0128 Maternal Sleep Quality Across Pregnancy Predicts Newborn Neurodevelopment

Introduction

The prenatal period is characterized by immense fetal neuronal growth. Such rapid growth can increase fetal susceptibility to prenatal environmental insults (Barker, 1998). A promising prenatal process that may alter fetal development is maternal prenatal sleep quality. Poor prenatal sleep quality is a public health concern affecting approximately 78% of pregnant individuals (Lucena et al., 2018). In rodents, maternal sleep deprivation across gestation predicts offspring hippocampal neurogenesis, with pups exposed to sleep deprivation early and late in pregnancy exhibiting more anxiety and depression-like behaviors (Peng et al., 2015). In humans, poor sleep quality in other developmental stages predicts hippocampi and amygdalae changes (Marshall & Born, 2007; Saghir et al., 2018). However, the relation between prenatal sleep quality and offspring brain development in humans remains poorly understood. The present study examined associations between maternal sleep quality in early, mid, and late pregnancy, and newborn hippocampal and amygdala volume, regions implicated in memory and emotion.

Methods

Pregnant individuals (N=94; Mage=30.5; SDage=5.3) reported on sleep quality three times during pregnancy. Newborn (Mageinweeks=5.1; SDageinweeks=2.7) hippocampi and amygdalae volumes were assessed during an unsedated sleep cycle using magnetic resonance imaging (MRI). Tissue segmentation was collected using a multiatlas iterative algorithm that individually segmented the regions of interest and subsequently combined T1- and T2-weighted high-resolution images (See neonate multiatlas at https://www.nitrc.org/projects/unc_brain_atlas/). Bivariate correlations examined the association between prenatal sleep quality and hippocampus and amygdala volume. Partial correlations examined these associations in the presence of significant cofounding variables including intracranial volume, body weight percentile, sex, and postconceptional age.

Results

Partial correlations revealed that poor maternal sleep quality early in pregnancy predicted larger newborn bilateral hippocampal volume (all rs<.25; ps<.038). Associations with sleep later in gestation persisted for the right hippocampus (all rs<.25; ps<.038). Prenatal maternal sleep quality did not significantly predict newborn amygdala volume (all rs<-.06; ps>.58).

Conclusion

This study provides novel evidence linking prenatal sleep quality and newborn hippocampal volume in humans, suggesting the presence of an intergenerational link between prenatal sleep health and offspring well-being.

Support (If Any)

Support (if any): NIMH R01MH109662, NHLBI R01HL155744, and diversity training supplement for 1st author; F32MH125572 for 2nd author.

0998 Health Care Utilization of Pediatric Sleep Disorders in Cerner Health Facts Database

Introduction

This study was aimed to identify health care utilization of sleep disorders in pediatrics and adults by using Cerner health facts database.

Methods

Health facts database has unidentified health records from all the participating facilities that have Cerner as their electronic medical records software. There are 68.7 million patients in the data warehouse with about 506.9 million encounters in about 100 healthcare systems. Sleep disorders are mostly seen in outpatient settings and therefore this study included outpatient records between the years 2010 to 2017.

Results

There were 20.5 million patients with total of 127.4 million outpatient encounters. In pediatric patients (ages 0-18 years), healthcare utilization of major sleep diagnoses per 100,000 encounters showed sleep related breathing disorders are the most commonly seen followed by parasomnia, insomnia, sleep movement disorders, hypersomnolence then circadian rhythm disorders (820.1, 258.1, 181.6, 68.3, 48.1 and 16.2 per 100,000 encounters). However, for adult patients the ranking was: sleep related breathing disorders, insomnia, sleep related movement disorders, hypersomnolence, parasomnia then circadian rhythm disorders (1352.6, 511.6, 166.3, 79.1, 25.7 and 4.2 per 100,000 encounters). Further analysis for the age groups showed bimodal pattern for sleep related breathing disorders and sleep movement disorders with the highest utilization were between the ages of 2-11 year and 40-60 years. Adolescents (age 12-18 years) showed increase utilization in the areas of circadian rhythm disorders.

