Homological percolation transitions in growing simplicial complexes

Simplicial complex (SC) representation is an elegant mathematical framework for representing the effect of complexes or groups with higher-order interactions in a variety of complex systems ranging from brain networks to social relationships. Here, we explore the homological percolation transitions (HPTs) of growing SCs using empirical datasets and model studies. The HPTs are determined by the first and second Betti numbers, which indicate the appearance of one- and two-dimensional macroscopic-scale homological cycles and cavities, respectively. A minimal SC model with two essential factors, namely, growth and preferential attachment, is proposed to model social coauthorship relationships. This model successfully reproduces the HPTs and determines the transition types as an infinite-order Berezinskii-Kosterlitz-Thouless type but with different critical exponents. In contrast to the Kahle localization observed in static random SCs, the first Betti number continues to increase even after the second Betti number appears. This delocalization is found to stem from the two aforementioned factors and arises when the merging rate of two-dimensional simplexes is less than the birth rate of isolated simplexes. Our results can provide a topological insight into the maturing steps of complex networks such as social and biological networks.

Cellulose derivatives agglomerated in a fluidized bed: Physical, rheological, and structural properties

Understanding the agglomeration of cellulose derivatives is crucial for the production of instant gum-based food thickeners. In the present study, physical, rheological, and structural properties of agglomerated water-soluble cellulose gums (CGs), such as carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), and methylcellulose (MC), were investigated at different concentrations of maltodextrin (MD) as a binder for fluidized-bed agglomeration. Among the CG agglomerates in the presence of MD, CMC exhibited better flowability and lower cohesiveness, showing lower Carr index and Hausner ratio values. The MC agglomerates with 20% MD exhibited higher porosity than the other CGs due to the size enlargement of MC particles, which was confirmed via scanning electron microscopy images and size distribution profiles. The dynamic moduli of the CG agglomerates were significantly decreased by the addition of MD and also decreased with increasing MD concentration. The tan δ values of the agglomerates increased with increasing MD concentration, indicating the enhancement of their viscous properties. These results suggest that the physical, rheological, and structural properties of cellulose derivatives with different types of CG can be greatly influenced by their agglomerate growths during fluidized-bed agglomeration of particles with the different concentrations of MD binder.

Molecular insights into the development of hepatic metastases in colorectal cancer: a metastasis prediction study

OBJECTIVE

Colorectal cancer is presently the third most commonly diagnosed cancer in the United States. In this study, we identified molecular differences between hepatic and non-hepatic metastases in colorectal cancer and evaluated their prognostic significance.

MATERIALS AND METHODS

We downloaded primary data from the NCBI Gene Expression Omnibus (GSE6988, GSE62321, GSE50760, and GSE28722). To identify the molecular differences, we used the Significance Analysis of Microarray method. We selected nine prognostic genes (SYTL2, PTPLAD1, CDS1, RNF138, PIGR, WDR78, MYO7B, TSPAN3, and ATP5F1) with hepatic metastasis prediction score in colorectal cancer (hereafter referred to as LASSO Score). We confirmed the prognostic significance of the LASSO Score by using Kaplan-Meier survival analysis, multivariate analysis, the time-dependent area under the curve (AUC) of Uno's C-index, and the AUC of the receiver operating characteristic curve at 1-5 years.

RESULTS

Survival analysis revealed that a high LASSO Score is associated with a poor prognosis in colorectal cancer patients with hepatic metastases (p = 0). Analysis of C-indices and AUC values from the receiver operating characteristic curve further supported this prediction by the LASSO Score. Multivariate analysis confirmed the prognostic significance of the LASSO Score (p = 1.13e-06).

CONCLUSIONS

This study reveals the biological mechanisms underlying hepatic metastases in colorectal cancer and will help in developing targeted therapies for colorectal cancer.

