"Somewhere to turn to with my questions": A pre-post pilot of an information linker service for caregivers who have a child with a Developmental and Epileptic Encephalopathy

BACKGROUND

Caregivers of a child with a Developmental and Epileptic Encephalopathy (DEE) often report challenges accessing relevant and understandable information regarding their child's condition. We developed GenE Compass, an information linker service where caregivers are invited to submit questions and receive high-quality, personalised reports. We conducted a pilot evaluation to determine the feasibility and acceptability of GenE Compass.

METHODS

We invited eligible caregivers to complete a baseline questionnaire (Q1) prior to receiving three months access to submit an unlimited number of questions to GenE Compass. We then invited caregivers to complete a follow-up questionnaire (Q2) and optional interview. Caregivers also had the opportunity to share report-specific feedback at the time of receiving each report.

RESULTS

Seventy-two caregivers completed Q1, of which 41 submitted at least one question (range = 1-7). We received a total of 76 questions. The median turnaround time was 12 working days for our information linker (range = 1-28). Thirty-seven caregivers completed Q2, of whom 32 submitted at least one question (87 %). Overall, caregivers were highly satisfied with GenE Compass and their reports, and indicated that they would use it in the future if they had another question. Caregivers' qualitative data from Q1 and interviews highlighted the ongoing need for an information linker service like GenE Compass due to a lack of understandable information and limited resources, and the benefit in reducing burden of constant information searching.

CONCLUSION

Our study shows that GenE Compass is feasible with the appropriate allocation of resources and highly acceptable to caregivers who have a child with a DEE.

Siblings of young people with chronic illness: Caring responsibilities and psychosocial functioning

Siblings of young people with chronic illness commonly undertake caring responsibilities for their affected brother/sister, which may encourage maturation, yet may also be perceived as a burden. Our study determined (1) siblings' caring responsibilities, (2) siblings' current emotional distress and psychosocial functioning, and (3) how siblings' caring responsibilities and psychosocial functioning related to familial relationships and coping strategies. Siblings completed questionnaires which contained Sibling Inventory of Behavior, Sibling Inventory of Differential Experiences, PedsQL, emotion thermometers, Brief COPE, and a checklist of caregiving responsibilities. We analyzed the data with t-tests and multi-level models. Forty-five siblings (mean age = 15.40 years, SD = 3.31 years; 60.0% female) participated. Siblings who had caring responsibilities (n = 26, 57.8%) reported lower anxiety symptoms, lower need for help, greater use of problem-focused coping, and more companionship and teaching/directiveness with their affected brother/sister than siblings without caring responsibilities. Siblings reported lower psychosocial and physical functioning when they perceived their parents provided them with less affection than their affected brother/sister. Family-based psychosocial interventions may aim to improve the sibling-parent relationship (including expressing affection) and the sibling-sibling relationship. Future interventions may also focus on increasing siblings' use of problem-focused coping strategies.

Cardiovascular disease-wide association study to investigate shared genetics with peak oxygen uptake

Introduction

Cardiorespiratory fitness, measured as peak oxygen uptake (VO2peak), is a strong predictor of cardiovascular disease (CVD) morbidity and mortality and is estimated to have a large genetic component (∼60%). However, the genetic determinants are yet to be established. Our research group recently identified novel genetic variants associated with directly measured VO2peak. Interestingly, most were specific to females. Looking into genetic pleiotropy between VO2peak and CVD can help elucidate the biological mechanisms explaining the link between this fitness related trait and disease, and potentially identify new therapeutic targets.

Purpose

The association study aims to investigate if genetic variants found to be associated with VO2peak in women is associated with any cardiovascular disease phenotypes.

Methods

34,188 female participants with genotype data from the Trøndelag Health Study (HUNT) were included in this study. ICD-coded hospital data related to cardiovascular disease was collected on each participant and the ICD codes were mapped to Phecodes, resulting in 100 disease-specific phenotypes. 26 single nucleotide polymorphisms (SNPs) previously found to be associated with directly measured VO2peak (p<5e-6) were included in the analyses, all common variants (minor allele frequency ≥1%). Each of the 26 genetic variants were tested for association with the 100 phenotypes using a logistic mixed model as implemented in SAIGE. The analysis was adjusted for birthyear and ten principal components of ancestry. The Benjamini-Hochberg false discovery rate (FDR) procedure controlling the FDR at 0.05 was used to correct for the number of tested SNPs and phenotypes.

Results

After testing each of the 26 SNPs for association with 100 cardiovascular disease phenotypes, 133 SNP-phenotype associations were nominally significant (p<0.05). The association between rs17066736 and myocarditis had the lowest p-value (1.7e-4). Among the other tested SNP-phenotype pairs were phenotypes related to ischemic heart disease, cardiac conduction disorders, heart failure, cerebrovascular disease, and diseases of arteries and veins. However, when adjusting for multiple testing, none reached overall statistical significance.

Conclusions

The findings showed no statistically significant associations between genetic variants associated with VO2peak and cardiovascular disease phenotypes in women. The role of inborn VO2peak in prediction of CVD (in women) needs further assessment.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): NTNU biotechnology

Improved cardiovascular disease risk prediction by implementing sex-specific cut-offs for intervention and new risk markers

Background

More than 17 million people die from cardiovascular disease (CVD) annually. CVDs are preventable and several risk prediction models are available for determining the 10-year risk of CVD, including the Norwegian NORRISK2 model. However, the available risk prediction models only explain a modest proportion of the incidence. For myocardial infarction (MI), it is estimated that 15–20% of the patients have none of the traditional risk factors and would be classified as “low risk”.

Purpose

Aim was to develop improved models for predicting the 10-year risk of MI.

Methods

We included 31.946 participants from the third wave of the Trøndelag Health Study (HUNT3) with no previous CVDs. HUNT data included 101 variables from interviews, clinical measurements, and biological samples on each participant. Totally, 11% of the men and 6% of the women experienced an MI between the HUNT3 and HUNT4 (10-year follow-up). The dataset was split 80/20 into a training set and a test set. XGBoost and logistic regression (LR) were used to fit two models for each sex predicting MI including variables from HUNT3. The models were evaluated by the area under the Receiver-Operating-Characteristic (ROC) curve and the Precision-Recall (PR) curve, both for the full test set and the test set divided into age groups. Thresholds for classification were suggested by maximizing different performance measures through 10-fold cross-validation on the training set. We then explored age- and sex-specific thresholds for intervention with a reasonable trade-off between sensitivity and specificity. All results were compared with NORRISK 2, which was implemented and applied to the same test set for exact comparison.

Results

For men, the XGBoost model improved risk prediction compared to NORRISK 2 for all age groups (AUC-ROC for XGBoost and NORRISK 2, respectively, 0.72 and 0.65 (age 45–54), 0.63 and 0.62 (age 55–64), 0.69 and 0.62 (age 65–74)). The liver-related enzyme alkaline phosphatase (ALP) was among the new predictors for MI in men. For women, NORRISK 2 performed best when evaluated by ROC curves, however, when evaluated by PR curves, the XGBoost models indicated improved prediction compared to NORRSIK 2 in the women 55–64 years (AUC-PR for XGBoost and NORRISK 2, respectively, 0.20 and 0.12). The thyroid stimulation hormone (TSH) was among the new predictors for MI in women. Regarding NORRISK 2, our results indicated that the thresholds for intervention should be increased for all age groups in men and decreased for all age groups in women for improved balance between sensitivity and specificity.

Conclusion

New risk factors should be considered implemented in CVD risk prediction algorithms, for improved identification of individuals at increased risk of MI. In addition, implementing sex-specific thresholds for intervention could be a useful step towards improved prevention of CVD for both men and women.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Regional Health Authorities

It’s made a really hard situation even more difficult: The impact of COVID-19 on families of children with chronic illness

Objective

For over two years, the global COVID-19 pandemic has forced major transformations on health, social, and educational systems, with concomitant impacts on mental health. This study aimed to understand the unique and additional challenges faced by children with chronic illness and their families during the COVID-19 era.

