Factors associated with mental health of young children during the COVID-19 pandemic in the Netherlands

BACKGROUND

The COVID-19 pandemic and accompanying societal measures have impacted children and their families all over the world. Little is known about the factors associated with mental health outcomes in young children (i.e., 1 to 6 years old) during the pandemic. The current study aimed to examine associations with potential risk and protective factors, i.e., direct COVID-19 exposure factors as well as within-family characteristics.

METHODS

Caregivers of children aged 1-6 years old were recruited in the Netherlands to participate in an ongoing longitudinal research project. In the current study, baseline data-collected during the 1st year of the pandemic-are reported. The final sample consisted of 2762 caregivers who answered questionnaires assessing negative and positive dimensions of their children's mental health (i.e., anxiety, depressive symptoms, anger, sleep problems, positive affect, and self-regulation). Furthermore, caregivers provided information regarding: (1) Direct COVID-19 related factors, i.e., parental infection and death of a family member or close friend due to COVID-19, (2) Family related COVID-19 factors, i.e., parental perceived impact of the pandemic and COVID-19 related parent-child emotion regulation strategies (i.e., active, avoidant and information-focused strategies), (3) General caregiver's distress, i.e., parental mental health, parental feelings of rejection towards their child. Regression analyses were used to examine associations with children's mental health.

RESULTS

Direct COVID-19 related factors were not associated with more mental health problems in the children, though parental COVID-19 infections were related with less anger in children. Family related COVID-19 factors and caregiver's distress were related with children's mental health. Higher parental perceived negative impact of the pandemic, lower parental perceived positive impact of the pandemic, more avoidant as well as more active and information-focused parent-child emotion regulation strategies, more caregiver's mental health problems and more parental feelings of rejection towards their child were related with more mental health problems in the child.

CONCLUSION

Direct exposure to COVID-19 was not related with more mental health problems in the child. Family related COVID-19 factors and caregiver's distress appear to play a more important role for young children's mental health. Findings may inform prevention and intervention programs for potential future global crises as well as other stressful events.

Are 4D Motion Sensors Valid and Reliable for Studying Baseball Pitching?

BACKGROUND

Baseball pitching injuries are on the rise. Inertial measurement units (IMUs) provide immediate feedback to players and coaches, allowing for collection outside of the traditional laboratory setting with real-world application. The 4D Motion system provides kinematics throughout the pitching motion and may be beneficial for individualized programs in the throwing athlete. A systematic analysis of these sensors has not been completed.

PURPOSE

To evaluate the validity of the 4D Motion IMU system for analyzing the baseball pitching motion compared with marker-based motion capture, and evaluate the internal reliability and consistency of the device.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten high school pitchers participated in this study (10 male; 9 right-hand dominant; mean age, 16.6 ± 1.3 years; mean body mass index, 24.1 ± 3.9). Participants were simultaneously outfitted with six 4D Motion IMU sensors and retroreflective markers. The pitchers threw fastballs at maximum effort off a mound at the standard height and distance. A comparison was made between the IMUs and corresponding motion capture values for shoulder external rotation, elbow flexion, chest extension, pelvis and chest rotation velocity, and rotation acceleration.

RESULTS

Significant differences were found for 5 of 7 metrics analyzed. The IMU overreported most metrics, except for elbow flexion and pelvis rotation angular acceleration, where both positive and negative errors were observed. The root mean square error and percentage errors indicated smaller discrepancies for chest extension (4°± 5°) and pelvis (38 ± 19 deg/s) and chest (96 ± 42 deg/s) rotation velocity, with elbow flexion having the largest variance (21°± 9°).

CONCLUSION

The values of the 4D Motion IMU system should not be considered equivalent when compared with marker-based motion capture studies. The system lacked internal consistency and reliability, with angular velocities being the most consistent. Caution should be used when using the metrics provided by an IMU-based system for individualized monitoring.

CLINICAL RELEVANCE

If found valid and reliable, IMUs could be used for longitudinal workload monitoring, individualized throwing and rehabilitation programs, and ultimately injury prevention. This study demonstrates that the data obtained from a 4D Motion system using Gen 3 sensors are not equivalent to the data obtained from a marker-based motion capture system.

