Intra-arterial thrombolysis in acute ischemic stroke: a review of pharmacologic approaches

Tissue Plasminogen Activator Combined With Human Recombinant Deoxyribonuclease Is Effective Therapy for Empyema in a Rabbit Model

OBJECTIVES

There have been no controlled studies to test the efficacy of tissue plasminogen activator (tPA) or recombinant human deoxyribonuclease (rhDNase) in the treatment of empyema. In vitro studies show that streptokinase without rhDNase does not liquefy empyemic material from rabbits. However, the combination of streptokinase and streptodornase and rhDNase have been shown to liquefy pus in vitro. The aim of this study was to determine if tPA or rhDNase, or a combination of the two, is more effective than saline solution in the treatment of empyema in rabbits.

MATERIALS AND METHODS

Empyema was induced in rabbits using 10(9) Pasteurella multicoda organisms in infusion agar injected via a surgically placed chest tube. Once empyema was verified, a blinded investigator administered one of four treatments via the chest tube: 3 mL of saline solution; 4 mg of alteplase (recombinant tPA); 1 mg of rhDNase; or 4 mg of alteplase and 1 mg of rhDNase. The rabbits received a treatment every 12 h following the initial for a total of six treatments. The animals were killed at day 10, and the degree of empyema and pleural peel was scored macroscopically on a scale of 0 to 4.

RESULTS

The combination group had a significantly lower mean empyema score (1.83 +/- 0.75) than did the saline solution group (3.86 +/- 0.38, p = 0.001), rhDNase group (3.17 +/- 0.75, p = 0.012), and alteplase group (3.71 +/- 0.49, p = 0.02) [+/- SD]. The total volume of pleural fluid was markedly higher in the alteplase and rhDNase combination group (142 +/- 79.1 mL) or the alteplase group (231 +/- 78.0 mL) compared to either the rhDNase group (0.8 +/- 1.6 mL) or the saline solution group (5.8 +/- 14.0 mL).

CONCLUSION

The combination of alteplase and rhDNase is more effective in the treatment of rabbit empyema than either agent alone. The intrapleural injection of alteplase alone or in combination with rhDNase leads to the production of large amounts of pleural fluid.

In-vivo imaging of tumor associated urokinase-type plasminogen activator activity

The ability to image tumor associated protease in vivo has biological and clinical implications. In the present study, we describe the development and validation of a urokinase-type plasminogen activator (uPA) sensitive fluorescence imaging probe. The activation of our probe is highly specific to uPA in both enzymatic and cellular-based assays. In two distinct in-vivo tumor models (human colon adenocarcinoma HT-29 and human fibrosarcoma HT-1080), the observed fluorescence changes correlate well with tumor associated uPA activity. The signal intensities of the tumors are about three-fold higher in animals with probe injections. Our results suggest a direct detection method for uPA activity in vivo and the approach can be used for monitoring tumor growth and development.

Passive catheter visualization in magnetic resonance–guided endovascular therapy using multicycle projection dephasers

PURPOSE

To improve upon the conventional projection dephaser (PD) method of background suppression and evaluate the use of multicycle projection dephasers to improve catheter conspicuity in background-suppressed MR images.

MATERIALS AND METHODS

Passive visualization of endovascular catheters in MR images is compared using two background suppression techniques: 1) the conventional PD method and 2) the multicycle PD method. Contrast-filled 4-French (1.3 mm) catheters were imaged in homogeneous and heterogeneous phantoms, and in the common carotid artery of a canine using a modified spoiled gradient echo imaging sequence. We used catheter-to-background contrast (ranging from -100% to 100%) as the metric to compare background suppression techniques.

RESULTS

In the homogeneous and heterogeneous phantoms, the contrast was -6.9% (catheter darker than background) and 15.0%, respectively, using the conventional PD method, and 50.6% and 44.0%, respectively, using the multicycle PD method. In the canine carotid artery, the contrast was -3.1% using the conventional PD method and 53.0% using the multicycle PD method.

CONCLUSION

This work shows that multicycle projection dephasers improve catheter conspicuity over the conventional PD method. The multicycle PD method has potential for use in guiding endovascular procedures.

Thrombolysis in acute ischaemic stroke: a guide to patient selection

Thrombolysis should be a routine treatment for selected patients with acute ischaemic stroke and shows promise in a much larger group of patients. This recommendation is based on data from two completed meta-analyses: the Cochrane Library and the rt-PA Study Group individual patient meta-analysis. In patients with ischaemic stroke, treatment with alteplase (recombinant tissue plasminogen activator; rt-PA) is associated with a non-significant excess of deaths, equivalent to about 19 extra deaths per 1000 treated. Furthermore, thrombolysis, regardless of which drug is used, definitely increases the odds of fatal intracranial haemorrhage by 4-fold. However, despite these risks, thrombolysis with alteplase reduces the odds of death or disability, with the benefit being equivalent to about 55 extra independent survivors per 1000 treated. Unfortunately, there are currently too few data to provide a comprehensive guide to patient selection. The available data suggest that younger patients (<80 years of age) who can be treated with alteplase within 3 hours of stroke onset have the most to gain, equivalent to about 100 more independent survivors per 1000 treated. The role of thrombolysis beyond 3 hours, in those with more extensive CT scan ischaemic change, and patients >80 years of age needs further evaluation. In summary, thrombolysis with alteplase is now an established treatment for acute ischaemic stroke, but clinicians need to cooperate in terms of enrolling more patients in further trials if we are to get the most out of this important treatment.

Overview of biologic agents in medicine and dermatology

Three agents have recently been approved by the Food and Drug Administration for the treatment of chronic plaque psoriasis: alefacept, efalizumab, and etanercept. The field of dermatology has now entered a new era, joining other disciplines of medicine that have been using biologic agents for decades. These new therapies offer psoriatic patients the potential for safe and effective long-term management of this disease. This article reviews how an increased understanding of the pathophysiology of psoriasis led to the development of these products.