Prevalence of modifiable risk factors and related poor cardiovascular outcomes following atrial fibrillation ablation

Background

Atrial fibrillation (AF) has become a global epidemic. Early catheter ablation and therapies modifying risk factors (RF) have been shown to improve outcomes of AF ablation. However, the time invested in pursuing risk factor modification may delay ablation, which could negate the procedural benefit.

Purpose

This study sought to investigate the prevalence and impact of potentially modifiable RF among AF patients undergoing catheter ablation in clinical practice.

Methods

This retrospective study included 724 consecutive patients undergoing AF ablation at a tertiary care center from 2012–2019. Pre-specified modifiable risks were examined, including the time from AF diagnosis to ablation, fluctuation/increase in BMI >5% prior to ablation, mean systolic/diastolic blood pressure >125/80 mmHg, obstructive sleep apnea with CPAP noncompliance, hyperlipidemia without statin therapy, tobacco use, excessive alcohol use, and diabetes mellitus with hemoglobin A1c (HbA1c) >6.5%. The primary outcome was a composite of recurrent atrial arrhythmias, cardiovascular (CV) hospitalizations and mortality following AF ablation. A multivariate analysis was performed.

Results

The mean age was 61±10 years old, 32.5% were female and 72.2% had persistent AF. Many study patients had modifiable RF, ranging from 4.7% with excessive alcohol use to 64.0% experiencing delayed AF ablation. The mean time from AF diagnosis to ablation was 4.7 years. During a mean follow-up of 1.6 years after ablation, 467 (64.5%) patients met the primary outcome. Independent RF for the primary outcome were an increase/fluctuation in BMI >5% (adjusted hazard ratio [AHR] 1.31, 95% confidence interval [CI] 1.07–1.60; P=0.008), diabetes with HbA1c >6.5% (AHR 1.50, 95% CI 1.09–2.03; P=0.014) and hyperlipidemia without statin therapy (AHR 1.30, 95% CI 1.08–1.57; P=0.005). Delayed AF ablation over 1.5 years did not alter the outcome, Figure 1.

Conclusion

Substantial portions of patients undergoing AF ablation have potentially modifiable RF. Increased or fluctuating BMI, diabetes with HbA1c >6.5%, and hyperlipidemia not treated with statin therapy portend an increased risk of recurrent atrial arrhythmia, CV hospitalizations and mortality. These findings underscore an importance pursuing RF management in patients with AF to reduce adverse outcomes after ablation.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The Jensen Family Research Sponsorship at the University of Nebraska Medical Center

Pre-ablation interatrial conduction delay or block predicts atrial fibrillation recurrence after ablation among obese patients

Funding Acknowledgements

Type of funding sources: None.

Background

Obesity is associated with greater risk of atrial fibrillation (AF) recurrence post-ablation and higher incidence of conduction delay compared to non-obese patients. Pre-ablation P-wave duration (PWD) and morphology (PWM) indicating interatrial delay are easily assessed in the clinic and may predict AF recurrence post-ablation in these patients.

Purpose

Evaluate the predictive value of PWD and PWM on AF recurrence post-ablation in obese patients.

Methods

Pre-ablation PWD and PWM (negative P-wave in lead II or III) were analyzed on consecutive patients with BMI ≥30 kg/m2 who underwent initial AF ablation from 2012–19. The primary outcome was recurrent AF after a 3-month post-ablation blanking period. Multivariate analysis adjusted for baseline characteristics was performed.

Results

For 205 patients (61.0±9.5 years old, 39.0% female), mean BMI was 36.9±5.7 kg/m2 and 71.7% had persistent AF pre-ablation. Recurrent AF post-ablation occurred in 115 (56.1%) during a median follow up of 491 (270, 1001) days. PWD >130 ms was significantly associated with higher AF recurrence (AHR of 1.62, 95%CI 1.04-2.57, p=0.03) after adjusting for age, persistent AF and left atrial volume index (LAVI). In a subgroup with LAVI <42 mL/m2 (n=112), PWD >130 ms and negative P-waves in lead II or III were independently associated with increased risk of recurrent AF (AHR 2.06, 95%CI 1.12-3.91; p=0.019 and AHR 1.94, 95% CI 1.00-3.56; p=0.05, respectively) (Figure 1).

Conclusion

AF recurred in >50% of obese patients within 1.5 years of ablation. Pre-ablation PWD >130 ms and negative P-waves in lead II or III independently predicted recurrent AF post-ablation in this cohort of obese patients. These easily assessed findings add predictive value to other risk factors.