Changes in Elbow Stress and Ball Velocity During Reduced Effort Pitching: A Marker-Based Motion Capture Analysis

BACKGROUND

Baseball pitchers often participate in throwing programs that involve throwing at reduced effort levels to gradually increase the amount of stress experienced across the elbow. It is currently unknown how reduced effort pitching compares with maximum effort with respect to elbow stress and ball velocity.

PURPOSE/HYPOTHESIS

The purpose was to determine the correlation between elbow stress and ball velocity with reduced effort pitching. We hypothesized that decreased perceived effort would disproportionately correlate with elbow stress and ball velocity.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten healthy male high school baseball pitchers threw 5 pitches from a regulation pitching mound at 3 effort levels: maximum effort, 75% effort, and 50% effort. Elbow stress, specifically elbow varus torque, was calculated for all pitches using a validated marker-based 3-dimensional motion capture system. Ball velocity was measured using a Doppler radar gun. Intrathrower variability was calculated for each effort level.

RESULTS

Elbow stress and ball velocity decreased with reduced effort throws (P < .001 and P = .003, respectively). However, the reductions in elbow stress and ball velocity were not proportional. At 75% effort throws, elbow stress measured 81% (intraclass correlation coefficient [ICC], 0.95), and ball velocity measured 90% (ICC, 0.80) of maximum, respectively. At 50% effort throws, elbow stress measured 75% (ICC, 0.93), and ball velocity measured 85% (ICC, 0.87) of maximum. Intrathrower reliability was excellent for elbow stress and ball velocity, with all ICCs ≥0.80.

CONCLUSION

Pitching at a reduced effort level resulted in decreased elbow stress and ball velocity. However, for every 25% reduction in perceived effort, elbow stress decreased by a mean 13%, and ball velocity decreased 7.5%. When baseball pitchers attempt to throw at a reduced effort of maximum, throwing metrics do not decrease proportionately.

CLINICAL RELEVANCE

While pitching at a reduced effort of maximum decreases elbow stress and ball velocity, the decrease is not proportional, subjecting the elbow to more stress than intended. This has significant clinical importance to pitchers, coaches, and medical professionals in the setting of injury prevention and return to sports.

Is maternal negative affectivity related to psychosocial behavior of preterm and term-born toddlers through mother–child interaction?

Introduction

Children born moderately to late preterm (MLP) are more prone to psychosocial difficulties than their term-born counterparts. Maternal negative affectivity (NA)–a relatively stable personality trait characterized by the tendency to experience negative thoughts, feelings and emotions–has been related to more psychosocial problems in their offspring, and to a lower quality of mother–child interactions. As MLP children seem more sensitive to their early caregiving environment, they might be more affected by maternal NA and interaction style than their term-born peers. The current study investigated whether maternal NA predicted child’s psychosocial outcomes through quality of mother–child interaction, and if these associations differed between MLP and term-born children.

Methods

The sample consisted of 108 MLP and 92 term-born children and their mothers. At 18 months corrected age, maternal NA was measured using a self-report questionnaire and mother–child interaction was observed during two structured tasks. Five subscales of mother–child interaction were assessed: negative interaction, reciprocal engagement, emotional support, maternal stimulation and mother-led interaction. At 24 months corrected age, social–emotional difficulties, internalizing, and externalizing problems were assessed using mother-report.

Results

For MLP children, maternal NA directly, positively, predicted social–emotional difficulties (b = 0.57) and internalizing problems (b = 0.45), but no mediation effect of mother–child interaction was found. For term-born children, no direct effect but a mediation effect of mother-led interaction was found. Higher levels of maternal NA predicted less mother-led interaction which in turn predicted more problems. Birth status did not moderate any of the relationships, showing that the differences in patterns of effects found within the MLP and term-born group did not reach statistical significance.

Discussion

Maternal NA was found to be a risk factor for psychosocial outcomes in toddlers, either directly for MLP children or indirectly through mother-led interaction for term-born children. These findings suggest that the process through which maternal NA affects psychosocial outcomes may be different for MLP and term-born children. However, as the examined moderation effects of birth status did not reach statistical significance, more research using larger sample sizes is needed to study mother–child interaction in greater detail.

