Electron microscopy examination of platelet whole mount preparations to quantitate platelet dense granule numbers: Implications for diagnosing suspected platelet function disorders due to dense granule deficiency.

INTRODUCTION: Dense granule (DG) deficiency (DGD) is a feature of some platelet function disorders (PFD) with a prevalence similar to von Willebrand disease. Most laboratories assess for DGD using whole mount platelet preparations and electron microscopy (EM). We evaluated our experiences with this test and associations between DGD and bleeding. METHODS: Dense granule EM records for 2006-2017 were examined for patients and simultaneously tested controls, and for an overlapping PFD study cohort to evaluate findings and their relationship to bleeding. RESULTS: More patient than control samples had reduced DG counts (6.5% vs 0.3%, P < .01). DG counts showed no relationship to age or mean platelet volume and had acceptable within-subject variability that was higher for DGD than control participants (28% vs 12%). Repeat tests confirmed DGD in all persons with initial DG counts <4.0/platelet, but not in those with less severe reductions (4.0-4.8 DG/platelet) or normal DG counts (≥4.9 DG/platelet). Aggregometry and adenosine triphosphate release tests, respectively, had only ~52% and 70% sensitivity for DGD. Confirmed DGD by EM was associated with higher bleeding scores and a bleeding disorder. CONCLUSION: Whole mount EM is useful for the evaluation of suspected PFD due to DGD and detects abnormalities associated with bleeding.

Genome-wide association study of alcohol consumption and genetic overlap with other health-related traits in UK Biobank (N=112 117).

Alcohol consumption has been linked to over 200 diseases and is responsible for over 5% of the global disease burden. Well-known genetic variants in alcohol metabolizing genes, for example, ALDH2 and ADH1B, are strongly associated with alcohol consumption but have limited impact in European populations where they are found at low frequency. We performed a genome-wide association study (GWAS) of self-reported alcohol consumption in 112 117 individuals in the UK Biobank (UKB) sample of white British individuals. We report significant genome-wide associations at 14 loci. These include single-nucleotide polymorphisms (SNPs) in alcohol metabolizing genes (ADH1B/ADH1C/ADH5) and two loci in KLB, a gene recently associated with alcohol consumption. We also identify SNPs at novel loci including GCKR, CADM2 and FAM69C. Gene-based analyses found significant associations with genes implicated in the neurobiology of substance use (DRD2, PDE4B). GCTA analyses found a significant SNP-based heritability of self-reported alcohol consumption of 13% (se=0.01). Sex-specific analyses found largely overlapping GWAS loci and the genetic correlation (rG) between male and female alcohol consumption was 0.90 (s.e.=0.09, P-value=7.16 × 10-23). Using LD score regression, genetic overlap was found between alcohol consumption and years of schooling (rG=0.18, s.e.=0.03), high-density lipoprotein cholesterol (rG=0.28, s.e.=0.05), smoking (rG=0.40, s.e.=0.06) and various anthropometric traits (for example, overweight, rG=-0.19, s.e.=0.05). This study replicates the association between alcohol consumption and alcohol metabolizing genes and KLB, and identifies novel gene associations that should be the focus of future studies investigating the neurobiology of alcohol consumption.

Molecular phenotype and bleeding risks of an inherited platelet disorder in a family with a RUNX1 frameshift mutation.

INTRODUCTION: Inherited defects in RUNX1 are important causes of platelet function disorders. AIM: Our goals were to evaluate RUNX1-related platelet disorders among individuals evaluated for uncharacterized, inherited platelet function disorders and test a proof of concept that bleeding risks could be quantitatively estimated for typical families with an inherited platelet function disorder. METHODS: Index cases with an uncharacterized inherited platelet function disorder were subjected to exome sequencing with confirmation of RUNX1 mutations by Sanger sequencing. Laboratory findings were obtained from medical records and persistence of platelet non-muscle myosin heavy chain IIB (MYH10), a biomarker of RUNX1 defects, was assessed by Western blotting. Bleeding histories were assessed using standardized assessment tools. Bleeding risks were estimated as odds ratios (OR) using questionnaire data for affected individuals compared to controls. RESULTS: Among 12 index cases who had their exomes sequenced, one individual from a family with eight study participants had a c.583dup in RUNX1 that segregated with the disease and was predicted to cause a frameshift and RUNX1 haploinsufficiency. Unlike unaffected family members (n = 2), affected family members (n = 6) had increased bleeding scores and abnormal platelet aggregation and dense granule release responses to agonists but only some had thrombocytopenia and/or dense granule deficiency. This family's mutation was associated with persistence of MYH10 in platelets and increased risks (OR 11-440) for wound healing problems and mild bleeding symptoms, including bleeding interfering with lifestyle in women. CONCLUSION: Inherited platelet dysfunction due to a RUNX1 haploinsufficiency mutation significantly increases bleeding risks.

