Comparison of inhibitory and binding characteristics of an antibody causing acquired von Willebrand syndrome: an assay for von Willebrand factor binding by antibody

An acquired inhibitor of von Willebrand factor (vWF) activity occurring in a patient with benign gammopathy and von Willebrand syndrome (vWS) has been partially characterized. The inhibitor-induced syndrome resulted in low to undetectable plasma levels of vWF/ristocetin, vWF/botrocetin, FVIIIR:Ag, and FVIII:C with a normal to slightly prolonged bleeding time. Platelet vWF was normal. Intensive and continuous infusion of a heat-treated factor VIII concentrate (Hemofil- T, Hyland, Glendale, Calif) elevated the FVIII:C plasma levels to about 100%, with an increase in FVIIIR:Ag levels to about 340% and vWF/ristocetin levels to about 40%, much lower than expected based on the dose of Hemofil-T and its content of vWF and FVIII:C activities. The inhibitor bound to staphylococcal protein A (SpA) with high affinity, indicating an IgG antibody (Ab). An assay for the vWF-binding capacity was developed on the basis of absorption of the Ab from serially diluted plasma by SpA and removal of vWF and FVIII:C activities from normal plasma by the SpA-Ab complex. The Ab-binding site was on the vWF component of the factor VIII complex. The Ab was unable to bind isolated FVIII:C. The combined use of the new vWF- binding assay and a battery of tests for inhibition of vWF-dependent platelet aggregation with ristocetin (which detects high molecular weight vWF), with botrocetin (which detects high and low molecular weight vWF), and with platelet-aggregating factor (which detects high molecular weight vWF) provided a means of analysis of Ab effect on in vitro vWF function. Using these tests, a comparison was made of the effects of the vWS Ab with those of an Ab inhibitor occurring in homozygous von Willebrand's disease. The Ab of the vWS patient had weak inhibitory action on vWF/ristocetin without having an effect on vWF/botrocetin and platelet-aggregating factor, a high titer vWF- binding capacity, and no anamnestic response following concentrate therapy. These findings contrasted with those of the Ab occurring in inhibitor von Willebrand's disease in which vWF inhibitor and binding values were similar, with a strong anamnestic response. The findings indicate that the vWS Ab binds to an epitope on the molecular vWF in such a way that causes only limited inhibition of vWF/ristocetin function and no inhibition of vWF/botrocetin function, suggesting that these two functional domains are at separate sites.     

Subtypes of Epstein-Barr virus (EBV) in Hodgkin's disease: association between B-type EBV and immunocompromise [see comments]

Epstein-Barr virus (EBV) has been associated with Hodgkin's disease (HD) in up to 50% of cases, but the subtype of EBV involved has only recently been studied. In this report, biopsy samples from 30 patients with HD were assessed for EBV sequences using both the polymerase chain reaction (PCR) and in situ hybridization (ISH). EBV sequences were localized to the malignant Reed-Sternberg cells and their mononuclear variants (Hodgkin's cells) in 9 of the 30 cases, with 7 demonstrating A- type and 2 B-type EBV sequences. Both of the patients with B-type EBV- associated HD had features to suggest pre-existing immune compromise: one was infected with human immunodeficiency virus (HIV) and had severe CD4+ T-lymphocyte depletion; the other was a debilitated elderly patient with dementia. A previous study suggested that A-type EBV alone is associated with HD and the finding of predominantly A-type EBV in the present series is in keeping with this report. The presence of B- type EBV in the HD of patients with pre-existing immunodeficiency, taken together with the recent report that B-type EBV occurs in HIV- associated non-Hodgkin's lymphoma, suggests that B-type EBV may be an important human pathogen in immunocompromised patients.     

Apolipoprotein B, non-HDL cholesterol and LDL cholesterol for identifying individuals at increased cardiovascular risk

Abstract. Holewijn S, den Heijer M, Swinkels DW, Stalenhoef AFH, de Graaf J. (Address: Division of Vascular Medicine, Department of General Internal Medicine; Department of Epidemiology and Biostatistics; Department of Endocrinology; and Department of Laboratory Medicine; Laboratory of Clinical Chemistry, all at the Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands) Apolipoprotein B, non‐HDL cholesterol and LDL cholesterol for identifying individuals at increased cardiovascular risk. J Intern Med 2010; 268 : 567–577. Background. To compare apolipoprotein B (apoB), nonhigh‐density lipoprotein‐cholesterol (non‐HDL‐c) and low‐density lipoprotein‐cholesterol (LDL‐c) for identifying individuals with a deteriorated cardiovascular (CV) risk profile, including a panel of subclinical atherosclerosis measurements and prevalent cardiovascular disease (CVD) in a Dutch population‐based cohort. Methods. Clinical and biochemical measurements and a panel of noninvasive parameters of subclinical atherosclerosis were determined in 1517 individuals, aged 50–70 years. Results. Both men and women with increasing levels of apoB and non‐HDL‐c were more obese, had higher blood pressure and fasting glucose levels, and a more atherogenic lipid profile. Furthermore, compared to the reference group (composed of those with apoB, non‐HDL‐c and LDL‐c levels in the bottom quartiles), participants with high apoB and high non‐HDL‐c levels had a lower ankle–brachial index at rest (?3.5% and ?3.1%, respectively) and after exercise (?6.3% and ?4.7%, respectively), a thicker near wall (+4.8% and +4.2%, respectively), far wall (both +6.2%), and mean intima–media thickness (+5.7% and +5.3%, respectively) and more plaques (+54.2% and +54.3%, respectively). In addition, they also showed increased stiffness parameters (e.g. pulse wave velocity both +3.6%). Less clear differences in CV risk profile and subclinical atherosclerosis parameters were observed when participants were stratified by LDL‐c level. Furthermore, apoB but not LDL‐c detected prevalent CVD, and non‐HDL‐c only detected prevalent CVD in men. The discriminatory power for prevalent CVD expressed as area under the receiver operating characteristic curve was 0.60 (P < 0.001) for apoB, 0.57 (P = 0.001) for non‐HDL‐c and 0.54 (P = 0.108) for LDL‐c. Conclusion. Our data support the use of first apoB and secondly non‐HDL‐c above LDL‐c for identifying individuals from the general population with a compromised CV phenotype.     

