"Insights into ALD & AUD diagnosis and prognosis: Exploring AI and multi-modal data streams".

The rapid evolution of artificial intelligence (AI) and the widespread embrace of digital technologies have ushered in a new era of clinical research and practice in hepatology. Although its potential is far from realization, these significant strides have generated new opportunities to address existing gaps in the delivery of care for patients with liver disease. In this review, we discuss how AI and opportunities for multimodal data integration can improve the diagnosis, prognosis and management of alcohol-associated liver disease (ALD). An emphasis is made on how these approaches will also benefit the detection and management of alcohol use disorder (AUD). Our discussion encompasses challenges and limitations, concluding with a glimpse into the promising future of these advancements.

Effect of digital ocular massage on intraocular pressure and Schlemm's canal dimensions.

Digital ocular massage has been reported to temporarily lower intraocular pressure (IOP). This could be related to an enhanced aqueous humor outflow; however, the mechanism is not clearly understood. Using anterior segment optical coherence tomography, the Schlemm's canal (SC) and trabecular meshwork (TM) can be imaged and measured. Here, 66 healthy adults underwent digital ocular massage for 10 min in their right eyes. The IOP and dimensions of the SC and TM were measured before and after ocular massage. All subjects demonstrated IOP reduction from 15.7 ± 2.5 mmHg at baseline to 9.6 ± 2.2 mmHg immediately after, and median of 11.6 mmHg 5-min after ocular massage (Friedman's test, p < 0.001). There was significant change in SC area (median 10,063.5 µm2 at baseline to median 10,151.0 µm2 after ocular massage, Wilcoxon test, p = 0.02), and TM thickness (median 149.8 µm at baseline to 144.6 ± 25.3 µm after ocular massage, Wilcoxon test, p = 0.036). One-third of the subjects demonstrated collapse of the SC area (-2 to -52%), while two-thirds showed expansion of the SC area (2 to 168%). There were no significant changes in SC diameter (270.4 ± 84.1 µm vs. 276.5 ± 68.7 µm, paired t-test, p = 0.499), and TM width (733.3 ± 110.1 µm vs. 733.5 ± 111.6 µm, paired t-test, p = 0.988). Eyes with a higher baseline IOP demonstrated a greater IOP reduction (Pearson correlation coefficient r = -0.521, p < 0.001). Eyes with smaller SC area at baseline showed greater SC area expansion (Pearson correlation coefficient = -0.389, p < 0.001). Greater IOP reduction appeared in eyes with greater SC area expansion (Pearson correlation coefficient r = -0.306, p = 0.01). Association between change in IOP and change in TM thickness was not significant (Spearman's ρ = 0.015, p = 0.902). Simple digital ocular massage is an effective method to lower IOP values, and change in the SC area was significantly associated with IOP changes.

One Score to Rule Them All? Comparing the Predictive and Concurrent Validity of 30 Hearts and Flowers Scoring Approaches.

The Hearts and Flowers (H&F) task is a computerized executive functioning (EF) assessment that has been used to measure EF from early childhood to adulthood. It provides data on accuracy and reaction time (RT) across three different task blocks (hearts, flowers, and mixed). However, there is a lack of consensus in the field on how to score the task that makes it difficult to interpret findings across studies. The current study, which includes a demographically diverse population of kindergarteners from Boston Public Schools (N = 946), compares the predictive and concurrent validity of 30 ways of scoring H&F, each with a different combination of accuracy, RT, and task block(s). Our exploratory results provide evidence supporting the use of a two-vector average score based on Zelazo et al.'s approach of adding accuracy and RT scores together only after individuals pass a certain accuracy threshold. Findings have implications for scoring future tablet-based developmental assessments.

Congenital Eyelid Imbrication and Floppy Eyelid Syndromes Complicated by Eversion due to Prostaglandin E Infusion in a Patient With Trisomy 21 and Tetralogy of Fallot.

Congenital eyelid imbrication syndrome is a rare eyelid finding where a long upper lid overlaps the lower lid when the eyes are closed. To date, congenital eyelid imbrication syndrome has been described in the literature less than 10 times. We present a case of congenital eyelid imbrication syndrome in a patient with trisomy 21 and tetralogy of Fallot on a prostaglandin E infusion to maintain a patent ductus arteriosus prior to definitive heart surgery. While on the infusion, the patient developed peripheral edema and flushing due to vasodilation. This coincided with eyelid swelling, conjunctival chemosis, and eversion of the eyelids. Upon cessation of the prostaglandin E1 infusion, his eyelid eversion resolved.