Poor glycemic control in diabetic patients increases the risk of recurrent atrial arrhythmia and cardiovascular hospitalizations among morbidly obese patients undergoing atrial fibrillation ablation

Background/Introduction

Obesity and atrial fibrillation (AF) coexist and share multiple cardiovascular risk factors. Lifestyle modifications can reduce AF burden in obese patients. However, the time invested in pursing lifestyle changes may delay AF ablation, which could negate the procedural benefit.

Purpose

To examine the effects of lifestyle modifications and the timing of catheter ablation on morbidly obese patients with AF.

Methods

This retrospective study included 217 consecutive AF patients with a body mass index (BMI) ≥35 kg/m2 undergoing AF ablation at a tertiary care center from 2012 to 2019. Modifiable risks were examined, including the time from AF diagnosis to ablation, fluctuation of BMI >5% or an increase in BMI >3% prior to ablation, mean systolic blood pressure >130 mmHg or diastolic blood pressure >80 mmHg, obstructive sleep apnea with CPAP noncompliance, hyperlipidemia without statin therapy, tobacco use, excessive alcohol use, and diabetes mellitus with hemoglobin A1c (HbA1c) ≥6.5%. The primary outcome was a composite of recurrent atrial arrhythmias and cardiovascular (CV) hospitalizations following AF ablation. A multivariate analysis adjusting for age, gender and modifiable risks was performed.

Results

The mean age was 61±9 years old, 58% were female and 45% had persistent AF. A substantial portion of the study patients had modifiable risk factors, ranging from 2.7% with excessive alcohol use to 67.3% experiencing delayed AF ablation, Figure 1. The median time from diagnosed AF to ablation was 1.3 years. During a mean follow-up of 2.9 years after AF ablation, 136 (62.7%) patients met the primary outcome. Only HbA1c ≥6.5% was an independent risk factor with adjusted hazard ratio of 1.57, 95% confidence interval 1.02–2.36, P=0.0412, Figure 2A. Delayed AF ablation did not alter the outcome, Figure 2B. There was no interaction between time of ablation and HbA1c ≥6.5% (P=0.67).

Conclusion

Substantial portions of morbidly obese patients undergoing AF ablation have potentially modifiable risk factors. Poor glycemic control with HbA1c ≥6.5% predicts an increased risk of recurrent atrial arrhythmias and CV hospitalizations, while delayed AF ablation does not. This finding underscores an importance of optimizing HbA1c in morbidly obese patients with AF to reduce adverse outcomes after ablation.

Funding Acknowledgement

Type of funding sources: None.

Impact of age on catheter ablation of premature ventricular contractions

Funding Acknowledgements

Type of funding sources: None.

Introduction

Catheter ablation (CA) of frequent premature ventricular contractions (PVC) is increasingly performed in older patients as the population ages.

Purpose

The purpose of this study was to assess the impact of age on procedural characteristics, safety and efficacy on PVC ablations.

Methods

Consecutive patients with symptomatic PVCs undergoing CA between 2015 and 2020 were evaluated. Acute ablation success was defined as the elimination of PVCs at the end of the procedure. Sustained success was defined as an elimination of symptoms, and  ≥80% reduction of PVC burden determined by Holter-ECG during long-term follow. Patients were sub-grouped based on age (< 65 years vs. ≥ 65 years).

Results

A total of 114 patients were enrolled (median age 64 years, 71% males) and followed up for a median duration of 228 days. Baseline and procedural data were similar in both age groups. A left-sided origin of PVCs was more frequently observed in the elderly patient group compared to younger patients (83% vs. 67%, p = 0.04, Figure 1). The median procedure time was significantly shorter in elderly patients (160 min vs. 193 min, p = 0.02). The rates of both acute (86% vs. 92%, p = 0.32) and sustained success (70% vs. 71%, p = 0.90) were similar between groups. Complications rates (3.7%) did not differ between the two groups.

Conclusion

In a large series of patients with a variety of underlying arrhythmia substrates, similar rates of acute procedural success, complications, and ventricular arrhythmia-free-survival were observed after CA of PVCs. Older age alone should not be a reason to withhold CA of PVCs. Abstract Figure 1

The broken circle method: a novel technique that enhances detection of Hill-Sachs lesions on internal rotation shoulder radiographs

AIM

To describe and test a new method that increases the conspicuity of a Hill-Sachs lesion on internal rotation (IR) radiographs.

