Hyperlipidemia: a novel etiologic factor in deep vein thrombosis

The possible association of hyperlipidemia and deep vein thrombosis (DVT) was investigated in 59 consecutive patients. The incidence of hyperlipidemia, judged by the value of serum total cholesterol and triglyceride, was unexpectedly high (overall 59%, high total cholesterol alone 25%, high triglyceride alone 9%, combined 25%), as compared with 29% of the control (p < 0.001). The idiopathic DVT patients (without known etiologic factors) had a higher incidence of hypercholesterolemia (63%) than the normal subjects (20%, p = 0.0002). The idiopathic DVT patients showed higher total cholesterol level of 255 +/- 72 mg/dl than that of 194 +/- 36 in the control subjects (p < 0.0001). And 67% of the idiopathic DVT patients were hyperlipidemic. Thereby, hyperlipidemia may be an important etiologic factor in DVT, which has not been recognized previously. The low incidence of DVT in Asians may, thus, be attributable to their lower cholesterol level.

Molecular cloning of cytidine monophospho-N-acetylneuraminic acid hydroxylase. Regulation of species- and tissue-specific expression of N-glycolylneuraminic acid

Cytidine monophospho-N-acetylneuraminic acid (CMP-NeuAc) hydroxylase, which is the key enzyme for the synthesis of N-glycolylneuraminic acid (NeuGc), has been purified from the cytosolic fraction of mouse liver, as described in our previous paper. The amino acid sequences of the purified CMP-NeuAc hydroxylase, and peptides obtained by lysylendopeptidase digestion, were used to synthesize specific oligonucleotide primers. A mouse cDNA clone of the enzyme was obtained by a combination of the polymerase chain reaction and rapid amplification of cDNA ends. The sequence of the clone contained an open reading frame coding for a protein of 577 amino acids with a predicted molecular mass of 66 kDa. The deduced sequence included the amino acid sequences obtained for the purified enzyme and peptides, and a complete match was obtained for 159 residues. The enzyme has neither a signal peptide sequence nor a membrane spanning domain, which is consistent with localization of the enzyme in the cytosol. Transfection of a cDNA construct to COS-1 cells increased the enzyme activity and the amount of NeuGc. Comparison of the sequence with GenBank data indicated that no similar sequence has been reported so far. Northern blot analysis of various mouse tissues with the enzyme cDNA as a probe indicated that expression of NeuGc is related to the level of CMP-NeuAc hydroxylase mRNA. On Southern blot analysis with the same probe, cross-hybridizing bands were detected in the human and fish genomes.

Genomic organization of 251 kDa acetyl-CoA carboxylase genes in Arabidopsis: tandem gene duplication has made two differentially expressed isozymes

Acetyl-CoA carboxylase (ACCase) catalyzes the carboxylation of acetyl-CoA, forming malonyl-CoA a key intermediate in the biosynthesis of fatty acids and a variety of secondary metabolites. Based upon amino acid sequences conserved among rat, chicken, and E. coli ACCases, PCR-primers were used to amplify a genomic fragment which codes for an ACCase of Arabidopsis. The resulting fragment was used for isolation of genomic and cDNA clones. We have determined the complete cDNA sequence coding for an Arabidopsis ACCase consists of 2,254 amino acids with the molecular mass of 251 kDa. This enzyme contains no recognizable plastid transit-peptide sequence. Therefore, this ACCase is presumably the cytosolic isozyme. Southern analysis indicates that there are two ACCase genes in the Arabidopsis genome. Surprisingly, the results of RFLP analysis and physical mapping of the isolated genomic clones demonstrate that these two genes, acc1 and acc2, are contiguously located within a 25-kbp genomic region near the middle of chromosome 1. Both genes are transcriptionally active, as transcripts from each gene were detected by reverse transcription-PCR analysis using gene-specific primers. The acc1 and acc2 transcripts accumulate in leaves and seedlings but only the acc1 transcript accumulates in developing siliques, unexpectedly. The differences in the expression patterns may be indicative of the differential role of the two genes.