Method

Parents of children receiving treatment for a chronic illness within the neurology, cancer, renal and respiratory clinics of Sydney Children’s Hospital were invited to participate. We used qualitative methodology, including a semi-structured interview guide, verbatim transcription, and thematic analysis supported by QSR NVivo.

Results

Thirteen parents of children receiving tertiary-level care, for nine chronic illnesses, participated. Parents reported intense fears relating to their ill child’s additional vulnerabilities, which included their risk of developing severe COVID-19 disease and the potential impact of COVID-19-related disruptions to accessing clinical care, medications, allied health support and daily care protocols should their parent contract COVID-19. Parents perceived telehealth as a highly convenient and preferred method for ongoing management of less complex healthcare needs. Parents reported that the accrual of additional stressors and responsibilities during the pandemic, experienced in combination with restricted social interaction and reduced access to usual support networks was detrimental to their own mental health. Hospital-based visitation restrictions reduced emotional support, coping, and resilience for both parents and children and in some cases led to marital discord, sibling distress, and financial loss. Supportive factors included increased time spent together at home during the pandemic and improved hygiene practices at school, which dramatically reduced the incidence of non-COVID-19-related communicable illnesses in chronically ill children.

Discussion

For families caring for a chronically ill child, COVID-19 made a difficult situation harder. The pandemic has highlighted the need for targeted psychosocial intervention for vulnerable families, to mitigate current mental health burden and prevent chronic psychological distress.

New genetic determinants of VO2max-level identified by GWAS: The HUNT Study

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Central Norway Regional Health Authority

Norwegian Health Association

Introduction

Cardiovascular disease (CVD) is the leading cause of death worldwide. Several studies have shown that low cardiorespiratory fitness (CRF) is a major risk factor for CVD and is suggested to be a stronger predictor of CVD morbidity and mortality than established cardiovascular risk factors.

CRF quantified as maximal oxygen uptake (VO2max) has a strong genetic component, estimated to be ~50%. Unfortunately, current studies on genetic markers for CRF are limited by small sample sizes. In addition, there are few studies on directly measured VO2max, as most of the previous studies are based on estimated CRF. To overcome these limitations, we performed a large-scale systematic screening for genetic variants associated with VO2max aiming to provide awaited insight to this complex trait and discover possible links between VO2max and CVD.

Purpose

To identify and validate genetic factors associated with VO2max.

Methods

The genotypes of 70,000 participants from the Trøndelag Health study (HUNT) were imputed providing information on 25 million single-nucleotide polymorphisms (SNPs). We conducted a genome-wide association study (GWAS) including 4,525 participants with directly measured VO2max from the HUNT3 Fitness study. The GWAS was performed using BOLT-LMM, adjusted for age, gender, physical activity, principal components, and genotyping batch. In addition, we ran a GWAS with the same covariates except physical activity. Further, gender specific analyses were conducted. For validation, similar analyses were performed in the United Kingdom Biobank (UKBB). In the UKBB, CRF was assessed through a submaximal bicycle test. The analyses of UKBB included ~60,000 participants and over 90 million SNPs. Functional analyses of the GWAS results were examined by functional mapping and annotation (FUMA).

Results

Two GWAS-significant (p < 5×10-8) SNPs associated with VO2max were identified in the total population, two in the male population, and 24 in the female population in HUNT. Two of the 24 SNPs found in the female population were nominally significant in the UKBB. One of the validated SNPs in the female population is located inside PIK3R5, that is shown to be of importance in cardiac function and CVD. In addition, the functional analyses in the total- and male population revealed candidate SNPs in a gene previously found to be associated with endurance, PPP3CA.

Conclusions

We have identified 28 novel SNPs associated with VO2max in the HUNT cohort. Two of these SNPs were nominally validated in females in UKBB. One of the validated SNPs resides within a gene previously reported to be related to heart function and CVD. In addition, the functional analyses in the total- and male population revealed candidate SNPs in a gene previously found to be associated with endurance. Further functional analyses using bioinformatic approaches may provide more information on the physiological importance of these findings and their relation to CVD.

Identifying new genetic markers for maximal oxygen uptake

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Central Norway Regional Health AuthorityNorwegian Health Association

Introduction

Cardiovascular disease (CVD) is the leading cause of death worldwide. Several studies have shown that low cardiorespiratory fitness (CRF) is a major risk factor for CVD. Low CRF is suggested to be a stronger predictor of CVD morbidity and mortality than established cardiovascular risk factors like obesity, diabetes, and cholesterol.

Several studies suggest that CRF quantified as maximal oxygen uptake (VO2max) has a strong genetic component, estimated to be ~50%. Unfortunately, current studies on genetic markers for CRF are limited by small sample sizes. In addition, there are few studies on directly measured VO2max, as most of the previous studies are based on estimated CRF. Directly measured VO2max is considered as the gold standard for measuring CRF. Thus, a large-scale systematic screening for genetic variants associated with VO2max may provide awaited insight to this complex trait and discover possible links between VO2max and CVD.

Purpose

To identify and validate genetic factors associated with VO2max.

Methods

The genotypes of 70.000 participants from the Trøndelag Health study (HUNT) were imputed providing information on 25 million SNPs. We conducted a genome-wide association study (GWAS) including 4525 participants with directly measured VO2max from the HUNT3 Fitness study. The GWAS was performed using BOLT-LMM, adjusted for age, gender, physical activity, principal components, and genotyping batch. In addition, we ran a GWAS with the same covariates except physical activity. Further, gender specific analyses were conducted. For validation, similar analyses were performed in the United Kingdom Biobank (UKBB). In the UKBB, CRF was assessed through a submaximal bicycle test. The analyses of UKBB included ~60.000 participants and over 90 million SNPs.

Results

Two GWAS-significant (p < 5x10-8) SNPs associated with VO2max were identified in the total population in HUNT. Further, 24 GWAS-significant SNPs associated with VO2max in females, and two GWAS-significant SNPs associated with VO2max in males were discovered. Two of the 24 SNPs found in the female population were nominally significant in the UKBB. The validated SNPs are rs376927175, an intergenic SNP downstream of APBA1, and rs551942830 (proxy for rs190675254 with LD = 1.0), a 3 Prime UTR variant inside PIK3R5. PIK3R5 encodes the regulatory subunit of one class of PI3Ks, that is shown to be of importance in cardiac function and CVD. None of the SNPs found in the total population nor the male population were validated in UKBB.

Conclusions

We have identified 28 novel SNPs associated with VO2max in the HUNT cohort. Two of these SNPs were nominally validated in females in UKBB. One of the validated SNPs resides within a gene previously reported to be related to heart function and CVD. Further functional analyses using bioinformatic approaches may provide more information on the physiological importance of these findings and their relation to CVD.

Hearing parents' voices: A priority-setting workshop to inform a suite of psychological resources for parents of children with rare genetic epilepsies

Objective

To understand parents' of children with developmental and epileptic encephalopathies needs and preferences for psychological resources.

Methods

Using a person-based approach, a multidisciplinary panel of clinician and researchers (n = 9) hosted a priority-setting workshop to 1) understand parents' needs and preferences for psychological resources and 2) to develop ‘guiding principles’ to inform a future suite of psychological resources. The multidisciplinary panel analysed the parent priority-setting workshop data, using a combination of thematic and lexical analysis.

Results

Thematic analysis identified six key domains wherein parents (n = 8) prioritised a need for psychological resources to support adaptation to their child's genetic DEE diagnosis. Lexical analysis revealed that connection to diagnosis-specific resources provided a pathway to promote enhanced psychological adaptation, by reducing social isolation and reorienting parents towards feelings of hope. Combination of both analyses generated six thematic informed ‘guiding principles’.

