Synthesis and biological assessment of 3,7-dihydroxytropolones.

3,7-Dihydroxytropolones (3,7-dHTs) are highly oxygenated troponoids that have been identified as lead compounds for several human diseases. To date, structure-function studies on these molecules have been limited due to a scarcity of synthetic methods for their preparation. New synthetic strategies towards structurally novel 3,7-dHTs would be valuable in further studying their therapeutic potential. Here we describe the successful adaptation of a [5 + 2] oxidopyrilium cycloaddition/ring-opening for 3,7-dHT synthesis, which we apply in the synthesis of a plausible biosynthetic intermediate to the natural products puberulic and puberulonic acid. We have also tested these new compounds in several biological assays related to human immunodeficiency virus (HIV), hepatitis B virus (HBV) and herpes simplex virus (HSV) in order to gain insight into structure-functional analysis related to antiviral troponoid development.

Bolus recombinant urokinase versus heparin in deep venous thrombosis: a randomized controlled trial.

Bolus urokinase (Abbokinase ) is effective for initial treatment of deep venous thrombosis but is associated with a high rate of rigors. This randomized controlled trial was undertaken among patients with deep venous thrombosis to evaluate the efficacy and safety of a novel thrombolytic agent, recombinant urokinase (rUK), administered as three bolus infusions of 1 million U over a 24-hour period versus heparin alone. Of 361 patients with DVT screened, 17 (5%) were enrolled. Recent surgery was the most common reason for exclusion (n = 113, 31%). Images of the patients were obtained at baseline, 24 to 48 hours after randomization, and before hospital discharge. Two patients in each treatment group had minor clot progression. One patient in the heparin group had no change; all other patients showed mild (< 50%; n = 5 in each group) or moderate (> 50%; n = 1 in each group) improvement. No bleeding complications or rigors developed in patients randomized to rUK. Mean bleeding times among patients given rUK were not significantly different from mean values of patients given heparin at any of the measured time points available for comparison (331 vs 387 seconds at baseline and 381 vs 416 seconds at 24 hours). However, mean fibrinogen levels declined with successive urokinase boluses and were significantly lower than levels in patients treated with heparin at 24 (233 mg/dl vs 466 mg/dl, p = 0.01) and 48 hours (270 mg/dl vs 474 mg/dl, p = 0.02). Although bolus rUK had a favorable safety profile, rUK was no more effective than heparin in achieving clot lysis at the doses used in this trial.

Intermittent pneumatic compression in chronic venous insufficiency favorably affects fibrinolytic potential and platelet activation.

Nineteen patients with symptoms of chronic venous insufficiency (CVI) were treated with 13-week cycles of intermittent pneumatic compression (IPC) during 2 h sessions twice weekly, with most treatments at home. At study completion, quantitative subjective scores for total symptomatology were improved in 16/19 patients (84%). Enhancement of fibrinolytic potential in vivo was detected in 86% of observations on specimens from CVI patients over 2 h of IPC, with accelerated euglobulin clot lysis times (ELT) noted within 15 min of initiating compression. The enhanced fibrinolytic potential was attributed to increased urokinase plasminogen activator (u-PA), probably released from perturbed endothelial cells by IPC. Significant decreases in total t-PA antigen (mass concentration) but not t-PA activity, were produced by IPC in CVI patients only (P = 0.0001), with greater effects noted in the non-anticoagulated versus the anticoagulated cohort. Plasminogen activator inhibitor type 1 (PAI-1) levels rose rapidly after IPC only in the controls and non-anticoagulated CVI patients. PAI-1 decreased in those receiving anticoagulation. No platelet perturbation was detected during IPC by measuring levels of beta-thromboglobulin or the thromboxane A2 metabolite, 11-dehydrothromboxane B2; however, significant (P < 0.003) decreases in plasma prostacyclin (PGI2) levels (measured as the stable 6-ketoprostaglandin F-1-alpha-metabolite) were observed after 15 min of IPC in non-anticoagulated CVI patients only. There was no evidence of increased thrombin generation by IPC, determined by urinary excretion of fibrinopeptide A and prothrombin fragment 1. Concurrent anticoagulation appears to mediate more favorable biochemical alterations in CVI, although subjective improvement did not correlate with anticoagulation. The mechanism(s) by which these physiologic changes compliment the mechanical effects of IPC remain to be elucidated and will require adequately controlled and powered studies.