P-444 Outcomes of oocyte vitrification in trans masculine persons

Study question

What are the outcomes of oocyte vitrification treatment(OVT) in trans masculine persons (TMPs) prior to, and after testosteroneuse? And how do these patients reflect on their treatment?

Summary answer

TMPs show a normal response to controlled ovarian hyperstimulation(COH). Even though the OVT was considered burdensome, most patients were satisfied with their treatment and outcome.

What is known already

The desire to parent genetic offspring is a relevant topic in the lives of many TMPs. To preserve their fertility prior to gender affirming hormone treatment or –surgeries, fertility preservation should be discussed by healthcare providers. However, the procedure may lead to an increase in dysphoric distress in TMPs. Only few studies have been published describing the outcomes of TMPs undergoing OVT. Their data suggest a comparable oocyte retrieval number in TMPs compared to cis gender women as well as similar fertilization and pregnancy rates. Outcomes of OVT in TMPs and their experiences undergoing said treatment remain under-explored.

Study design, size, duration

This single center, retrospective cohort study was performed by the Center of Expertise on Gender and the fertility clinic at the Amsterdam UMC, location VUmc, Amsterdam, the Netherlands. Between January 2017 and June 2021, all TMPs who had undergone OVT where approached for participation and 24/30 TMPs were included in our cohort.

Participants/materials, setting, methods

Demographic characteristics and data on OVT were retrieved from the medical records. Oocyte vitrification at our center is performed in persons between the age of 16 and 39 using a long agonist COH protocol. TMPs who had initiated testosterone were advised 3 months cessation prior to stimulation. Evaluation of the oocyte vitrification procedure was collected via an online questionnaire comprising of 10 multiple choice and open ended questions.

Main results and the role of chance

The median age and BMI of participants was 21.1 years (IQR 19.4 – 24.1) and 22.1 kg/m2 (IQR 20.8 – 25.4), respectively. Seven persons were using testosterone, two persons were using puberty suppression (GnRH analogues) and seven persons were using other hormonal cycle regulation prior to their OVT.

The median anteral follicle count on cycle day three was 28(IQR 24.5 – 35.0). After a median of 12 FSH stimulation days (IQR 10 – 13), a trigger was administered. The mean peak serum estradiol(E2) was 11062 pmol/L (SD 5385). A median of 20 oocytes (IQR 16 – 26) were found and a median of 17 oocytes (IQR 14 – 22) were frozen. Six participants (25%) developed an ovarian hyperstimulation syndrome(OHSS). Four of which were classified as severe. There were no significant differences between the prior testosterone users and non-testosterone users.

The median time between OPU and taking the questionnaire was 19.2 months(IQR 3.2 – 27.5). The response rate was 100%. Almost half of participants(46%) were most anxious for the internal examination prior to starting OVT. Interestingly, afterwards only 13% described the internal examination as the most strenuous part of the treatment. Hormone injections were considered the most strenuous part of OVT (29%).

Limitations, reasons for caution

A limitation of this study is the small sample size, especially when comparing prior testosterone users to non-testosterone users. Another limitation is that the effect of previous testosterone on the chance of live birth rate remains unknown since no participants have chosen to pursue conception yet.

Wider implications of the findings

This is the first study describing OVT outcomes in the TMPs in the Netherlands. This study shows no difference between prior testosterone use or not. The survey results identify the most burdensome aspect of the procedure for TMPs and improve transgender specific fertility strategies.

Trial registration number

not applicable

OP0021 IDENTIFICATION OF DIFFERENTIALLY EXPRESSED GENES IN EARLY RHEUMATOID ARTHRITIS PATIENTS RESPONDING TO TOCILIZUMAB

Background:

Tocilizumab (TCZ) is a monoclonal antibody that binds to the interleukin 6 receptor (IL-6R), inhibiting IL-6R signal transduction to downstream inflammatory mediators. TCZ has shown to be effective as monotherapy in early rheumatoid arthritis (RA) patients (1). However, approximately one third of patients inadequately respond to therapy and the biological mechanisms underlying lack of efficacy for TCZ remain elusive (1). Here we report gene expression differences, in both whole blood and peripheral blood mononuclear cells (PBMC) RNA samples between early RA patients, categorized by clinical TCZ response (reaching DAS28 < 3.2 at 6 months). These findings could lead to identification of predictive biomarkers for TCZ response and improve RA treatment strategies.