The Mars 2020 Engineering Cameras and Microphone on the Perseverance Rover: A Next-Generation Imaging System for Mars Exploration

The Mars 2020 Perseverance rover is equipped with a next-generation engineering camera imaging system that represents an upgrade over previous Mars rover missions. These upgrades will improve the operational capabilities of the rover with an emphasis on drive planning, robotic arm operation, instrument operations, sample caching activities, and documentation of key events during entry, descent, and landing (EDL). There are a total of 16 cameras in the Perseverance engineering imaging system, including 9 cameras for surface operations and 7 cameras for EDL documentation. There are 3 types of cameras designed for surface operations: Navigation cameras (Navcams, quantity 2), Hazard Avoidance Cameras (Hazcams, quantity 6), and Cachecam (quantity 1). The Navcams will acquire color stereo images of the surface with a 96 ∘ × 73 ∘ field of view at 0.33 mrad/pixel. The Hazcams will acquire color stereo images of the surface with a 136 ∘ × 102 ∘ at 0.46 mrad/pixel. The Cachecam, a new camera type, will acquire images of Martian material inside the sample tubes during caching operations at a spatial scale of 12.5 microns/pixel. There are 5 types of EDL documentation cameras: The Parachute Uplook Cameras (PUCs, quantity 3), the Descent stage Downlook Camera (DDC, quantity 1), the Rover Uplook Camera (RUC, quantity 1), the Rover Descent Camera (RDC, quantity 1), and the Lander Vision System (LVS) Camera (LCAM, quantity 1). The PUCs are mounted on the parachute support structure and will acquire video of the parachute deployment event as part of a system to characterize parachute performance. The DDC is attached to the descent stage and pointed downward, it will characterize vehicle dynamics by capturing video of the rover as it descends from the skycrane. The rover-mounted RUC, attached to the rover and looking upward, will capture similar video of the skycrane from the vantage point of the rover and will also acquire video of the descent stage flyaway event. The RDC, attached to the rover and looking downward, will document plume dynamics by imaging the Martian surface before, during, and after rover touchdown. The LCAM, mounted to the bottom of the rover chassis and pointed downward, will acquire 90 ∘ × 90 ∘ FOV images during the parachute descent phase of EDL as input to an onboard map localization by the Lander Vision System (LVS). The rover also carries a microphone, mounted externally on the rover chassis, to capture acoustic signatures during and after EDL. The Perseverance rover launched from Earth on July 30th, 2020, and touchdown on Mars is scheduled for February 18th, 2021.

Non-alcoholic fatty liver disease fibrosis score predicts cardiovascular mortality in post percutaneous coronary intervention patients: a 5-years results from observational registry

Background and aims

The nonalcoholic fatty liver disease fibrosis score (NFS) is comprised of metabolic risk indicators that may accurately predict residual cardiovascular risk in patients with CAD.

Method

This is a nested case control study of the post PCI registry from single tertiary hospital. Among 5589 patients who underwent PCI from 2010 through 2014, previously diagnosed 1510 NAFLD patients and 296 consecutive NAFLD patients who had undergone both PCI and ultrasonography of abdomen within 1 year between the tests were enrolled. (median age, 64y (IQR 55–73)). We applied the NFS to the patients at baseline, using validated NFS cut-offs and 201 patients with higher NFS, defined as NFS >0.67 at PCI, were 1:1 matched with controls, based on propensity scores for higher NFS >0.67.

Results

Higher NFS (NFS >0.67) was more prevalent in patients with left ventricle (LV) dysfuction (LVEF at PCI <40%) than in those without (81.0% vs 33.6%, p<0.001). Baseline higher NFS was significantly associated with LV dysfunction (adjusted OR 1.86, 95% CI 1.36 to 2.55, p<0.001), and baseline higher NFS and persistent higher NFS at 1 year after PCI were independent predictor of a 5-years CV death, after adjustment for LVEF (adjusted HR 1.42, 95% CI 1.03 to 1.95, p=0.023; adjusted HR 1.52, 95% CI 1.08 to 2.64, p=0.033).

Conclusion

With a longitudinal assessment of the association between NAFLD status by NFS and the risk of CV death, we found post-PCI patients with persistent higher NFS were at higher risk of CV death compared with those without.