MATERIALS AND METHODS

This study had institutional review board approval. A retrospective search for patients with a prior shoulder dislocation and a Hill-Sachs lesion documented on magnetic resonance imaging (MRI) was performed over a 10-year period identifying 256 test patients. In Part 1, the IR radiographs from test cases were randomised with controls, and three readers scored them independently for the defect. The readers were then taught the Broken Circle (BC) method and re-scored the radiographs. In Part 2, 15 cases of Hill-Sachs lesions that were missed by all readers in Part 1 were randomised with controls, and were shown to 25 radiology residents before (pre-test) and after (post-test) learning the BC method. A paired t-test was used to compare the differences in sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV).

RESULTS

In Part 1, the sensitivity increased 19.7% (54.1%-73.8%; p<0.05) and NPV increased 10.8% (62.5%-73.3%; p<0.01). In Part 2, post-test sensitivity for residents increased 16.3% (55.2%-71.5%; p<0.0001), accuracy increased 13.4% (64%-77.4%; p<0.0001), and NPV increased 13.3% (40.8%-54.1%; p<0.0001) independent of the level of training. The change in accuracy was also statistically significant for every individual class.

CONCLUSION

The BC method was an effective technique that facilitated detection of a Hill-Sachs lesion at all levels of training, and was useful as a teaching tool.

P1127Occurrence, management and outcomes of iatrogenic aortic dissections as a complication of catheter ablation. A multicenter study

Background

Data on occurrence, management and outcomes of iatrogenic aortic dissections (IAD) as a complication of catheter ablation (CA) do not exist.

Purpose

To evaluate multicenter data on occurrence, management and outcomes of IAD as a complication of CA.

Methods

Data on occurrence, management and outcomes of documented vascular dissections from 10 centers were evaluated.

Results

IADs occurred in 7 patients (2 females, age 63 ± 8 years). Indications for CA were frequent premature ventricular complexes (PVC)/ventricular tachycardia (VT) in 6 patients (86%) and left-sided accessory pathway in the remaining one (14%). Hypertension was most frequent comorbidity (4 pts, 57%).  All IADs occurred during retrograde advancement of ablation catheter. In the vast majority of patients creation of IAD during catheter advancement was not associated with any symptoms (6 pts, 86%). IAD was initially detected using trans-luminal angiogram in 5 (71%) and further confirmed using computed tomography (CT) (5 pts, 71%), conventional angiography (2 pts, 28%) and ultrasound (2 pts, 28%). One IAD was detected during CT scan performed for other indication after CA. There was one IAD-related death and IAD was evaluated post-mortem. Follow-up lasted 10 ± 19 months. Four patients were treated conservatively, one patient underwent descending aorta stenting and one femoral artery stenting.

Conclusions

IAD during CA is a rare but can be devastating. Early recognition can be difficult. Conservative management of IAD is an option of treatment.

P1652Limited correlation of calculated plasma volume status with invasive right heart pressures in patients with heart failure

Background

Estimated plasma volume (ePV) can be calculated from haematocrit and body weight, and has been shown to correlate with PV measured using 125Iodine labelled human serum albumin. Comparing a patient's ePV to ideal PV (iPV), an estimate of a patient's relative congestion, called PV status (PVS), is possible. Higher PVS is associated with increased mortality in patients with heart failure (HF), and has been proposed as a simple, cheap, and non-invasive way of assessing congestion.

Purpose

Whether PVS is associated with invasively measured markers of congestion is unknown. We calculated PVS in patients with HF who had right heart catheterisation (RHC), and assessed any correlation between PVS and invasive measures of congestion.

Methods

We calculated PVS in consecutive patients who had RHC performed as part of transplant assessment. iPV was calculated as: iPV = c × weight (kg) where c=39 in males and c=40 in females. ePV was calculated using subjects' haematocrit and weight as follows: ePV = (1 − haematocrit) × [a + (b × weight in kg)], where haematocrit is a fraction, a=1530 in males and a=864 in females, and b=41 in males and b=47.9 in females. PVS was calculated as: PVS = PVS = (ePV − iPV) /iPV × 100%. Correlation between PVS and invasive wedge pressure, mean right atrial (RA) pressure, and NTproBNP were made using Pearson correlation.

Results

PV indices and RHC data were available for 61 patients, 43 (71%) were male. Median age was 55 [IQR 48, 58] years. 20 (33%), 24 (39%), and 15 (25%) were NYHA association class II, III, and IV respectively. The median NTproBNP was 1390 [IQR 512, 3612] pg/ml and median ejection fraction was 29 [IQR 20, 35] %. The median PVS was −5.9% (IQR −12.5, −1.6]. Median wedge and mean-RA pressures were 14 [7, 21] and 4 [1, 8] mmHg, respectively. Correlation between mean RA pressure and PVS is shown in the figure. There was no correlation between PVS and mean RA pressure (r=0.12, p=0.34) or wedge pressure (r=0.01, p=0.92). There was a weak correlation between NTproBNP and PVS (r=0.31, p=0.01)

Correlation mean RA pressure and PVS

Conclusion

PVS did not correlate with the invasive measures of congestion, mean RA and wedge pressure, but was weakly correlated with NTproBNP. Although there were limited number of patients in this study, we question the conclusion that PVS is a marker of congestion, and whether it can be used clinically for this purpose.

