von Willebrand factor (VWF) propeptide binding to VWF D'D3 domain attenuates platelet activation and adhesion

Noncovalent association between the von Willebrand factor (VWF) propeptide (VWFpp) and mature VWF aids N-terminal multimerization and protein compartmentalization in storage granules. This association is currently thought to dissipate after secretion into blood. In the present study, we examined this proposition by quantifying the affinity and kinetics of VWFpp binding to mature VWF using surface plasmon resonance and by developing novel anti-VWF D'D3 mAbs. Our results show that the only binding site for VWFpp in mature VWF is in its D'D3 domain. At pH 6.2 and 10mM Ca(2+), conditions mimicking intracellular compartments, VWFpp-VWF binding occurs with high affinity (K(D) = 0.2nM, k(off) = 8 × 10(-5) s(-1)). Significant, albeit weaker, binding (K(D) = 25nM, k(off) = 4 × 10(-3) s(-1)) occurs under physiologic conditions of pH 7.4 and 2.5mM Ca(2+). This interaction was also observed in human plasma (K(D) = 50nM). The addition of recombinant VWFpp in both flow-chamber-based platelet adhesion assays and viscometer-based shear-induced platelet aggregation and activation studies reduced platelet adhesion and activation partially. Anti-D'D3 mAb DD3.1, which blocks VWFpp binding to VWF-D'D3, also abrogated platelet adhesion, as shown by shear-induced platelet aggregation and activation studies. Our data demonstrate that VWFpp binding to mature VWF occurs in the circulation, which can regulate the hemostatic potential of VWF by reducing VWF binding to platelet GpIbα.     

Monozygotic twins affected with major depressive disorder have greater variance in methylation than their unaffected co-twin

Our understanding of major depressive disorder (MDD) has focused on the influence of genetic variation and environmental risk factors. Growing evidence suggests the additional role of epigenetic mechanisms influencing susceptibility for complex traits. DNA sequence within discordant monozygotic twin (MZT) pairs is virtually identical; thus, they represent a powerful design for studying the contribution of epigenetic factors to disease liability. The aim of this study was to investigate whether specific methylation profiles in white blood cells could contribute to the aetiology of MDD. Participants were drawn from the Queensland Twin Registry and comprised 12 MZT pairs discordant for MDD and 12 MZT pairs concordant for no MDD and low neuroticism. Bisulphite treatment and genome-wide interrogation of differentially methylated CpG sites using the Illumina Human Methylation 450 BeadChip were performed in WBC-derived DNA. No overall difference in mean global methylation between cases and their unaffected co-twins was found; however, the differences in females was significant (P=0.005). The difference in variance across all probes between affected and unaffected twins was highly significant (P<2.2 × 10⁻¹⁶), with 52.4% of probes having higher variance in cases (binomial P-value<2.2 × 10⁻¹⁶). No significant differences in methylation were observed between discordant MZT pairs and their matched concordant MZT (permutation minimum P=0.11) at any individual probe. Larger samples are likely to be needed to identify true associations between methylation differences at specific CpG sites.     

Preference Between Precoital and Daily Use of Duet? and BufferGel in Zimbabwe

Duet(?) is a microbicide-delivery system and cervical barrier for use daily or precoitally. We conducted a crossover study among 80 Zimbabwean women to explore factors associated with use-regimen preference. Women were assigned in random order to 14?days of precoital and 14?days of daily Duet and BufferGel use. About 51?% of women preferred precoital use, 39?% preferred daily use, and 10?% liked both equally. Overall product adherence during sex was similar for both use-regimens. In multivariable analysis, diaphragm experience was associated with preference for precoital use (AOR 2.80, 95?% CI 1.01-7.76). Reasons for preferring precoital use included use only when needed, cleanliness, and discomfort with daily use. Daily use preference included convenience, discreetness, and being prepared for "sex-on-demand." Different personal and life circumstances may result in varying use-regimen preferences. Methods that can accommodate both coitally-related and daily use may be advantageous by providing more choice to users.     

Identifying Appropriate Recipients for CDC Infectious Risk Donor Kidneys

Over 10% of deceased donors in 2011 met PHS/CDC criteria for infectious risk donor (IRD), and discard rates are significantly higher for kidneys from these donors. We hypothesized that patient phenotypes exist for whom the survival benefit outweighs the infectious risk associated with IRDs. A patient‐oriented Markov decision process model was developed and validated, based on SRTR data and meta‐analyses of window period risks among persons with IRD behaviors. The Markov model allows patients to see, for their phenotype, their estimated survival after accepting versus declining an IRD offer, graphed over a 5‐year horizon. Estimated 5‐year survival differences associated with accepting IRDs ranged from ?6.4% to +67.3% for a variety of patient phenotypes. Factors most predictive of the survival difference with IRD transplantation were age, PRA, previous transplant, and the expected time until the next non‐IRD deceased donor offer. This study suggests that survival benefit derived from IRD kidneys varies widely by patient phenotype. Furthermore, within the inherent limitations of model‐based prediction, this study demonstrates that it is possible to identify those predicted to benefit from IRD kidneys, and illustrates how estimated survival curves based on a clinical decision can be presented to better inform patient and provider decision‐making.

     

Variant (divergent) histologic differentiation in urothelial carcinoma is under-recognized in community practice: Impact of mandatory central pathology review at a large referral hospital

Background and objectiveUrothelial carcinoma (UC) demonstrating variant histologic differentiation is associated with poor outcomes, and certain variants exhibit differing therapeutic responses compared with pure conventional UC. Little is known about the awareness and reporting practices of UC with variant histology in community practice.Materials and MethodsPatients diagnosed with UC based on an outside pathologic review had their pathology centrally reviewed before instituting therapy. A discordant diagnosis was defined as the presence of variant histologic differentiation not reported by the referring institution. Variant histologic differentiation was quantitated as focal (10%–50%) or extensive (>50%).ResultsOf 589 transurethral biopsies (TURBTs), 115 (19.5%) UCs demonstrated variant histologic differentiation. Muscle invasion at TURBT and extravesical disease at cystectomy was present in 69% and 52%, respectively. Of 56 patients with at least 1 year follow-up, recurrence-free survival was 56%. The majority (90%) showed a single variant histology, which was extensive in 58% of cases. Squamous differentiation (32%) was the most common variant histology identified, followed by small cell (16%), glandular (13%), micropapillary (12%), nested (8%), sarcomatoid (6%), lymphoepithelial (3%), and plasmacytoid (1%) type. Variant histologic differentiation was not documented by the referring institution in 44% of cases, of which 47% were extensive. Commonly under-recognized patterns included lymphoepithelial (2) and plasmacytoid (1) types (100%), nested (7, 87%), micropapillary (10, 83%), and small cell (7, 44%).ConclusionsThis study emphasizes the importance of central pathology review in the management of bladder cancer patients and the need for increased awareness of this relatively common phenomenon in UC.