Objectives:

To identify potential baseline gene expression markers for TCZ response in early RA patients using an RNA-sequencing approach.

Methods:

Two cohorts of RA patients were included and blood was collected at baseline, before initiating TCZ treatment (8 mg/kg every 4 weeks, intravenously). DAS28-ESR scores were calculated at baseline and clinical response to TCZ was defined as DAS28 < 3.2 at 6 months of treatment. In the first cohort (n=21 patients, previously treated with DMARDs), RNA-sequencing (RNA-seq) was performed on baseline whole blood PAXgene RNA (Illumina TruSeq mRNA Stranded) and differential gene expression (DGE) profiles were measured between responders (n=14) and non-responders (n=7). For external replication, in a second cohort (n=95 therapy-naïve patients receiving TCZ monotherapy), RNA-seq was conducted on baseline PBMC RNA (SMARTer Stranded Total RNA-Seq Kit, Takara Bio) from the 2-year, multicenter, double-blind, placebo-controlled, randomized U-Act-Early trial (ClinicalTrials.gov identifier: NCT01034137) and DGE was analyzed between 84 responders and 11 non-responders.

Results:

Whole blood DGE analysis showed two significantly higher expressed genes in TCZ non-responders (False Discovery Rate, FDR < 0.05): urotensin 2 (UTS2) and caveolin-1 (CAV1). Subsequent analysis of U-Act-Early PBMC DGE showed nine differentially expressed genes (FDR < 0.05) of which expression in clinical TCZ non-responders was significantly higher for eight genes (MTCOP12, ZNF774, UTS2, SLC4A1, FECH, IFIT1B, AHSP, and SPTB) and significantly lower for one gene (TND2P28M). Both analyses were corrected for baseline DAS28-ESR, age and gender. Expression of UTS2, with a proposed function in regulatory T-cells (2), was significantly higher in TCZ non-responders in both cohorts. Furthermore, gene ontology enrichment analysis revealed no distinct gene ontology or IL-6 related pathway(s) that were significantly different between TCZ-responders and non-responders.

Conclusion:

Several genes are differentially expressed at baseline between responders and non-responders to TCZ therapy at 6 months. Most notably, UTS2 expression is significantly higher in TCZ non-responders in both whole blood as well as PBMC cohorts. UTS2 could be a promising target for further analyses as a potential predictive biomarker for TCZ response in RA patients in combination with clinical parameters (3).

References:

[1]Bijlsma JWJ, Welsing PMJ, Woodworth TG, et al. Early rheumatoid arthritis treated with tocilizumab, methotrexate, or their combination (U-Act-Early): a multicentre, randomised, double-blind, double-dummy, strategy trial. Lancet. 2016;388(10042):343-55.

[2]Bhairavabhotla R, Kim YC, Glass DD, et al. Transcriptome profiling of human FoxP3+ regulatory T cells. Human Immunology. 2016;77(2):201-13.

[3]Gosselt HR, Verhoeven MMA, Bulatovic-Calasan M, et al. Complex machine-learning algorithms and multivariable logistic regression on par in the prediction of insufficient clinical response to methotrexate in rheumatoid arthritis. Journal of Personalized Medicine. 2021;11(1).

Disclosure of Interests:

None declared

Parental personality, parenting and toddlers' externalising behaviours

This study examined the mediating role of parenting on the relation between parental personality and toddlers' externalising behaviours. Participants were 112 boys and their parents. The data were analysed using multilevel modelling and moderated mediation analyses. Several associations were found between parental personality and parenting dimensions. Additionally, several parenting dimensions were associated with children's externalising behaviours. Emotional stability was the only parental personality trait that was related to children's externalising behaviours. The effect of maternal emotional stability on children's aggressive behaviours appeared to be mediated by maternal support. For fathers, there appeared to be a direct effect of emotional stability on children's aggressive behaviours. In addition, for both mothers and fathers, emotional stability was directly related to children's attention problems. Copyright © 2007 John Wiley & Sons, Ltd.