Conclusion

Codesigned psychological resources may help parents to cope with the unique and complex interplay of stressors associated with their child's DEE diagnosis and treatment. Our ‘guiding principles’ will be translated to inform a future suite of tailored psychological resources.

Innovation

This study demonstrates an innovative codesign approach to inform tailored psychological resources for families of children with rare genetic conditions.

•

There is a deficit of research exploring the psychological impacts of parenting children with genetic DEEs.

•

Tailored and codesigned psychological resources are essential due to the complexity and uniqueness of genetic DEEs.

•

We collaborated with parents to codesign the content and scope of a future suite of person-based psychological resources.

•

Thematic and lexical analyses combined identified that person-based resources reduced parent isolation and promoted hope.

•

Insights generated from this study will be applied to inform psychological resources tailored for rare disease families.

Diagnostic Yield of Whole Genome Sequencing After Nondiagnostic Exome Sequencing or Gene Panel in Developmental and Epileptic Encephalopathies

OBJECTIVE

To assess the benefits and limitations of whole genome sequencing (WGS) compared to exome sequencing (ES) or multigene panel (MGP) in the molecular diagnosis of developmental and epileptic encephalopathies (DEE).

METHODS

We performed WGS of 30 comprehensively phenotyped DEE patient trios that were undiagnosed after first-tier testing, including chromosomal microarray and either research ES (n = 15) or diagnostic MGP (n = 15).

RESULTS

Eight diagnoses were made in the 15 individuals who received prior ES (53%): 3 individuals had complex structural variants; 5 had ES-detectable variants, which now had additional evidence for pathogenicity. Eleven diagnoses were made in the 15 MGP-negative individuals (68%); the majority (n = 10) involved genes not included in the panel, particularly in individuals with postneonatal onset of seizures and those with more complex presentations including movement disorders, dysmorphic features, or multiorgan involvement. A total of 42% of diagnoses were autosomal recessive or X-chromosome linked.

CONCLUSION

WGS was able to improve diagnostic yield over ES primarily through the detection of complex structural variants (n = 3). The higher diagnostic yield was otherwise better attributed to the power of re-analysis rather than inherent advantages of the WGS platform. Additional research is required to assist in the assessment of pathogenicity of novel noncoding and complex structural variants and further improve diagnostic yield for patients with DEE and other neurogenetic disorders.

Evaluation of an educational video providing key messages for doctors to counsel families following a first afebrile seizure

AIM

The aim was to evaluate an educational video in educating doctors on the key messages and follow-up pathways following a first afebrile seizure presentation. A multidisciplinary expert team developed the video (http://www.pennsw.org.au/families/resources/first-seizure-pack-and-video) based on available evidence and best-practice. It contains a role-play between the parent/child and physician. It addresses: key messages to impart following a first seizure, seizure first aid, safety messages including necessary precautions post-discharge, contents of the First Seizure Pack for families, follow-up pathway and issues for discussion with the paediatrician at a later appointment.

METHODS

Paediatric/Emergency department (ED) trainees across three Australian sites were recruited during terms 1 and 2, 2019. A repeated measures design was used. Multilevel modelling analyses were performed. The primary outcome was clinician knowledge. Secondary outcomes were confidence in answering questions and counselling families. Qualitative data on the utility, strengths and weaknesses of the video were evaluated.

RESULTS

A total of 127 participants consented, one withdrew prior to commencing. A total of 126 baseline surveys, 115 follow-up surveys and 45 1-month follow-up surveys were returned. Viewing the video significantly improved knowledge of key messages at immediate follow-up (P < 0.001) and 1-month follow-up (P = 0.048). Likewise, confidence was significantly improved; 96.5% of responders found the video useful, 90.3% were likely to use the resource in the future and 82% would change their approach to counselling. Most liked aspects of the resource were clarity/conciseness of the information (n = 70) and comprehensiveness (n = 38).

CONCLUSION

This education video significantly improved clinician knowledge and confidence in counselling families following first seizure.

RLIM Is a Candidate Dosage-Sensitive Gene for Individuals with Varying Duplications of Xq13, Intellectual Disability, and Distinct Facial Features

Interpretation of the significance of maternally inherited X chromosome variants in males with neurocognitive phenotypes continues to present a challenge to clinical geneticists and diagnostic laboratories. Here we report 14 males from 9 families with duplications at the Xq13.2-q13.3 locus with a common facial phenotype, intellectual disability (ID), distinctive behavioral features, and a seizure disorder in two cases. All tested carrier mothers had normal intelligence. The duplication arose de novo in three mothers where grandparental testing was possible. In one family the duplication segregated with ID across three generations. RLIM is the only gene common to our duplications. However, flanking genes duplicated in some but not all the affected individuals included the brain-expressed genes NEXMIF, SLC16A2, and the long non-coding RNA gene FTX. The contribution of the RLIM-flanking genes to the phenotypes of individuals with different size duplications has not been fully resolved. Missense variants in RLIM have recently been identified to cause X-linked ID in males, with heterozygous females typically having normal intelligence and highly skewed X chromosome inactivation. We detected consistent and significant increase of RLIM mRNA and protein levels in cells derived from seven affected males from five families with the duplication. Subsequent analysis of MDM2, one of the targets of the RLIM E3 ligase activity, showed consistent downregulation in cells from the affected males. All the carrier mothers displayed normal RLIM mRNA levels and had highly skewed X chromosome inactivation. We propose that duplications at Xq13.2-13.3 including RLIM cause a recognizable but mild neurocognitive phenotype in hemizygous males.

Lipoprotein subfraction LDL-5 and the presence of coronary atherosclerosis

Background

Coronary artery disease (CAD) has high mortality rates and is a frequent cause of death globally. Serum lipids play a pivotal role in the development of atherosclerosis, and elevated levels of total cholesterol, low density lipoprotein (LDL) cholesterol, and triglycerides are well known risk factors of cardiovascular disease (CVD). However, there are limitations in the ability to predict CVD risk, which has led to an increased clinical interest in identifying novel risk markers. With the advances in lipidomic technology, lipoprotein subfractions may provide additional information that is missing in today's evaluation of CVD risk. Lipoprotein subfractions differ in size and density, and recent studies suggest that high density of small LDL particles provide a greater risk for CVD.

Purpose

To investigate whether lipoprotein subfractions are associated with the presence and extent of coronary atherosclerosis.

Methods

Fasting serum samples from 60 participants with suspected stable CAD were collected before scheduled coronary angiography, and analysed by nuclear magnetic resonance (NMR). The presence and extent of atherosclerosis were quantified by the Gensini Score. Participants were classified into one of three Gensini groups based on severity (&lt;20.5, normal; 20.6–30, non-significant CAD; &gt;30.1, significant CAD).

Results

A three-way ANOVA, adjusted for statin-use and sex, revealed statistically significant differences (p&lt;0.005) in LDL-5 particle number, LDL-5 triglycerides, and LDL-5 phospholipids between the Gensini groups. In addition, significant differences (p&lt;0.005) were found in the ratios apolipoprotein A/apolipoprotein B and LDL cholesterol/HDL cholesterol between the Gensini groups. All significant variables, identified by the three-way ANOVA, displayed the highest levels in the Gensini group with significant CAD.

Conclusion

Despite no difference in the traditional clinical measurements (total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides), NMR-lipidomics revealed significant differences in LDL-5 between the Gensini groups. Interestingly, our results reveal that those with significant CAD have a higher density of small LDL subfractions.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Norwegian Health Association, The Liaison Committee for Education, Research and Innovation in Central Norway

The information needs of parents of children with early-onset epilepsy: A systematic review

OBJECTIVE

Early-onset epilepsy has broad physical and psychosocial impacts, and parents have a wide variety of information needs. This systematic review set out to assess 1) whether parents of children with early-onset epilepsy have unmet information needs and 2) their preferences regarding information content and style of information delivery.