Iv gamma globulin treatment of Kawasaki disease in Japan: results of a nationwide survey

The administration of i.v. gamma globulin (IVGG) for Kawasaki disease was investigated throughout Japan in 1993 by obtaining information from the pediatric departments of 2652 hospitals with more than 100 beds. A total of 1826 hospitals (68.9%) responded, reporting on 11,221 patients who were diagnosed during the survey period from January 1991 to December 1992. There were 8958 patients (79.8%) who received IVGG treatment. The most common treatment modality was 200 mg/kg (29.6%), followed by 400 mg/kg (18.7%) and 300 mg/kg (12.9%), all for 5 days. The distributions of total dose were: 1000 mg/kg or less, 45.7%; 1001-1500 mg/kg, 27.3%; and over 1500 mg/kg, 23.8%. For all patients to whom IVGG was administered, treatment was started in 53.8% by day 5 of illness and in 86.1% by day 7. The proportion of those with cardiac sequelae was higher in patients who were treated with IVGG, possibly due to the fact that those who were more severely affected were more likely to be treated with IVGG.

A case of extrahepatic portal vein aneurysm accompanying lupoid hepatitis

Portal vein aneurysm, especially that of the extrahepatic portal vein, is a very rare entity. We recently observed a case of aneurysm at the junction of the superior mesenteric vein and the splenic vein which accompanied lupoid hepatitis. Abdominal ultrasonography, color Doppler ultrasonography, abdominal computed tomography (CT), magnetic resonance imaging (MRI), and angiography revealed a portal vein aneurysm that increased in size after a period of about 10 months.

Results of 12 nationwide epidemiological incidence surveys of Kawasaki disease in Japan

OBJECTIVE

To describe the long-term trend of incidence and other epidemiological pictures of Kawasaki disease in Japan, by using the results of 12 nationwide epidemiological surveys on Kawasaki disease that have been conducted throughout Japan (ie, surveys that have encompassed the pediatric departments of hospitals with more than 100 beds) every 2 years since 1970.

RESULTS

At the end of December 1992, the total number of patients with this disease was 116,848 (males, 67,815; females, 49,033; male-female ratio, 1.38). The number of cases increased year by year, with three outbreaks in 1979, 1982, and 1986. There have been no cyclical changes since 1986. The incidence was higher in males and in those children who were 1 year of age or younger. The fatality rate decreased from 1% in 1974 to 0.04% in 1992.

CONCLUSIONS

The patterns of descriptive epidemiology, such as seasonality and cyclical changes in incidence, supported the theory of an infectious agent as the causal agent. However, the incidence data since 1986 provide less support for an infectious theory.

Tokaracetin, a new platelet antagonist that binds to platelet glycoprotein ib and inhibits von Willebrand factor-dependent shear-induced platelet aggregation

A new platelet antagonist, tokaracetin, was isolated from the venom of Trimeresurus tokarensis by ion-exchange chromatography, heparin-Sepharose chromatography and hydrophobic HPLC. The purified protein showed an apparent molecular mass on SDS/PAGE of 28.9 kDa under non-reducing conditions. On reduction, 16.1 and 15.4 kDa subunits were observed, suggesting that the molecule is a heterodimer. Tokaracetin inhibited the binding of 125I-labelled bovine von Willebrand factor (vWF) and 125I-labelled human vWF in the presence of botrocetin to fixed human platelets. It did not block ADP-, collagen- or thrombin receptor agonist peptide-induced platelet aggregation in human platelet-rich plasma (PRP), or induce platelet agglutination in PRP. On reduction, tokaracetin lost its inhibitory activity on the agglutination of fixed human platelets by bovine vWF. 125I-Tokaracetin specifically bound to washed human platelets with high affinity (Kd 3.9 +/- 1.4 nM) at 47,440 +/- 2780 binding sites per platelet. Binding of tokaracetin to fixed human platelets was reversible, and was inhibited by monoclonal antibody GUR83-35, which is directed against the N-terminal vWF-binding domain of human glycoprotein Ib (GPIb). Tokaracetin completely inhibited vWF-dependent shear-induced platelet aggregation in PRP at 3 micrograms/ml. The N-terminal amino acid sequences of tokaracetin subunits showed a high degree of identity with those of alboaggregin-B. These results suggest that this new platelet antagonist may be a useful tool in the development of specific inhibitors of the vWF-GPIb interaction.