Behavioral Management of Respiratory/Phonatory Dysfunction for Dysarthria Associated With Neurodegenerative Disease: A Systematic Review.

PURPOSE: This systematic review represents an update to previous reviews of the literature addressing behavioral management of respiratory/phonatory dysfunction in individuals with dysarthria due to neurodegenerative disease. METHOD: Multiple electronic database searches and hand searches of prominent speech-language pathology journals were conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards. RESULTS: The search yielded 1,525 articles, from which 88 met inclusion criteria and were reviewed by two blinded co-investigators. A large range of therapeutic approaches have been added to the evidence base since the last review, including expiratory muscle strength training, singing, and computer- and device-driven programs, as well as a variety of treatment modalities, including teletherapy. Evidence for treatment in several different population groups-including cerebellar ataxia, myotonic dystrophy, autosomal recessive spastic ataxia of Charlevoix-Saguenay, Huntington's disease, multiple system atrophy, and Lewy body dementia-were added to the current review. Synthesis of evidence quality provided strong evidence in support of only one behavioral intervention: Lee Silverman Voice Treatment Program (LSVT LOUD) in people with Parkinson's disease. No other treatment approach or population included in this review demonstrated more than limited evidence, reflecting that these approaches/populations require urgent further examination. CONCLUSION: Suggestions about where future research efforts could be significantly strengthened and how clinicians can apply research findings to their practice are provided. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.24964473.

Priming chondrocytes during expansion alters cell behavior and improves matrix production in 3D culture.

OBJECTIVE: Cartilage tissue engineering strategies that use autologous chondrocytes require in vitro expansion of cells to obtain enough cells to produce functional engineered tissue. However, chondrocytes dedifferentiate during expansion culture, limiting their ability to produce chondrogenic tissue and their utility for cell-based cartilage repair strategies. The current study identified conditions that favor cartilage production and the mechanobiological mechanisms responsible for these benefits. DESIGN: Chondrocytes were isolated from juvenile bovine knee joints and cultured with (primed) or without (unprimed) a growth factor cocktail. Gene expression, cell morphology, cell adhesion, cytoskeletal protein distribution, and cell mechanics were assessed. Following passage 5, cells were embedded into agarose hydrogels to evaluate functional properties of engineered cartilage. RESULTS: Priming cells during expansion culture altered cell phenotype and chondrogenic tissue production. Unbiased ribonucleic acid-sequencing analysis suggested, and experimental studies confirmed, that growth factor priming delays dedifferentiation associated changes in cell adhesion and cytoskeletal organization. Priming also overrode mechanobiological pathways to prevent chondrocytes from remodeling their cytoskeleton to accommodate the stiff, monolayer microenvironment. Passage 1 primed cells deformed less and had lower yes associated protein 1 activity than unprimed cells. Differences in cell adhesion, morphology, and cell mechanics between primed and unprimed cells were mitigated by passage 5. CONCLUSIONS: Priming suppresses mechanobiologic cytoskeletal remodeling to prevent chondrocyte dedifferentiation, resulting in more cartilage-like tissue-engineered constructs.

Smartphone sensor data estimate alcohol craving in a cohort of patients with alcohol-associated liver disease and alcohol use disorder.

BACKGROUND: Sensors within smartphones, such as accelerometer and location, can describe longitudinal markers of behavior as represented through devices in a method called digital phenotyping. This study aimed to assess the feasibility of digital phenotyping for patients with alcohol-associated liver disease and alcohol use disorder, determine correlations between smartphone data and alcohol craving, and establish power assessment for future studies to prognosticate clinical outcomes. METHODS: A total of 24 individuals with alcohol-associated liver disease and alcohol use disorder were instructed to download the AWARE application to collect continuous sensor data and complete daily ecological momentary assessments on alcohol craving and mood for up to 30 days. Data from sensor streams were processed into features like accelerometer magnitude, number of calls, and location entropy, which were used for statistical analysis. We used repeated measures correlation for longitudinal data to evaluate associations between sensors and ecological momentary assessments and standard Pearson correlation to evaluate within-individual relationships between sensors and craving. RESULTS: Alcohol craving significantly correlated with mood obtained from ecological momentary assessments. Across all sensors, features associated with craving were also significantly correlated with all moods (eg, loneliness and stress) except boredom. Individual-level analysis revealed significant relationships between craving and features of location entropy and average accelerometer magnitude. CONCLUSIONS: Smartphone sensors may serve as markers for alcohol craving and mood in alcohol-associated liver disease and alcohol use disorder. Findings suggest that location-based and accelerometer-based features may be associated with alcohol craving. However, data missingness and low participant retention remain challenges. Future studies are needed for further digital phenotyping of relapse risk and progression of liver disease.