FRI0554 DEVELOPMENT OF A DISEASE ACTIVITY INDEX FOR RA PATIENTS USING HANDSCAN

Background:

Disease activity in RA patients is usually measured by DAS28,1a composite measure consisting of 28 swollen and/or tender joint counts (SJC28/TJC28), an acute phase reactant (APR, e.g. ESR/CRP) and patient’s general health typically using a visual analogue scale (VAS). Particularly assessment of joint counts is time consuming, requires a trained health professional and its inter-observer variety is high. The HandScan is developed to measure inflammation in hand joints using optical spectral transmission (OST, score 0 to 66) without taking time of a health professional.2The correlation between DAS28 and a single measurement of OST is moderate.3We hypothesised that a composite measure including OST (representing joint inflammation), VAS and APR would lead to an appropriate disease activity index.

Objectives:

To establish a method for assessing disease activity in RA patients using HandScan +/- other disease activity parameters, with cut-offs for remission and low disease activity (LDA).

Methods:

RA patients, visiting the outpatient clinic of Máxima Medical Center Eindhoven, were eligible for inclusion. Inclusion criteria were; (1) RA according to classification criteria, (2) at least one HandScan and DAS28 measurement performed at the same visit, and (3) aged ≥18. Data was extracted from medical records. A random sample of 2/3 of included patients was used as development cohort, the remaining 1/3 was used as validation cohort. In the development cohort, linear regression analyses were performed to create a formula for an OST index (DASost). In these, DAS28 was the outcome variable and, OST, ESR and VAS were predictors. Also other parameters were tested in the model to see if they increased the fit of the model or modified the association between OST and DAS28. A final model was derived, based on statistical significance of predictors and improvement of model fit (adjusted R-square). Agreement of DAS28 with DASost was tested with the random one-way intraclass correlation coefficient (ICC). DAS28 based remission and LDA were calculated for DASost using the established DAS28 cut-offs (i.e. DASost<2.6 and DASost<3.2). A cut-off for DASost for Boolean remission was defined using receiver operating characteristic (ROC) curves and Youden’s index. In the validation cohort, diagnostic values were calculated for DASost using the cut-offs as defined above.

Results:

Data of 3358 observations within 1505 unique RA patients were extracted. Patients’ demographic and clinical data are shown in Table 1. The formula for DASost derived in the development cohort was: -0.44 + (OST*0.03) + (male*-0.11) + (LN(ESR)*0.77) + (VAS*0.03). The optimal cut-off on DASost found for Boolean remission was 2.2. The ICC was 0.88 (95%CI 0.87 - 0.89). The explained variance of DASost in the validation cohort was 78%. Diagnostic accuracy of DASost in the validation cohort for DAS28 based remission, LDA and Boolean remission are shown in Table 2.

Table 1.

Patients’ demographics and clinical data

Patient demographicsNumber of patients1505 (100%)Females976 (65%)Age (year)65.5 (12.1)duration of RA (year)11.5 (8.3)Seropositivity1068 (71%)Clinical dataNumber of observations3358DAS282.5 (1.3)ESR (mm/hr)9.0 (5.0 – 21.0)SJC0 (0 – 2)TJC0 (0 – 2)VAS30.0 (10.0 – 50.0)OST12.6 (5.0)

Data are n (%), mean (SD), or median (IQR).

Table 2.

Diagnostic values of DASost

Disease activity stateAU ROCSensitivitySpecificityPPVNPVaccuracyRemission0.9389%83%88%84%86%LDA0.9291%67%89%73%85%Boolean remission0.8791%95%39%98%94%

AU ROC= area under the receiver operating characteristic curve, PPV= positive predictive value, NPV= negative predictive value.

Conclusion:

The HandScan could be used as a tool to quickly assess disease activity in RA patients, if OST is combined with other disease activity parameters into an index.

