinant interferon beta (IFN-βser) in patients with recurrent glioma

Recombinant interferon beta (IFN-_ser) has been administered by intravenous bolus injection three times weekly at a dose of 90 × 10⁶ IU to 14, patients with recurrent malignant glioma in an ongoing study. The treatment period has ranged from 1 to 40 weeks. The most common adverse experiences were fever, chills, malaise, and headache. Fever, chills and headache were worse with the first two doses and were usually relieved with acetaminophen. All patients tolerated subsequent treatments without any difficulties. No neurologic or hematologic toxicities were observed. Of ten evaluable patients, five had progressive disease in 4 to 8 weeks; three had stable disease for 12 to 21 weeks; one has had a minor response for 13 weeks; and one has had a complete resolution of tumor for 150 + weeks. IFN-_ser appears to have activity in human glioma and is well tolerated at this dosage and schedule.     

The effect of recombinant human erythropoietin therapy on red cell expansion during autologous blood donation

As the result of the institution of coordinated programs involving regional blood centers, hospital blood banks, information services, and physicians, preoperative autologous blood donation, a previously underutilized practice, has become a standard of care in a number of elective surgical procedures. In addition, the administration of recombinant human erythropoietin has been shown to facilitate the collection of autologous blood from patients scheduled for elective orthopaedic surgery. An analysis of the findings in a study of 263 orthopaedic surgical patients in which the relationship between autologous blood ordering, collection and storage, and subsequent blood transfusion was studied indicates that both blood ordering and blood procurement practices are significant factors with regard to allogeneic blood exposure.