A case of thrombotic thrombocytopenic purpura refractory to plasma exchange

We experienced a case of thrombotic thrombocytopenic purpura (TTP) finally relieved after 74 sessions of plasma exchange (PE). The patient was a 56-year-old male. In August 1999, he was examined in emergency because of brown urine and a lowered level of consciousness. As TTP was suspected according to the laboratory findings of abnormally high lactate dehydrogenase and total bilirubin, decreased platelet counts, and numerous fragmented erythrocytes, he was admitted to the ICU of our hospital. Immediately after admission, PE was started consecutively. Upon concomitant use of antiplatelet drugs and prostacyclin, the level of platelet counts recovered to 100,000/microl once, but decreased again. Thus, in addition to the PE, prednisolone and vincristine were administrated, which elevated the level of platelet counts to 200,000 to 300,000/microl. Since the erythrocyte fragmentation was noted frequently, PE was continued twice a week. From the 60th day of admission onward, however, his body temperature rose above 40 degrees C with a rapid increase of C-reactive protein. A blood culture detected methicillin-resistant Staphylococcus aureus (MRSA) which derived from a left lung abscess. During the course of anti-MRSA treatment, he presented acute renal failure and acute hepatic dysfunction, but survived because of the combined therapy. He was discharged on the 180th day of admission. These results suggest that a combined therapy of steroid and vincristine is effective to treat TTP refractory to PE, but careful attention should be paid to the complications caused by immunosuppression.

A new method for removal of albumin-binding uremic toxins: efficacy of an albumin-dialysate

It is difficult for conventional hemodialysis to remove albumin-binding uremic toxins (ABUTs) even though they are low molecular weight substances. We investigated the efficiency of albumin-dialysate (AD) for removal of ABUT. Phenols and indoxyl sulfate were selected as ABUT. In vitro dialysis was performed for 2 h in the closed circuit with ABUT containing plasma as a test solution using conventional dialysate (CD) or AD. By the use of CD, the ABUT concentration in the test solution only was reduced by 20 to 30%. On the other hand, AD caused a marked reduction and an increase in test solution and dialysate concentration of ABUT, respectively. ABUT in AD could be adsorbed effectively by activated-charcoal column; accordingly, the ABUT concentration in the test solution continued to decrease throughout the study period. These results suggest that AD could remove ABUT more efficiently than CD, and AD may be useful for reducing accumulated ABUT levels.

A case of factor VIII inhibitor-positive acquired hemophilia treated by plasmapheresis

We report on a case of factor VIII inhibitor-positive acquired hemophilia in which combined therapy of plasma exchange (PE) and steroids was effective. The patient, a 68-year-old man, had undergone hemodialysis since April 1998, due to chronic renal failure caused by diabetic nephropathy. The hemostasis of blood access sites gradually became difficult after the initiation of dialysis and the prolongation of activated partial thromboplastin time (APTT) (74.5 s), and a decrease in factor VIII (0.02%) and an abnormally high concentration of factor VIII inhibitor (111 U/ml) were found. Under the diagnosis of factor VIII inhibitor-positive acquired hemophilia, 3 consecutive PE were performed, followed by a large dose administration of gamma globulin. However, the effect of this therapy disappeared within 20 days. Then the PE therapy was performed again accompanied by pulse methylprednisolone therapy. After that, factor VIII inhibitor was suppressed and the patient's hemostatic defect continued to improve even after the reduction of the steroid dose. These results suggest that PE is very effective in treating factor VIII inhibitor-positive acquired hemophilia.

Effects of trapidil and suramin on growth factor-induced calcium response and tyrosine phosphorylation in human glioma cells

Platelet-derived growth factor (PDGF) and epidermal growth factor (EGF) induce the proliferation of glioma cells in vitro. Trapidil and suramin inhibit this growth factor-stimulated glioma cell growth, but the mechanisms are not fully understood. The effects of trapidil and suramin on PDGF- and EGF-induced early biochemical events in T98G cells were studied. PDGF induced a rapid increase of intracellular free calcium concentration ([Ca2+]i) in fura-2/acetoxymethyl ester-loaded single glioma (T98G) cells. This increase was completely inhibited by removal of extracellular Ca2+ with ethylene glycol bis(beta-aminoethyl ether)-N,N,N,N-tetraacetic acid but not by an L-type calcium channel blocker (nicardipine), suggesting that PDGF may cause calcium influx through voltage-independent calcium channels in T98G cells. Trapidil and suramin blocked the PDGF-induced calcium response and inhibited the PDGF-initiated tyrosine phosphorylation of the PDGF receptor as detected by Western blot analysis using an antibody specific for phosphotyrosine. Trapidil and suramin also inhibited EGF-initiated calcium response in T98G cells, but only partially inhibited EGF-initiated tyrosine phosphorylation at the same concentrations. Our results suggest that trapidil and suramin inhibit PDGF- and EGF-initiated early biochemical events, and thus suppress growth factor-induced cell proliferation.

[Experimental study on secondary living bone graft--method of creating new donor by vascular bundle implantation to isolated bone]

The purpose of this study was to demonstrate the possibility of creating a new donor for a vascularized bone graft by a vascular bundle implantation to an isolated bone. Preliminary experiments on rats were performed preliminarily in order to investigate the revascularization of bone by a vascular bundle implantation and/or by implanting in muscular tissues (experiment-1). When a vascular bundle was implanted to the intramedullary cavity of an isolated bone and then the bone was implanted in muscular tissues, the isolated bone was more readily revascularized and revitalized than under other conditions. In experiment-2, the revascularized bone was transferred to the abdominal subcutaneous space on the vascular pedicle that was an implanted vascular bundle. Histologic and fluorochrome bone labeling studies showed that the revascularized bone was kept revitalized after the transfer. These results demonstrate that muscle and vascular bundle co-operated effectively in the revascularization of bone. Vascular bundle can also act as a pedicle for transferring the revascularized bone.