Telomerase activity correlates with tumor aggressiveness and reflects therapy effect in breast cancer

Telomerase appears to be an important factor for the control of cellular proliferation capacity and for tumorigenesis. Enzyme activity is highly increased in almost all human tumors and distinguishes them from benign lesions. Besides its diagnostic value, telomerase activity appears to be associated with tumor progression. The purpose of our study was to evaluate the significance of telomerase activity as a clinical marker in breast cancer. Twenty-five tumor samples from breast cancer patients were analyzed retrospectively for telomerase activity in chemotherapy-treated and untreated tumors. For each patient an identical number of cells was measured quantitatively for telomerase activity using the Telomerase-PCR-ELISA based on the TRAP (telomerase repeat amplification protocol) method. The findings were compared to clinical course, therapy and staging parameters. Telomerase activity was detected in all breast cancers. A significant correlation was found between enzyme activity and tumor size, lymph node status and stage: with ongoing tumor progression, telomerase activity appeared to increase in primary carcinomas. No correlation was seen between enzyme activity and the clinical course of patients. Without exception, telomerase activity was strongly decreased in all chemotherapy-treated tumors compared to untreated tumors. Our preliminary data indicate that telomerase activity is associated with aggressiveness of breast tumors and appears to mirror the anti-proliferative effects of chemotherapy.

Effects of recombinant apolipoprotein A-I(Milano) on aortic atherosclerosis in apolipoprotein E-deficient mice

BACKGROUND

We previously reported marked inhibitory effects of recombinant apolipoprotein (apo) A-I(Milano)/phospholipid complex (A-I[Milano]/PC) on neointimal lesions in balloon-injured iliofemoral arteries of hypercholesterolemic rabbits. In this study, we tested the hypothesis that apo A-I(Milano)/PC would inhibit aortic atherosclerosis in apo E-deficient mice.

METHODS AND RESULTS

Thirty-five apo E-deficient mice fed a high-cholesterol diet were included in the study. Control mice were killed at 20 (n=8) or 25 (n=7) weeks. Treated mice received 18 injections of either 40 mg/kg apo A-I(Milano)/PC (n=15) or PC only (n=5) intravenously every other day from 20 weeks until death at 25 weeks. Aortic atherosclerosis was identified with Sudan IV staining. Lipid and macrophage contents of the aortic sinus plaques were measured after oil-red O and Mac-1 antibody staining, respectively, and quantified with computed morphometry. In control mice, from 20 to 25 weeks, aortic atherosclerosis increased by 59% (11 +/- 1% versus 17 +/- 5% of the aortic surface, P=.002), and lipid content increased by 45% (22 +/- 8% versus 32 +/- 6% of plaque area, P=.02) without a significant change in macrophage content (10.8 +/- 2% versus 13.2 +/- 6%). Compared with 20-week-old untreated control mice, PC only-treated mice at 25 weeks demonstrated a 32% increase in aortic atherosclerosis (11 +/- 1% versus 15 +/- 4%, P=.01) and an increase in lipid content (22 +/- 8% versus 47 +/- 3%, P<.0001) without a change in macrophage content (10.8 +/- 2% versus 11 +/- 2%). In comparison with 20-week-old untreated control mice, 25-week-old apo A-I(Milano)/PC-treated mice demonstrated no increase in aortic atherosclerosis (11 +/- 1% versus 10 +/- 4%, P=NS), a 40% reduction in lipid content (22 +/- 8% versus 13 +/- 8%, P=.01), and a 46% reduction in macrophage content (10.8 +/- 2% versus 5.8 +/- 2.9%; P=.03). Serum cholesterol levels were markedly elevated in all groups and did not change significantly with apo A-I(Milano)/PC or PC only. In vitro, apo A-I(Milano)/PC stimulated cholesterol efflux from cholesterol-loaded FU5AH hepatoma cell lines in a dose-dependent manner, whereas PC only or PC-free apo A-I(Miano) had no effect.