Serine palmitoyltransferase is the primary target of a sphingosine-like immunosuppressant, ISP-1/myriocin

ISP-1/myriocin is a new type of remarkably potent immunosuppressant, the structure of which is homologous to sphingosine. ISP-1/myriocin inhibited the proliferation of an IL-2-dependent mouse cytotoxic T cell line, CTLL-2, at nanomole concentrations. ISP-1/myriocin inhibits serine palmitoyltransferase activity at picomole concentrations. This enzyme catalyzes the first step of sphingolipid biosynthesis and reduces the intracellular pool of sphingolipid intermediates. The growth inhibition induced by ISP-1/myriocin was completely abolished by the addition of sphingosines or sphingosine-1-phosphate, but not by sphingomyelin or glycosphingolipids. These results suggest that sphingosines or sphingosine-1-phosphate are associated with CTLL-2 proliferation, and ISP-1/myriocin suppresses T cell proliferation by the modulation of sphingolipid metabolism. ISP-1/myriocin should be a useful tool for the study of the sphingolipid pathway, which has been associated with various kinds of signal transduction.

Antithrombotic effect of a humanized anti-GPIIb/IIIa monoclonal antibody, YM207, in a photochemically induced thrombosis model in monkeys

We investigated the antithrombotic effects of a F(ab')2 fragment of a humanized anti-platelet glycoprotein (GP) IIb/IIIa monoclonal antibody, YM207, in a platelet-rich thrombosis model. Thrombus was induced in a mesenteric venule of squirrel monkeys by irradiation with filtered light in combination with i.v. administration of a fluorescent dye (sodium fluorescein). Time to occlusive thrombus formation was significantly prolonged by i.v. bolus injection of 0.3 mg/kg of YM207. At doses of 1 mg/kg and 3 mg/kg, complete occlusion did not occur during 60 min of the observation. Platelet aggregation in platelet-rich plasma was inhibited by YM207 at doses 0.3 mg/kg or more. A good correlation was obtained between inhibition of platelet aggregation and the percentage of GPIIb/IIIa receptors blocked by YM207. Bleeding time was significantly prolonged at a dose of 3 mg/kg. Platelet counts showed no significant change. These results suggest that YM207 is effective in preventing platelet-rich thrombus formation without inducing the prolongation of bleeding time or a significant decrease in platelet count. YM207 may be a useful therapeutic agent for the treatment of thrombotic disorders.

Flavocetin-A and -B, two high molecular mass glycoprotein Ib binding proteins with high affinity purified from Trimeresurus flavoviridis venom, inhibit platelet aggregation at high shear stress

Two high molecular mass proteins, flavocetin-A and flavocetin-B, were purified from Trimeresurus flavoviridis venom. On polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, the apparent molecular mass of flavocetin-A and -B were 149 and 139 kDa, respectively, under nonreducing conditions. On reduction, flavocetin-A showed two distinct subunits (17 and 14 kDa), and flavocetin-B three distinct subunits (17, 15 and 14 kDa). At 1 microgram/ml, flavocetin-A and -B (flavocetins) inhibited the von Willebrand factor (vWF)-dependent aggregation of fixed human platelets. However, flavocetins (10 micrograms/ml) had no effect on ADP- and collagen-induced platelet aggregation in PRP. Flavocetins (3 micrograms/ml) also inhibited shear-induced platelet aggregation at high shear stress. Furthermore, flavocetin-A completely inhibited the aggregation of and ATP release from washed platelets stimulated with a low concentration of thrombin. Flavocetin-A specifically bound to platelet with high affinity (Kd = 0.35 +/- 0.13 nM) at 21,500 +/- 1760 binding sites per platelet. The N-terminal amino acid sequences of the subunits of flavocetin-A show a high degree of homology with those of echicetin, botrocetin, alboaggregin-B and factor IX/factor X-binding protein. These results suggest that flavocetins may be a useful tool for further investigation of the GPIb-vWF interaction.

Structure, organization, and chromosomal location of the gene encoding a form of rice soluble starch synthase

A rice (Oryza sativa L.) genomic clone encoding the gene for a form of soluble starch synthase (SSS1) and its 5'- and 3'-flanking regions has been isolated and sequenced. The SSS1 gene contained 15 exons interrupted by 14 introns. The exon/intron organization of the SSS1 gene was divergent from that of the rice Waxy gene coding for granule-bound starch synthase, thus suggesting that the SSS1 and granule-bound starch synthase genes have evolved from an ancestral gene in a different way or that the two genes are products of different ancestral genes that have converged during evolution. However, these two genes were closely located to each other on rice chromosome 6 at an approximate map distance of 5 centimorgans. The nucleotide sequence of the 5'-end region of the gene is unique because of the presence of some repetitive sequences.

A novel resin glycoside, merremin (tuguajalapin X dimer), from Merremia hungaiensis

A novel resin glycoside, merremin (1), has been isolated from the root of Merremia hungaiensis (Convolvulaceae). The structure has been determined to be an ester-type dimer of tuguajalapin X (2) on the basis of chemical and spectral data.