Variability in platelet dense granule adenosine triphosphate release findings amongst patients tested multiple times as part of an assessment for a bleeding disorder.

INTRODUCTION: Lumi-aggregometry quantification of platelet dense granule adenosine triphosphate (ATP) release is commonly used for diagnosing platelet function disorders. As the test findings show considerable variability for healthy controls, we postulated that patient findings might also be variable and investigated patients who were assessed for dense granule ATP release defects more than once. METHODS: Analyses were performed on prospectively collected data for first and second tests for subjects tested for dense granule ATP release defects more than once by the Hamilton Regional Laboratory Program (HRLMP) between January 2007 and June 2013 (cohort I). Similar analyses were performed for subjects who were recruited to a platelet disorder study (cohort II) and were assessed for ATP release defects more than once before October 2015. RESULTS: A total of 150 unique subjects had multiple ATP release tests. Results with individual agonists were variable for many subjects. While normal findings with all tested agonists were often confirmed by the second test (cohort I: 83%; cohort II: 100%), impaired release with multiple agonists was confirmed in only some subjects (cohort I: 34%; cohort II: 54%). Inconsistent findings were common (cohort I: 36%; cohort II: 39%). ISTH bleeding scores showed no relationship to the test findings. The finding of impaired ATP release with 2 or more agonists on both tests was not associated with an increased likelihood of a definite bleeding disorder. CONCLUSION: The variability in platelet dense granule ATP release findings amongst patients assessed for diagnostic purposes suggests that the test has limited value for diagnosing platelet disorders.

Development of an E-learning System for the Endoscopic Diagnosis of Early Gastric Cancer: An International Multicenter Randomized Controlled Trial.

BACKGROUND: In many countries, gastric cancer is not diagnosed until an advanced stage. An Internet-based e-learning system to improve the ability of endoscopists to diagnose gastric cancer at an early stage was developed and was evaluated for its effectiveness. METHODS: The study was designed as a randomized controlled trial. After receiving a pre-test, participants were randomly allocated to either an e-learning or non-e-learning group. Only those in the e-learning group gained access to the e-learning system. Two months after the pre-test, both groups received a post-test. The primary endpoint was the difference between the two groups regarding the rate of improvement of their test results. FINDINGS: 515 endoscopists from 35 countries were assessed for eligibility, and 332 were enrolled in the study, with 166 allocated to each group. Of these, 151 participants in the e-learning group and 144 in the non-e-learning group were included in the analysis. The mean improvement rate (standard deviation) in the e-learning and non-e-learning groups was 1·24 (0·26) and 1·00 (0·16), respectively (P<0·001). INTERPRETATION: This global study clearly demonstrated the efficacy of an e-learning system to expand knowledge and provide invaluable experience regarding the endoscopic detection of early gastric cancer (R000012039).

A K(ATP) channel gene effect on sleep duration: from genome-wide association studies to function in Drosophila.

Humans sleep approximately a third of their lifetime. The observation that individuals with either long or short sleep duration show associations with metabolic syndrome and psychiatric disorders suggests that the length of sleep is adaptive. Although sleep duration can be influenced by photoperiod (season) and phase of entrainment (chronotype), human familial sleep disorders indicate that there is a strong genetic modulation of sleep. Therefore, we conducted high-density genome-wide association studies for sleep duration in seven European populations (N=4251). We identified an intronic variant (rs11046205; P=3.99 × 10(-8)) in the ABCC9 gene that explains ≈5% of the variation in sleep duration. An influence of season and chronotype on sleep duration was solely observed in the replication sample (N=5949). Meta-analysis of the associations found in a subgroup of the replication sample, chosen for season of entry and chronotype, together with the discovery results showed genome-wide significance. RNA interference knockdown experiments of the conserved ABCC9 homologue in Drosophila neurons renders flies sleepless during the first 3 h of the night. ABCC9 encodes an ATP-sensitive potassium channel subunit (SUR2), serving as a sensor of intracellular energy metabolism.

Take heart: bariatric surgery in obese patients with severe heart failure. Two case reports.