High-throughput digital quantification of Alzheimer disease pathology and associated infrastructure in large autopsy studies.

High-throughput digital pathology offers considerable advantages over traditional semiquantitative and manual methods of counting pathology. We used brain tissue from 5 clinical-pathologic cohort studies of aging; the Religious Orders Study, the Rush Memory and Aging Project, the Minority Aging Research Study, the African American Clinical Core, and the Latino Core to (1) develop a workflow management system for digital pathology processes, (2) optimize digital algorithms to quantify Alzheimer disease (AD) pathology, and (3) harmonize data statistically. Data from digital algorithms for the quantification of ß-amyloid (Aß, n = 413) whole slide images and tau-tangles (n = 639) were highly correlated with manual pathology data (r = 0.83 to 0.94). Measures were robust and reproducible across different magnifications and repeated scans. Digital measures for Aß and tau-tangles across multiple brain regions reproduced established patterns of correlations, even when samples were stratified by clinical diagnosis. Finally, we harmonized newly generated digital measures with historical measures across multiple large autopsy-based studies. We describe a multidisciplinary approach to develop a digital pathology pipeline that reproducibly identifies AD neuropathologies, Aß load, and tau-tangles. Digital pathology is a powerful tool that can overcome critical challenges associated with traditional microscopy methods.

Liver disease progression in patients with alpha-1 antitrypsin deficiency and protease inhibitor ZZ genotype with or without lung disease.

BACKGROUND: Alpha-1 antitrypsin deficiency (AATD) is caused by mutations in SERPINA1, which encodes alpha-1 antitrypsin, a protease inhibitor (Pi). Individuals with AATD and the homozygous Pi*ZZ genotype have variable risk of progressive liver disease but the influence of comorbid lung disease is poorly understood. AIMS: To characterise patients with AATD Pi*ZZ and liver disease (AATD-LD-Pi*ZZ) with or without lung disease and describe liver disease-related clinical events longitudinally. METHODS: This was an observational cohort study of patients in the Mayo Clinic Healthcare System (January 2000-September 2021). Patients were identified using diagnosis codes and natural language processing. Fibrosis stage (F0-F4) was assessed using a hierarchical approach at baseline (90 days before or after the index date) and follow-up. Clinical events associated with liver disease progression were assessed. RESULTS: AATD-LD-Pi*ZZ patients with lung disease had a longer median time from AATD diagnosis to liver disease diagnosis versus those without lung disease (2.2 vs. 0.2 years, respectively). Compared to those without lung disease, patients with lung disease had a longer time to liver disease-related clinical events (8.5 years and not reached, respectively). AATD-LD-Pi*ZZ patients without lung disease were more likely to undergo liver transplantation compared with those with lung disease. CONCLUSION: In patients with AATD and lung disease, there is a delay in the diagnosis of comorbid liver disease. Our findings suggest that liver disease may progress more rapidly in patients without comorbid lung disease.

TPL2 kinase activity regulates microglial inflammatory responses and promotes neurodegeneration in tauopathy mice.

Tumor progression locus 2 (TPL2) (MAP3K8) is a central signaling node in the inflammatory response of peripheral immune cells. We find that TPL2 kinase activity modulates microglial cytokine release and is required for microglia-mediated neuron death in vitro. In acute in vivo neuroinflammation settings, TPL2 kinase activity regulates microglia activation states and brain cytokine levels. In a tauopathy model of chronic neurodegeneration, loss of TPL2 kinase activity reduces neuroinflammation and rescues synapse loss, brain volume loss, and behavioral deficits. Single-cell RNA sequencing analysis indicates that protection in the tauopathy model was associated with reductions in activated microglia subpopulations as well as infiltrating peripheral immune cells. Overall, using various models, we find that TPL2 kinase activity can promote multiple harmful consequences of microglial activation in the brain including cytokine release, iNOS (inducible nitric oxide synthase) induction, astrocyte activation, and immune cell infiltration. Consequently, inhibiting TPL2 kinase activity could represent a potential therapeutic strategy in neurodegenerative conditions.

Characterization of vision in pediatric retinoblastoma survivors beyond visual acuity.