Noninvasive tissue adhesive for cardiac implantable electronic device pocket closure: the TAPE pilot study

PURPOSE

Device infection is a serious complication of cardiac implantable electronic devices (CIED). Ensuring complete pocket closure can be time consuming, but remains vital to prevent infection. The Zip® Surgical Skin Closure (ZIP) is a noninvasive adhesive device applied to the skin as an alternative to subcuticular sutures for skin closure. We hypothesized that using this device would decrease pocket closure times without increasing the risk of pocket infections. This is a single center, retrospective cohort study to compare pocket closure times and infection rates between ZIP and standard suture for CIED pocket closure.

METHODS

Two separate groups of consecutive new intravenous implants, upgrades, and pulse generator replacements from October 2015 to April 2017 were included. A total of 175 patients were included, using either ZIP (n = 80) or suture (n = 95). Total procedure time (local anesthetic to dressing application) and pocket closure time (fascial suture to dressing application) were compared. Pocket infections were defined as infections leading to CIED extraction or wound dehiscence requiring repeat procedure. Statistical analysis was performed using chi square test and Student's t test.

RESULTS

Pocket closure time and procedure time were significantly shorter for the ZIP group (14.9 ± 6.8 vs 20.1 ± 11.09 min, p = 0.0003) and (65.02 ± 30.4 vs 83.83 ± 40.3 min, p = 0.0008), respectively. No pocket infections occurred in the Zip group, while the suture group had 2:1 wound dehiscence and 1 pocket infection.

CONCLUSION

The ZIP device resulted in significantly shorter pocket closure and procedure times without increasing device pocket infections.

Intracranial haemorrhage in children with inherited bleeding disorders in the UK 2003-2015: A national cohort study

INTRODUCTION

Intracranial haemorrhage in children with inherited bleeding disorders is a potentially life-threatening complication and presents a significant therapeutic challenge.

AIM

To define the characteristics, management and outcomes of intracranial haemorrhage presenting in UK children ≤16 years of age with inherited bleeding disorders from 2003 to 2015.

METHOD

Retrospective analysis of children treated at UK haemophilia centres.

RESULTS

Of 66 children presenting with Intracranial haemorrhage (ICH), 82% had haemophilia A or B, 3% VWD and 15% a rare IBD. The IBD was a severe phenotype in 91%. The rates of ICH were 6.4 and 4.2 per 1000 patient years for haemophilia A and B, respectively. Median age at presentation was 4 months (33% neonates; 91% children <2 years of age). In neonates, delivery was spontaneous vaginal (SV) in 11, instrumental in 6, caesarean in 4 and unknown in 1. In children with haemophilia, the risk of ICH after instrumental delivery was 10.6 times greater than after SV delivery. Trauma was more common in children >2 years (67%) than in children 1 month to 2 years (18%; P = .027). Prior to ICH, only 4.5% of children were on prophylaxis. 6% of haemophiliacs had an inhibitor. The median duration of initial replacement therapy was 15 days. Mortality was 13.5%. Neurological sequelae occurred in 39% of survivors, being more common following intracerebral bleeding. In haemophilia survivors, 52% subsequently developed a FVIII inhibitor.

CONCLUSION

Intracranial haemorrhage occurs most frequently in children with severe IBDs, during the first 2 years of life and in children not receiving prophylaxis. Intracranial haemorrhage often occurs without documented trauma.

The impact of education, country, race and ethnicity on the self-report of postpartum depression using the Edinburgh Postnatal Depression Scale

BACKGROUND

Universal screening for postpartum depression is recommended in many countries. Knowledge of whether the disclosure of depressive symptoms in the postpartum period differs across cultures could improve detection and provide new insights into the pathogenesis. Moreover, it is a necessary step to evaluate the universal use of screening instruments in research and clinical practice. In the current study we sought to assess whether the Edinburgh Postnatal Depression Scale (EPDS), the most widely used screening tool for postpartum depression, measures the same underlying construct across cultural groups in a large international dataset.

METHOD

Ordinal regression and measurement invariance were used to explore the association between culture, operationalized as education, ethnicity/race and continent, and endorsement of depressive symptoms using the EPDS on 8209 new mothers from Europe and the USA.