METHODS

We searched Medline, Embase, PsychInfo, and CINAHL using keywords relating to information needs, information resources, and preferences for information delivery. We limited the search to parent populations and included all peer-reviewed publications published in English after the year 2005.

RESULTS

Eleven studies met our inclusion criteria. Parents reported a clear need for understandable, realistic, and focused information, highlighting a particular need for content about comorbidities and emotional support. Parents reported limited availability of detailed information resources on early-onset epilepsy, which compromised their ability to access appropriate healthcare services. Unmet information needs were associated with greater levels of stress, poorer psychosocial outcomes, and lower satisfaction with healthcare services.

SIGNIFICANCE

The results highlight the importance of detailed epilepsy information for families. Healthcare professionals should be aware of the impact of a lack of epilepsy information on family wellbeing. Multipronged and tailored interventions targeting the information needs of families are warranted.

P3528Circulating microRNA-210 concentrations are increased in patients with acute heart failure and provide prognostic information

Background

MicroRNA (miR)-210 is induced by cellular hypoxia and circulating miR-210 concentrations are associated with clinical outcome in patients with myocardial infarction and aortic stenosis. Whether circulating miR-210 concentrations provide diagnostic and prognostic information in unselected patients with dyspnea is not known.

Purpose

To assess the diagnostic and prognostic value of circulating miR-210 concentrations in patients hospitalised due to acute dyspnea.

Methods

We extracted microRNA from plasma samples obtained on admission from 314 patients hospitalised for acute dyspnea and 10 healthy control subjects. miR-210 concentrations were measured by quantitative polymerase chain reaction and we used miR-425 for normalisation. The merit of circulating miR-210 concentrations to diagnose and provide prognostic information in patients with acute heart failure (HF) was compared to the merit of N-terminal pro-B-type natriuretic peptide (NT-proBNP).

Results

In total, 143 patients (46%) were adjudicated as hospitalised due to acute heart failure (HF) and 84 patients (27%) due to acute exacerbation of chronic obstructive lung disease (AECOPD). All patients and control subjects had miR-210 concentrations within the range of detection (Cq 26–32) and analytical variation was low. miR-210 concentrations correlated with age, NT-proBNP and cardiac troponin T concentrations in the total cohort. Circulating miR-210 concentrations were increased in patients with HF (4.7±3.3 fold increase, p<0.0001) and AECOPD (3.4±1.7 fold increase, p<0.0001) compared to control subjects. Circulating miR-210 concentrations were not different between patient groups and receiver operating characteristics area under the curve (AUC) for miR-210 to diagnose acute HF was 0.50 (95% CI 0.43–0.57) compared to AUC 0.85 (0.81–0.89) for NT-proBNP. During a median 817 days of follow-up, 66 patients (46%) with acute HF died and 35 patients (42%) with AECOPD died. Circulating miR-210 concentrations separated acute HF patients with a poor and favourable outcome (Figure 1; p by the log rank test =0.017). Circulating miR-210 concentrations were also associated with mortality during follow-up in Cox regression model: hazard ratio (HR) for lnRQ of miR-210 was 2.11 (95% CI 1.27–2.50), p=0.004. The association between circulating miR-210 concentrations and outcome was attenuated and no longer significant after adjusting for NT-proBNP concentrations. Circulating miR-210 concentrations did not predict outcome in patients with AECOPD: HR 1.38 (0.65–2.93); p=0.4.

Figure 1

Conclusions

Circulating miR-210 concentrations are increased in patients with acute HF, and provide prognostic information during follow-up. Still, circulating miR-210 concentrations did not diagnose acute HF among unselected patients with dyspnea and the association with outcome was attenuated by NT-proBNP.

Acknowledgement/Funding

Nasjonalforeningen for Folkehelsen

4101Identification of genetic variants associated with the cardiovascular disease risk factor, low aerobic fitness - The HUNT study

Abstract

Background: Low maximal oxygen uptake (VO2max) is a strong and independent risk factor for all-cause and cardiovascular disease (CVD) mortality. Although physical activity is a major determinant of VO2maxlevel, genetics contribution is estimated to be ∼50%.

Methods

We performed a genetic association study on 123.545 single-nucleotide polymorphisms (SNPs) and directly measured VO2max in 3470 individuals (exploration cohort). The candidate SNPs were subsequently analyzed in a separate cohort of 718 individuals (validation cohort), in addition to 7 wild-card SNPs previously associated with VO2max, but not included on the chip used in the exploration cohort. Sub-analyses were performed for each gender. In silico analysis and genotype-phenotype databases were used to predict physiological function of the SNPs.

Results

In the exploration cohort, 42 SNPs were associated with VO2max (p<5.0×10–4). Six of the candidate SNPs were also found to be associated with VO2max in the validation cohort (p<0.05, either in men, women or both), in addition to three wild-card SNPs. By using these nine SNPs we created a genetic score for inborn VO2max-level. Together, these nine SNPs explained ∼8% of the variation in VO2max, and discriminate individuals with inborn high versus low VO2max based on simultaneous carriage of multiple favorable alleles. The cumulative number of favorable SNPs correlated negatively with the presence of several CVDrisk factors, e.g. waist-circumference, visceral fat, fat %, cholesterol levels and BMI. In silico analysis indicated that several of the SNPs influence gene expression across multiple organs, including adipose tissue, skeletal muscle and heart.

Conclusion

We identified six novel genetic variants associated with VO2max, and validated three SNPs previously associated with fitness related traits.

Acknowledgement/Funding

K.G. Jebsen Foundation, the Norwegian Health Association, the Liaison Committee between the Central Norway Regional Health Authority (RHA) and NTNU

P4154MicroRNA Signatures Predict Early Major Coronary Events in Middle Aged Men and Women

Background

The role of microRNA as biomarkers able to predict major coronary events (MACE) has not been fully elucidated, reproducibility being a critical issue.

Aim

To identify circulating microRNA signatures able to predict MACE.

Methods

We employed a PCR-based method to screen 754 microRNAs in a cohort of 60-year-olds (60YOs) from Stockholm, using a nested case-control design (100 cases vs 100 matched controls). The association of microRNAs and their interaction with the risk of MACE (myocardial infarction (MI), angina and sudden cardiac death) was estimated with random-effect logistic regression and expressed as OR with 95% CI. A bioinformatics approach identified microRNA clusters based on predicted targets. Main findings were tested in 58 MI and 60 age and sex matched referents from the the Nord-Trøndelag Health (HUNT) Study, a longitudinal population health study conducted in Norway.

Results

Fifty-five microRNAs were found to be associated with risk of MACE in the 60YO. MicroRNA-145-3p was associated with the largest estimated risk increase of MACE after adjustment for the common CV risk factors (OR: 2.18; 95% CI: 1.27–3.75). Interaction analysis revealed that increasing plasma levels of microRNA-320b modulated the association of 16 microRNAs with risk of MACE. As an example the estimated MACE risk associated with microRNA-145-3p was 1.47 (0.87–2.47) in the presence of low (<25th percentile) and 4.00 (1.79- 8.93) in the presence of high (>75th percentile) miRNA 320b expression levels. Sixteen microRNA pairs could be classified in 4 functional clusters with 492 predicted gene targets, mainly involved in the regulation of inflammation, thrombosis and lipid metabolism. Eight miRNAs interacting pairs belonging to cluster 2 and 4 showed a similar association trend with MI risk in the HUNT study.

Conclusions

We report the identification of microRNA signatures predicting risk of MACE in middle-aged Scandinavian men and women. These signatures could be a valuable tool to improve CV disease prediction in the aged.