References:

[1] Felson D., et al. Ann Rheum Dis. 2011;70:404-13

[2] Besselink N., et al. Trials. 2019;20:226

[3]van Onna M., et al. Ann Rheum Dis. 2016;75:511-18

Disclosure of Interests:

Maxime Verhoeven: None declared, Paco Welsing: None declared, Janneke Tekstra: None declared, Jacob M. van Laar Grant/research support from: MSD, Genentech, Consultant of: MSD, Roche, Pfizer, Eli Lilly, BMS, Floris Lafeber Shareholder of: Co-founder and shareholder of ArthroSave BV, Johannes W.G. Jacobs Grant/research support from: for UActEarly published in 2016 in Lancet, Speakers bureau: 2011, Anton A.A. Westgeest: None declared

Split-weaning before altrenogest synchronization of multiparous sows alters follicular development and reduces embryo survival

This study used split-weaning (SW) to induce differences in follicle size at weaning and study its consequences for follicle development during and after post-weaning altrenogest feeding and for reproductive performance. Multiparous sows (n=47) were assigned to SW (n=23; litter size reduced to the six smallest piglets 3 days before weaning) or control (C; n=24; normal weaning). Altrenogest (20 mg/day) was fed to all 47 sows from Day -1 till Day 5 (complete weaning = Day 0). Follicle size on Day 1, 2 and 8 was smaller in C than in SW (p ≤ 0.05). Ovulation rate was similar, but C sows had higher embryo survival rate (ESR) than SW sows (83 ± 19 and 58 ± 31%, respectively; p=0.001). SW sows with low ESR (<63%; n=10) had a greater follicle size on days 3-6 than SW sows with high ESR (>63%; n=10; p ≤ 0.04). A decrease in follicle size between Day 5 and 6 of altrenogest feeding was associated with increased ESR in both treatments (p=0.002). Follicle pool analyses (assessment of all follicles >2 mm) revealed that on Day 3, sows with low ESR had a higher % of follicles >5 mm compared with sows with high ESR (30% vs 10%; p=0.04). Thus, sows in which follicle growth was less suppressed during altrenogest feeding had a lower ESR. These effects on follicle development and ESR were more pronounced in split-weaned sows.

Externalizing behaviors and minor unintentional injuries in toddlers: common risk factors?

OBJECTIVE

To investigate predictors for externalizing behaviors and minor unintentional injuries in toddlers and to examine whether common risk factors can be identified.

METHODS

Linear regression models were used to investigate the contributions of predictors belonging to the domains of child characteristics and parental characteristics. Participants were 117 boys (M = 16.9 months) and their parents.

RESULTS

Two common risk factors for externalizing behaviors and minor injuries were identified: maternal low conscientiousness and paternal low self-control. In addition, children's inhibitory control and dispositional frustration as well as maternal externalizing symptoms contributed independently to children's externalizing behaviors.

CONCLUSIONS

Results supply some evidence for the interrelatedness of negative outcomes and on the existence of common risk factors. Interventions could aim to address these common risk factors in order to pursue a number of goals at the same time, instead of focusing on only one type of negative outcome.

Alternative fixation of bioprostheses

The glutaraldehyde fixation technique for bioprosthetic tissue valves has been used for about 30 years. It is more or less generally recognized, however, that a solution to the ongoing problems of calcification and immunomodulated inflammation can only be achieved with the development of alternative fixation techniques that differ from fixation with glutaraldehyde. This review reports on the chemistry behind newly developed tissue-fixation processes and the preliminary results achieved with these.

Antithrombin activity of surface-bound heparin studied under flow conditions

Polyacrylamide-grafted polyetherurethane sheets were modified by end-point and multipoint attachment of heparin. The surface-bound heparin was firmly attached. No release of heparin activity could be detected when the surface was rinsed at a wall shear rate of 2000 s-1. Uptake of antithrombin and thrombin inactivation were investigated under well-defined flow conditions by the use of a spinning device with an attached disk-shaped heparinized surface. It is demonstrated that the rate of thrombin inactivation at the antithrombin-heparin surface equals the maximal rate of transport of thrombin toward the surface when the surface coverage of antithrombin exceeds 10 pmol/cm2. This result indicates that a higher intrinsic catalytic efficiency of a surface does not necessarily result in a higher antithrombin activity. We varied the heparin content of the surfaces between 0 and 35 micrograms/cm2 by increasing the number of functional groups to which heparin could be covalently attached. The uptake of antithrombin increased with the heparin content of the surface, but the stoichiometry decreased from 2 to 0.5 pmol antithrombin/micrograms heparin. Apparently, antithrombin could not bind to heparins buried in the poly(acrylamide) layer. The rate of thrombin inactivation at surfaces with low heparin content (2 micrograms/cm2) fells below the transport limit of thrombin and became proportional with the heparin content of the surface. Although the contribution of surface-bound heparin to the neutralization of fluid-phase thrombin was found to be negligible compared with the effect of fluid-phase antithrombin at physiologic relevant concentrations, these heparinized surfaces markedly delayed the onset of thrombin generation in platelet-rich plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood-biomaterial interactions in a flow system in the presence of bacteria: effect of protein adsorption