Impact of waist circumference versus adiponectin level on subclinical atherosclerosis

Abstract. Holewijn S, den Heijer M, van Tits LJ, Swinkels DW, Stalenhoef AFH, de Graaf J (Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands). Impact of waist circumference versus adiponectin level on subclinical atherosclerosis. A cross‐sectional analysis in a sample from the general population. J Intern Med 2010; 267 :588–598. Objective. Waist circumference is a clinical marker of obesity and an established risk factor for cardiovascular (CV) disease. Adiponectin, an adipocyte‐derived hormone and new biomarker of obesity, was recently proposed as the missing link between obesity and increased cardiovascular risk. We evaluated waist and adiponectin in a middle‐aged population‐based cohort to compare the impact of both obesity‐markers on subclinical atherosclerosis, in relation to other CV risk factors. Design, setting & subjects. Seven noninvasive measurements of atherosclerosis (NIMA), as surrogate markers of (subclinical) atherosclerosis, were determined in 1517 participants of the Nijmegen Biomedical Study, aged 50–70 years, who were drawn from the Dutch community. Results. Both men and women with a high waist (M >104 cm; F >95 cm) showed increased pulse wave velocity (PWV) (M: +9.4%; F: +8.3%) and thicker intima‐media thickness (IMT) (M: +7.3%; F: +4.3%) and women also showed increased plaque thickness (+16.6%). After adjustment for other CV risk factors both men and women showed increased IMT (M: +4.8%; F: +2.8%) and men also showed increased PWV (+9.6%). Both men and women with a low adiponectin level (M <2.2 mg L^?1; F <3.5 mg L^?1) showed a decreased ankle‐brachial index after exercise (M: ?9.5%; F: ?3.9%) and increased IMT (M: +3.7%; F: +3.6%) and women also showed increased PWV (+6.8%), but after adjustment for other CV risk factors low adiponectin level was no longer associated with deteriorated outcomes of NIMA. Conclusions. Waist circumference showed independent associations with noninvasive measurements of subclinical atherosclerosis, whereas the association of adiponectin level with subclinical atherosclerosis was not independent of other CV risk factors. Prospective studies are needed to elucidate, if the atherogenic effect of a low adiponectin level is mediated by other CV risk factors and not by low adiponectin level intrinsically.     

Recent advances in the understanding of iron overload in sideroblastic myelodysplastic syndrome

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal haematopoietic stem cell malignancies. A subgroup, the so‐called sideroblastic MDS, shows ring sideroblasts in the bone marrow aspirate that represent mitochondrial iron accumulation. Patients with sideroblastic MDS also develop systemic iron overload and generally have a low‐risk MDS. Therefore it is important to understand the mechanisms responsible for iron accumulation and the associated toxicity in these patients. Recently, low levels of the iron‐regulatory peptide hepcidin were found to contribute to body iron overload in β‐thalassaemia patients. A similar mechanism may account for systemic iron accumulation in sideroblastic MDS. Mitochondrial iron accumulation is observed in several subtypes of MDS, and predominantly in refractory anaemia with ring sideroblasts. The presence of ring sideroblasts is also the diagnostic hallmark in patients with inherited forms of sideroblastic anaemia. The ever‐increasing insights into the affected pathways in inherited sideroblastic anaemia may lead to a better comprehension of the pathogenesis of mitochondrial iron accumulation in MDS patients. Overall, an improved understanding of the mechanisms responsible for iron overload in MDS will lead to novel treatment strategies to reduce both systemic and mitochondrial iron overload, resulting in less tissue damage and more effective erythropoiesis.     