KM rates of CV death according to NFS

Funding Acknowledgement

Type of funding source: None

Undiagnosed type 2 diabetes during pregnancy is associated with increased perinatal mortality: a large population-based cohort study in Ontario, Canada

AIM

To compare perinatal outcomes in women with undiagnosed diabetes with gestational diabetes alone, pre-existing diabetes and women without diabetes, and to identify risk factors which distinguish them from women with gestational diabetes alone.

METHODS

This population-based cohort study included administrative data on all women who gave birth in Ontario, Canada, during 2002-2015. Maternal/neonatal outcomes were compared across groups using logistic regression, adjusting for confounders. A nested case control study compared women with undiagnosed type 2 diabetes with women with gestational diabetes alone to determine risk factors that would help identify these women.

RESULTS

Among 995 990 women, 68 163 had gestational diabetes (6.8%) and, of those women with gestational diabetes,1772 had undiagnosed type 2 diabetes (2.6%). Those with undiagnosed type 2 diabetes were more likely to be older, from a lower income area, have parity > 3 and BMI ≥ 30 kg/m² compared with gestational diabetes alone. Infants had a higher risk of perinatal mortality (OR 2.3 [1.6-3.4]), preterm birth (OR 2.6 [2.3-2.9]), congenital anomalies (OR 2.1 [1.7-2.5]), neonatal intensive care unit admission (OR 3.1 [2.8-3.5]) and neonatal hypoglycaemia (OR 406.0 [357-461]), which were similar to women with pre-existing diabetes. The strongest predictive risk factors included early gestational diabetes diagnosis, previous gestational diabetes and chronic hypertension.

CONCLUSIONS

Women diagnosed with gestational diabetes who develop diabetes within 1 year postpartum are at higher risk of adverse pregnancy outcomes, including perinatal mortality. This highlights the need for earlier diagnosis, preferably pre-pregnancy, and more aggressive treatment and surveillance of suspected type 2 diabetes during pregnancy.

TEK is a novel prognostic marker for clear cell renal cell carcinoma

OBJECTIVE

Clear cell renal cell carcinoma (ccRCC) is the most common type of kidney cancer. However, effective therapeutics for ccRCC are lacking. Novel biomarkers could provide critical information when determining prognoses for patients with ccRCC. In this study, we sought to determine if the expression of receptor tyrosine kinase (TEK) could be a potential novel prognostic biomarker for ccRCC. TEK, originally identified as an endothelial cell-specific receptor, plays an important role in the modulation of vasculogenesis and remodeling. Altered TEK expression has been observed in tumor tissues (e.g., oral squamous cell carcinomas, leukemia) and breast, gastric and thyroid cancers. However, the role of TEK in ccRCC remains unknown.

PATIENTS AND METHODS

Differential TEK expression between non-metastatic (stage M0) and metastatic (stage M1) ccRCC patient cohorts was determined from The Cancer Genome Atlas (TCGA) and the International Cancer Genome Consortium (ICGC). Furthermore, TEK expression was assessed as a prognostic factor using the time-dependent area under the curve (AUC) of Uno's C-index, the AUC value of the receiver operating characteristics (ROC) at 5 years, Kaplan-Meier survival curves and multivariate analyses.

RESULTS

A Kaplan-Meier curve analysis revealed that the downregulation of TEK expression was associated with a poor prognosis for patients with ccRCC with good discrimination (p<0.0001 and p=0.0044 for the TGCA and ICGC cohorts, respectively). Analyses of C-indices and receiver operating characteristic AUC values further support this discriminative ability. Moreover, multivariate analyses showed the prognostic significance of TEK expression levels (p<0.001).

CONCLUSIONS

Although additional clinical investigations will be needed, our results suggest that TEK is a potential biomarker for ccRCC.

Alteration in brain connectivity in patients with Dravet syndrome after vagus nerve stimulation (VNS): exploration of its effectiveness using graph theory analysis with electroencephalography

OBJECTIVE

Vagus nerve stimulation (VNS) is a nonpharmacologic therapeutic option for patients who have pharmaco-resistant Dravet syndrome (DS). Plentiful efforts have been made for delivering VNS to DS patients, but its effectiveness still requires further verification. We investigated the effectiveness of the VNS treatment of DS patients using brain connectivity analysis with electroencephalography (EEG).