Bariatric surgery may be an effective treatment for obese heart failure patients, enabling access to cardiac transplantation and/or improvement of symptoms. We report the outcomes of two morbidly obese patients with end-stage heart failure, where obesity precluded cardiac transplantation and underwent laparoscopic gastric banding. A 42 year-old male with idiopathic dilated cardiomyopathy weighing 124.4 kg (BMI 42 kg/m(2)) lost 34 kg and was successfully transplanted 11 months later. A 40 year-old woman with familial dilated cardiomyopathy weighing 105 kg (BMI 40 kg/m(2)) lost 14 kg with sufficient symptomatic resolution to no longer require cardiac transplantation. In selected patients with severe heart failure and concomitant morbid obesity, bariatric surgery may be a reasonable treatment option.

Simultaneous measurement of adenosine triphosphate release and aggregation potentiates human platelet aggregation responses for some subjects, including persons with Quebec platelet disorder.

Platelet aggregometry and dense granule adenosine triphosphate (ATP) release assays are helpful to diagnose platelet disorders. Some laboratories simultaneously measure aggregation and ATP release using Chronolume® a commercial reagent containing D-luciferin, firefly luciferase and magnesium. Chronolume® can potentiate sub-maximal aggregation responses, normalising canine platelet disorder findings. We investigated if Chronolume® potentiates human platelet aggregation responses after observing discrepancies suspicious of potentiation. Among patients simultaneously tested by light transmission aggregometry (LTA) on two instruments, 18/43 (42%), including 14/24 (58%) with platelet disorders, showed full secondary aggregation with one or more agonists only in tests with Chronolume®. As subjects with Quebec platelet disorder (QPD) did not show the expected absent secondary aggregation responses to epinephrine in tests with Chronolume®, the reason for the discrepancy was investigated using samples from 10 QPD subjects. Like sub-threshold ADP (0.75 µM), Chronolume® significantly increased QPD LTA responses to epinephrine (p<0.0001) and it increased both initial and secondary aggregation responses, leading to dense granule release. This potentiation was not restricted to QPD and it was mimicked adding 1-2 mM magnesium, but not D-luciferin or firefly luciferase, to LTA assays. Chronolume® potentiated the ADP aggregation responses of QPD subjects with a reduced response. Furthermore, it increased whole blood aggregation responses of healthy control samples to multiple agonists, tested at concentrations used for the diagnosis of platelet disorders (p values <0.05). Laboratories should be aware that measuring ATP release with Chronolume® can potentiate LTA and whole blood aggregation responses, which alters findings for some human platelet disorders, including QPD.

Effect of young maternal age and skeletal growth on placental growth and development.

OBJECTIVES: Teenagers are susceptible to delivering small-for-gestational-age infants. Previous studies implicate continued skeletal growth as a contributory factor, and impaired placental development was the primary cause of fetal growth restriction in growing adolescent sheep. The aims of this study were to examine the impact of young maternal age and growth on placental development. STUDY DESIGN: Placentas were collected from 31 teenagers, of which 12 were growing and 17 non-growing based on knee height measurements. An adult control group (n = 12) was included. MAIN OUTCOME MEASURES: Placental weight and morphometric measurements of villous, syncytiotrophoblast, fibrin and vessel areas, as well as indices of proliferation and apoptosis, were analysed in relation to maternal growth and age. RESULTS: Growing teenagers had a higher birthweight:placental weight ratio than non-growing teenagers (p < 0.05). Villous area, syncytial area, fibrin content, vascularisation and cell turnover did not differ between growing and non-growing teenagers. There were no differences in placental weight or morphometry between adult and teenage pregnancies. Maternal smoking, a potential confounding factor, did not exert a major influence on the placental parameters examined, except for a stimulatory effect on placental proliferation (p < 0.05) and syncytial knot formation (p < 0.05). CONCLUSIONS: We were unable to detect any major differences in placental size or composition between growing and non-growing teenagers. Birthweight:placental weight ratio was higher in growing compared to non-growing teenagers. This suggests that maternal growth may affect placental function rather than development, and is consistent with our recent observations that maternal growth was not detrimental to fetal growth.

Effects of anemia correction with epoetin beta in patients receiving radiochemotherapy for advanced cervical cancer.