CONCLUSIONS

Recombinant A-I(Milano)/PC prevented progression of aortic atherosclerosis and reduced lipid and macrophage content of plaques in apo E-deficient mice despite severe hypercholesterolemia. Thus, A-I(Milano)/PC may have a role in inhibiting progression and promoting stabilization of atherosclerosis.

Perivascular delivery of a nitric oxide donor inhibits neointimal hyperplasia in vein grafts implanted in the arterial circulation

OBJECTIVE

Nitric oxide has been reported to reduce intimal hyperplasia as a response to arterial injury. This study was designed to assess the possible effect of perivascular application of a nitric oxide donor on neointimal proliferation occurring in veins exposed to the dynamics of the arterial circulation in a hypercholesterolemic rabbit model.

METHODS

Autologous jugular vein grafts were implanted in the carotid circulation of 20 hypercholesterolemic rabbits. A mixture of a biodegradable polymer and the nitric oxide donor, spermine/nitric oxide, which releases nitric oxide with a half-life of 39 minutes, was applied periadventitially at the time of implantation. Controls were veins bathed in saline solution, polymer alone, and polymer plus the carrier vehicle spermine without nitric oxide. Animals (n = 5 in each group) were put to death on day 28 for morphometric analysis, cell count, and immunohistochemical staining.

RESULTS

Treatment with perivascular nitric oxide donor significantly decreased wall thickness (126 +/- 24 microm vs 208 +/- 45 microm, p = 0.0017) and area (124 +/- 22 microm2/microm vs 211 +/- 37 microm2/microm, p = 0.005). With the carrier vehicle spermine alone, there was a trend toward reduced intimal thickness, but the change was not statistically significant. In the grafts treated with nitric oxide donor, expression of insulin-like growth factor, fibroblast growth factor, thrombospondins, fibronectin, and tenascin was reduced.

CONCLUSION

The periadventitial delivery of nitric oxide donor produces a reduction of neointimal hyperplasia in veins implanted in the arterial circulation. The mechanism of action is not entirely clear, but the reduction cannot be explained on the basis of decreased cell proliferation alone. Other possibilities are modulation of protein synthesis of vascular smooth muscle cells and production of extracellular matrix components.

Telomerase activity correlates with tumor aggressiveness and reflects therapy effect in breast cancer

Telomerase appears to be an important factor for the control of cellular proliferation capacity and for tumorigenesis. Enzyme activity is highly increased in almost all human tumors and distinguishes them from benign lesions. Besides its diagnostic value, telomerase activity appears to be associated with tumor progression. The purpose of our study was to evaluate the significance of telomerase activity as a clinical marker in breast cancer. Twenty-five tumor samples from breast cancer patients were analyzed retrospectively for telomerase activity in chemotherapy-treated and untreated tumors. For each patient an identical number of cells was measured quantitatively for telomerase activity using the Telomerase-PCR-ELISA based on the TRAP (telomerase repeat amplification protocol) method. The findings were compared to clinical course, therapy and staging parameters. Telomerase activity was detected in all breast cancers. A significant correlation was found between enzyme activity and tumor size, lymph node status and stage: with ongoing tumor progression, telomerase activity appeared to increase in primary carcinomas. No correlation was seen between enzyme activity and the clinical course of patients. Without exception, telomerase activity was strongly decreased in all chemotherapy-treated tumors compared to untreated tumors. Our preliminary data indicate that telomerase activity is associated with aggressiveness of breast tumors and appears to mirror the anti-proliferative effects of chemotherapy.

Quantification of myocardial blood flow with ultrasound-induced destruction of microbubbles administered as a constant venous infusion

BACKGROUND

Ultrasound can cause microbubble destruction. If microbubbles are administered as a continuous infusion, then their destruction within the myocardium and measurement of their myocardial reappearance rate at steady state will provide a measure of mean myocardial microbubble velocity. Conversely, measurement of their myocardial concentration at steady state will provide an assessment of microvascular cross-sectional area. Myocardial blood flow (MBF) can then be calculated from the product of the two.