Conclusion

Patients with sleep disorders have relatively low health care utilization despite high prevalence of these sleep disorders in the general population. This may highlight underrecognized sleep problem or decreased access to health care. In addition, this study highlights the effect of age on different sleep disorders which may have an impact on allocating resources.

Support

None

Health resource utilization of labor induction versus expectant management

BACKGROUND

Although induction of labor of low-risk nulliparous women at 39 weeks reduces the risk of cesarean delivery compared with expectant management, concern regarding more frequent use of labor induction remains, given that this intervention historically has been thought to incur greater resource utilization.

OBJECTIVE

The objective of the study was to determine whether planned elective labor induction at 39 weeks among low-risk nulliparous women, compared with expectant management, was associated with differences in health care resource utilization from the time of randomization through 8 weeks postpartum.

STUDY DESIGN

This is a planned secondary analysis of a multicenter randomized trial in which low-risk nulliparous women were assigned to induction of labor at 39 weeks or expectant management. We assessed resource utilization after randomization in 3 time periods: antepartum, delivery admission, and discharge through 8 weeks postpartum.

RESULTS

Of 6096 women with data available, those in the induction of labor group (n = 3059) were significantly less likely in the antepartum period after randomization to have at least 1 ambulatory visit for routine prenatal care (32.4% vs 68.4%), unanticipated care (0.5% vs 2.6%), or urgent care (16.2% vs 44.3%), or at least 1 antepartum hospitalization (0.8% vs 2.2%, P < .001 for all). They also had fewer tests (eg, sonograms, blood tests) and treatments (eg, antibiotics, intravenous hydration) prior to delivery. During the delivery admission, women in the induction of labor group spent a longer time in labor and delivery (median, 0.83 vs 0.57 days), but both women (P = .002) and their neonates (P < .001) had shorter postpartum stays. Women and neonates in both groups had similar frequencies of postpartum urgent care and hospital readmissions (P > .05 for all).

CONCLUSION

Women randomized to induction of labor had longer durations in labor and delivery but significantly fewer antepartum visits, tests, and treatments and shorter maternal and neonatal hospital durations after delivery. These results demonstrate that the health outcome advantages associated with induction of labor are gained without incurring uniformly greater health care resource use.

Using social network analysis to characterize the collaboration network of backyard poultry trainers in ackCalifornia

In order to better understand collaboration among trainers in the backyard poultry community (i.e. feed store managers, youth development programs (i.e. 4-H), veterinarians, government agencies, extension resources and backyard poultry club leaders), Social Network Analysis (SNA) was used as a tool to better characterize and quantify the current collaboration network structure of backyard poultry trainers in California. Invited trainer attendees of two "Train-the-Trainers" poultry workshops (n = 67) held in Northern and Southern California were given a survey that asked them to list contacts that they collaborated with on backyard poultry (BYP) related work. The collaboration network in this study included a total of 109 trainers, 18 practitioners, and 32 individuals who are both trainers and practitioners for a total of 170 nodes (11 individuals did not have affiliation information available). In order to help identify central actors or collaboration leaders, the surveys were analyzed using Social Network Analysis (SNA), which allows for a quantitative analysis of relationships among various stakeholders. While the SNA showed that the existing collaboration network is disconnected with a clustering coefficient of 0.043 and median total degree centrality of 1 (range 9) and therefore not conducive for collaboration, key insights that could help restructure and improve the network were identified. As an example, among different poultry groups, 4-H was identified as the organization with the second highest median coverage score and fifth highest median centrality score. In addition, 4-H group leaders act as both trainers and practitioners. Consequently, outreach to 4-H group leaders throughout the state would potentially have the greatest impact with respect to overall coverage both inside and outside the 4-H network due to their high centrality and boundary spanning roles. Using SNA to strengthen the collaboration network infrastructure of backyard poultry trainers ultimately offers a more targeted approach toward extension for backyard poultry owners, which could ultimately facilitate communication and knowledge-sharing with BYP owners during a disease outbreak.