P1547Circulating lipoprotein subfractions as new non-invasive biomarkers of coronary atherosclerosis

Objectives

Coronary artery disease (CAD) is the most common cause of death globally. In the next decade, the number of people at risk is expected to increase, due to obesity, inactivity and diabetes. Therefore, precise risk-prediction models will be increasingly important for the healthcare system, to be able to initiate cost-efficient prevention strategies. One of the first steps in CAD-development is sub-clinical atherosclerosis. Biomarkers that could reflect the presence of coronary atherosclerosis would be extremely valuable for risk prediction of myocardial infarction (MI). Serum cholesterol levels are key variables in risk prediction; however, there is growing interest for exploring the potential of other lipid subclasses. The aim of this study is to identify specific lipoprotein subfractions that are associated with the extent of coronary atherosclerosis.

Methods

60 patients with suspected CAD were enrolled. Blood samples were collected before the partiens underwent coronary angiography. The extent of coronary atherosclerosis were quantified using the Gensini score. The partients were classified into three groups based on their Gensini score (<20.5: normal, 20.6–30: non-significant CAD and >30.1: significant CAD). The blood samples were analyzed by nucelar magnetic resonance (NMR) lipidomics. Univariate and multivariate statistical tests were used to determine whether lipoprotein subfractions were associated with the extent of coronary atherosclerosis.

Results and discussion

Of the 117 lipoprotein subfractions quantified, 10 were different in patients with significant CAD compared to patients with normal vessels in non-statin users (p=0.005). Despite no difference in total cholesterol, LDL and HDL cholesterol between the three Gensini groups, NMR lipidomics revealed that patients with significant CAD had twice as many circulating LDL-5 and LDL-6 particles as patients with normal vessels. Furthermore, three types of small LDL-subfractions, called LDL-5-TG, LDL-5-ApoB and LDL-6-ApoB, were significantly increased in patients with significant CAD. Interestingly, previous studies have suggested that small LDL particles are more atherogenic than larger particles. In addition, patients with significant CAD had low levels of ApoA1 containing HDL particles, and high levels of two different small VLDL particles. Previous studies have indicated that small VLDLs are more atherogenic than larger VLDLs, and does to a greater extent penetrate the vessel intima.

Conclusions

This study reveals strong associations between serum lipoprotein subfractions and the degree of coronary atherosclerosis quantified by Gensini score. Especially, the high levels of certain types of small LDL-particles in patients with CAD, indicates that measuring lipoprotein subfractions may provide added value to risk prediction models for MI. However, these findings needs to be further explored and validated in large cohort studies.

Acknowledgement/Funding

Norwegian Health Association, the Liaison Committee between the Central Norway Regional Health Authority (RHA) and NTNU

Body weight, body composition and survival after 1 year: follow-up of a nutritional intervention trial in allo-HSCT recipients

The role of body weight change in survival among recipients of hematopoietic stem-cell transplantation is controversial. We assessed the effect of optimizing energy and protein intake on 1-year survival, body weight and body composition, and the effect of body weight and body composition on 1-year survival in 117 patients (57 intervention, 60 control) in a randomized controlled trial. Cox regression was used to study effects of the intervention, weight and body composition on death, relapse, and nonrelapse mortality (NRM). We found no significant effect of intervention versus control on death hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.54-2.04, p = 0.88), relapse (HR 1.15, 95% CI 0.48-2.27, p = 0.75), and NRM (HR 0.95, 95% CI 0.39-2.28, p = 0.90). Body weight, fat-free mass index, body fat mass index and total body water changed over time (p < 0.001), similarly in both groups (0.17 ≤ p ≤ 0.98). In multivariable analyses adjusted for group, gender and age, HRs and 95% CIs per one kilo increase in weight were 1.03 (1.01-1.06) and 1.04 (1.01-1.08) for death and NRM after 1 year (p ≤ 0.02), respectively, and 1.08 (1.01-1.15) for relapse after 3 months (p = 0.02). In conclusion, weight gain is possibly due to fluid retention and is an indicator of a complication in HSCT, rather than a marker of improved nutritional status.

De Novo Variants Disrupting the HX Repeat Motif of ATN1 Cause a Recognizable Non-Progressive Neurocognitive Syndrome

Polyglutamine expansions in the transcriptional co-repressor Atrophin-1, encoded by ATN1, cause the neurodegenerative condition dentatorubral-pallidoluysian atrophy (DRPLA) via a proposed novel toxic gain of function. We present detailed phenotypic information on eight unrelated individuals who have de novo missense and insertion variants within a conserved 16-amino-acid "HX repeat" motif of ATN1. Each of the affected individuals has severe cognitive impairment and hypotonia, a recognizable facial gestalt, and variable congenital anomalies. However, they lack the progressive symptoms typical of DRPLA neurodegeneration. To distinguish this subset of affected individuals from the DRPLA diagnosis, we suggest using the term CHEDDA (congenital hypotonia, epilepsy, developmental delay, digit abnormalities) to classify the condition. CHEDDA-related variants alter the particular structural features of the HX repeat motif, suggesting that CHEDDA results from perturbation of the structural and functional integrity of the HX repeat. We found several non-homologous human genes containing similar motifs of eight to 10 HX repeat sequences, including RERE, where disruptive variants in this motif have also been linked to a separate condition that causes neurocognitive and congenital anomalies. These findings suggest that perturbation of the HX motif might explain other Mendelian human conditions.

A Mild PUM1 Mutation Is Associated with Adult-Onset Ataxia, whereas Haploinsufficiency Causes Developmental Delay and Seizures

Certain mutations can cause proteins to accumulate in neurons, leading to neurodegeneration. We recently showed, however, that upregulation of a wild-type protein, Ataxin1, caused by haploinsufficiency of its repressor, the RNA-binding protein Pumilio1 (PUM1), also causes neurodegeneration in mice. We therefore searched for human patients with PUM1 mutations. We identified eleven individuals with either PUM1 deletions or de novo missense variants who suffer a developmental syndrome (Pumilio1-associated developmental disability, ataxia, and seizure; PADDAS). We also identified a milder missense mutation in a family with adult-onset ataxia with incomplete penetrance (Pumilio1-related cerebellar ataxia, PRCA). Studies in patient-derived cells revealed that the missense mutations reduced PUM1 protein levels by ∼25% in the adult-onset cases and by ∼50% in the infantile-onset cases; levels of known PUM1 targets increased accordingly. Changes in protein levels thus track with phenotypic severity, and identifying posttranscriptional modulators of protein expression should identify new candidate disease genes.

A De Novo Mutation in the Sodium-Activated Potassium Channel KCNT2 Alters Ion Selectivity and Causes Epileptic Encephalopathy

Early infantile epileptic encephalopathies (EOEE) are a debilitating spectrum of disorders associated with cognitive impairments. We present a clinical report of a KCNT2 mutation in an EOEE patient. The de novo heterozygous variant Phe240Leu SLICK was identified by exome sequencing and confirmed by Sanger sequencing. Phe240Leu rSlick and hSLICK channels were electrophysiologically, heterologously characterized to reveal three significant alterations to channel function. First, [Cl^-]_i sensitivity was reversed in Phe240Leu channels. Second, predominantly K⁺-selective WT channels were made to favor Na⁺ over K⁺ by Phe240Leu. Third, and consequent to altered ion selectivity, Phe240Leu channels had larger inward conductance. Further, rSlick channels induced membrane hyperexcitability when expressed in primary neurons, resembling the cellular seizure phenotype. Taken together, our results confirm that Phe240Leu is a "change-of-function" KCNT2 mutation, demonstrating unusual altered selectivity in K_Na channels. These findings establish pathogenicity of the Phe240Leu KCNT2 mutation in the reported EOEE patient.