APPROACH

Twenty pharmaco-resistant DS patients were selected to undergo VNS implantation and classified into responder and non-responder groups after 24 months post-VNS. The effect of VNS between 6 months pre- and 6, 12, and 24 months post-VNS in all patients, responders, and non-responders on four different frequency categories of four brain parameters were compared using resting-state EEG.

MAIN RESULTS

In alpha and beta bands, all patients showed positive results for characteristic path length (CPL), global efficiency (GE), and transitivity after VNS treatment, and changes in betweenness centrality (BC) were not significant. The difference in transitivity between responders and non-responders is more pronounced than those in CPL and GE are, in both the alpha (p < 0.015) and beta (p < 0.001) bands. There was an obvious change in BC, especially in the alpha band, as the hubs tended to move from frontal lobe to parietal lobe for responders; however, there was no change for the non-responders.

SIGNIFICANCE

We investigated the alteration in brain connectivity of DS patients in alpha and beta bands during a long-term follow-up and found the responders have a decreased transitivity after the VNS treatment. Moreover, the hubs with high values in the alpha band tended to move from frontal lobe to parietal lobe for responders after VNS treatment.

0321 Increased Slow-Wave Activity Predicts Slower Processing Speed in Toddlers

Introduction

Slow-wave activity (SWA) shows an inverted U-shaped time course during development. Specifically, maximal SWA undergoes a posteroanterior shift from 2 to 20 years of age, which may reflect cortical maturation. Previously, we showed that greater slow sigma power during sleep predicted faster reaction time in preschool-aged children. To date, little is known about the relationship between SWA and processing speed (PS), a basic fundament underlying complex cognitive skills in early development.

Methods

This project examined the relationship between SWA and PS in 2.5-3.0-year-old children (n=26, 50% males) via home-based assessments. After a 5-day stabilization sleep schedule, a baseline sleep EEG recording was performed on participants at 4 electrode placements: Fz, Oz, C3, and C4. SWA EEG spectral power was quantified in the 0.75-4.5 Hz rangeduring the first 60 minutes of NREM sleep. PS was obtained as part of a standard cognitive assessment via a computer-based task one hour after waking from a midday nap.

Results

On average, reaction time (PS) was 2111 ± 08 ms and SWA was 856.4 ± 300.7 µV2/Hz. Increased SWA in the occipital region was predictive of a longer reaction time and therefore slower PS (r = 0.44, p = 0.03). This relationship showed differences between sexes, suggesting that females (r = 0.26, p = 0.07) may show a stronger association between SWA in the occipital brain region and PS than males (r = 0.09, p = 0.33).

Conclusion

Interestingly, these findings contradict our hypothesis based on previous data with older children indicating that greater SWA was associated with more advanced behavioral and cognitive skills. This discrepancy may reflect the stark individual differences present within this rapidly maturing age group.

Support

Research support from NIH R01-MH086566 to MKL.

Comparative Analysis of Gait Speed Estimation Using Wideband and Narrowband Radars, Thermal Camera, and Motion Tracking Suit Technologies

Research has shown that cognitive and physical functioning of older adults can be reflected in indicators such as walking speed. While changes in cognition, mobility, or health cause changes in gait speed, often gradual variations in walking speed go undetected until severe problems arise. Discrete clinical assessments during clinical consultations often fail to detect changes in day-to-day walking speeds and do not reflect walking speeds in everyday environments, where most of the mobility issues happen. In this paper, we compare four walking speed measurement technologies to a GAITRite mat (gold standard): (1) an ultra wideband radar (covering the band from 3.3 GHz to 10 GHz), (2) a narrow band 24-GHz radar (with a bandwidth of 250 MHz), (3) a perception Neuron Motion Tracking suit, and (4) a thermal camera. Data were collected in parallel using all sensors at the same time for 10 healthy adults for normal and slow walking paces. A comparison of the sensors indicates better performance at lower gait speeds, with offsets (when compared to GAITRite) between 0.1 and 20% for the ultra wideband radar, 1.9 and 17% for the narrowband radar, 0.1 and 38% for the thermal camera, and 1.7 and 38% for the suit. This paper supports the potential of unobtrusive radar-based sensors and thermal camera technologies for ambient autonomous gait speed monitoring for contextual, privacy-preserving monitoring of participants in the community.