METHODS AND RESULTS

Ex vivo and in vitro experiments were performed in which either flow was held constant and pulsing interval (interval between microbubble destruction and replenishment) was altered, or vice versa. In vivo experiments were performed in 21 dogs. In group 1 dogs (n=7), MBF was mechanically altered in a model in which coronary blood volume was constant. In group 2 dogs (n=5), MBF was altered by direct coronary infusions of vasodilators. In group 3 dogs (n=9), non-flow-limiting coronary stenoses were created, and MBF was measured before and after the venous administration of a coronary vasodilator. In all experiments, microbubbles were delivered as a constant infusion, and myocardial contrast echocardiography was performed using different pulsing intervals. The myocardial video intensity versus pulsing interval plots were fitted to an exponential function: y=A(1-e[-betat]), where A is the plateau video intensity reflecting the microvascular cross-sectional area, and beta reflects the rate of rise of video intensity and, hence, microbubble velocity. Excellent correlations were found between flow and beta, as well as flow and the product of A and beta.

CONCLUSIONS

MBF can be quantified with myocardial contrast echocardiography during a venous infusion of microbubbles. This novel approach has potential for measuring tissue perfusion in any organ accessible to ultrasound.

Myocardial perfusion characteristics and hemodynamic profile of MRX-115, a venous echocardiographic contrast agent, during acute myocardial infarction

We sought to determine whether MRX-115, a new venous echocardiographic contrast agent, could accurately assess risk area during coronary occlusion and infarct size after reperfusion by using novel imaging modalities meant to selectively enhance contrast signals. In 12 open-chest dogs, venous injections of 0.5 ml of MRX-115 were performed during baseline and coronary occlusion and after reperfusion in the presence of exogenous hyperemia. Ultrasound was transmitted at 2 MHz and received at both 2 MHz (fundamental) and 4 MHz (harmonic) frequencies during continuous and intermittent (end-systolic only) imaging. The risk area during coronary occlusion was compared with technetium autoradiography, and the infarct size after reperfusion was compared with postmortem tissue staining. MRX-115 produced no alterations in hemodynamic or pulmonary gas exchange at any stage. During continuous (both fundamental and harmonic) and intermittent fundamental imaging, measurements of perfusion defects were precluded in many dogs by either poor signal enhancement or posterior wall attenuation. By comparison, these measurements were possible during intermittent harmonic imaging in all dogs except one, which had a very small infarction during reflow. Correlation analysis between perfusion defect size on intermittent harmonic imaging and either autoradiographic risk area or postmortem infarct size gave r values of 0.83 and 0.92, respectively. We conclude that MRX-115 is hemodynamically well tolerated and, when imaging is performed after venous injection, can accurately assess regions of hypoperfusion when combined with intermittent harmonic imaging. These results are promising for the use of this approach in patients with acute myocardial infarction.

Pharmacokinetics of a nootropic agent, BMY-21502, and its metabolites in beagle dogs

A preliminary investigation into the pharmacokinetics of BMY-21502, a nootropic agent, and two of its metabolites, BMY-42191 and BMY-40440, was performed in 4 beagle dogs. Following oral dosing of a solution of BMY-21502 (0.61 mmoles), plasma samples were obtained for 24 h and analyzed for the three analytes by a validated HPLC assay. BMY-21502 was rapidly absorbed (Tmax = 0.5 +/- 0.3 h), followed by a rapid decline of the plasma levels (T1/2 = 0.95 +/- 0.1 h). The hydroxy metabolite, BMY-42191, was rapidly formed and the peak concentrations in plasma were obtained by 2.88 +/- 0.2 h. On the contrary, there was a considerable delay in the peaking of the ketone metabolite, BMY-40440 (Tmax = 6 h). The T1/2 values for BMY-40440 (5.58 +/- 0.5 h) were longer than those for BMY-42191 (4.28 +/- 1.2 h). Comparison of AUC values for BMY-42191 (326.43 +/- 63.3 h x microM) with those of BMY-40440 (67.52 +/- 8.4 h x microM) or BMY-21502 (69.35 +/- 7.3 h x microM) indicated that BMY-42191 was the major circulating species in dog plasma. In conclusion, the preliminary data indicate that the metabolism of BMY-21502 is complex and may encompass hydroxy-ketone metabolic interconversions, as reported for other xenobiotics.