Integrating exome sequencing into a diagnostic pathway for epileptic encephalopathy: Evidence of clinical utility and cost effectiveness

Background

Epileptic encephalopathies are a devastating group of neurological conditions in which etiological diagnosis can alter management and clinical outcome. Exome sequencing and gene panel testing can improve diagnostic yield but there is no cost‐effectiveness analysis of their use or consensus on how to best integrate these tests into clinical diagnostic pathways.

Methods

We conducted a retrospective cost‐effectiveness study comparing trio exome sequencing with a standard diagnostic approach, for a well‐phenotyped cohort of 32 patients with epileptic encephalopathy, who remained undiagnosed after “first‐tier” testing. Sensitivity analysis was included with a range of commercial exome and multigene panels.

Results

The diagnostic yield was higher for the exome sequencing (16/32; 50%) than the standard arm (2/32; 6.2%). The trio exome sequencing pathway was cost‐effective compared to the standard diagnostic pathway with a cost saving of AU$5,236 (95% confidence intervals $2,482; $9,784) per additional diagnosis; the standard pathway cost approximately 10 times more per diagnosis. Sensitivity analysis demonstrated that the majority of commercial exome sequencing and multigene panels studied were also cost‐effective. The clinical utility of all diagnoses was reported.

Conclusion

Our study supports the integration of exome sequencing and gene panel testing into the diagnostic pathway for epileptic encephalopathy, both in terms of cost effectiveness and clinical utility. We propose a diagnostic pathway that integrates initial rapid screening for treatable causes and comprehensive genomic screening. This study has important implications for health policy and public funding for epileptic encephalopathy and other neurological conditions.

Perinatal hypothalamic-pituitary-adrenal axis regulation among women with eating disorders and their infants

BACKGROUND

Psychiatric illness is associated with heightened hypothalamic-pituitary-adrenal (HPA) axis activity during pregnancy which may have long term effects on infant stress regulation. HPA axis regulation has not previously been investigated in women with eating disorders (ED) or their infants during the perinatal period.

METHODS

Women were recruited to a prospective longitudinal study in three groups: 1) current or active ED (C-ED=31), 2) past ED (P-ED=29) and healthy control (HC=57). Maternal psychopathology, diurnal cortisol levels, corticotropin-releasing hormone (CRH) and CRH binding protein (CRH-BP) were measured during the third trimester of pregnancy. At eight weeks postpartum infant cortisol was obtained before and after routine immunisations to determine infant hormonal response to a stressful situation.

RESULTS

Women with current ED had a significantly lower cortisol decline throughout the day compared to HC, in both adjusted and unadjusted analyses. Lower cortisol decline among women with a current ED were associated with higher levels of psychopathology during pregnancy. Women's cortisol awakening response, CRH and CRH-BP levels did not differ across the three groups. Infants' stress response was also significantly higher among those in the C-ED group, although this effect was attenuated after controlling for confounders.

CONCLUSIONS

During pregnancy women with ED have lower cortisol declines, suggestive of blunted diurnal cortisol rhythms. Postnatally, their infants also have a heightened response to stress. This is the first study to identify HPA axis dysfunction in pregnancy in women with ED, and to show an intergenerational effect. Since dysfunctions in HPA activity during childhood may represent a risk factor for psychological and physical health problems later in life, further investigation of the potential long-term implications of these findings is crucial.

Intake of a Protein-Enriched Milk and Effects on Muscle Mass and Strength. A 12-Week Randomized Placebo Controlled Trial among Community-Dwelling Older Adults

OBJECTIVES

To investigate the effect of 20 g protein with breakfast and evening meal on muscle mass, muscle strength and functional performance in older adults.

DESIGN

A double-blinded randomized controlled study.

SETTING

Oslo and Akershus University College of Applied Sciences, Norway.

PARTICIPANTS

Healthy community-dwelling men and women (≥ 70 years) with reduced physical strength and/or performance.

INTERVENTION

Subjects were randomly assigned to receive either protein-enriched milk (2 x 0.4 L/d; protein group) or an isocaloric carbohydrate drink (2 x 0.4 L/d; control group) with breakfast and evening meal for 12 weeks.

MEASUREMENTS

The primary endpoints were muscle mass measured by dual X-ray absorptiometry, and tests of muscle strength (one repetition maximum test of chest press and leg press) and functional performance (handgrip strength, stair calimb and repeated chair rise).

RESULTS

In total, 438 subjects were screened, 50 subjects were randomized and 36 completed the study. Chest press improved significantly in the protein (1.3 kg (0.1-2.5), p=0.03) and the control group (1.5 kg (0.0-3.0), p=0.048), but with no difference between the groups (p=0.85). No significant change in leg press (p=0.93) or muscle mass (p=0.54) were observed between the protein and the control group. Nor did we observe any significant differences in the functional performance tests (p>0.05 for all tests) between the groups.

CONCLUSION

Increased protein intake (2 x 20 g/d) did not significantly improve muscle mass, muscle strength or functional performance in healthy older weight stable adults. Whether intake of > 20 g protein to each meal is necessary for preservation of muscle mass and strength in older adults should be further investigated in a larger study. This underscores the need for well-designed studies that can differentiate between the effect of protein intake and increased energy. This trial was registered at Clinicaltrials.gov (ID no. NCT02218333).

Neuronal deficiency of ARV1 causes an autosomal recessive epileptic encephalopathy

We report an individual who presented with severe neurodevelopmental delay and an intractable infantile-onset seizure disorder. Exome sequencing identified a homozygous single nucleotide change that abolishes a splice donor site in the ARV1 gene (c.294 + 1G > A homozygous). This variant completely prevented splicing in minigene assays, and resulted in exon skipping and an in-frame deletion of 40 amino acids in primary human fibroblasts (NP_073623.1: p.(Lys59_Asn98del). The p.(Lys59_Asn98del) and previously reported p.(Gly189Arg) ARV1 variants were evaluated for protein expression and function. The p.(Gly189Arg) variant partially rescued the temperature-dependent growth defect in arv1Δ yeast, while p.(Lys59-Asn98del) completely failed to rescue at restrictive temperature. In contrast to wild type human ARV1, neither variant expressed detectable levels of protein in mammalian cells. Mice with a neuronal deletion of Arv1 recapitulated the human phenotype, exhibiting seizures and a severe survival defect in adulthood. Our data support ARV1 deficiency as a cause of autosomal recessive epileptic encephalopathy.

Asparagine Synthetase Deficiency causes reduced proliferation of cells under conditions of limited asparagine

Asparagine Synthetase Deficiency is a recently described cause of profound intellectual disability, marked progressive cerebral atrophy and variable seizure disorder. To date there has been limited functional data explaining the underlying pathophysiology. We report a new case with compound heterozygous mutations in the ASNS gene (NM_183356.3:c. [866G>C]; [1010C>T]). Both variants alter evolutionarily conserved amino acids and were predicted to be pathogenic based on in silico protein modelling that suggests disruption of the critical ATP binding site of the ASNS enzyme. In patient fibroblasts, ASNS expression as well as protein and mRNA stability are not affected by these variants. However, there is markedly reduced proliferation of patient fibroblasts when cultured in asparagine-limited growth medium, compared to parental and wild type fibroblasts. Restricting asparagine replicates the physiology within the blood-brain-barrier, with limited transfer of dietary derived asparagine, resulting in reliance of neuronal cells on intracellular asparagine synthesis by the ASNS enzyme. These functional studies offer insight into the underlying pathophysiology of the dramatic progressive cerebral atrophy associated with Asparagine Synthetase Deficiency.

Severe hemorrhagic meningoencephalitis due to Angiostrongylus cantonensis among young children in Sydney, Australia

Angiostrongylus cantonensis is the most common cause of eosinophilic meningitis worldwide. We describe 2 cases among young children from Sydney, Australia, where locally acquired infection of children has not been reported previously. Both cases manifested as severe hemorrhagic meningoencephalitis, one resulting in death. Angiostrongyliasis must be considered in acute neurological presentations occurring among individuals who live in endemic areas.