Pulmonary embolism and deep venous thrombosis during pregnancy or oral contraceptive use: prevalence of factor V Leiden.

Activated protein C resistance caused by factor V Leiden mutation is the most common inherited cause of an underlying predisposition to pulmonary embolism (PE) and deep venous thrombosis (DVT). We studied the frequency of the factor V Leiden mutation in 50 women who had PE and/or DVT during or after pregnancy or during oral contraceptive use. Ten (20%; 95% CI 10% to 34%) of the 50 women were heterozygous for the mutation. First-trimester PE or DVT developed in 6 (60%; 95% CI, 26% to 88%) of the 10 women with the mutation compared with 3 (8%; 95% CI 2% to 20%) of 40 women without the mutation (p = 0.0009). These data indicate that the factor V Leiden mutation is an important risk factor for PE or DVT during pregnancy (especially the first trimester), after pregnancy, or during oral contraceptive use.

Shortened hospitalization by means of adjusted-dose subcutaneous heparin for deep venous thrombosis.

Adjusted-dose subcutaneous unfractionated heparin (SC heparin) was used in the initial management of deep venous thrombosis (DVT) to allow shortened hospital stay. Of 78 patients screened, 41% were eligible and 18 (23%) were enrolled. Follow-up venous ultrasound examination was performed 6 weeks after discharge. Of enrolled patients, 16 (89%) completed the protocol. Hospital length of stay was 2 days in protocol patients compared with 5 days for patients receiving conventional inpatient heparin with a continuous intravenous infusion (p = 0.0009). Very high heparin doses (mean 42,000 to 62,000 U daily, given in three divided doses every 8 hours) and a median time of 21 hours were required initially to achieve a target activated partial thromboplastin time (aPTT) > 55 seconds. Subsequently many patients had supratherapeutic levels, yet there were no bleeding complications. Four patients (25%) did not show improvement at follow-up ultrasound in spite of aPTTs > 55 seconds after the second injection. Clot regression was evident in remaining patients. Hospital cost savings were offset partially by the need for time- and labor-intensive outpatient monitoring after hospital discharge.

Prevention of venous thrombosis after coronary artery bypass surgery (a randomized trial comparing two mechanical prophylaxis strategies).

Although venous thrombosis may occur often after coronary artery bypass grafting, prophylaxis with low-dose heparin is rarely used due to the risk of bleeding. Therefore, we compared the efficacy of 2 mechanical regimens of prophylaxis against deep vein thrombosis (DVT). Consecutive patients undergoing coronary artery bypass without concomitant valve surgery or coronary endarterectomy were randomized to either a more intensive regimen of intermittent pneumatic compression (IPC) plus graduated compression stockings (GCS) versus standard compression stockings alone. Of 611 patients screened, 184 were excluded due to peripheral vascular disease, postoperative intraaortic balloon support, or immediate postoperative anticoagulation. An additional 83 patients refused consent, leaving 172 in each prophylaxis group. The primary study end point was DVT diagnosed by a predischarge leg ultrasound examination performed on postoperative days 4 to 6. Of 344 patients enrolled, 330 (96%) underwent predischarge ultrasonography. DVT was detected in 19% of patients assigned to IPC plus stockings versus 22% assigned to GCS alone (95% confidence interval for the difference, -11% to 6%, p = 0.62). The addition of IPC did not add significant incremental benefit to GCS alone for DVT prophylaxis among patients undergoing coronary artery bypass surgery.

Prevalence of deep venous thrombosis among patients in medical intensive care.