82 Stage-specific expression of lineage marker genes and pluripotency marker distribution in porcine pre-implantation embryos

Lineage specification in pre-implantation embryos has been revealed, and it was expedited recently by single cell studies. However, data on expression marker genes and proteins in porcine embryos were still missing. We aimed to investigate the expression and distribution of marker genes and proteins, respectively, in IVF and parthenogenetically activated (PA) embryos. For this, cumulus-free oocytes were co-incubated with sperm in modified Tris-buffered medium (mTBM) for 5h and PA was performed using an electric pulse in activation medium. Following this, the embryos were incubated in porcine zygote medium 3 (PZM3). We first tested gene expression level of lineage candidates (internal control; β-actin). In IVF embryos (30, 25, 20, 15, 10, and 5 embryos pooled on Day 2, 3, 4, 5, 6, and 7; replicated 3 times), trophectoderm (TE)-specific genes (Dab2, Gata3) showed peaks on Day 4-5. Within the 2 genes, Dab2 had an earlier peak than Gata3. Inner cell mass (ICM) marker candidates (Nanog, Sox2, and Hnf4a) had diverse patterns. The Nanog and Sox2 genes had peak expression on Day 3. The Nanog expression dropped gradually, but Sox2 dropped suddenly on Day 4. Otherwise, Hnf4a expressed little in Day 3 and expression was sustained from Day 4 to 7. Primitive endoderm markers showed the highest expression on Day 4. We also checked expression level of ICM markers (Sox2, Oct4, and Nanog) in PA embryos (20, 20, 20, 10, and 5 embryos were pooled in 2, 4, 6-8 cells, morula, early, and late blastocyst stages; replicated 3 times). Expression of markers was similar (the highest in the 6-8-cell stage; at least 7.3-, 4.5-, and 3.7-fold compared with the other stages in Sox2, Oct4, and Nanog). We used analysis of variance and Tukey's test for statistical analysis. Following this, we conducted immunocytochemistry with both IVF and PA embryos (20 in each condition). Primary antibodies were treated overnight at 4°C and appropriate secondary antibodies were treated 1h at room temperature. In the case of IVF, well-known ICM markers (SOX2, OCT4, NANOG, and SOX17) showed restricted distribution in nuclei of ICM cells. However, DAB2 was distributed in the cytoplasm of TE cells. In PA embryos, SOX2 and NANOG distributions were similar to IVF. The OCT4 in ICM cells from morula to early blastocyst was restricted, but not in Day 7 embryos. In conclusion, marker genes showed diverse expression pattern in IVF, but all ICM-specific genes had a similar pattern in PA. Also, ICM marker proteins were restricted in nuclei of ICM cells only except Day 7 PA. Our results provide eye-opening information on marker contribution to lineage specification of porcine embryos. This work was supported by the National Research Foundation in Korea (NRF) funded by the Ministry of Education (NRF-2017R1D1A1B03032256, NRF-2019R1C1C1004514).