Pulmonary arteriovenous fistula with cerebral arteriovenous malformation without hereditary hemorrhagic telangiectasia. Unusual case report and literature review

An unusual and rare case of a central pulmonary arteriovenous fistula (PAVF) with concomitant cerebral arteriovenous malformation (CAVM) in the absence of hereditary hemorrhagic telangiectasia is reported. Presentation was in the form of a cerebrovascular accident (CVA). Clinical presentations and management strategies of PAVF with associated CAVM are broadly discussed along with a pertinent literature review.

Three-dimensional myocardial contrast echocardiography: validation of in vivo risk and infarct volumes

OBJECTIVES

The aim of this study was to determine whether three-dimensional (3D) myocardial contrast echocardiography (MCE) could provide an accurate in vivo assessment of risk and infarct volumes.

BACKGROUND

MCE has been shown to accurately define risk area and infarct size in single tomographic slices. The ability of this technique to measure risk and infarct volumes by using three-dimensional echocardiography (3DE) has not been determined.

METHODS

Fifteen open chest dogs underwent variable durations of coronary artery occlusion followed by reperfusion. At each stage, MCE was performed by using left atrial injection of AIP201, a deposit microbubble with a mean diameter of 10 +/- 4 microm and a mean concentration of 1.5 x 10(7) x ml(-1). Images were obtained over a 180 degree arc with use of an automated rotational device and were stored in computer as a 3D data set. Postmortem risk area and infarct size were measured in six to eight left ventricular short-axis slices of equal thickness using technetium-99m autoradiography and tissue staining, respectively. MCE images corresponding to these planes were reconstructed off-line.

RESULTS

A close linear relation was noted between the volume of myocardium not showing contrast enhancement on 3D MCE during coronary occlusion and postmortem risk volume (y = 1.2x - 3.0, r = 0.83, SEE = 5.1, n = 15). The volume of myocardium not showing contrast enhancement on 3D MCE after reperfusion also closely correlated with postmortem infarct volume (y = 1.1x - 3.9, r = 0.88, SEE = 4.8, n = 11). No changes in systemic hemodynamic variables were noted with injections of AIP201.

CONCLUSIONS

When combined with AIP201, a deposit microbubble, 3D MCE can be used to accurately determine both risk and infarct volumes in vivo. This method could be used to assess the effects of interventions that attempt to alter the infarct/risk volume ratio.

Myocardial contrast echocardiography

MCE has evolved from a laboratory tool to a clinical procedure. It would be wrong to consider it merely another tool for imaging of myocardial perfusion. As discussed, it allows physicians to bring physiology and pathophysiology to the bedside, providing a better understanding of the underlying mechanisms of abnormal findings in individual patients. MCE can provide quantitative measurements that can be repeated as often as necessary in a patient. Because of its complexity, large clinical studies are necessary to define the role of MCE in the general clinical milieu. Advances in MCE continue at a very rapid pace, and its potential for the study of endothelial function, site-specific targeting, and local delivery of drugs appears promising. Its role will continue to evolve into the early part of the next century. What we learn of the myocardium can be easily applied to other organ systems accessible to ultrasound. The future of MCE appears very exciting.