Synthesis and antitumor activities of glycine-exchanged analogs of spicamycin

A series of SPM VIII analogs were synthesized to investigate the effect of the amino acid moiety on the antitumor activity. The L-threonine analog and the glycylglycine analog of SPM VIII showed much higher cytotoxicity to P388 murine leukemia cells (IC50 5.8 nM and 0.11 nM, respectively) than SPM VIII (IC50 25nM). However, replacement of the glycine moiety with other amino acids greatly reduced the antitumor activity against COL-1 human colon cancer xenograft model. This study indicated that the glycine moiety of SPM VIII is crucial for the antitumor effect.

The differences in structural specificity for recognition and binding between asialoglycoprotein receptors of liver and macrophages

The Gal/GalNAc-specific lectin on the surface of rat peritoneal macrophages (macrophage asialoglycoprotein binding protein, M-ASGP-BP), which consists of a single polypeptide chain of 42 kDa, can form a homo-oligomeric receptor exhibiting high affinity for asialoorosomucoid (ASOR) [Ozaki K., Ii M., Itoh N., Kawasaki T. (1992) J Biol Chem 267: 9229-35]. In this study, the binding affinity of M-ASGP-BP was studied by using a series of synthetic or natural glycosides as inhibitors of 125I-ASOR binding to recombinant M-ASGP-BP expressed on COS-1 cells (rM-ASGP-BP), and the results were compared with those of human hepatic lectin (HHL) on Hep G2 cells. Clustering of multiple Gal (or GalNAc) residues increased the binding affinity to M-ASGP-BP as well as to HHL. In contrast to HHL and other mammalian hepatic lectins, rM-ASGP-BP bound Gal residues tighter than GalNAc residues. A galactose-terminated triantennary N-glycoside, having one N-acetyl-lactosamine unit on the 6 branch and two N-acetyl-lactosamine units on the 3 branch of the trimannosyl core structure, showed affinity enhancement of approximately 10(5) over a monovalent ligand for HHL, while the same glycopeptide showed enhancement of about 2000-fold for rM-ASGP-BP. These results suggest that spatial arrangements of sugar combining sites and subunit organization of macrophage and hepatic lectins are different.

Dissecting thoracic aorta and fusiform aneurysm of the abdominal aorta

A 59-year-old woman with dissection of the thoracic aorta and a fusiform aneurysm of the abdominal aorta without evidence of Marfan's syndrome underwent aneurysmorrhaphy with a bifurcated expanded polytetrafluoroethylene graft. Histological specimens of the aneurysmal wall revealed the presence of idiopathic cystic medial necrosis. As typical findings of idiopathic cystic medial necrosis in the aortic wall are very rare except in cases of Marfan's syndrome, the present case is reported and the implications of this condition are discussed.

DIDS binding 30-kDa protein regulates the calcium release channel in the sarcoplasmic reticulum

The gating properties of the Ca2+ release channel in the heavy fraction of the sarcoplasmic reticulum (HSR) was monitored by measuring the choline permeation through the channel using a light scattering method. The choline permeation was increased by the treatment of the HSR vesicles with 4,4'-diisothiocyano-stilbene-2,2'-disulfonic acid (DIDS), and this effect was only observed at low extravesicular Ca2+ concentrations. This result indicates that DIDS locked the Ca2+ channel at the open state. An SDS-PAGE of the junctional face membrane (JFM) that was treated with 3H2-DIDS showed that 3H2-DIDS binding protein is not the Ca2+ release channel but the 30 kDa protein. Furthermore, it was found that this 30 kDa protein is also one of the calsequestrin interacting proteins. These results suggest that this 30 kDa protein regulates the Ca2+ release channel.