81 Linoleic acid required for reduction of apoptosis through nuclear transcription factor-kappa B during pig embryo development

Recent studies suggest that endogenous and exogenous free fatty acids play various important roles in mammalian oocyte and pre-implantation embryo development. Among fatty acids, linoleic acid (LA) has been reported to affect the apoptosis pathway via nuclear transcription factor-kappa B (NF-κB). The transcription factor NF-κB is a key modulator of apoptosis in a variety of cell types, but to date, this specific function of NF-κB has not been demonstrated in porcine pre-implantation embryos. To examine the effect of linoleic acid on invitro-produced parthenogenetic pig embryos, we treated LA by concentration (0, 10, 25, 50, and 100 µM) to identify developmental rate, NF-κB expression, and mRNA level of apoptotic-related genes. In addition, the mechanism was confirmed by examining the protein and mRNA expression of NF-kb and c-jun by immunostaining and quantitative PCR at the blastocyst stage. Linoleic acid had a positive effect on embryo development without toxicity at a certain concentration (25 µM), but toxicity was confirmed at higher (50-100μM) concentrations. Furthermore, it was confirmed that the concentration of NF-κB increased as the treatment concentration of LA increased, which was found to increase even at the concentration at which embryo development decreased. Previous studies have shown that the NF-κB pathway is involved in regulating anti- and pro-apoptotic gene expression. We also investigated the effects of LA on anti- (Bcl-xL, Mcl-1) and pro- (BAX1, TP53, Caspase3) apoptotic genes and NF-κB activation-related genes (RelA, JNK1, JNK2, IL-6) in porcine embryos. We have found that down-regulation of pro-apoptotic gene expression occurs in the LA-treated group. It was also found that Bcl-xL, one of the anti-apoptotic genes, was not affected by LA, which appears to be an effect of IL-6. In contrast, Mcl-1, an anti-apoptotic gene known not to be affected by IL-6, was found to have increased expression mRNA level in LA-treated pig embryos. Furthermore, through double-staining of apoptosis and immunocytochemistry, as the concentration of NF-kB level increases, the nuclear translocation of c-jun, the protein of which was also related with apoptosis, increased gradually depending on the LA concentration. These data could support that porcine embryo can use exogenous LA as a metabolic energy source. The data also demonstrate the important role of NF-kB in porcine early embryo development. Support was provided by the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (IPET) through the Development of High Value-Added Food Technology program funded by the Ministry of Agriculture, Food and Rural Affairs (MAFRA, 118042-03-1-HD020).

Combined effects of HIV and obesity on the gastrointestinal microbiome of young men who have sex with men

OBJECTIVES

The prevalence of obesity is rising among people living with HIV, which may synergistically increase inflammation and the risk of associated diseases. Disruption of gut bacterial communities may be one of the key drivers of this inflammation; however, the combined effects of HIV and obesity on the microbiome have not been explored.

METHODS

This study included 381 men who have sex with men. Thirty-nine were HIV-positive and obese (H+O+), 143 were HIV-positive and nonobese, 64 were HIV-negative and obese, and 135 were HIV-negative and nonobese. Microbiome composition was assessed by targeted sequencing of the V4 region of the 16S ribosomal RNA (rRNA) gene using rectal swab samples. Inverse probability of treatment-weighted marginal structural models were used to investigate differences in microbial composition between groups while controlling for numerous clinical and behavioural confounders.

RESULTS

Significant variability in microbial composition was explained by the combination of HIV and obesity, over and above each condition alone (R² for the marginal contribution of the H+/O+ group = 0.008; P = 0.001). H+O+ participants had the highest ratios of Prevotella to Bacteroides, a pro-inflammatory enterotype that has been described in HIV infection and obesity independently. H+O+ participants had lower levels of Bacteroides and Veillonella than all other groups, suggesting a synergistic effect of HIV and obesity on these genera.

CONCLUSIONS

Our findings support the hypothesis that HIV and obesity act together to disrupt gut microbial communities, which may help explain higher levels of generalized inflammation among people living with both HIV and obesity.

Analysis of the relationship between changes in the auditory brainstem response and prognosis in patients with sudden hearing loss

OBJECTIVE

To analyse how the auditory brainstem response changes in patients with sudden sensorineural hearing loss.

METHOD

Data were collected via retrospective medical chart review.

RESULTS

Forty-three patients were included in this study. The mean latency of auditory brainstem response wave 1 was significantly longer for the affected side than for the unaffected side (p = 0.003). The mean latency of auditory brainstem response wave 1 was significantly shorter, and the mean amplitude of auditory brainstem response wave 1 was significantly larger, in the good response group compared to the poor response group. In forward conditional logistic regression analysis, auditory brainstem response wave 1 latency was an independent predictor of a good response (odds ratio = 34.37, 95 per cent confidence interval = 1.56-757.15, p = 0.025).