Patients with cervical cancer frequently suffer from anemia. This two-stage, adaptive-design study investigated the effect of anemia correction with epoetin beta on treatment outcomes. Patients with stage IIB-IVA cervical cancer received radiochemotherapy (RCT) and were randomized to epoetin 150 IU/kg three times weekly (n = 34) or standard care (control; n = 40) for up to 12 weeks. Primary end point for stage 1 aimed to establish a correlation between anemia correction and treatment failure (no complete response or relapsing within 6 months after RCT initiation) as a proof of concept before moving into stage 2. Secondary end points included progression/relapse-free survival, overall survival, response to RCT, hemoglobin (Hb) response, and safety. Median baseline Hb was 11.4 and 11.6 g/dL in epoetin and control groups, respectively. At treatment end point, median Hb increased by 1.3 g/dL with epoetin, but decreased by 0.7 g/dL in the control group (P < 0.0001). No significant correlation between Hb increase and treatment failure was demonstrated. There were no significant differences between epoetin and control groups in progression/relapse-free survival (29.4% vs 32.5% patients with events; P = 0.96), overall survival (23.5% vs 12.5% patients with events; P = 0.22) or overall complete response (53% vs 58%; P = 0.86). Adverse events were well matched between groups. This study shows that epoetin beta rapidly, effectively, and safely increases Hb levels in patients with cervical cancer receiving RCT. No positive correlation of Hb increase and improvement in clinical outcomes could be demonstrated.

The use of pharmacokinetic and pharmacodynamic end points to determine the dose of AQ4N, a novel hypoxic cell cytotoxin, given with fractionated radiotherapy in a phase I study.

BACKGROUND: AQ4N (1,4-bis[[2-(dimethylamino)ethyl] amino]-5,8-dihydroxyanthracene-9, 10-dione bis-N-oxide dihydrochloride) is a prodrug which is selectively activated within hypoxic tissues to AQ4, a topoisomerase II inhibitor and DNA intercalator. PATIENTS AND METHODS: In the phase I study, 22 patients with oesophageal carcinoma received an i.v. infusion of AQ4N (22.5-447 mg/m(2)) followed, 2 weeks later, by further infusion and radiotherapy. Pharmacokinetics and lymphocyte AQ4N and AQ4 levels were measured after the first dose. At 447 mg/m(2), biopsies of tumour and normal tissue were taken after AQ4N administration. RESULTS: Drug-related adverse events were blue discolouration of skin and urine, grade 2-3 lymphopenia, grade 1-3 fatigue, grade 1-2 anaemia, leucopenia and nausea. There were no drug-related serious adverse events (SAEs). Three patients had reductions in tumour volume >50%, nine had stable disease. Pharmacokinetics indicated predictable clearance. Plasma area under the curve (AUC) at 447 mg/m(2) exceeded AQ4N concentrations in mice at therapeutic doses and tumour biopsies contained concentrations of AQ4 greater than those in normal tissue. Tumour concentrations of AQ4 exceeded in vitro IC(50) values for most cell lines investigated. CONCLUSIONS: No dose-limiting toxic effects were observed and a maximum tolerated dose was not established. Tumour AQ4 concentrations and plasma AUC at 447 mg/m(2) exceeded active levels in preclinical models. This dose was chosen for future studies with radiotherapy.

Epoetin beta (NeoRecormon) therapy in patients with solid tumours receiving platinum and non-platinum chemotherapy: a meta-analysis.

BACKGROUND: Anaemia is a common complication of chemotherapy (CT), including both non-platinum (Pt)-based as well as Pt-based CT. PATIENTS AND METHODS: Patients from three controlled trials with solid tumours receiving either Pt- or non-Pt-based CT, who had been randomised to epoetin beta treatment or standard care, were included in this meta-analysis (n=255, n=199, respectively), to see if epoetin beta was equally effective in both CT types. The primary endpoint was haemoglobin (Hb) change. Secondary end-points included transfusion requirement, adverse events (AEs), survival, time to tumour progression and thromboembolic events (TEEs). RESULTS: All patients responded rapidly to epoetin beta treatment, showing a median Hb increase of > or = 1 g/dl from baseline at week 4. A median Hb of 12.2, 12.5 and 11.8 g/dl was achieved in all patients, those receiving Pt-based CT and those receiving non-Pt-based CT, respectively, after 16 weeks of treatment. Transfusion risk reductions associated with epoetin beta treatment of 53% (p<0.0001), 61% (p<0.0001) and 26% (non significant) were observed for all patients, Pt- and non-Pt-based CT patients, respectively. Overall, for all three populations, there were no risks identified for tumour progression or overall survival. There was a statistically non-significant incidence of TEEs (5.9% versus 4.5%) and no marked differences were observed between groups for frequency or type of AEs reported. CONCLUSION: The type of CT has no impact on the ability of epoetin beta to rapidly increase Hb in patients with solid tumours and CT-induced anaemia.