RESULTS

Education, but not ethnicity/race, influenced the reporting of postpartum depression [difference between robust comparative fit indexes (∆*CFI) 0.01), but not between European countries (∆*CFI < 0.01).

CONCLUSIONS

Investigators and clinicians should be aware of the potential differences in expression of phenotype of postpartum depression that women of different educational backgrounds may manifest. The increasing cultural heterogeneity of societies together with the tendency towards globalization requires a culturally sensitive approach to patients, research and policies, that takes into account, beyond rhetoric, the context of a person's experiences and the context in which the research is conducted.

Highly Pathogenic Avian Influenza (H5N1) Virus in Feathers

H5N1 highly pathogenic avian influenza (HPAI) virus causes high mortality of infected birds, with infection in multiple organs, including in feathers. Feathers have been proposed as samples for diagnosis of HPAI infection in birds, and this study is part of a broader investigation validating the use of feathers for diagnostic purposes. To understand and characterize the morphological basis for feather infection, sections from 7 different skin tracts of ducks and chickens infected with 3 different clades of H5N1 HPAI virus from Indonesia and Vietnam were examined histologically. Results showed that in ducks, lesions and viral antigen were mainly detected in the epidermis of feathers and follicles, whereas in chickens, they were mostly found in the dermis of these structures. Abundant viral antigen was found in nearly all the feathers examined from chickens, and there was no apparent difference between virus isolates or skin tracts in the proportion of feathers that were antigen positive. By immunohistochemistry, the majority of feathers from most skin tracts from ducks infected with a Vietnamese H5N1 HPAI virus contained abundant levels of viral antigen, while few feathers were antigen positive from ducks infected with 2 Indonesian viruses. These results support and inform the use of feathers for diagnostic detection of H5N1 HPAI virus in birds.

The influence of the biological pump on ocean chemistry: implications for long-term trends in marine redox chemistry, the global carbon cycle, and marine animal ecosystems

The net export of organic matter from the surface ocean and its respiration at depth create vertical gradients in nutrient and oxygen availability that play a primary role in structuring marine ecosystems. Changes in the properties of this 'biological pump' have been hypothesized to account for important shifts in marine ecosystem structure, including the Cambrian explosion. However, the influence of variation in the behavior of the biological pump on ocean biogeochemistry remains poorly quantified, preventing any detailed exploration of how changes in the biological pump over geological time may have shaped long-term shifts in ocean chemistry, biogeochemical cycling, and ecosystem structure. Here, we use a 3-dimensional Earth system model of intermediate complexity to quantitatively explore the effects of the biological pump on marine chemistry. We find that when respiration of sinking organic matter is efficient, due to slower sinking or higher respiration rates, anoxia tends to be more prevalent and to occur in shallower waters. Consequently, the Phanerozoic trend toward less bottom-water anoxia in continental shelf settings can potentially be explained by a change in the spatial dynamics of nutrient cycling rather than by any change in the ocean phosphate inventory. The model results further suggest that the Phanerozoic decline in the prevalence ocean anoxia is, in part, a consequence of the evolution of larger phytoplankton, many of which produce mineralized tests. We hypothesize that the Phanerozoic trend toward greater animal abundance and metabolic demand was driven more by increased oxygen concentrations in shelf environments than by greater food (nutrient) availability. In fact, a lower-than-modern ocean phosphate inventory in our closed system model is unable to account for the Paleozoic prevalence of bottom-water anoxia. Overall, these model simulations suggest that the changing spatial distribution of photosynthesis and respiration in the oceans has exerted a first-order control on Earth system evolution across Phanerozoic time.

Quantification of sodium pentobarbital residues from equine mortality compost piles

Sodium pentobarbital, a euthanasia drug, can persist in animal carcasses following euthanasia and can cause secondary toxicosis to animals that consume the remains. This experiment was conducted to observe the effects of composting on euthanized horse carcass degradation and sodium pentobarbital residues in compost material up to 367 d. Six separate compost bins were constructed on pastureland. Three bins served as the control while 3 served as the treatment. The carbonaceous material, or bulking agent, consisted of hardwood chips mixed with yard waste wetted to approximately 50% moisture content. Bulking agent was added to each bin at a depth of 0.46 m, creating the pad. A licensed veterinarian provided 6 horse carcasses for use in the experiment. These horses had required euthanasia for health reasons. All horses were weighed and then sedated with an intravenous injection of 8 mL of xylazine. After sedation the 3 horses in the treatment group were euthanized by intravenous injection of 60 mL of sodium pentobarbital. The 3 control group horses were anesthetized by intravenous injection of 15 mL of ketamine hydrochloride and then humanely euthanized by precise gunshot to the temporal lobe. Following euthanasia, each carcass was placed on the center of the pad and surrounded with 0.6 m of additional bulking agent. Serum and liver samples were obtained immediately following death. Compost samples were obtained on d 7, 14, 28, 56, 84, 129, 233, and 367 while soil samples were obtained on d -1 and 367. Each sample was analyzed for sodium pentobarbital concentration. Compost pile and ambient temperatures were also recorded. Composting successfully degraded soft tissue with only large bones remaining. Data illustrate that sodium pentobarbital was detectable up to 367 d in compost piles with no clear trend of concentration reduction. Drug residues were detected in soil samples indicating that sodium pentobarbital leached from the carcass and through the pad. These findings confirm the persistence of sodium pentobarbital from equine mortality compost piles and emphasize the importance of proper carcass management of animals euthanized with a barbiturate to reduce environmental impact and secondary toxicosis.