CONCLUSION

In patients with sudden sensorineural hearing loss, the latency of wave 1 of the auditory brainstem response was significantly increased and was related to prognosis.

Mechanical stimulation of growth plate chondrocytes: Previous approaches and future directions

Growth plate cartilage resides near the ends of long bones and is the primary driver of skeletal growth. During growth, both intrinsically and extrinsically generated mechanical stresses act on chondrocytes in the growth plate. Although the role of mechanical stresses in promoting tissue growth and homeostasis has been strongly demonstrated in articular cartilage of the major skeletal joints, effects of stresses on growth plate cartilage and bone growth are not as well established. Here, we review the literature on mechanobiology in growth plate cartilage at macroscopic and microscopic scales, with particular emphasis on comparison of results obtained using different methodological approaches, as well as from whole animal and in vitro experiments. To answer these questions, macroscopic mechanical stimulators have been developed and applied to study mechanobiology of growth plate cartilage and chondrocytes. However, the previous approaches have tested a limited number of stress conditions, and the mechanobiology of a single chondrocyte has not been well studied due to limitations of the macroscopic mechanical stimulators. We explore how microfluidics devices can overcome these limitations and improve current understanding of growth plate chondrocyte mechanobiology. In particular, microfluidic devices can generate multiple stress conditions in a single platform and enable real-time monitoring of metabolism and cellular behavior using optical microscopy. Systematic characterization of the chondrocytes using microfluidics will enhance our understanding of how to use mechanical stresses to control the bone growth and the properties of tissue-engineered growth plate cartilage.

Strong dose response after immunotherapy with PQ grass using conjunctival provocation testing

Background

Pollinex Quattro Grass (PQ Grass) is an effective, well-tolerated, short pre-seasonal subcutaneous immunotherapy to treat seasonal allergic rhinoconjunctivitis (SAR) due to grass pollen. In this Phase II study, 4 cumulative doses of PQ Grass and placebo were evaluated to determine its optimal cumulative dose.

Methods

Patients with grass pollen-induced SAR were randomised to either a cumulative dose of PQ Grass (5100, 14400, 27600 and 35600 SU) or placebo, administered as 6 weekly subcutaneous injections over 31-41 days (EudraCT number 2017-000333-31). Standardized conjunctival provocation tests (CPT) using grass pollen allergen extract were performed at screening, baseline and post-treatment to determine the total symptom score (TSS) assessed approximately 4 weeks after dosing. Three models were pre-defined (Emax, logistic, and linear in log-dose model) to evaluate a dose response relationship.

Results

In total, 95.5% of the 447 randomized patients received all 6 injections. A highly statistically significant (p < 0.0001), monotonic dose response was observed for all three pre-specified models. All treatment groups showed a statistically significant decrease from baseline in TSS compared to placebo, with the largest decrease observed after 27600 SU (p < 0.0001). The full course of 6 injections was completed by 95.5% of patients. Treatment-emergent adverse events were similar across PQ Grass groups, and mostly mild and transient in nature.

Conclusions

PQ Grass demonstrated a strong curvilinear dose response in TSS following CPT without compromising its safety profile.

P2618Association of left ventricular ejection fraction with mortality and hospitalizations

Background

Although 2-dimensional echocardiography (2DE) is widely used to measure left ventricular ejection fraction (LVEF), the prognostic value of 2DE-derived LVEF has not been clearly demonstrated in a broad range of patients, including those acutely hospitalized as well as ambulatory patients. In particular, the prognostic value of echocardiographic LVEF has not been demonstrated for cardiovascular and heart failure hospitalizations.

Purpose

To determine if greater degrees of LV dysfunction are associated with progressively increasing risks of death or cardiovascular hospitalizations among patients undergoing echocardiography in hospital or outpatient settings.

