The effect of fibrinogen sialic acid residues on ex vivo platelet deposition on biomaterials

The effect of fibrinogen sialic acid residues on platelet deposition onto polymer surfaces was examined using a canine ex vivo shunt model. To test the hypothesis that desialylated fibrinogen may enhance platelet deposition when precoated on biomaterials, canine fibrinogen was desialylated and precoated on polyvinyl chloride (PVC) shunts. When protein-coated PVC shunts were exposed to flowing whole blood, both the native and the desialylated fibrinogen elicited the same profile of platelet deposition. This study indicates that platelet deposition and thrombus formation on biomaterial surfaces is not mediated by a mechanism which involves the sialic acid residues of fibrinogen.

Human leukocyte antigen (HLA) in Korean patients with autoimmune thyroid diseases

In previous studies, there has been evidence of different allelic associations with a particular disease among various ethnic groups. The present study was done to investigate the associations between HLA and autoimmune thyroid diseases in the Korean. We found no association between Graves’ disease and HLA-B8 or -B35. However, increased frequencies of HLA-A11 and -DRw8, and the decreased frequencies of HLA-A10 and B12 were found in patients with Graves’ disease. In the cases of Hashimoto’s disease, the frequencies of HLA-A2 and -DRw8 were found to be significantly increased and the frequency of HLA-DRw6y decreased. These data indicate that the association between autoimmune thyroid disease and HLA in the Korean would appear to be different from that in most other racial groups, including Caucasians, Japanese and Chinese.

Acute surface-induced thrombosis in the canine ex vivo model: importance of protein composition of the initial monolayer and platelet activation

The initial events occurring at the blood-polymer interface were examined using a canine ex vivo arteriovenous shunt model. Thrombogenic (fibrinogen) and nonthrombogenic (albumin) proteins were preadsorbed on poly(vinyl chloride), polyethylene, and silicone rubber shunt surfaces, and the blood responses were analyzed using the platelet deposition profile as an indicator of surface thrombogenicity. The distributions of preadsorbed protein molecules on the various polymer surfaces were studied using an immunogold bead (colloidal gold particles coated with antibodies) staining technique and shown to be homogeneous. A sequential protein adsorption technique was developed to probe the nature of competitive protein adsorption and to observe the effect of surface protein concentration on thrombogenicity. The thrombogenicity of a surface was determined by the composition of the initial protein layer rather than the total concentration of protein on the polymer surfaces. The composition of this layer determines the extent of platelet activation and the adhesive strength between platelets and the polymer surface.

An anti-i biphasic hemolysin in chronic paroxysmal cold hemoglobinuria

Paroxysmal cold hemoglobinuria (PCH) was diagnosed in an elderly patient with a history of chronic lymphocytic leukemia. In this case, the Donath-Landsteiner antibody demonstrated anti-i specificity rather than the more commonly reported anti-P specificity. This unusual case of a biphasic hemolysin with anti-i specificity emphasizes the importance of performing a Donath-Landsteiner test when presented with serological or clinical findings that are suggestive of PCH.

The influence of preadsorbed canine von Willebrand factor, fibronectin and fibrinogen on ex vivo artificial surface-induced thrombosis