Human platelets express endothelial protein C receptor, which can be utilized to enhance localization of factor VIIa activity

Essentials Factor VIIa binds activated platelets to promote hemostasis in hemophilia patients with inhibitors. The interactions and sites responsible for platelet-FVIIa binding are not fully understood. Endothelial cell protein C receptor (EPCR) is expressed on activated human platelets. EPCR binding enhances the efficacy of a FVIIa variant and could impact design of new therapeutics.

SUMMARY

Background High-dose factor VIIa (FVIIa) is routinely used as an effective bypassing agent to treat hemophilia patients with inhibitory antibodies that compromise factor replacement. However, the mechanism by which FVIIa binds activated platelets to promote hemostasis is not fully understood. FVIIa-DVQ is an analog of FVIIa with enhanced tissue factor (TF)-independent activity and hemostatic efficacy relative to FVIIa. Our previous studies have shown that FVIIa-DVQ exhibits greater platelet binding, thereby suggesting that features in addition to lipid composition contribute to platelet-FVIIa interactions. Objectives Endothelial cell protein C receptor (EPCR) also functions as a receptor for FVIIa on endothelial cells. We therefore hypothesized that an interaction with EPCR might play a role in platelet-FVIIa binding. Methods/results In the present study, we used flow cytometric analyses to show that platelet binding of both FVIIa and FVIIa-DVQ is partially inhibited in the presence of excess protein C or an anti-EPCR antibody. This decreased binding results in a corresponding decrease in the activity of both molecules in FXa and thrombin generation assays. Enhanced binding to EPCR was sufficient to account for the increased platelet binding of FVIIa-DVQ compared with wild-type FVIIa. As EPCR protein expression has not previously been shown in platelets, we confirmed the presence of EPCR in platelets using immunofluorescence, flow cytometry, immunoprecipitation, and mass spectrometry. Conclusions This work represents the first demonstration that human platelets express EPCR and suggests that modulation of EPCR binding could be utilized to enhance the hemostatic efficacy of rationally designed FVIIa analogs.

Influence of microstructure on symmetry determination of piezoceramics

The origin of the complex reflection splitting in potassium sodium niobate doped with lithium and manganese was investigated using temperature-dependent high-resolution X-ray and neutron diffraction as well as electron probe microanalysis and scanning electron microscopy. Two structural models were developed from the diffraction data. A single-phase monoclinic Pm model is known from the literature and is able to reproduce the diffraction patterns perfectly. However, a model with phase coexistence of two classical orthorhombic Amm2 phases can also reproduce the diffraction data with equal accuracy. Scanning electron microscopy in combination with electron probe microanalysis revealed segregation of the A-site substituents potassium and sodium. This favours the model with phase coexistence and confirms the need for comprehensive analyses with complementary methods to cover a broad range of length scales as well as to assess both average and local structure.

Constipation: an emerging risk factor for Parkinson's disease?

Constipation is the most prominent and disabling manifestation of lower gastrointestinal (GI) dysfunction in Parkinson's disease (PD). The prevalence of constipation in PD patients ranges from 24.6% to 63%; this variability is due to the different criteria used to define constipation and to the type of population enrolled in the studies. In addition, constipation may play an active role in the pathophysiological changes that underlie motor fluctuations in advanced PD through its negative effects on absorption of levodopa. Several clinical studies now consistently suggest that constipation may precede the first occurrence of classical motor features in PD. Studies in vivo, using biopsies of the GI tract and more recently functional imaging investigations, showed the presence of α-synuclein (α-SYN) aggregates and neurotransmitter alterations in enteric tissues. All these findings support the Braak proposed model for the pathophysiology of α-SYN aggregates in PD, with early pathological involvement of the enteric nervous system and dorsal motor nucleus of the vagus. Therefore, constipation could have the potential sensitivity to be used as a clinical biomarker of the prodromal phase of the disease. The use of colonic biopsies to look at α-SYN pathology, once confirmed by larger prospective studies, might eventually represent a feasible, albeit partially invasive, new diagnostic biomarker for PD.