Methods

We examined quantitative LVEFs from patient-level echocardiographic reports at 3 large hospital laboratories, which were linked to the Canadian Institute for Health Information hospitalization database and to death registries in Ontario, Canada. LVEF was categorized as <25%, 25–35%, 36–45%, or 46–55% (reference). Analyses were performed using cause-specific hazard competing risk models and stratified by: a) outpatient vs. inpatient echocardiogram, and b) if inpatient study, whether the reason for hospitalization was cardiac or noncardiac in nature.

Results

In the echocardiographic cohort of 27,323 patients (median age 68 [IQR: 58–77], 14,828 women [31.7%]), greater reductions in LVEF were associated with higher rates of all-cause mortality, with adjusted hazard ratios (95% CI) of 1.67 (1.57, 1.77) for LVEF <25%, 1.30 (1.24, 1.36) for LVEF 25–35%, and 1.17 (1.11, 1.23) for LVEF 36–45%, compared to LVEF 46–55% (all p<0.001). The cumulative incidence of cardiovascular death was higher as LVEF progressively worsened (Figure). The rate of heart failure hospitalizations was also increased with hazard ratios of 1.71 (1.59, 1.85) for LVEF <25%, 1.39 (1.31, 1.48) for LVEF 25–35%, and 1.21 (1.13, 1.29) for LVEF 36–45%, compared to LVEF 46–55% (all p<0.001). Cardiovascular hospitalizations were also increased with hazard ratios of 1.35 (1.27, 1.42), 1.21 (1.16, 1.27), and 1.13 (1.07, 1.18) for LVEFs <25%, 25–35%, and 36–45%, respectively (all p<0.001). The risk of mortality and hospitalizations increased comparably with greater reductions in LVEF during both inpatient cardiac or noncardiac admissions (p<0.001).

Cumulative incidence of CV death

Conclusions

Quantitative LVEF assessed by 2DE is potent prognostically and was able to stratify the risk of both death and hospitalization outcomes in a wide range of clinical settings. Patients with reduced LVEF measured on inpatient or outpatient echocardiograms, and even in the context of non-cardiac admission, should be considered an at-risk group in whom quality of care metrics could be evaluated in future studies.

Acknowledgement/Funding

Canadian Institutes of Health Research, Heart and Stroke Foundation, and the Ted Rogers Centre for Heart Research

First Measurement of the Total Neutron Cross Section on Argon between 100 and 800 MeV

We report the first measurement of the neutron cross section on argon in the energy range of 100-800 MeV. The measurement was obtained with a 4.3-h exposure of the Mini-CAPTAIN detector to the WNR/LANSCE beam at LANL. The total cross section is measured from the attenuation coefficient of the neutron flux as it traverses the liquid argon volume. A set of 2631 candidate interactions is divided in bins of the neutron kinetic energy calculated from time-of-flight measurements. These interactions are reconstructed with custom-made algorithms specifically designed for the data in a time projection chamber the size of the Mini-CAPTAIN detector. The energy averaged cross section is 0.91±0.10(stat)±0.09(syst)  b. A comparison of the measured cross section is made to the GEANT4 and FLUKA event generator packages, where the energy averaged cross sections in this range are 0.60 and 0.68 b, respectively.

Within-cluster resampling for multilevel models under informative cluster size

A within-cluster resampling method is proposed for fitting a multilevel model in the presence of informative cluster size. Our method is based on the idea of removing the information in the cluster sizes by drawing bootstrap samples which contain a fixed number of observations from each cluster. We then estimate the parameters by maximizing an average, over the bootstrap samples, of a suitable composite loglikelihood. The consistency of the proposed estimator is shown and does not require that the correct model for cluster size is specified. We give an estimator of the covariance matrix of the proposed estimator, and a test for the noninformativeness of the cluster sizes. A simulation study shows, as in Neuhaus & McCulloch (2011), that the standard maximum likelihood estimator exhibits little bias for some regression coefficients. However, for those parameters which exhibit nonnegligible bias, the proposed method is successful in correcting for this bias.