Myocardial viability in patients with chronic coronary artery disease and previous myocardial infarction: comparison of myocardial contrast echocardiography and myocardial perfusion scintigraphy

The aim of this study was to compare perfusion patterns on myocardial contrast echocardiography with those on myocardial perfusion scintigraphy for the assessment of myocardial viability in patients with previous myocardial infarction. Accordingly, perfusion scores with the two techniques were compared in 91 ventricular regions in 21 patients with previous (>6 weeks old) myocardial infarction. Complete concordance between the two techniques was found in 63 (69%) regions; 25 (27%) regions were discordant by only 1 grade, and complete discordance (2 grades) was found in only 3 (3%) regions. A kappa statistic of 0.65 indicated good concordance between the two techniques. Although the scores on both techniques demonstrated a relation with the wall motion score, the correlation between the myocardial contrast echocardiography and wall motion scores was closer (r = -0.63 vs r = -0.50, p = 0.05). It is concluded that myocardial contrast echocardiography provides similar information regarding myocardial viability as myocardial perfusion scintigraphy in patients with coronary artery disease and previous myocardial infarction.

Recent advances in myocardial contrast echocardiography

In the past few years, significant advances have been made in the production of microbubbles that are more stable in the circulation. Our understanding of the interactions between microbubbles and ultrasound has also led to the development of new ultrasound imaging techniques that result in excellent myocardial opacification after an intravenous administration of microbubbles. This review focuses on advances made with these technologies in the setting of acute coronary syndromes and chronic coronary artery disease.

Influence of retinol deficiency and curcumin/turmeric feeding on tissue microsomal membrane lipid peroxidation and fatty acids in rats

The effect of retinol deficiency and curcumin/turmeric on lipid peroxidation and fatty acid profile was studied in liver, kidney, spleen and brain microsomes of rats. Results revealed an increase in lipid peroxidation in retinol deficient liver by 32%, kidney 30%, spleen 24% and brain 43% compared to the controls. Feeding 0.1% curcumin or turmeric for three weeks in diet to retinol deficient rats reduced the lipid peroxidation respectively to 12.5 or 22.6%, in liver, 23.7 or 24.1% in kidney, 14.4 or 18.0% in spleen and 16.0 or 31.4% in brain. Retinol deficiency lead to a reduction in the essential fatty acids. In liver C18:1 showed a reduction by 45.6%, C18:2 by 31.6% and C20:4 by 22.8%. In kidney C18:1 was reduced by 33.6%, 18:2 by 24.6% and 20:4 by 13.7%. In spleen and brain C18:1 showed a reduction by 10.2% and 33.9%, C18:2 by 37.9% and 12.1% and C20:4 by 15.7% and 35.3% respectively. Curcumin and turmeric fed group showed a significant increase in the abnormally reduced fatty acid levels.

Modeling the myocardial dilution curve of a pure intravascular indicator

The dispersion and dilution of contrast medium through the myocardial vasculature is examined first with a serial model comprised of arterial, capillary, and venous components in series to determine their time-concentration curves (TCC) and the myocardial dilution curve (MDC). Analysis of general characteristics shows that the first moment of the MDC, adjusted for that of the aortic TCC and mean transit time (MTT) from the aorta to the first intramyocardial artery, is one-half the MTT of the myocardial vasculature and that the ratio of the area of the MDC and aortic TCC is the fractional myocardial blood volume (MBV). The use of known coronary vascular morphometry and a set of transport functions indicates that the temporal change in MDC is primarily controlled by the MTT. An analysis of several models with heterogeneous flow distributions justifies the procedures to calculate MTT and MBV from the measured MDC. Compared with previously described models, the present model is more general and provides a physical basis for the effects of flow dispersion and heterogeneity on the characteristics of the MDC.

New developments in ultrasound systems for contrast echocardiography

Contrast echocardiography (CE) has evolved significantly in the past decade. Contrast agents and the hardware and software used to detect them and display optimal images have developed in tandem. Not only are hardware and contrast agents available that allow left ventricular cavity enhancement, but recent research points to the usefulness of CE for the evaluation of myocardial perfusion in the cardiac catheterization laboratory and operating room. Advances in ultrasound technology, such as transient harmonic imaging and integrated backscatter, coupled with the development of newer contrast agents that contain smaller, more stable microbubbles capable of transpulmonary passage for intravenous injection, promise a vast increase in the applications of CE in clinical practice.