BACKGROUND: Retinoblastoma (RB) and its associated treatments can significantly impact visual acuity. However, little is known regarding other measures of vision, such as contrast sensitivity or saccades. The aim of this study was to describe contrast sensitivity and saccades in children treated for retinoblastoma. METHODS: This cross-sectional study included children aged 5-17 years who had completed treatment for RB. Visual acuity, saccades via fixation analysis, and contrast sensitivity by Cardiff contrast sensitivity were assessed, and multivariable linear regression was performed. RESULTS: Eleven children were enrolled (mean age, 10.7 ± 3.9 years). Treatment included enucleation (8 children [73%]) and chemotherapy (10 [91%]). Of the 11, one participant was unable to complete testing of saccades, and another was unable to complete contrast sensitivity testing. Decreased saccade parameters (velocity, latency, or accuracy) and impaired contrast sensitivity were observed in all 10 participants who underwent visual testing. Multivariable analysis revealed that worse logMAR visual acuity (B, -4.54 [-6.8, -2.2]; P = 0.004) and bilateral disease (B, -3.9 [-6.4, -1.4]; P = 0.009) were associated with worse contrast sensitivity. Germline disease was associated with decreased vertical saccade accuracy (P = 0.02). CONCLUSIONS: Decreased contrast sensitivity and impaired saccades were universally observed in this cohort of RB survivors. Comprehensive visual evaluation should be considered for all RB survivors to provide optimal rehabilitative services for these patients.

Eye-related quality of life and activities of daily living in pediatric retinoblastoma patients: A single-center, non-controlled, cross-sectional analysis.

INTRODUCTION: Childhood retinoblastoma (RB) survivors are known to experience long-term morbidity; however, eye-related quality of life (QoL), which may significantly impact activities of daily living (ADL), has not been extensively studied in this population. The purpose of this cross-sectional study was to assess QoL and ADL morbidity among school-age RB survivors. METHODS: The Pediatric Eye Questionnaire (PedEyeQ) and Roll Evaluation Activities of Life (REAL) were administered to childhood RB survivors between ages 5 and 17 followed at St. Louis Children's Hospital. Visual outcomes and demographic predictors of ADL and QoL were examined. RESULTS: Total 23 patients (mean age 9.6 years) consented for participation in this study. All children experienced at least one domain on the PedEyeQ ≤ 80%. Subjects and parents marked functional vision to be the most impacted domain with a median score of 82.5 and 83.4, respectively. Only 10.5% of participants scored above 75% on the ADL percentile rank. On multivariable analysis, decreased visual acuity (VA) was associated with worse "Child Functional" (odds ratio [OR] -59.2, p = .004) and "Parent Worry Function" (OR -66.5, p = .03) metrics. Decreased contrast sensitivity was associated with worse "Parent Impact" (OR 21.0, p = .02) and "Parent Worry Function" (OR 3.70, p = .04) metrics. Longer saccade horizontal latency was associated with a worse "Parent Worry Function" metric (OR 43.0, p = .009). On multivariable analysis, no variable was significantly associated with ADL. CONCLUSION: RB survivors have impaired QoL and ADL. Screening for such difficulties should strongly be considered for all RB patients. Additional studies may help predict morbidity based on visual metrics and demographic data.

PYK-SubstitutionOME: an integrated database containing allosteric coupling, ligand affinity and mutational, structural, pathological, bioinformatic and computational information about pyruvate kinase isozymes.

Interpreting changes in patient genomes, understanding how viruses evolve and engineering novel protein function all depend on accurately predicting the functional outcomes that arise from amino acid substitutions. To that end, the development of first-generation prediction algorithms was guided by historic experimental datasets. However, these datasets were heavily biased toward substitutions at positions that have not changed much throughout evolution (i.e. conserved). Although newer datasets include substitutions at positions that span a range of evolutionary conservation scores, these data are largely derived from assays that agglomerate multiple aspects of function. To facilitate predictions from the foundational chemical properties of proteins, large substitution databases with biochemical characterizations of function are needed. We report here a database derived from mutational, biochemical, bioinformatic, structural, pathological and computational studies of a highly studied protein family-pyruvate kinase (PYK). A centerpiece of this database is the biochemical characterization-including quantitative evaluation of allosteric regulation-of the changes that accompany substitutions at positions that sample the full conservation range observed in the PYK family. We have used these data to facilitate critical advances in the foundational studies of allosteric regulation and protein evolution and as rigorous benchmarks for testing protein predictions. We trust that the collected dataset will be useful for the broader scientific community in the further development of prediction algorithms. Database URL https://github.com/djparente/PYK-DB.