The sulphated carbohydrate-protein linkage region isolated from chondroitin 4-sulphate chains of inter-alpha-trypsin inhibitor in human plasma

Inter-alpha-trypsin inhibitor (ITI) in human plasma has a unique structural architecture composed of three polypeptide chains (H1, H2 and L chains), which are linked to each other through a chondroitin 4-sulphate chain. The structure of the carbohydrate-protein linkage region of the chondroitin 4-sulphate chain attached to the L chain was investigated. The peptide-chondroitin sulphate fraction was isolated by anion-exchange chromatography after exhaustive digestion with lysyl endopeptidase and then V8 protease. The chondroitin 4-sulphate chain was released from the peptides by beta-elimination using NaB3H4 and then digested with chondroitinase ABC. These treatments resulted in a single 3H-labelled hexasaccharide alditol fraction derived from the linkage region which had been associated with the L chain. Chemical and enzymatic analyses as well as fast-atom bombardment-mass spectrometry (FAB-MS) analysis revealed that the 3H-labelled hexasaccharide alditol had the following structure: delta HexA-alpha 1-3GalNAc(4-sulphate)beta 1-4GlcA beta 1-3Gal(4-sulphate)beta 1-3Gal beta 1-4Xyl-ol (where delta HexA is 4-deoxy-alpha-L-threo-hex-4-enepyranosyluronic acid and Xyl-ol is xylitol). The structure contained the novel 4-sulphated Gal residue, which was previously demonstrated in a linkage hexasaccharide isolated from chondroitin 4-sulphate of rat chondrosarcoma (Sugahara et al., J. Biol. Chem., 263, 10168-10174, 1988) and of whale cartilage (Sugahara et al., Eur. J. Biochem., 202, 805-811, 1991). The above disulphated hexasaccharide alditol was the only component detected in the linkage region fraction of the chondroitin 4-sulphate chain of ITI, which implies some biological significance of this novel structure.

An infection-resistant PTFE vascular graft; spiral coiling of the graft with ofloxacin-bonded PTFE thread

OBJECTIVE

To develop an infection-resistant polytetrafluoroethylene (PTFE) vascular graft for potential clinical use in grafting in sites of bacterial contamination and in replacement of the infected grafts.

SETTING

Experimental study in rabbits.

MATERIALS AND METHODS

An antibiotic ofloxacin (OFLX) was bonded to a sheet of PTFE by impregnation, which was cut and twisted into fine threads. The in-vitro antibacterial activity of OFLX-PTFE thread was determined by measuring the zone of growth inhibition against Escherichia coli. The thread was spirally coiled around a ridged outerwall PTFE to make the OFLX-PTFE graft. OFLX-PTFE graft or control graft was interposed in the inferior vena cava (IVC) of rabbits and the entire graft was covered with fibrin containing a fixed number of E. coli. Three or 7 days after the grafting, the grafts with perigraft tissue were harvested and subjected to bacteriological studies.

RESULTS

In spite of early phase rapid elution of OFLX, a significant antibacterial activity was retained for more than 2 weeks. The antibacterial activity of OFLX-PTFE threads implanted in the subcutaneous space of rabbits decreased to 48% after 24 h and to approximately 1% after a week. The swab culture of all the control grafts was positive, while only one of 13 PTFE-OFLX grafts was positive. The number of viable bacteria in the perigraft tissue of OFLX-PTFE grafts was remarkably low in comparison with that of control grafts. Thus, the OFLX-PTFE grafts exhibited a marked in-vivo antibacterial activity.

CONCLUSION

By a unique method, it was possible to furnish PTFE graft with an excellent infection-resistant property, without affecting the original biological behaviour.

Cytoskeletal reorganization of human platelets induced by the protein phosphatase 1/2 A inhibitors okadaic acid and calyculin A

Okadaic acid (OA) and calyculin A (CLA), which are potent and specific inhibitors of serine/threonine protein phosphatases type 1 and 2A, have been shown to induce drastic changes in platelet morphology. The aim of this study was to analyse the molecular mechanisms of OA- or CLA-induced cytoskeletal reorganization, with a specific focus on microtubules and actin filaments. Confocal fluorescence microscopy revealed that OA or CLA altered the distribution of microtubules from marginal band arrangements to homogeneous patterns, consistent with the transmission-electron-microscopic finding that microtubules were fragmented and redistributed into pseudopod-like processes. In thrombin-activated platelets, OA or CLA induced extremely long pseudopods containing an array of microtubules and actin filaments, and a condensed mass of actin filaments in the centre of platelets. OA or CLA induced the constriction of actin filaments without an increase in filamentous (F)-actin, and also rather significantly inhibited actin polymerization in thrombin-activated platelets. Furthermore, neither OA or CLA enhanced phosphorylation of myosin light chain (MLC). By immunoprecipitation of platelet lysate with anti-alpha-tubulin antibody, a 90 kDa protein was co-precipitated with tubulin and was predominantly phosphorylated in the presence of OA. As the time-dependent phosphorylation of 90 kDa protein correlated well with the reorganization of microtubules, these data suggest that phosphorylation and dephosphorylation of this protein might play a role in the regulation of microtubule organization. These findings indicate that OA or CLA induces reorganization of microtubules and actin filaments via the phosphorylation of a microtubule-associated 90 kDa protein and an MLC-phosphorylation-independent mechanism. mechanism.