OBJECTIVE--To determine the frequency of deep venous thrombosis (DVT) in medical intensive care unit (MICU) patients. DESIGN--Prospective ultrasound case series. SETTING--An MICU in a large tertiary care hospital in Boston, Mass. SUBJECTS--Patients older than 18 years of age admitted to the MICU with an anticipated stay of more than 48 hours. MAIN OUTCOME MEASURE--Deep venous thrombosis as detected by ultrasonography with color Doppler imaging performed twice weekly in the MICU and once within 1 week of discharge from the MICU. RESULTS--Deep venous thrombosis was detected in 33% (95% confidence interval, 24% to 43%) of 100 eligible patients during the 8-month study period. Forty-eight percent (16/33) were proximal lower extremity DVT, and 15% (5/33) were upper extremity DVT associated with central venous catheters, with one patient having both upper and proximal lower extremity DVT. Ultrasound examination results led to inferior vena cava filter placement in three patients, initiation of full-dose anticoagulation in four patients, initiation or continuation of low-dose subcutaneous heparin in 10 patients, follow-up ultrasound studies in three patients, central line removal in one patient, and no intervention in 10 patients due to active bleeding, prior filter, or heparin-induced thrombocytopenia. Two patients remained anticoagulated for other reasons. In this series, there was no difference in age, gender, body mass index, diagnosis of cancer, recent surgery, duration of hospitalization prior to DVT detection, and DVT prophylaxis between patients with DVT and those without. CONCLUSIONS--An unexpectedly high rate of DVT was detected by ultrasound in these MICU patients despite prophylaxis in 61%. Traditionally recognized DVT risk factors failed to identify patients who developed DVT. Routine ultrasound surveillance or more intensive prophylaxis regimens may be warranted in this patient population if these DVT rates are confirmed in other settings.

Prolonged bleeding time as a marker of venous clot lysis during streptokinase therapy.

Despite their expense and inconvenience, serial ultrasound or venographic examinations are currently the only available methods to assess the efficacy of thrombolysis for deep venous thrombosis (DVT). We therefore tested whether the bleeding time (BT), a simple and inexpensive test, is useful in assessing lytic efficacy and might thus be a valuable adjunct in guiding the dose and duration of the thrombolytic agent. Serial BTs were obtained daily in 16 patients (eight men and eight women, average age 45.5 years, range 19 to 70) receiving streptokinase (SK) for proximal lower extremity DVT (n = 5), for upper extremity DVT (n = 10), or for renal vein thrombosis (n = 1). Duration of treatment averaged 89.9 +/- 43.6 hours (range 35 to 198 hours). Clot lysis on ultrasound, venogram, or magnetic resonance imaging (MRI) was defined as: complete (greater than or equal to 90%), moderate (50% to 90%), minimal (less than 50%), or none. Important (complete or moderate) clot lysis occurred in 9 of 15 patients for whom follow-up studies were available. BT prolongation was defined as greater than 9.5 minutes and, during SK therapy, had a sensitivity of 0.67 and a specificity of 0.67 for important clot lysis. The positive predictive value of prolonged BT for clot lysis was 0.75. Calculated likelihood ratios revealed that a patient with BT prolongation was twice as likely to have important clot lysis rather than minimal or no lysis. These findings suggest that the BT should undergo further investigation as a simple, adjunctive, noninvasive marker of thrombolytic efficacy among DVT patients treated with SK.

Frequency of deep venous thrombosis in asymptomatic patients with coronary artery bypass grafts.

The frequency of deep vein thrombosis (DVT) in patients undergoing coronary artery bypass graft (CABG) surgery has not been established. Therefore to estimate the frequency of clinically silent DVT, we performed ultrasound examinations of the leg veins in 29 asymptomatic CABG patients before hospital discharge. We used high-resolution B-mode ultrasonography with color Doppler imaging. Fourteen (48.3%, 95% confidence interval 30.1 to 66.4%) had 20 documented leg vein thromboses, and all but one patient had DVT limited to the calf veins. Of the 20 thrombi 10 (50.0%) were present in the leg ipsilateral and 10 (50.0%) in the leg contralateral to the saphenous vein harvest site. None of the DVTs were suspected clinically. DVT was not associated with any local sign attributed to saphenous vein harvest such as pitting edema, incisional drainage, or local tenderness or with any putative risk factor for DVT such as cigarette use, distant history of malignancy, or varicose veins. Follow-up of these patients 5 to 11 months after CABG surgery showed no clinical evidence of DVT or pulmonary embolism. Our findings indicate that asymptomatic DVT of the calf occurs with surprisingly high frequency, 44.8% after CABG surgery. Future studies in patients undergoing CABG surgery should address the natural history of asymptomatic DVT, determine its clinical importance, and develop optimal strategies for prophylaxis and treatment.