Discontinuation of pegylated interferon plus ribavirin in patients who are not responding to therapy -- patients' views of early cessation of therapy.

BACKGROUND: Current therapy for chronic hepatitis C infection involves a course of pegylated interferon and ribavirin. Patients who do not show a virological response after 12 weeks of therapy have a low probability of sustained virological response and it is therefore recommended that such patients stop treatment. AIM: To assess patients' views of early treatment cessation. METHODS: We conducted a open-labelled study in three UK centres, in which patients with biopsy-proven chronic hepatitis C requiring therapy were offered the choice of a full course of therapy with 40 kDa pegylated interferon-alpha 2a plus ribavirin (24 or 48 weeks depending on viral genotype) or early cessation if therapy had failed after 12 weeks. RESULTS: Ninety-five participants were enrolled and the majority (69%) did not wish to discontinue therapy even if it had low probability of success. In this unselected UK population, very few patients (4%) did not achieve an early virological response with the 40-kDa pegylated interferon-alpha 2a plus ribavirin and two of the four early virological non-responders decided to continue therapy. CONCLUSION: Early discontinuation of 'ineffective' anti-viral therapy may prove less popular with patients than with health care providers, and further patient-directed education regarding the cost-effectiveness of therapy will be needed if early discontinuation of unsuccessful therapy is to be accepted by patients.

Azathioprine dose escalation in inflammatory bowel disease.

BACKGROUND: Forty per cent of patients with inflammatory bowel disease fail to respond to standard dose azathioprine (2 mg/kg/day). AIMS: To evaluate the efficacy and safety of increasing the azathioprine dose according to a fixed schedule and guided by clinical response and adverse effects. METHODS: We reviewed the records of all patients with inflammatory bowel disease treated by a single clinician over 6 years, unresponsive to at least 3 months treatment with standard dose azathioprine, and whose dose was subsequently increased. RESULTS: Forty patients (27 male; 24 Crohn's, 16 ulcerative colitis) with chronic active disease or recurrent flares despite standard dose azathioprine for a median 8 months (range 3-114) increased their dose from a median 2.02 (1.61-3.19) mg/kg/day to 2.72 (2.37-3.99) mg/kg/day in one to four increments of 0.5 mg/kg/day, and were followed over a median 6 (0.5-54) months. Eleven of the 40 patients (seven Crohn's, four ulcerative colitis) responded or had reduced frequency of flare-ups at the end of follow-up, while 17 of the 40 patients had no benefit. Response was more likely for maximum doses < or =2.5 mg/kg/day (six of 11 patients) than for doses >2.5 mg/kg/day (five of 29 patients) (P = 0.042). Twelve patients (11 of whom received maximum doses >2.5 mg/kg/day) were unable to maintain an increased azathioprine dose because of leukopenia in eight, nausea in three, and raised liver enzymes in one (all transient and reversible). CONCLUSIONS: Increasing the azathioprine dose up to 2.5 mg/kg/day appears beneficial in patients who have not responded to 2 mg/kg/day. Further increase above 2.5 mg/kg/day is less likely to be efficacious, and is associated with a substantial risk of adverse reactions.

Tamoxifen is not detrimental to endothelial function in postmenopausal women with breast cancer.