Recent trends in breast, cervical, and colorectal cancer screening test utilization in Canada, using self-reported data from 2008 and 2012

In Canada, self-reported data from the Canadian Community Health Survey 2008 and 2012 provide an opportunity to examine overall utilization of breast, cervical, and colorectal cancer screening tests for both programmatic and opportunistic screening. Among women 50-74 years of age, utilization of screening mammography was stable (62.0% in 2008 and 63.0% in 2012). Pap test utilization for women 25-69 years of age remained high and stable across Canada in 2008 and 2012 (78.9% in 2012). The percentage of individuals 50-74 years of age who reporting having at least 1 fecal test within the preceding 2 years increased in 2012 (to 23.0% from 16.9% in 2008), but remains low. Stable rates of screening mammography utilization (about 30%) were reported in 2008 and 2012 among women 40-49 years of age, a group for which population-based screening is not recommended. Although declining over time, cervical cancer screening rates were high for women less than 25 years of age (for whom screening is not recommended). Interestingly, an increased percentage of women 70-74 years of age reported having a Pap test. In 2012, a smaller percentage of women 50-69 years of age reported having no screening test (5.9% vs. 8.5% in 2008), and more women reported having the three types of cancer screening tests (19.0% vs. 13.2%). Efforts to encourage use of screening within the recommended average-risk age groups are needed, and education for stakeholders about the possible harms of screening outside those age groups has to continue.

Functional profiling in Streptococcus mutans: construction and examination of a genomic collection of gene deletion mutants

A collection of tagged deletion mutant strains was created in Streptococcus mutans UA159 to facilitate investigation of the aciduric capability of this oral pathogen. Gene-specific barcoded deletions were attempted in 1432 open reading frames (representing 73% of the genome), and resulted in the isolation of 1112 strains (56% coverage) carrying deletions in distinct non-essential genes. As S. mutans virulence is predicated upon the ability of the organism to survive an acidic pH environment, form biofilms on tooth surfaces, and out-compete other oral microflora, we assayed individual mutant strains for the relative fitness of the deletion strain, compared with the parent strain, under acidic and oxidative stress conditions, as well as for their ability to form biofilms in glucose- or sucrose-containing medium. Our studies revealed a total of 51 deletion strains with defects in both aciduricity and biofilm formation. We have also identified 49 strains whose gene deletion confers sensitivity to oxidative damage and deficiencies in biofilm formation. We demonstrate the ability to examine competitive fitness of mutant organisms using the barcode tags incorporated into each deletion strain to examine the representation of a particular strain in a population. Co-cultures of deletion strains were grown either in vitro in a chemostat to steady-state values of pH 7 and pH 5 or in vivo in an animal model for oral infection. Taken together, these data represent a mechanism for assessing the virulence capacity of this pathogenic microorganism and a resource for identifying future targets for drug intervention to promote healthy oral microflora.

Limited role of functional differentiation in early diversification of animals

The origin of most animal phyla and classes during the Cambrian explosion has been hypothesized to represent an ‘early burst’ of evolutionary exploration of functional ecological possibilities. However, the ecological history of marine animals has yet to be fully quantified, preventing an assessment of the early-burst model for functional ecology. Here we use ecological assignments for 18,621 marine animal genera to assess the relative timing of functional differentiation versus taxonomic diversification from the Cambrian to the present day. We find that functional diversity increased more slowly than would be expected given the history of taxonomic diversity. Contrary to previous inferences of rapid ecological differentiation from the early appearances of all well-fossilized phyla and classes, explicit coding of functional characteristics demonstrates that Cambrian genera occupied comparatively few modes of life. Functional diversity increased in the Ordovician and, especially, during the recoveries from the end-Permian and end-Cretaceous mass extinctions. Permanent shifts in the relationship between functional and taxonomic diversity following the era-bounding extinctions indicates a critical role for these biotic crises in coupling taxonomic and functional diversity.