An activated factor VII variant with enhanced tissue factor-independent activity speeds wound healing in a mouse hemophilia B model

Essentials Disorders of hemostasis can lead to delayed and defective wound healing. In hemophilia B (HB) mice, 7 days of Factor (F)IX or VIIa are needed to normalize wound healing. One dose of a highly active FVIIa variant (DVQ) restored normal wound closure time in HB mice. Coagulation factors with enhanced activity may acquire biological effects not due to hemostasis.

SUMMARY

Introduction We have previously reported that hemophilia B (HB) mice have delayed healing of cutaneous wounds and alterations in wound histology. Administration of a single dose of either factor IX or recombinant activated FVII (rFVIIa) (NovoSeven) prior to wounding did not improve wound closure time or histology. The FVIIa analog DVQ (V158D, E296V and M298Q mutations) was designed to have higher tissue factor-independent activity than rVIIa. We hypothesized that a single dose of DVQ would be more effective in restoring wound healing in HB mice. Methods Cutaneous punch wounds were made on the backs of HB and wild-type mice, and the time to wound closure was monitored. HB mice were treated with a dose of rFVIIa (10 mg kg(-1) ) or DVQ (1 mg kg(-1) ) that corrected the tail bleeding time. Skin samples were taken at various time points after wounding, fixed, and stained, and the histology was examined. Results As previously reported, wound closure times in HB mice given one dose of rFVIIa were not improved over those in untreated HB mice. Surprisingly, healing times in HB mice treated with an equally hemostatic dose of DVQ were normalized to that in wild-type mice. However, DVQ did not correct all histologic abnormalities in HB mice. Conclusions As the doses of DVQ and rFVIIa were chosen to support comparable levels of hemostasis, our data suggest that the improved healing seen with DVQ is not solely attributable to its hemostatic activity. It is possible that the improved wound healing arises through the effect of DVQ on cell signaling mechanisms.

Coated platelets and severe haemophilia A bleeding phenotype: Is there a connection?

INTRODUCTION

Coated platelets are a subpopulation of platelets that possess highly prothrombotic properties. Previous observational data suggest that bleeding phenotype in severe haemophilia A is associated with coated platelet levels. Haemophilia A patients with higher coated platelet levels may have a mild bleeding phenotype; those with lower levels may have a more severe bleeding phenotype.

AIM

The aim of the study was to test the hypothesis that coated platelet levels are correlated with clinical bleeding phenotype.

METHODS

This cross-sectional, observational study enrolled 20 severe haemophilia A patients, including 15 with severe and five with a mild bleeding phenotype, and a control group of 12 healthy volunteers. The haemophilia bleeding phenotype was determined by the patient's medical history and haemophilia treatment centre records. Blood was obtained from each patient by venipuncture and platelets were analysed by flow cytometry.

RESULTS

Patients categorized as having a severe bleeding phenotype experienced a median eight bleeds per year compared to one bleed annually in the mild bleeding phenotype group. Both groups had similar total platelet counts and fibrinogen levels. There was no difference in coated platelet percentage between severe and mild bleeding phenotype (17 and 16% respectively), however, both groups had significantly lower % coated platelets compared to controls (44%, P < 0.0001).

CONCLUSION

Coated platelet levels were not associated with bleeding phenotype in this study; however, these data may suggest coated platelet levels are lower in haemophilia patients relative to healthy volunteers.

Evolution of lung breathing from a lungless primitive vertebrate

Air breathing was critical to the terrestrial radiation and evolution of tetrapods and arose in fish. The vertebrate lung originated from a progenitor structure present in primitive boney fish. The origin of the neural substrates, which are sensitive to metabolically produced CO2 and which rhythmically activate respiratory muscles to match lung ventilation to metabolic demand, is enigmatic. We have found that a distinct periodic centrally generated rhythm, described as "cough" and occurring in lamprey in vivo and in vitro, is modulated by central sensitivity to CO2. This suggests that elements critical for the evolution of breathing in tetrapods, were present in the most basal vertebrate ancestors prior to the evolution of the lung. We propose that the evolution of breathing in all vertebrates occurred through exaptations derived from these critical basal elements.

