Risk Associations in the Thrombotic Disorders

Acyclic Isoprenoid Attenuates Lipid Anomalies and Inflammatory Changes in Hypercholesterolemic Rats

The present study was aimed to explore the antihyperlipidemic and anti-inflammatory effect of acyclic isoprenoid on high fat diet fed rats. Hypercholesterolemia was induced by the diet comprising of the normal rat chow 84.3%, lard 5%, yolk powder 10%, cholesterol 0.2% and 0.5% bile salt were fed to the rats for the period of 8 weeks. The results showed that abnormally elevated levels of plasma lipid profiles. Three different doses of acyclic isoprenoid (20, 40 and 80 mg/kg b.w/day) were administered orally to hypercholesterolemia suffering rats for the period of 30 days. Among these three doses of acyclic isoprenoid, the dose 80 mg/kg b.w. was significantly decreased the plasma lipid profiles when compared to other two doses. The effect produced by acyclic isoprenoid (80 mg/kg b.w) was comparable to that of simvastatin. Therefore, 80 mg/kg b.w was fixed as a effective dose and used for further analyses. Acyclic isoprenoid administration reinstated the elevated levels of cardiac and inflammatory markers in both blood and serum of hypercholesterolemic rats. In addition, acyclic isoprenoid administration decreased activity of 3-hydroxy 3-methyl-glutaryl-CoA reductase and increased the activity of lecithin cholesterol acyl transferase. These findings suggest that the administration of acyclic isoprenoid was potentially ameliorated the cardiac marker enzymes and inflammatory markers in addition to its antihypercholesterolemic effect.

Favourable modulation of the inflammatory changes in hypercholesterolemic atherogenesis by a low-molecular-weight heparin derivative

BACKGROUND

In the hypercholesterolemic state, the net result of combined oxidative and nitrosative stress is a pro-inflammatory phenotype that is manifested as increased adhesion molecule expression, enhanced leucocyte trafficking, and increased vascular permeability. The present work explores the inflammatory aspects of hypercholesterolemic atherogenesis, and also evaluates the role of a low-molecular-weight heparin derivative (LMWH), Certoparin, on a biochemical basis.

METHODS AND RESULTS

Two groups of male Wistar rats were fed an atherogenic diet (normal rat chow plus 4% cholesterol, 1% cholic acid and 0.5% thiouracil-CCT diet) for 2 weeks. While one was left untreated, the other was administered LMWH (300 microg/day/rat commencing on day 8 and continued for a week). Increased concentrations of plasma C-reactive protein and fibrinogen and cardiac TNF-alpha indicated severe inflammation in the atherogenic diet fed rats. In comparison, these biochemical indices of inflammation diminished significantly in the LMWH treated group (p < 0.001). Significant depletion of thiols, along with accentuated activities of the glutathione metabolising was observed in the cardiac and hepatic tissues of the untreated atherogenic rats, indicating heightened oxidative response. Tissue damage was marked by elevated levels of plasma and tissue hexose, hexosamine, hexuronic acid and sialic acid, which were reversed towards normalcy on LMWH administration. The activities of lysosomal enzymes (N-acetyl glucosaminidase, beta-glucuronidase, beta-galactosaminidase and cathepsin-D) showed a marked increase in the CCT-diet fed rats, while LMWH treated rats showed normal activities (p < 0.001). The osmotic fragility test revealed that the untreated hyperlipidemic rat erythrocytes were significantly fragile at high salt concentrations, while the response was normalized in the LMWH treated group (p < 0.05). Further, hypercholesterolemia induced downregulation of physiological nitric oxide levels was corrected upon treatment with heparin-derivative.

CONCLUSION

The results of this work highlight the inflammatory changes in atherogenic conditions and that the low-molecular-weight heparin derivative affords substantial protection.

Diagnosis of deep venous thrombosis and pulmonary embolism

Diagnostic evaluation in the patient with suspected deep vein thrombosis (DVT) and pulmonary embolism (PE) includes a clear correlation between clinical probability, test selection and test interpretation. Real-time B-mode ultrasound with color Doppler remains the imaging technique of choice in suspected DVT. The ventilation/perfusion (V/Q) lung scan is the preferred diagnostic modality in suspected PE. The D-dimer assay may be useful in excluding PA. New diagnostic techniques, including spiral computerized tomography may further modify the diagnostic algorithm.