Functional differentiation and taxonomic diversity are related in modern ecosystems. Here, the authors show that functional differentiation lags behind taxonomic diversification early in the evolutionary history of marine animals and that important shifts in this relationship occur at major mass extinction events.

Antenatal prediction of postpartum depression with blood DNA methylation biomarkers

Postpartum depression (PPD) affects ∼10-18% of women in the general population and results in serious consequences to both the mother and offspring. We hypothesized that predisposition to PPD risk is due to an altered sensitivity to estrogen-mediated epigenetic changes that act in a cell autonomous manner detectable in the blood. We investigated estrogen-mediated epigenetic reprogramming events in the hippocampus and risk to PPD using a cross-species translational design. DNA methylation profiles were generated using methylation microarrays in a prospective sample of the blood from the antenatal period of pregnant mood disorder patients who would and would not develop depression postpartum. These profiles were cross-referenced with syntenic locations exhibiting hippocampal DNA methylation changes in the mouse responsive to long-term treatment with 17β-estradiol (E2). DNA methylation associated with PPD risk correlated significantly with E2-induced DNA methylation change, suggesting an enhanced sensitivity to estrogen-based DNA methylation reprogramming exists in those at risk for PPD. Using the combined mouse and human data, we identified two biomarker loci at the HP1BP3 and TTC9B genes that predicted PPD with an area under the receiver operator characteristic (ROC) curve (area under the curve (AUC)) of 0.87 in antenatally euthymic women and 0.12 in a replication sample of antenatally depressed women. Incorporation of blood count data into the model accounted for the discrepancy and produced an AUC of 0.96 across both prepartum depressed and euthymic women. Pathway analyses demonstrated that DNA methylation patterns related to hippocampal synaptic plasticity may be of etiological importance to PPD.

Population characteristics and survival in 127 referred cats with hypertrophic cardiomyopathy (1997 to 2005)

OBJECTIVES

To evaluate the characteristics and survival of a recent population of cats with hypertrophic cardiomyopathy.

METHODS

Records at the Royal Veterinary College Queen Mother Hospital for Animals were searched for cats diagnosed with hypertrophic cardiomyopathy between 1997 and 2005. Referring veterinarians and owners were contacted to determine survival times.

RESULTS

Cats with hypertrophic cardiomyopathy were evaluated for population characteristics (n=127) and survival times (n=109). Overall median survival from date of hypertrophic cardiomyopathy diagnosis at the Queen Mother Hospital for Animals was 1276 days. Cats with hypertrophic cardiomyopathy were younger (P=0·009), and more likely to be male (P<0·001) compared to a hospital control group (n=1473), and Ragdolls were over-represented (P<0·05). Characteristics associated with increased survival in univariate analysis included younger age (P=0·007), asymptomatic status (P<0·001), normal left atrial size (P<0·001) and presence of systolic anterior motion of the mitral valve (P=0·003). Systolic anterior motion was associated with asymptomatic status, and did not influence survival in asymptomatic cats or those in congestive heart failure. Age, left atrial size and breed were significantly associated with survival time in a multivariate analysis.

CLINICAL SIGNIFICANCE

Cats with hypertrophic cardiomyopathy and left atrial enlargement have a poorer prognosis. The positive influence of systolic anterior motion on survival is likely to be linked to its association with asymptomatic status.

Divertor IR thermography on Alcator C-Mod

Alcator C-Mod is a particularly challenging environment for thermography. It presents issues that will similarly face ITER, including low-emissivity metal targets, low-Z surface films, and closed divertor geometry. In order to make measurements of the incident divertor heat flux using IR thermography, the C-Mod divertor has been modified and instrumented. A 6° toroidal sector has been given a 2° toroidal ramp in order to eliminate magnetic field-line shadowing by imperfectly aligned divertor tiles. This sector is viewed from above by a toroidally displaced IR camera and is instrumented with thermocouples and calorimeters. The camera provides time histories of surface temperatures that are used to compute incident heat-flux profiles. The camera sensitivity is calibrated in situ using the embedded thermocouples, thus correcting for changes and nonuniformities in surface emissivity due to surface coatings.

Genome-wide linkage and follow-up association study of postpartum mood symptoms

OBJECTIVE

Family studies have suggested that postpartum mood symptoms might have a partly genetic etiology. The authors used a genome-wide linkage analysis to search for chromosomal regions that harbor genetic variants conferring susceptibility for such symptoms. The authors then fine-mapped their best linkage regions, assessing single nucleotide polymorphisms (SNPs) for genetic association with postpartum symptoms.