Rational dose selection for a nonnucleoside reverse transcriptase inhibitor through use of population pharmacokinetic modeling and Monte Carlo simulation

In order to choose a rational dose for GW 420867X, we first set a goal of therapy. We hypothesized that, for optimal antiretroviral activity, the trough free drug concentration should remain above the 90% effective concentration (EC90) of human immunodeficiency virus type 1. We performed population pharmacokinetic analysis on three different doses of GW 420867X (50, 100, and 200 mg). Monte Carlo simulation was performed, assuming a log-normal distribution for 1,000 simulated subjects for each dose, and was repeated three times. The trough concentrations were divided by 76 to account for protein binding and for the difference between EC50 and EC90. We then determined the fraction of the simulated population whose free drug trough concentrations would exceed an EC90 over a broad range of values. The target attainment for all three doses exceeded 95% out to a starting EC50 of 10 nM. For 16 viral isolates, the EC50 range encountered for GW 420867X did not exceed 8 nM, implying that the three doses could not be differentiated by effect in a clinical trial in naive patients. This prediction was shown to be correct in a randomized, double-blind trial with 1 week of monotherapy with GW 420867X.

Pharmacodynamics of abacavir in an in vitro hollow-fiber model system

Abacavir is a potent new carbocyclic nucleoside analogue. We employed our hollow-fiber pharmacodynamic modeling system to examine the antiretroviral effects of different abacavir exposures, as well as the impact of the schedule of drug administration on efficacy. Dose ranging of abacavir revealed that a concentration of four times the 50% effective concentration (EC(50)) (approximately the EC(95)) was required to inhibit the replication of human immunodeficiency virus type 1 (HIV-1) (strain MN) either in a continuous-infusion hollow-fiber experiment or in a classical tissue culture flask experiment. In contrast to earlier work with another drug class (HIV-1 protease inhibitors), addition of physiological amounts of the human drug binding proteins albumin and alpha(1) acid glycoprotein revealed that there was little impact on the antiviral effect of the drug. Comparison of equivalent exposures (an area under the concentration-time curve [AUC] developed by approximately 500 mg per day of orally administered abacavir), either in a continuous-infusion mode or as a single oral dose of abacavir, demonstrated no difference in the ability to suppress either strain III(B) or strain MN. Comparison of administration of 250 mg every 12 h (q12h) versus once-daily administration of 500 mg for strain MN again showed no significant difference in suppressive effect. These experiments were carried out over 8 to 15 days. Because of these promising initial results, we extended the experiment to 30 days and examined three different schedules of administration that generated the same AUC at 24 h (AUC(24)): 300 mg q12h, 600 mg q24h, and 1,200 mg q48h. The aim of the last of these regimens was to definitively demonstrate schedule failure. There was little difference between the 1,200-mg q48h treatment group and the untreated control at 30 days. Likewise, there was little difference between the 600-mg q24h and 300-mg q12h treatment groups. However, at circa day 18 of the experiment, there was a small increase in viral output of p24 in the once-daily dosing unit. Examination of virus from all groups demonstrated no phenotypic or genotypic differences. The small difference in hollow-fiber unit p24 in the once-daily dosing group was not due to emergence of resistance over the 30-day single-drug exposure. We conclude that the dose of abacavir currently being studied in clinical trials (300 mg orally q12h) will be efficacious for the majority of sensitive clinical isolates of HIV-1. These in vitro data also suggest that this drug may be able to be administered to patients on a once-daily basis at a dose of 600 mg.

Transport characteristics of the anti-human immunodeficiency virus nucleoside analog, abacavir, into brain and cerebrospinal fluid

The role of the blood-brain and blood-cerebrospinal fluid (CSF) barriers in the distribution of anti-human immunodeficiency virus (HIV) drugs is integral to the design of effective treatment regimens for HIV infection within the brain. Abacavir (formerly 1592U89) is a nucleoside analog reverse transcriptase inhibitor, which has activity against HIV. The ability of this drug to reach the brain at therapeutic concentrations has been explored by means of an established bilateral in situ brain perfusion model in combination with high-performance liquid chromatography analysis in the anesthetized guinea pig. The influence of other drugs on the entry of abacavir into the brain was also investigated and is of special significance with the use of three of more anti-HIV drugs as the recommended treatment for HIV infection. The results of this study indicate that intact [(14)C]abacavir can cross the blood-brain and blood-CSF barriers and enter the brain and cisternal CSF. Further studies, at a perfusion time of 10 min, revealed that the uptake (R(cerebrum)) of this (14)C-labeled drug (10.1 +/- 0.6%) was not affected by the presence of 0.86 to 200 microM unlabeled abacavir (6.8 microM; 11.0 +/- 1.4%), the nucleoside transport inhibitor [10 microM 6-(4-nitrobenzyl)thio-9-beta-D-ribofuranosylpurine; 9.7 +/- 3.3%], or a substrate for the nucleobase transporter (100 microM adenine; 12.7 +/- 3.0%). This would suggest that the entry of abacavir into the brain would not be affected by the presence of other anti-HIV drugs. The results of this animal study indicate that abacavir would be a useful addition to a treatment regimen against HIV-infection within the brain.

Computer-assisted drug development (CADD): an emerging technology for designing first-time-in-man and proof-of-concept studies from preclinical experiments

Computer-assisted drug development (CADD) is an emerging technology for accelerating drug development based on the integration of mathematical modelling and simulation. This methodology provides a knowledge-based decisional tool on alternative development strategies based on the evaluation of potential risks on drug safety, and the definition of experimental design of new trials with expected power and probability of success. An example of CADD implementation is presented to design the first-time-in-man (FTIM) and the proof-of-concept (PoC) study of a new CNS compound. The final objective of the example presented is not necessarily to supply a success story of a correct prediction of human data from animal studies but to define a credible strategy suitable to design FTIM and PoC studies using preclinical data without the support of any human in vivo information. Rhesus monkey and human PK were initially estimated using allometric scaling on data collected in dogs, cynomolgus monkeys and rats. A PK/PD model was derived from a study conducted in rodent and validated by comparing the model predicted response to the one observed in a PET experiment conducted in rhesus monkey. The final PK/PD model, incorporating potential variability and uncertainty on scaled human prediction together with a receptor affinity adjustment derived from in vitro binding studies, was used to design the first-time-in-man and the proof-of-concept study.

Population pharmacokinetic-pharmacodynamic model of craving in an enforced smoking cessation population: indirect response and probabilistic modeling

PURPOSE

A population pharmacokinetic-pharmacodynamic model accounting for placebo effect was used to relate nicotine concentration and enforced smoking cessation craving score measured by the Tiffany rating scale short form.

METHODS

Twenty-four smokers were enrolled in a placebo-controlled, randomized, double-blind, three periods, crossover trial. The study objective was to describe the nicotine-induced changes on craving scores. Two modeling strategies based on a mechanistic (indirect response models with drug-related inhibition on the k(in) synthesis rate and with a drug-related stimulation of the k(out) removal rate were evaluated) and a probabilistic (logistic regression) approach were used.

RESULTS

Placebo response model properly fitted the circadian changes on craving scores. The analysis revealed that the indirect response model with inhibition on k(in) was the preferred model for the smoking data whereas the preferred model for the Nicotine Replacement Therapy data was the one with stimulation on k(out). The logistic analysis showed that the nicotine concentration was a significant predictor of reduction in craving during the free-smoking period.

CONCLUSIONS

Nicotine dosage regimen can influence the nicotine mechanism of action: an instantaneous delivery at an individually selected time seems to inhibit the onset of craving while constant delivery at a pre-defined time seems to attenuate the craving.