Surgical treatment of severe congenital thoracolumbar kyphosis through a single posterior approach

A combined anterior and posterior surgical approach is generally recommended in the treatment of severe congenital kyphosis, despite the fact that the anterior vascular supply of the spine and viscera are at risk during exposure. The aim of this study was to determine whether the surgical treatment of severe congenital thoracolumbar kyphosis through a single posterior approach is feasible, safe and effective.

We reviewed the records of ten patients with a mean age of 11.1 years (5.4 to 14.1) who underwent surgery either by pedicle subtraction osteotomy or by vertebral column resection with instrumented fusion through a single posterior approach.

The mean kyphotic deformity improved from 59.9° (45° to 110°) pre-operatively to 17.5° (3° to 40°) at a mean follow-up of 47.0 months (29 to 85). Spinal cord monitoring was used in all patients and there were no complications during surgery. These promising results indicate the possible advantages of the described technique over the established procedures. We believe that surgery should be performed in case of documented progression and before structural secondary curves develop. Our current strategy after documented progression is to recommend surgery at the age of five years and when 90% of the diameter of the spinal canal has already developed.

Cite this article: Bone Joint J 2013;95-B:1527–32.

Progressive improvement in wound healing with increased therapy in haemophilia B mice

Previous work has shown that normalized haemostasis only at the time of an injury is not sufficient to promote optimal wound healing in haemophilia B (HB) mice. However, the duration of treatment required for optimal healing has not been established. The goal of these studies was to determine the effect of different durations of replacement or bypassing therapy [factor IX(FIX) or factor VIIa (FVIIa)] on wound healing parameters in a mouse model of HB. A dermal wound was placed on the back of HB mice. Animals were either untreated or pretreated and then subsequently treated for 3 days, 5 days, or 7 days with FIX or FVIIa. Wound area, time to wound healing, haematoma formation and iron deposition were measured. All treated animals showed shortened time to healing relative to untreated animals. Haematoma formation was prevented by treatment and bleeding into the wounds, measured by iron scores, was reduced by treatment. In addition, there was a progressive improvement in healing with 7 days of treatment more effective than 5 days which was more effective than 3 days. Replacement therapy with FIX had slightly shorter healing times than bypassing therapy with FVIIa. HB mice treated with FIX had slightly smaller wound area than untreated animals; by contrast, FVIIa-treated animals had much smaller wound areas that were close to the wound areas seen in wild-type animals. The data suggest that sustained therapy is required for normal wound healing.

Bleeding risk in warfarinized patients with a therapeutic international normalized ratio: the effect of low factor IX levels

OBJECTIVE

Bleeding is the main complication of warfarin therapy, even patients with an international normalized ratio (INR) in the target range can suffer bleeding, suggesting that INR does not perfectly reflect the therapeutic effect of warfarin. We hypothesized the INR might underestimate the level of anticoagulation in a subject with a lower factor (F) IX level than average.

METHODS AND RESULTS

We modeled warfarin anticoagulation in our in vitro thrombin generation (TG) model by adjusting the levels of vitamin K-dependent factors to those of patients with an INR of 2-3. Variation in FIX had a marked effect on TG but had no effect on the prothrombin time (PT)-INR. A prospective observational, cross-sectional clinical study including 341 consecutive patients admitted to the emergency department with an INR between 2 and 3, showed a statistically lower FIX activity in bleeders (P = 0.004) compared with others. No correlation was found between TG capacity and PT-INR results (P = 0.36). However, in patients, presenting with a warfarin-related hemorrhage, TG was significantly lower (P < 0.001) than others. A correlation on the boundary of significance was observed between TG capacity and FIX levels (P = 0.09).

CONCLUSION

These data demonstrates that patients who bleed when their PT-INR is in the target range 2-3 might have defective TG related to a lower level of FIX than expected.