We have examined the effects of preadsorption of several canine plasma proteins on surface-induced thrombogenesis in a canine ex vivo model. Our technique allowed determination of initial deposition and subsequent embolization of 51Cr-labeled platelets and 125I-fibrinogen onto and from polymeric arterio-venous shunts in non-anticoagulated canines. Segments of the tubing were removed at various time points between 2 and 120 minutes of blood contact for examination of the morphology of the thrombus by scanning electron microscopy. Thrombus deposition was measured on uncoated plasticized poly(vinyl chloride) (PVC) and PVC precoated with canine von Willebrand factor (vWF), fibronectin, partially purified fibrinogen (fibrinogen which contained vWF and fibronectin as impurities), or purified fibrinogen (fibrinogen which had been further purified to remove fibronectin and vWF). Preadsorption of all proteins studied enhanced the thrombogenic response relative to that of the uncoated surface. Precoating with vWF or partially purified fibrinogen resulted in the deposition of the greatest number of thrombi, and embolization was slower than on shunts precoated with canine fibronectin or purified fibrinogen. The deposition-embolization profiles for the fibronectin and purified fibrinogen-coated surfaces were similar. The amount and time sequence of initial adhesion and spreading of platelets was related to the extent and time sequence of peak thrombus formation. The partially purified fibrinogen-coated and vWF-coated surfaces had more adhered and spread platelets at the earliest time points and a greater number of larger thrombi at the peak deposition times. The slowest rate of platelet adhesion and spreading was seen on the purified fibrinogen-coated surface. White blood cells were present very early on surfaces precoated with vWF and partially purified fibrinogen, and were present prior to embolization on all surfaces. Major conclusions from this work indicate that, although fibrinogen and fibronectin promote thrombogenesis when adsorbed to a surface, vWF is even more active in promoting platelet deposition and in anchoring thrombi to the surface of biomaterials. Thus, differences in vWF adsorption to biomaterials may be a determinant of surface-induced thrombogenesis.

[Combination chemotherapy with cyclophosphamide, adriamycin, vincristine and prednisolone (VEPA) for non-Hodgkin's lymphoma]

Combination Chemotherapy with Adriamycin (VEPA) was applied to 16 patients with non-Hodgkin's lymphoma. The effects of VEPA therapy were compared with those of combination chemotherapy without Adriamycin (non-VEPA). Complete remission rate achieved with VEPA therapy was 37.5% while that with non-VEPA therapy was 27.6%. Histologically, the complete remission rate in cases of large-cell type treated with VEPA therapy was 40%, while that with non-VEPA therapy was 14.3%. No cases of stage IV showed complete remission, whereas the complete remission rate for cases of stage III was 37.5% for VEPA therapy, but 27.6% for non-VEPA therapy. From these results we concluded that VEPA therapy is more effective for non-Hodgkin's lymphoma, especially large-cell type, than non-VEPA therapy.

Simplified separation of myosin from rabbit liver

Myosin was extracted from fresh rabbit liver using a solution with an ionic strength of 0.3 with two protease inhibitors and ATP. The myosin fraction was centrifuged at high speed in the presence of ATP and MgCl2. Its precipitate was dissolved in 0.6 M KCl, and the solution was treated with ammonium sulfate (30-60%). The fraction that precipitated was dissolved in 0.6 M KCl and put on a Sephacryl column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the myosin obtained was 90% pure. Its molecular weight was 220,000 by gel electrophoresis; by Sephacryl S-300 column chromatography, it was found to be a complex at high ionic strengths. The protein had high ATPase activity, comparable to that of the myosin prepared by D. L. Brandon (1976, Eur. J. Biochem. 65, 139-146). Electron micrographs of our myosin looked like myosins from nonmuscle cells purified by other workers. Slow preparation gave poor yields of myosin with low ATPase activity and extra bands on SDS-PAGE. Rapid handling of fresh materials is essential for obtaining myosin of satisfactory quality. Our simple method saves time and reagents.

[High dose of methotrexate-leucovorin treatment in advanced non-Hodgkin's lymphoma]

High doses of methotrexate (MTX) and leucovorin (LCV) as a rescue treatment were applied to five patients with non-Hodgkin's lymphoma, refractory to standard combination chemotherapy. Two of 5 patients showed a complete remission, and 2 patients showed a partial remission. One patient with massive pleural effusion showed an improvement by the treatment without any severe side effect under monitoring and controlling the dose of MTX. However, the remission duration of the treatment was short; therefore, additive therapy was required of later. From these results we assumed that the high dose of MTX and LCV could be effective for malignant lymphoma being resistant to other combination therapies.