Unique form of rickets with low serum 25-hydroxyvitamin D in two normally nourished children

We present an unusual type of rickets involving two children: a 2 year old boy and a 15 month old boy, who presented with marked bowing of the lower extremities and bulging of costochondral junctions. Both children had normal growth, with their height and body weight greater than the 50th and 97th percentile for age. Roentgenograms of their extremities showed the typical changes of vitamin D refractory rickets. Serum alkaline phosphatase levels were elevated and serum levels of calcium and phosphate were both within the normal range. No primary cause for the rickets, including nutritional deficiencies, was found in the two patients. Characteristic findings were persistently low serum 25-hydroxyvitamin D (25-OH-D) and normal 1,25-dihydroxyvitamin D (1,25-(OH)2-D). Improvements in clinical and X-ray findings were observed after either oral administration of 1 alpha-(OH)-D3 (9-15 micrograms per day) or massive vitamin D2 therapy (600,000 IU single injection). The low serum levels of 25-OH-D did not increase unless massive vitamin D2 therapy was also given. These two cases represent a unique form of rickets that does not meet the criteria for any type of previously known rickets.

Effects of phenylephrine and prostaglandin E1 on ventriculo-arterial matching during halothane anaesthesia

We have investigated the effects of phenylephrine alone and combined with prostaglandin E1 (PGE1) on ventriculo-arterial matching during halothane anaesthesia in dogs. The ratio of left ventricular end-systolic elastance (Ees) to effective arterial elastance (Ea) was used as an index of ventriculo-arterial matching. In group 1 (n = 7), measurements were performed at control, 1.5% halothane, halothane+phenylephrine 1-10 micrograms kg-1 min-1, and halothane+phenylephrine+PGE1 0.2-1.0 or 1.0-2.0 micrograms kg-1 min-1. In group 2 (n = 5), dobutamine 2 and 5 micrograms kg-1 min-1 was infused during halothane anaesthesia. Halothane 1.5% decreased mean arterial pressure (MAP), cardiac output and Ees. Phenylephrine restored MAP, but further decreased cardiac output. The decrease in Ees produced by halothane was reversed by phenylephrine. PGE1 increased cardiac output and reversed the increases in Ea and Ea/Ees during phenylephrine infusion. Dobutamine also reversed halothane-induced decreases in MAP, cardiac output and Ees, and improved Ea/Ees. Our results indicate that combined use of PGE1 with phenylephrine can eliminate the vasoconstrictive property of phenylephrine, resulting in an improvement in ventriculo-arterial matching.

Impaired high-shear-stress-induced platelet aggregation in patients with chronic renal failure undergoing haemodialysis

We investigated shear-induced platelet aggregation (SIPA) in 30 patients with chronic renal failure (CRF) undergoing haemodialysis. 26 patients showed a significant decrease in SIPA at high shear stress but no change in SIPA at low shear stress. The former reaction reflects the interaction between plasma von Willebrand factor (vWF) and its platelet receptors, glycoprotein (GP) Ib-IX and IIb/IIIa complex, whereas the latter is assumed to involve the binding of plasma fibrinogen to GP IIb/IIIa complex. These SIPA profiles in CRF patients after haemodialysis showed almost no change compared to those before haemodialysis. The ratio of ristocetin cofactor/vWF antigen in plasma was slightly lower in CRF patients than in controls (P < 0.01). However, the level of GPIb antigen in the platelets of these patients was significantly reduced (42.1 +/- 20.3% of normal platelets), with partial destruction of GPIb antigen. The number of vWF receptors on the GPIb molecule was quantitated using the GPIb-binding protein alboaggregin-B (AL-B), purified from the snake venom of Trimeresurus albolabris. AL-B bound to GPIb at a total of 48,760 +/- 9944 molecules per normal platelet and a Kd of 85.44 +/- 15.70 nM at saturation. In contrast, binding in CRF platelets was 22,980 +/- 6395 molecules per platelet and Kd was 50.08 +/- 13.83 nM. Taking these results together, we conclude that the impaired SIPA found in CRF patients is due to both abnormalities in plasma vWF and in its platelet GPIb receptor.