Utilization of family members to provide hospital care in Malawi: the role of Hospital Guardians

AIM

Like most of sub-Saharan Africa, Malawi suffers from a paucity of human resources in the health sector. With an average of one physician for every 50,000 persons, and a health care professional to in-patient population ratio of 1:277, patient care suffers. At Kamuzu Central Hospital (KCH) of Lilongwe, Malawi, family members, termed Hospital Guardians, are utilized to provide basic care for patients. The aim of our study is to characterize this population and explore their role in the health care system of KCH.

METHODS

Seventy three semi-qualitative surveys and nineteen in-depth interviews were conducted with hospital administrators, Guardians, nurses, and physicians from these wards. The results were analyzed using descriptive analysis and emergent coding.

RESULTS

It was found that Hospital Guardians were primarily female family members of patients and have a low literacy rate. They performed a wide range of daily tasks in patient care from wound care to advocacy. Despite their essential role in the health care system, the Guardians were provided with little support from the hospital. There was often conflict between the Guardians and hospital personnel due to overcrowding with more than one Guardian per patient; a lack of understanding of hospital rules and regulations; and a lack of respect for the Guardian role by hospital staff.

CONCLUSIONS

Until their role can be reduced by additional trained health care professionals, patient care could be improved by institutional support including a clarification of the role of the Hospital Guardians. Recommendations include a one-patient one-guardian policy; Guardian education; and enhancing Guardian resources.

Mechanisms and monitoring of bypassing agent therapy

Understanding the mechanism of action of normal hemostasis and how the bypassing agents recombinant activated factor VII (rFVIIa; NovoSeven) and plasma-derived activated prothrombin complex concentrate (Factor Eight Inhibitor Bypassing Agent [FEIBA]) control abnormal bleeding is imperative for healthcare professionals who treat patients with hemophilia and other bleeding disorders. A cell-based model has improved our understanding of in vivo mechanisms of hemostasis and the basis of the bleeding tendency in hemophilia. Bypassing agents do not restore the normal pathways of hemostasis in hemophilia, but rather boost thrombin generation in spite of a lack of platelet surface FVIIIa-FIXa ('tenase') activity. Thus, the common clinical laboratory coagulation assays do not reflect the clinically relevant hemostatic activity of bypassing agents, and no validated assay is available with which to measure the in vivo efficacy of these agents or predict individual patient responses to treatment. Global hemostasis assays measuring overall coagulation capacity have potential for assessment of the effects of bypassing agents. This review will focus on the mechanisms of clotting and their relationship to understanding the mechanisms of action of the bypassing agents in vivo and the methodologies that are emerging to monitor the clinical efficacy of bypassing agent therapy.

Ceramic-like wear behaviour of human dental enamel

This paper reports a transmission electron microscopy (TEM) analysis of subsurfaces of enamel specimens following in vitro reciprocating wear tests with an enamel cusp sliding on a flat enamel specimen under hydrated conditions. The obtained results show that crack formation occurred in the wear scar subsurface. The path followed by these cracks seems to be dictated either by the histological structure of enamel or by the contact stress field. Moreover, the analysis of a set of enamel wear results obtained from the literature and application of fracture-based models, originally developed for ceramics, correlate well, confirming the similar wear processes taking place in these materials. This analysis also reveals a marked influence of coefficient of friction on the enamel wear rate: for a higher coefficient of friction value, enamel wear can be severe even under forces generated during normal operation of teeth.

No association of vitamin D intake or 25-hydroxyvitamin D levels in childhood with risk of islet autoimmunity and type 1 diabetes: the Diabetes Autoimmunity Study in the Young (DAISY)

AIMS/HYPOTHESIS

The aim of the study was to investigate the association between vitamin D intake and status and the risk of islet autoimmunity (IA) and subsequent type 1 diabetes in children at increased risk of type 1 diabetes.

