ALBERT

Description: Type I von Willebrand disease (vWD) is characterized by equally low plasma concentrations of von Willebrand factor antigen (vWF:Ag) and ristocetin cofactor (RiCof) and by the presence of all vWF multimers in sodium dodecyl sulfate (SDS)-agarose gel electrophoresis. For 17 patients (13 kindreds) diagnosed with these criteria, we have studied the platelet contents of vWF:Ag and RiCof and the changes of these in plasma after DDAVP infusion. Platelet vWF:Ag and RiCof were normal in four kindreds (called “platelet normal” subgroup); following 1-deamino- 8-D-arginine vasopressin; plasma vWF:Ag, RiCof and the bleeding time (BT) became normal. In six kindreds, platelet vWF:Ag and RiCof were equally low (platelet low); after DDAVP, plasma vWF:Ag and RiCof remained low, and the BT was prolonged. In three additional kindreds, platelets contained normal concentrations of vWF:Ag, but RiCof was very low (platelet discordant); even though a complete set of multimers was found in plasma and platelets, there was a relatively small amount of large multimers. After DDAVP, plasma vWF:Ag became normal, but RiCof remained low and the BT was very prolonged. These findings demonstrated that there can be an abnormal vWF (RiCof less than vWF:Ag) even in type I vWD, coexisting with a complete set of vWF multimers (platelet discordant); that the abnormal vWF can be shown more clearly in platelets than in plasma or else in plasma after DDAVP infusion; and that DDAVP normalizes the BT only in those patients with normal platelet levels of both vWF:Ag and RiCof (platelet normal).

Description: To verify the clinical usefulness of extracellular cyclic nucleotide determination as a tumor marker, plasma cyclic AMP (cAMP) and cyclic GMP (cGMP) levels were measured in 70 normal subjects and 173 acute leukemia patients studied in different stages of their disease. Mean plasma cAMP levels were similar in leukemic and normal subjects, although in 48 patients in the active stage of the disease, first diagnosis, or relapse, the cAMP values were below the normal range, and most of these patients failed to respond to chemotherapy. Plasma cGMP levels were markedly elevated in untreated patients, normalized in all patients who attained complete remission, and increased promptly to pretreatment values in patients who relapsed, suggesting that their determination may be useful to monitor the patients' response to treatment.

Description: A patient with a lifelong bleeding disorder was diagnosed as having Type II von Willebrand disease. The larger multimers of von Willebrand factor were absent from her plasma but present in platelets. A high- resolution electrophoretic technique was used to study the complex structure of individual von Willebrand factor multimers. In normal plasma, each multimer could be resolved into five bands: a more intense central one and four less intense, two moving faster and two slower than the central band. In normal platelets, each multimer could also be resolved into five bands. The central one had a mobility similar to that in plasma, whereas the four satellite bands had a mobility that differed from that of the corresponding plasma bands. In the patient, platelet von Willebrand factor antigen content and ristocetin cofactor activity were normal, and von Willebrand factor showed the same structure of individual multimers as seen in normal platelets. On the other hand, plasma von Willebrand factor antigen and ristocetin cofactor activity were decreased, and the structure of individual von Willebrand factor multimers was different from that of normal plasma and similar to that seen in normal and patient's platelets. After infusion of 1-deamino-8-D-arginine vasopressin, the largest von Willebrand factor multimers, as well as new satellite bands with a mobility similar to those in normal plasma, appeared in the patient plasma, and the levels of von Willebrand factor antigen and ristocetin cofactor activity became normal. Yet no relevant change in the prolonged bleeding time was observed. This new variant of von Willebrand disease, therefore, is characterized by the presence of a dysfunctional von Willebrand factor molecule that exhibits unique structural abnormalities in plasma but appears to be normal in platelets. The designation of Type IIF is proposed for this type of von Willebrand disease in accordance with the terminology that has been previously used.