METHOD

Subjects were ascertained from two studies: the NIMH Genetics Initiative Bipolar Disorder project and the Genetics of Recurrent Early-Onset Depression. Subjects included women with a history of pregnancy, any mood disorder, and information about postpartum symptoms. In the linkage study, 1,210 women met criteria (23% with postpartum symptoms), and 417 microsatellite markers were analyzed in multipoint allele sharing analyses. For the association study, 759 women met criteria (25% with postpartum symptoms), and 16,916 SNPs in the regions of the best linkage peaks were assessed for association with postpartum symptoms.

RESULTS

The maximum linkage peak for postpartum symptoms occurred on chromosome 1q21.3-q32.1, with a chromosome-wide significant likelihood ratio Z score (Z(LR)) of 2.93 (permutation p=0.02). This was a significant increase over the baseline Z(LR) of 0.32 observed at this locus among all women with a mood disorder (permutation p=0.004). Suggestive linkage was also found on 9p24.3-p22.3 (Z(LR)=2.91). In the fine-mapping study, the strongest implicated gene was HMCN1 (nominal p=0.00017), containing four estrogen receptor binding sites, although this was not region-wide significant.

CONCLUSIONS

This is the first study to examine the genetic etiology of postpartum mood symptoms using genome-wide data. The results suggest that genetic variations on chromosomes 1q21.3-q32.1 and 9p24.3-p22.3 may increase susceptibility to postpartum mood symptoms.

PCB concentrations in lake trout (Salvelinus namaycush) are correlated to habitat use and lake characteristics

This study considers the importance of lake trout habitat as a factor determining persistent organochlorine (OC) concentration. Lake trout is a stenothermal, cold water species and sensitive to hypoxia. Thus, factors such as lake depth, thermal stratification, and phosphorus enrichment may determine not only which lakes can support lake trout but may also influence among-lake variability in lake trout population characteristics including bioaccumulation of OCs. A survey of 23 lakes spanning much of the natural latitudinal distribution of lake trout provided a range of lake trout habitat to test the hypothesis that lake trout with greater access to littoral habitat for feeding will have lower concentrations of OCs than lake trout that are more restricted to pelagic habitat. Using the delta13C stable isotope signature in lake trout as an indicator of influence of benthic littoral feeding, we found a negative correlation between lipid-corrected delta13C and sigmaPCB concentrations supporting the hypothesis that increasing accessto littoral habitat results in lower OCs in lake trout. The prominence of mixotrophic phytoplankton in lakes with more contaminated lake trout indicated the pelagic microbial food web may exacerbate the biomagnification of OCs when lake trout are restricted to pelagic feeding. A model that predicted sigmaPCB in lake trout based on lake area and latitude (used as proximate variables for proportion of littoral versus pelagic habitat and accessibility to littoral habitat respectively) explained 73% of the variability in sigmaPCBs in lake trout in the 23 lakes surveyed.

Fetal alcohol syndrome: a prospective national surveillance study

OBJECTIVE

To describe the epidemiology of cases of fetal alcohol syndrome (FAS) seen by Australian paediatricians.

METHODS

Active, national case-finding using the Australian Paediatric Surveillance Unit (APSU). Monthly reporting of incident cases aged <15 years by paediatricians between January 2001 and December 2004.

RESULTS

Over 1150 paediatricians submitted reports each month to the APSU. Of 169 reported cases, 92 fulfilled the study criteria for FAS. There was a significant increase in the number of children reported each year from 2001 to 2004. Of 92 children, 53.3% were male, 35.7% were preterm (<37 weeks' gestation) and 64.6% were of low birth weight (<2.5 kg). Most (94.4%) had high risk exposure to alcohol in utero and 78.3% were exposed to one or more additional drugs. The median age at diagnosis was 3.3 years (range: newborn to 11.9 years): 6.5% were diagnosed at birth and 63% by 5 years of age. Of the 92 cases, 56% had growth deficiency, 53.2% had microcephaly, 85.9% had evidence of central nervous system dysfunction, 24% had additional birth defects, 5.4% had sensorineural deafness and 4.3% had visual impairment. Of children with FAS, 65% were Indigenous, 51% had a sibling with FAS, and only 40.2% lived with a biological parent.

CONCLUSION

Our data are the only prospective national data available on FAS throughout the world. These findings highlight the severity, complexity and impact of FAS, the need for effective strategies for prevention, and the necessity for education to facilitate earlier diagnosis, referral and reporting of cases.