METHODS

The Diabetes Autoimmunity Study in the Young (DAISY) in Denver, CO, USA, has been following children at increased risk of diabetes since 1993. As of February 2011, 198 children developed IA during follow-up of 2,644 DAISY children. Vitamin D intake and plasma 25-hydroxyvitamin D [25(OH)D] were measured longitudinally. Proportional hazards regression analyses of time to IA, or type 1 diabetes in IA-positive children, were conducted, with vitamin D intake and 25(OH)D as time-varying covariates. HRs were calculated for a standard deviation difference in exposure, with adjustment for confounders.

RESULTS

Intake of vitamin D was not associated with the risk of IA (adjusted HR 1.13; 95% CI 0.95, 1.35; p = 0.18) nor progression to diabetes in IA-positive children (adjusted HR 1.30; 95% CI 0.91, 1.86; p = 0.15). Moreover, 25(OH)D level was not associated with the risk of IA (adjusted HR 1.12; 95% CI 0.88, 1.43; p = 0.36), nor progression to diabetes in IA-positive children (adjusted HR 0.91; 95% CI 0.68, 1.22; p = 0.54). In the 128 children in whom we measured 25(OH)D at 9 months of age, 25(OH)D was not associated with risk of IA (n = 30 IA-positive children) (adjusted HR 1.02; 95% CI 0.96, 1.07; p = 0.58).

CONCLUSIONS/INTERPRETATION

Neither vitamin D intake nor 25(OH)D levels throughout childhood were associated with the risk of IA or progression to type 1 diabetes in our population.

Platelet binding and activity of a factor VIIa variant with enhanced tissue factor independent activity

BACKGROUND AND OBJECTIVES

Platelet binding and activity play important roles in the efficacy of factor VIIa (FVIIa) as a bypassing agent for hemophilia treatment. An analog of FVIIa with increased tissue factor (TF)-independent activity, NN1731, has been produced by introducing three amino acid changes in the protease domain. NN1731 has a conformation similar to TF-bound FVIIa, even in the absence of TF. This results in much greater intrinsic proteolytic activity, but similar activity in the presence of TF.

OBJECTIVES

We hypothesized that these changes would not alter binding to platelets or phospholipid, a characteristic thought to be localized to the Gla domain. The goal of the current work was to compare platelet binding and activity of NN1731 and wild-type FVIIa.

METHODS/RESULTS

FVIIa and NN1731 bound identically to phospholipid vesicles as assessed by both activity assays and electrophoretic quasielastic light scattering techniques. However, NN1731 bound to a greater number of sites on activated platelets than FVIIa, as assessed by flow cytometry. Removal of the Gla domain abolished binding of both FVIIa and NN1731. Inhibition of the active site did not reduce NN1731 binding to the level of FVIIa. When corrected for the amount of protein bound, NN1731 had greater activity than FVIIa on platelet surfaces.

CONCLUSIONS

While the Gla domain is essential for FVIIa binding to platelets, changes in the protease domain in NN1731 enhanced platelet binding as well as proteolytic activity. Features in addition to lipid composition appear to contribute to binding of rFVIIa and, especially, NN1731 to platelets.

Wound healing in haemophilia--breaking the vicious cycle

Our group has been studying how haemostasis interacts with repair processes and also how to optimize treatment of bleeding disorders in a mouse model of haemophilia B. We have found that cutaneous wounds heal more slowly in haemophilic mice than in wild-type mice, and also exhibit histological abnormalities, even after closure of the skin defect. The haemophilic wounds showed reduced influx of inflammatory cells and increased angiogenesis. Even after surface closure, the haemophilic animals experienced repeated episodes of re-bleeding and progressive accumulation of iron in the wound bed and deeper tissues. A dose of replacement or bypassing therapy sufficient to establish initial haemostasis did not normalize wound healing. In fact, daily dosing for 7 days was required to normalize wound closure. Thus, normal healing requires adequate haemostatic function for an extended period of time. We have hypothesized that this is because angiogenesis during healing predisposes to bleeding, especially in the setting where haemostasis is impaired. Thus, normalizing haemostasis, until the process of angiogenesis has resolved, may be required to prevent re-bleeding and additional tissue damage.