An in vitro continuous flow system with whole human blood was used to study blood-biomaterial interactions on a base polyurethane and three modified surfaces in the presence and absence of circulating Staphylococcus epidermidis. We hypothesized that the composition of the protein layer adsorbed on the surface of the biomaterial would influence the response of blood components and bacteria. We examined the test surfaces for adsorption of nine plasma proteins and adsorption profiles differed on the four surfaces. The positively charged surface, UC, adsorbed significantly higher amounts of fibronectin (P < .01), von Willebrand factor (P < .01), and fibrinogen (P < .05) than the other materials. As a consequence of increased adsorption of these adhesive proteins, the adhesion of platelets and bacteria was greater on UC than on any other surface. On the base polyurethane, BC, and the negatively charged surface, UA, protein adsorption was low, and these materials were largely free of adherent blood cells and bacteria. The heparinized surface, UH, adsorbed higher quantities (P < .01) of Hageman factor and high molecular weight kininogen relative to the other surfaces. Platelet adhesion, and surface coagulation were prominent on UC, and may have contributed to increased bacterial adhesion on this surface. In the presence of circulating bacteria, adsorption was generally lower than in the absence of bacteria. The pattern of protein adsorption was largely unaffected by the strain of circulating bacteria, but platelet responses (adhesion and activation) were greater in the presence of slime-producing S. epidermidis as compared to the non-slime-producing strain, suggesting that slime may have a direct activating effect on platelets.

Human monocyte/macrophage adhesion and cytokine production on surface-modified poly(tetrafluoroethylene/hexafluoropropylene) polymers with and without protein preadsorption

To study surface property-dependent human monocyte adhesion and cytokine (IL-1 beta, IL-6, TNF-alpha) production, poly(tetrafluoroethylene/hexafluoropropylene) (FEP) polymer was modified to exhibit neutral, anionic, or cationic properties by incorporating amide (CONH2) and/or carboxyl (COOH) or aminoethyl amide [CONH(CH2CH2NH)nCH2CH2NH2] groups on the surface. Monocyte adhesion on surface-modified FEP polymers and cytokines released by monocytes/macrophages (MC/MO) into the culture medium were compared to control tissue culture polystyrene (TCPS) at days 1 and 8. On day 1, the neutral surface FEP polymer with incorporated amide (NH2) groups showed the greatest inhibition of adhesion, 89% (P < .01), and cytokine production (IL-1 beta with 58%, IL-6 with 70%, and TNF-alpha with 39%) compared to control TCPS. In contrast, the highly cationic [CONH(CH2CH2NH)nCH2CH2NH2] surface did not show significant (P > .01) inhibition of monocyte adhesion and cytokine production. When fibrinogen or IgG was preadsorbed to the surface, the inhibitory effects of the neutral surface FEP polymer on monocyte adhesion and cytokine production were not altered. In addition, other surface-modified FEP polymers showed similar inhibition of monocyte adhesion and cytokine production compared to TCPS. Specifically, as the incorporation of carboxyl (COOH) group content increased on FEP polymer surfaces, monocyte adhesion and cytokine production were also increased on day 1 with IgG preadsorption. On day 8, all surface-modified FEP polymers showed significant (P < .01) inhibition of monocyte adhesion when fibrinogen or IgG was preadsorbed. However, without protein (fibrinogen or IgG) preadsorption, monocyte adhesion was not significantly inhibited compared to control TCPS. In addition, cytokine production detected by ELISAs on day 8 showed no detectable levels of IL-1 beta and significantly decreased levels of IL-6 compared to day 1 for all tested polymers, with or without protein preadsorption. Interestingly, the level of TNF-alpha production on day 8 remained high although not as high as on day 1. Based on these results, we suggest that FEP polymers with neutral hydrophilic surface properties may adhere and activate the least number of monocytes, which are important mediators of biocompatibility.