Description: In this cooperative study, we explored the role of the carbohydrate moiety (CHO) of von Willebrand factor (vWF) in supporting platelet adhesion. Because of previous discrepant results, all purification steps and CHO modifications by various enzymes were critically evaluated. Under our conditions, CHO-modified vWF preparations contained less than 5% of the initial sialic acid ([Neu]-ase-vWF) and less than 45% ([Neu-Gal]-ase-vWF) or 21% ([Neu-Gal-eF]-ase-vWF) of the D-galactose. These preparations usually showed increased electrophoretic mobility but no significant loss of high-mol-wt multimers when proteolysis had been prevented. Some degree of proteolysis was noted in some carbohydrate-modified vWFs, but the degree of degradation observed did not correlate with the removal of D- galactose. Platelet adhesion to various matrices increased after removal of the terminal sialic acid ([Neu]-ase-vWF) and approximately 45% of the D-galactose ([Neu-Gal]-ase-vWF), but returned to normal values when greater than 70% of the total carbohydrate had been removed by endoglycosidase F [Neu-Gal-ef]-ase-vWF). These changes in reactivity were also reflected in the spontaneous aggregation in normal platelet- rich plasma (PRP) after CHO removal.

Description: Platelet adhesion-aggregation reactions play an early and pivotal role in the pathogenesis of systemic sclerosis in scleroderma, but the mechanisms are incompletely understood. We determined whether or not plasma from 11 consecutive patients with scleroderma contained a subset of larger than normal (“supranormal”) multimers of von Willebrand factor (vWF) that are potent inducers of platelet aggregation and adhesion. Supranormal multimers were found in all patients on at least one of two different occasions 9 to 12 months apart, whatever the duration and severity of the disease, but in none of the normal controls. Administration of low-dose aspirin (40 mg) to five of the 11 patients for ten days to inhibit the platelet release reaction slightly reduced the amounts of supranormal multimers suggesting that they might originate in part from platelets. Supranormal multimers may contribute to the pathogenesis of systemic sclerosis by inducing platelet aggregation and enhancing adhesion to subendothelium under the conditions of elevated shear stress occurring in the partially occluded vessels of the arterial microcirculation of scleroderma.

Description: To examine whether enhanced in vivo proteolysis of von Willebrand factor (vWF) would account for the reported loss of larger multimers in acute thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), we studied eight patients with acute TTP/HUS whose blood samples were collected into an anticoagulant containing a cocktail of protease inhibitors to impede in vitro proteolysis. In all, enhanced proteolytic degradation of vWF was expressed as a relative decrease in the intact 225-Kd subunit of vWF and a relative increase in the 176-Kd fragment. However, instead of the loss of larger forms of normal multimers reported by other investigators, the plasma of all but one of our patients (whether they had TTP or HUS) contained a set of larger than normal (supranormal) multimers. Hence, although proteolytic fragmentation of vWF was enhanced during acute TTP/HUS, this phenomenon was not associated with the loss of larger multimers. In the five patients who survived the acute disease and underwent plasma exchange (three with HUS and two with chronic relapsing TTP), subunits and fragments returned to normal values, and supranormal multimers were no longer detected in plasma. In conclusion, even though vWF proteolysis is enhanced in acute TTP/HUS, it does not lead to loss of larger multimers.

Description: When normal volunteers or patients with type I von Willebrand disease (VWD) are given desmopressin (DDAVP), a set of larger-than-normal (supranormal) von Willebrand factor (VWF) multimers, similar to those present in VWF-containing cells such as platelets megakaryocytes and endothelial cells, appear transiently in postinfusion plasma. In two kindreds with mild lifelong bleeding symptoms transmitted as an autosomal dominant trait, all ten symptomatic members (but none of the five asymptomatic members) had a supranormal multimeric structure for plasma VWF, apparently identical to that seen for postdesmopressin normal plasma. Plasma factor VIII coagulant activity (VIII:C), VWF antigen (VWF:Ag), ristocetin-induced platelet agglutination, and ristocetin cofactor (RiCof) activity were low. Platelet VWF:Ag and RiCof levels (tested for three patients only) were normal. Bleeding times were normal or slightly prolonged. The patients' platelet multimeric structure was the same as that for normal platelets. After desmopressin infusion the plasma VWF multimeric structure remained supranormal as for preinfusion plasma, with VIII:C VWF:Ag and RiCof increasing markedly over baseline values and disappearing at a normal rate. Examination of the VWF subunit composition from three of these patients indicated that proteolytic processing of their VWF did not differ from normal. This study describes the first variant of VWD with a supranormal multimeric structure.