Externalizing behaviors in preadolescents: familial risk to externalizing behaviors and perceived parenting styles

The aim was to investigate the contribution of familial risk to externalizing behaviors (FR-EXT), perceived parenting styles, and their interactions to the prediction of externalizing behaviors in preadolescents. Participants were preadolescents aged 10–12 years who participated in TRAILS, a large prospective population-based cohort study in the Netherlands (N = 2,230). Regression analyses were used to determine the relative contribution of FR-EXT and perceived parenting styles to parent and teacher ratings of externalizing behaviors. FR-EXT was based on lifetime parental externalizing psychopathology and the different parenting styles (emotional warmth, rejection, and overprotection) were based on the child’s perspective. We also investigated whether different dimensions of perceived parenting styles had different effects on subdomains of externalizing behavior. We found main effects for FR-EXT (vs. no FR-EXT), emotional warmth, rejection, and overprotection that were fairly consistent across rater and outcome measures. More specific, emotional warmth was the most consistent predictor of all outcome measures, and rejection was a stronger predictor of aggression and delinquency than of inattention. Interaction effects were found for FR-EXT and perceived parental rejection and overprotection; other interactions between FR-EXT and parenting styles were not significant. Correlations between FR-EXT and perceived parenting styles were absent or very low and were without clinical significance. Predominantly main effects of FR-EXT and perceived parenting styles independently contribute to externalizing behaviors in preadolescents, suggesting FR-EXT and parenting styles to be two separate areas of causality. The relative lack of gene–environment interactions may be due to the epidemiological nature of the study, the preadolescent age of the subjects, the measurement level of parenting and the measurement level of FR-EXT, which might be a consequence of both genetic and environmental factors.     

Six-minute walking-induced systemic inflammation and oxidative stress in muscle-wasted COPD patients

BACKGROUND: Systemic inflammation and oxidative stress are potential mechanisms for muscle wasting in COPD patients. Six-minute walking testing (6MWT) has been suggested as simple and valid exercise test in COPD that is well tolerated, and reflective of activities of daily living. The present study investigated physiologic and systemic immunologic responses to a 6MWT in muscle-wasted patients with COPD and compared them with maximal cardiopulmonary exercise testing (CPET). METHODS: Ten patients with muscle-wasted COPD were included (fat-free mass index [FFMI]: men, < 16 kg/m2; women, < 15 kg/m2). 6MWT and CPET were performed in random order. The physiologic response was followed by a mobile oxycon. Arterial blood was obtained at rest and after exercise to measure blood gases and markers of systemic inflammation and oxidative stress. RESULTS: In these patients (FEV1 55 +/- 4% of predicted [mean +/- SE]), the 6MWT was a submaximal, albeit intense, exercise as reflected by oxygen uptake (VO2), minute ventilation, heart rate, and lactate values. Leukocytosis was less intense after 6MWT compared to CPET. Contrary, the increase in interleukin-6, free radical release by neutrophils, oxidation of proteins and lipids, and the reduction in antioxidant capacity were similar after both exercises. FFMI was inversely related to 6MWT-induced increases in protein and lipid peroxidation. CONCLUSIONS: This study shows that a 6MWT induces a systemic immunologic response in muscle-wasted patients with COPD, which is comparable to CPET-induced responses. The correlation between systemic oxidative stress and the degree of muscle wasting supports a possible causal relation between systemic inflammation, oxidative stress, and muscle wasting.     

Bladder cancer diagnosis and recurrence prognosis: comparison of markers with emphasis on survivin

Expression of the anti-apoptotic protein survivin is hardly detectable or even absent in many differentiated adult tissues, but is upregulated in almost any type of cancer. Furthermore, high survivin mRNA or protein expression generally correlates with an adverse disease course. Both these important features of survivin expression have been investigated for diagnostic and prognostic purposes in many human cancers, including bladder cancer. In this review, the role of survivin in the detection of bladder tumors and the prediction of tumor recurrence in patients with superficial bladder cancer will be discussed and compared to that of other markers/tests. The most promising marker(s) will be outlined. Also, important requirements for a successful implementation of such markers in a hospital setting are discussed. Finally, future directions for the discovery of new diagnostic or prognostic candidate markers will be mentioned.     

Rapid immunoassay for the determination of glial fibrillary acidic protein (GFAP) in serum

BACKGROUND: This study was aimed to develop a sensitive and rapid assay for the determination of glial fibrillary acidic protein (GFAP) in serum and to evaluate the clinical applicability in serum samples from patients with acute stroke. METHODS: The two-site chemiluminometric immunoassay, intended to use in a near-patient setting with a single incubation step (20 min), was used to measure serum samples from healthy blood donors and from patients with brain injury and correlated to serum S100B levels. RESULTS: The GFAP assay covered a concentration range up to 18 microg/L with an analytical sensitivity of 0.014 microg/L. The intra-assay precision was 3.5% at 1.55 microg/L (n=20) and 4.1% at 0.39 microg/L (n=20). The inter-assay precision was 3.8% at 9.1 microg/L (n=10) and 10.3 % at 0.21 microg/L (n=9). Normal controls (n=46) showed non-detectable GFAP with a 99% upper limit of <0.04 microg/L. GFAP values were associated with progression and severity of the illness in acute stroke patients. CONCLUSIONS: We have developed an improved assay for the measurement of GFAP levels in serum. Serum GFAP is a potential marker for prognosis and outcome in patients with central nervous system disorders.