Laboratory parameters to monitor safety and efficacy during thrombolytic therapy.

Thrombolytic therapy is being used with increasing frequency in myocardial infarction (MI), pulmonary embolism, deep venous thrombosis (DVT), and peripheral arterial occlusion. Use of these agents, however, is hampered by concerns regarding safety and efficacy. Numerous laboratory parameters have been evaluated for monitoring the risk of bleeding complications, with levels of fibrinogen (and percentage of decrease) and fibrin/fibrinogen degradation products (FDPs) correlating to a variable extent with clinical bleeding. The bleeding time (BT) test has also been proposed as a potential predictor of bleeding during thrombolytic therapy. With respect to efficacy, the D-dimer fragment of FDPs, when corrected for soluble fibrin polymers, has been shown to correlate with clot lysis in venous thromboembolism but not MI. The BT also is being considered as a marker of lysis in patients with DVT. Given the increasing concomitant use of antiplatelet agents during thrombolytic therapy, the BT, as an in vivo test of hemostasis and platelet function, has potential utility as a noninvasive, adjunctive marker of thrombolytic efficacy.

Program for the prevention of venous thromboembolism in high-risk orthopaedic patients.

Postoperative orthopaedic patients remain at risk for venous thromboembolism (VTE) after hospital discharge. Therefore, the authors designed and implemented a program for prevention of VTE that included outpatient adjusted-dose warfarin using twice-weekly prothrombin time (PT) determinations, a dedicated telephone line for PT results, and vigilant nurse-physician supervision to administer prophylaxis to 125 postoperative orthopaedic patients against VTE for an average of 31.4 days after discharge. PT was maintained between 13.2 and 18.3 seconds (1.1-1.5 x control) in the average patient. There was a failure rate of 3.2% and 0.8% for clinically suspected and radiologically confirmed deep venous thrombosis (DVT) and pulmonary embolism (PE), respectively. The rate of bleeding complications was 3.2%, but none of these patients required transfusion or hospital readmission for hemorrhage. The authors conclude that the described program for VTE prevention is a safe, effective, and practical program to administer prophylaxis to postoperative orthopaedic patients against clinically evident VTE for the first month after hospital discharge.

Bleeding time and other laboratory tests to monitor the safety and efficacy of thrombolytic therapy.

Widespread use of thrombolytic agents in a variety of settings has highlighted the need for measures of safety and efficacy. Previously used laboratory parameters, such as decreasing levels of fibrinogen and increasing levels of fibrin(ogen) degradation products (FDPs), have failed to correlate consistently with hemorrhagic events and have not yet been useful in predicting patients at risk for bleeding. Although the bleeding time (BT) has been considered primarily to reflect platelet function, it also reflects the interaction of platelets with vessel wall and coagulation pathways. Recently, the BT has been considered as a potential predictor of clinical bleeding during thrombolysis. The BT, as a measure of in vivo hemostatic competence, may be particularly well-suited for this application. Serial BTs during thrombolytic therapy may provide valuable information regarding safety and efficacy, but further studies are needed to confirm preliminary findings.

The bleeding time: its potential utility among patients receiving thrombolytic therapy.

The BT as a test of hemostatic function was first described 80 years ago. It has generally been considered a primitive and tedious test. Improvements in technique and standardization have increased the BT's reliability and led to its consideration as a preoperative screening measure. Current use has not been widespread, however, except for patients undergoing neurosurgery and organ biopsy. Recently, though, there has been a renewed interest in the BT for patients receiving thrombolytic therapy because levels of fibrinogen and fibrin(ogen) degradation products have been only weak predictors of hemorrhagic complications. The rationale for using the BT in this setting is that thrombolysis appears to impair platelet function, either through depletion of platelet granules or through direct proteolytic actions on platelets. Further research will determine whether these platelet effects are manifest as BT prolongation; whether increased BT will correlate with hemorrhagic complications; and, finally, whether patients who fail to achieve clot lysis or those at risk for bleeding can be identified prospectively.