Absorption kinetics after inhalation of fluticasone propionate via the Diskhaler, Diskus and metered-dose inhaler in healthy volunteers

OBJECTIVE

The aim of this analysis was to assess the rate and extent of systemic availability of inhaled fluticasone propionate (FP) from 2 dry powder systems (Diskhaler and Diskus) and a metered-dose inhaler (MDI) by deconvolution analysis.

METHODS

The inhalation devices were evaluated in 3 separate studies with identical protocols. 12 healthy male volunteers were randomised to receive FP given as a 1000 microg inhaled dose and 250 microg by intravenous infusion according to a double-blind double-dummy crossover design. The bioavailability of FP after inhalation represents absorption of the drug from the lungs, since the bioavailability of the swallowed portion of the inhaled dose is negligible.

RESULTS

When corrected for the bioavailability (of FP) achieved by each inhalation device, the rate of absorption of FP over the first 2 hours was rapid from all devices. The mean time for absorption of 50% of the bioavailable dose was 1.6, 2.4, and 2.2 hours for the Diskhaler, Diskus and MDI, respectively. Thereafter, absorption from each device was prolonged, with approximately 10% of the dose remaining in the lungs 12 hours after inhalation.

CONCLUSION

Irrespective of the inhalation device used, the prolonged absorption of FP into the systemic circulation indicates a long residence time in the lungs.

Systemic exposure to fluticasone propionate administered via metered-dose inhaler containing chlorofluorocarbon or hydrofluoroalkane propellant

OBJECTIVE

The pharmacokinetic profile of a single dose of inhaled fluticasone propionate (FP) administered via a metered-dose inhaler (MDI), containing either a chlorofluorocarbon (CFC) or hydrofluoroalkane (HFA) propellant was investigated in healthy volunteers.

METHODS

Two randomised, double-blind, crossover studies were conducted, each in 12 male volunteers. Both studies compared pharmacokinetic data after a single inhaled dose of FP 1000 microg from a MDI containing either CFC (CFC MDI) or HFA (HFA MDI) with a single intravenous dose of FP 250 microg.

RESULTS

The maximum plasma FP concentrations after inhalation via the 2 types of MDI were almost identical (0.56 and 0.54 microg/L for CFC MDI and HFA MDI, respectively); bioavailability values of inhaled FP from the 2 MDIs were also similar (geometric mean values: 26.4% via the CFC MDI and 28.6% via the HFA MDI). Inhalation of FP via both MDI formulations produced similar reductions in urinary cortisol excretion over 12 and 24 hours postdose.

CONCLUSION

The bioavailability values of FP after inhalation via a CFC MDI and an HFA MDI are similar. The 2 formulations deliver comparable amounts of FP, and systemic exposures to FP from the 2 devices, measured by urinary cortisol excretion, are not significantly different.

Pharmacokinetics of fluticasone propionate inhaled via the Diskhaler and Diskus powder devices in healthy volunteers

OBJECTIVE

The aim of these studies was to determine the absolute bioavailability in healthy volunteers of inhaled fluticasone propionate (FP) administered as a single dose via the Diskhaler and Diskus powder devices, and the pharmacokinetics of inhaled FP after repeated administration via the Diskhaler device.

METHODS

In 2 of the studies, single inhaled doses of FP were administered via the Diskhaler and the Diskus powder devices, and, in the third study, repeated doses of FP were administered via the Diskhaler. In the single dose studies, 12 healthy volunteers were randomised to receive FP 1000 microg by inhalation and FP 250 microg intravenously, using a double-blind crossover design. In the repeated dose study, 24 healthy volunteers received FP 1000 microg twice daily for 7.5 days.

RESULTS

Systemic exposure to FP after administration of a single 1000 microg inhaled dose of FP via the 2 powder devices was similar; the area under the plasma FP concentration-time curve (AUC) to infinite time (AUCinfinity) was 2.08 microg/L x h [95% confidence intervals (CI): 1.63-2.64] for Diskhaler and 2.49 microg/L x h (95% CI: 2.09-2.96) for Diskus. Maximum plasma FP concentration (Cmax) was 0.34 microg/L for both devices. Mean bioavailability values via the Diskhaler and Diskus were 11.9% (95% CI: 9.0-15.7%) and 16.6% (95% CI: 13.6-20.3%), respectively. No clinically significant reductions in urinary cortisol excretion were recorded in these 2 studies. After repeated administration with the Diskhaler, steady state was achieved by dose 3 (i.e. day 2) onwards. After dose 15, the AUC up to 12 hours (AUC12h) was 2.25 microg/L x h and Cmax was 0.38 microg/L. The mean steady-state to single dose accumulation ratio after twice-daily administration was 1.49 (95% CI: 1.36-1.62).

CONCLUSION

The pharmacokinetics of FP administered by the 2 powder devices are similar in healthy volunteers, although systemic bioavailability was greater with the Diskus.

The relationship between systemic exposure to fluticasone propionate and cortisol reduction in healthy male volunteers

OBJECTIVE

The aim of this analysis was to assess the pharmacokinetic/pharmacodynamic relationship between systemic exposure to fluticasone propionate (FP) and reductions in the plasma cortisol level and urinary cortisol excretion.

METHODS

A total of 122 healthy male volunteers participating in 7 different studies received either oral (5 to 40 mg), inhaled (500 to 2000 microg) or intravenous (250 to 1000 g) single morning doses of FP or placebo. Data on systemic exposure to FP, expressed in terms of the area under the FP concentration-time curve up to 24 hours (AUC(24h,FP)) for the 3 different routes of administration were pooled, together with corresponding data on the 24-hour plasma cortisol level or urinary cortisol excretion. The data were used to develop a pharmacokinetic/pharmacodynamic model, from which parameter estimates and 95% confidence intervals (CI) for the estimates could be derived.

RESULTS

The intercept in the absence of drug (E0) was -0.5% (95% CI: -0.6, -0.3%) and the maximum drug-induced reduction in mean plasma cortisol levels (Emax) was 72% (95% CI: 64, 79%). The systemic exposure to FP that resulted in half the maximum possible reduction in plasma cortisol levels (AUC50) was 3.2 microg/L x h (95% CI: 2.8, 3.7 microg/L x h); this equates approximately to the plasma FP concentration obtained after administration of a 1000 microg inhaled dose. A similar relationship was seen between AUC50 and urinary cortisol excretion, although the variability in AUC50 for urinary cortisol was much greater than for plasma cortisol.

CONCLUSION

A pharmacokinetic/pharmacodynamic model has been established which relates systemic exposure to FP (after a single morning dose) to the percentage reduction in urinary or plasma cortisol. The relationship is independent of both dose and route of administration.

Bioavailability of orally administered micronised fluticasone propionate

OBJECTIVE

The aim of this study was to determine the absolute oral bioavailability of fluticasone propionate (FP) in healthy volunteers.

METHODS

A 3-period incomplete block crossover design was used. On separate occasions, 21 male volunteers received a single 250 microg intravenous dose of FP (n = 21) and twice daily oral doses of either micronised FP 0.1 mg (n = 9), 1 mg (n = 12), 10 mg (n = 11) or placebo (n = 9) for 4 days.

RESULTS

FP was not measurable in the plasma after twice daily oral administration of a 0.1 mg dose. FP concentrations just above the limit of quantification could be measured in only 5 volunteers, and only at some time points, after administration of FP 1 mg twice daily. At a dose of 10 mg twice daily the absolute oral bioavailability of the drug was <1% when a liquid chromatography-mass spectrometry assay was used to assess plasma concentrations. Only oral doses of FP 10 mg twice daily, 10 times greater than the recommended maximum inhaled dose, produced any detectable change in urinary cortisol excretion.

CONCLUSION

The results of this study confirm that oral absorption of FP into the systemic circulation is negligible. The swallowed portion of an inhaled dose of FP is unlikely to increase the systemic exposure to the drug, thus decreasing the likelihood of adverse systemic effects.