BACKGROUND: Tamoxifen has mixed estrogen agonist and antagonist properties in estrogen-regulated tissues. Its effect on the cardiovascular system is not well defined. We carried out a study to investigate the effect of tamoxifen on peripheral vascular endothelial function. METHODS: Three groups of postmenopausal women (median age, 56 years; range, 39 to 69 years) with breast cancer were studied. Patients in group 1 (n = 10) were newly diagnosed with breast cancer and studied before and after 4 weeks treatment with tamoxifen. Group 2 women (n = 6) had been receiving long-term tamoxifen (3 to 5 years) and were studied while taking tamoxifen and 4 weeks after stopping it. The final group of 6 subjects were in remission from primary breast cancer and were not receiving or had previously received tamoxifen. Ultrasound assessments of endothelial function were done before and 4 weeks after the initiation or discontinuation of tamoxifen with the nontreatment group acting as control. All ultrasound imaging was made by a single investigator blinded to the therapeutic status of the subject. Brachial artery diameter was measured by ultrasound at baseline and 1 minute after reactive hyperemia. Flow-mediated reactivity (FMR) was defined as percent change in artery diameter from baseline 1 minute after reactive hyperemia. RESULTS: There was no change in FMR in patients before compared with 4 weeks after starting tamoxifen (4.06% +/- 1.44% vs 3.97% +/- 1.20%, respectively, mean +/- standard error of the mean [SEM], P =.97). There was no significant change in FMR on withdrawal from tamoxifen (1.84% +/- 1.98% vs -0.42% +/- 1.44% on tamoxifen vs off tamoxifen, mean +/- SEM, P =.36). FMR in subjects taking tamoxifen was no different from the control group (3.17% +/- 1.05% vs 3.16% +/- 0.91%, respectively, mean +/- SEM, P =.995). CONCLUSIONS: Tamoxifen does not appear to affect endothelial function in the short term in postmenopausal women with breast cancer.

Effects of storage solutions on in vitro vasoreactivity of radial artery conduits.

OBJECTIVES: Surgical preparation of coronary conduits for coronary artery bypass grafting may affect their early and long-term patency; one mechanism may involve endothelial damage. We investigated the effect of 3 commonly used solutions-Ringer's solution, normal saline solution, and heparinized whole blood-on in vitro endothelial and contractile functions of the human radial artery. METHODS: Radial artery segments were harvested, cut into 3-mm rings, and stored in unoxygenated Ringer's solution, normal saline solution, or heparinized whole blood for 45 minutes. Rings stored in Krebs solution were used as controls. The rings were then mounted and stretched to an optimal resting tension in oxygenated Krebs solution at 37 degrees C. Contraction responses to potassium, norepinephrine, and serotonin and relaxation responses to acetylcholine, verapamil, and nitroprusside were evaluated. RESULTS: Fifty-six radial artery ring segments from 14 patients (n = 7 rings for each contraction-relaxation curve) were studied. Equilibrated resting tension was 9.6 +/- 0.3 mN (5.9 +/- 0.2 g), and resting internal circumference was 6.4 +/- 0.2 mm. Absolute maximum contraction to potassium was significantly less in rings stored in normal saline solution than in rings stored in control solution (10.7 +/- 0.6 g vs 14.5 +/- 0.6 g, P <.01; 95% confidence intervals, 0.9-6.9). There was no difference in the contraction to norepinephrine (P =.11) and serotonin (P =.25) among the 3 solutions compared with the control solution. Rings stored in heparinized whole blood had significantly greater endothelium-dependent relaxation to acetylcholine (P <.007), whereas those stored in normal saline solution had reduced responses. Endothelium-independent relaxation to verapamil and nitroprusside were similar among the 3 solutions. CONCLUSION: Heparinized whole blood is a better physiologic medium for preservation of radial artery endothelial and contractile functions during storage before grafting.

Decreased von Willebrand factor protease activity associated with thrombocytopenic disorders.

Recent studies investigating thrombotic thrombocytopenic purpura (TTP) have implicated abnormal plasma von Willebrand factor (vWF)-cleaving metalloprotease activity in this disorder. It has been proposed that a metalloprotease cleaves unusually large (UL) multimers of vWF, which enter the circulation from the endothelium. Abnormal metalloprotease activity could result in ULvWF, which could participate in TTP. However, the diagnostic specificity of abnormalities in the plasma metalloprotease activity has not been established. A prospective study of vWF protease activity was performed using samples from 20 healthy controls, 20 patients with acute TTP, 20 patients with immune idiopathic thrombocytopenic purpura (ITP), 10 patients with disseminated intravascular thrombocytopenia (DIC), 10 patients with systemic lupus erythematosus (SLE,) and 5 thrombocytopenic patients with leukemia. Studies were performed blinded to the diagnosis. Samples from hospitalized patients with normal platelet counts were also tested. The vWF digests and multimer analysis were done using previously described methods. Six laboratory personnel independently scored each of the multimer gels. Reduced protease activity was observed in 9 of 20 patients with TTP. Reduced activity was also observed in 6 of 20 patients with ITP, 6 of 10 patients with DIC, 5 of 10 patients with SLE, 1 of 5 patients with leukemia, 2 of 20 healthy controls, and 3 of 25 hospitalized patients. This study indicates that abnormalities of vWF protease activity are not restricted to patients with the diagnosis of TTP.