Deep vein thrombosis. Diagnosis and management

In at least 50% of patients with suspected deep vein thrombosis, the diagnosis is not confirmed by objective testing. The addition of impedance plethysmography and real-time B-mode ultrasound with color-enhanced Doppler imaging to the available diagnostic modalities has altered the approach to clinical evaluation. Pharmacologic treatment has evolved to place emphasis on the use of subcutaneous heparins of greater efficacy and the reduction of hemorrhagic risk with the use of the INR system when warfarin is recommended for long-term therapy. Use of new approaches for diagnosis and management offers the potential of more prompt and accurate diagnosis, more effective therapy, and a reduction in the incidence of pulmonary thromboembolism.

Thromboembolic risk factors in patients undergoing maxillofacial surgery for malignancies

Venous thromboembolism is a common complication in patients undergoing major surgery. We studied blood coagulation profiles in 16 patients undergoing extensive maxillofacial surgery for oral malignant diseases. Activity of coagulation factor V and levels of antithrombin III were significantly reduced on the first postoperative day. Fibrinogen level showed a continuous increase throughout the observation period. However, no thromboembolic events were observed. It can be concluded that despite a severe alteration of the blood clotting system, maxillofacial surgery does not seem to be associated with postoperative thromboembolism.

Internal carotid artery occlusion in association with Crohn's disease

A 38-year-old white male with small bowel Crohn's disease presented with an acute right-sided cerebrovascular accident. He died 36 hr later and postmortem revealed thrombosis over the whole length of an otherwise completely normal left internal carotid artery. Histological examination of the artery revealed no abnormalities and in particular no evidence of arteritis. This brings the total number of such cases reported to three, but this is the first with postmortem data. The occurrence of such an event in a young person with normal carotid arteries and no other risk factors would suggest an association with his Crohn's disease, possibly as a result of a coagulation abnormality.

Fibrinogen mediated activation of platelet aggregation and thromboxane A2 release: pathological implications in vascular disease

The effect of a human fibrinogen preparation on in vitro platelet aggregation was assessed. Platelets were obtained from healthy volunteers. Human fibrinogen induced platelet aggregation in 65% of platelet rich plasma samples and enhanced submaximal platelet aggregation induced by heparin or by several conventional agonists in all samples. Aggregation induced by fibrinogen alone was reversed by the in vitro addition of human albumin. Fibrinogen induced aggregation was associated with the release of the vasoconstrictor, thromboxane A2. Preincubation with indomethacin inhibited both the aggregation and the release of thromboxane A2. Fibrinogen had no effect on in vitro vascular prostaglandin I2 synthesis (rat aortic rings) during a 60 minute incubation. The observed effects of fibrinogen on platelet function may be relevant to clinical conditions in which hyperaggregability of platelets is associated with hyperfibrinogenemia and thrombosis.

Thrombocytopenia and lupus-like anticoagulant in a patient with peripheral vascular disease: response to infusion of prostacyclin

A 46 year old man with intermittent claudication due to severe peripheral vascular disease had a circulating lupus like anticoagulant (LLAC), thrombocytopenia (79 X 109/1), markedly reduced platelet survival and a normal bone marrow. He was treated with intravenous prostacyclin (PGI2) infusions which resulted in improvement of the patient's exercise tolerance and normalisation of his platelet count (300 X 109/1) and platelet aggregation could then be assessed. The platelets were markedly hyperaggregable and generated supranormal quantities of thromboxane A2. A diagnosis of consumptive thrombocytopenia secondary to peripheral vascular disease and platelet hyperaggregability was made. Despite therapy with aspirin and dipyridamole, gradual and progressive reduction in platelet count followed and his exercise tolerance declined over the next three months. Immunoglobulin prepared from the patient's serum did not inhibit vascular PGI2 synthesis in vitro. To our knowledge this is the first reported case of consumptive thrombocytopenia due to severe peripheral vascular disease and platelet hyperaggregability. PGI2 administration caused a transient resolution of these features which was not sustained by aspirin and dipyridamole.