Description: The characteristics of a human cell line (LP-1) derived from the peripheral blood of a patient with IgG-lambda myeloma in leukemic transformation are described. The cells resemble immature plasma cells in that they exhibit a membrane phenotype that is intermediate between late B lymphocytes and plasma cells, even though they secrete IgG- lambda chains. Treatment of LP-1 cells with 12–0 tetradecanoylphorbol- 13-acetate (TPA) or pokeweek mitogen (PWM) induces the appearance of surface markers and ultrastructural features typical of mature plasma cells but does not affect their proliferative activity. Molecular analysis of the cell line showed an increased expression of the c-myc protooncogene and the presence of abnormally sized transcripts. Conventional cytogenetics and pulsed-field gel electrophoresis showed no structural rearrangements of the c-myc gene, suggesting that the abnormal c-myc expression may be due to point mutations or small deletions within the gene. The LP-1 cell line is a useful model in which to study the process of B-cell maturation; such study may lead to the uncovering of unusual mechanisms of c-myc activation. Furthermore, the LP-1 cell is a potential partner in the generation of human hybridomas.

Description: In this cooperative study, we explored the role of the carbohydrate moiety (CHO) of von Willebrand factor (vWF) in supporting platelet adhesion. Because of previous discrepant results, all purification steps and CHO modifications by various enzymes were critically evaluated. Under our conditions, CHO-modified vWF preparations contained less than 5% of the initial sialic acid ([Neu]-ase-vWF) and less than 45% ([Neu-Gal]-ase-vWF) or 21% ([Neu-Gal-eF]-ase-vWF) of the D-galactose. These preparations usually showed increased electrophoretic mobility but no significant loss of high-mol-wt multimers when proteolysis had been prevented. Some degree of proteolysis was noted in some carbohydrate-modified vWFs, but the degree of degradation observed did not correlate with the removal of D- galactose. Platelet adhesion to various matrices increased after removal of the terminal sialic acid ([Neu]-ase-vWF) and approximately 45% of the D-galactose ([Neu-Gal]-ase-vWF), but returned to normal values when greater than 70% of the total carbohydrate had been removed by endoglycosidase F [Neu-Gal-ef]-ase-vWF). These changes in reactivity were also reflected in the spontaneous aggregation in normal platelet- rich plasma (PRP) after CHO removal.

Description: Platelet adhesion-aggregation reactions play an early and pivotal role in the pathogenesis of systemic sclerosis in scleroderma, but the mechanisms are incompletely understood. We determined whether or not plasma from 11 consecutive patients with scleroderma contained a subset of larger than normal (“supranormal”) multimers of von Willebrand factor (vWF) that are potent inducers of platelet aggregation and adhesion. Supranormal multimers were found in all patients on at least one of two different occasions 9 to 12 months apart, whatever the duration and severity of the disease, but in none of the normal controls. Administration of low-dose aspirin (40 mg) to five of the 11 patients for ten days to inhibit the platelet release reaction slightly reduced the amounts of supranormal multimers suggesting that they might originate in part from platelets. Supranormal multimers may contribute to the pathogenesis of systemic sclerosis by inducing platelet aggregation and enhancing adhesion to subendothelium under the conditions of elevated shear stress occurring in the partially occluded vessels of the arterial microcirculation of scleroderma.