Land-use change is associated with multi-century loss of elephant ecosystems in Asia.

Understanding historic patterns of land use and land cover change across large temporal and spatial scales is critical for developing effective biodiversity conservation management and policy. We quantify the extent and fragmentation of suitable habitat across the continental range of Asian elephants (Elephas maximus) based on present-day occurrence data and land-use variables between 850 and 2015 A.D. We found that following centuries of relative stability, over 64% (3.36 million km2) of suitable elephant habitat across Asia was lost since the year 1700, coincident with colonial-era land-use practices in South Asia and subsequent agricultural intensification in Southeast Asia. Average patch size dropped 83% from approximately 99,000-16,000 km2 and the area occupied by the largest patch decreased 83% from ~ 4 million km2 (45% of area) to 54,000 km2 (~ 7.5% of area). Whereas 100% of the area within 100 km of the current elephant range could have been considered suitable habitat in the year 1700, over half was unsuitable by 2015, driving potential conflict with people. These losses reflect long-term decline of non-forested ecosystems, exceeding estimates of deforestation within this century. Societies must consider ecological histories in addition to proximate threats to develop more just and sustainable land-use and conservation strategies.

The Type I Interferon Signature Reflects Multiple Phenotypic and Activity Measures in Dermatomyositis.

OBJECTIVE: The type 1 interferon (IFN) pathway is up-regulated in dermatomyositis (DM). We sought to define how organ-specific disease activity as well as autoantibodies and other clinical factors are independently associated with systemic type I IFN activity in adult patients with DM. METHODS: RNA sequencing was performed on 355 whole blood samples collected from 202 well-phenotyped DM patients followed up during the course of their clinical care. A previously defined 13-gene type I IFN score was modeled as a function of demographic, serologic, and clinical variables using both cross-sectional and longitudinal data. RESULTS: The pattern of type I IFN-driven transcriptional response was stereotyped across samples with a sequential modular activation pattern strikingly similar to systemic lupus erythematosus. The median type I IFN score was higher or lower in patients with anti-melanoma differentiation-associated protein 5 (anti-MDA-5) or anti-Mi-2 antibodies, respectively, compared to patients without these antibodies. Absolute type I IFN score was independently associated with muscle and skin disease activity, interstitial lung disease, and anti-MDA-5 antibodies. Changes in the type I IFN score over time were significantly associated with changes in skin or muscle disease activity. Stratified analysis accounting for heterogeneity in organ involvement and antibody class revealed high correlation between changes in the type I IFN score and skin disease activity (Spearman's ρ = 0.84-0.95). CONCLUSION: The type I IFN score is independently associated with skin and muscle disease activity as well as certain clinical and serologic features in DM. Accounting for the effect of muscle disease and anti-MDA-5 status revealed that the type I IFN score is strongly correlated with skin disease activity, providing support for type I IFN blockade as a therapeutic strategy for DM.

Trachoma, the world's leading infectious cause of blindness: The remaining gap in care and access to basic handwashing facilities.

PURPOSE: Trachoma, the world's leading infectious cause of blindness, has been targeted by the WHO for elimination through the SAFE strategy: surgery, antibiotics, facial cleanliness, and environmental improvement. Although significant progress has been made, there remains a gap in care. This project studied the association of geographical distribution of the remaining need for trachoma intervention and its association with access to basic handwashing facilities at home, as an indicator of water/sanitation infrastructure. We hypothesized that poor water sanitation would correspond to areas where trachoma intervention is still required. DESIGN: Retrospective analysis using the WHO Global Health Observatory. Spatial, correlation, and simple and multivariable regression analyses were used. METHODS: Using data from the WHO Global Health Observatory, a total of 194 countries were analyzed. Two choropleth maps were created, with inset maps focused on the South Pacific region, where the top 5 countries with the greatest population proportion requiring trachoma intervention are located. RESULTS: Correlations and the simple regression model of total population with access to handwashing facilities as the only risk factor were insignificant. However, the multivariable regression models with access to handwashing facilities (total, urban, and rural) and population density as risk factors for trachoma intervention were significant. CONCLUSION: Poor water/sanitation infrastructure correlates with trachoma burden. Therefore, water/sanitation infrastructure improvement is a worthwhile target in the efforts toward trachoma elimination, but further research on the association between these important public health indicators is warranted.

Dynamics of immune responses are inconsistent when trauma patients are grouped by injury severity score and clinical outcomes.

The injury severity score (ISS) is used in daily practice to evaluate the severity of trauma patients; however, the score is not always consistent with the prognosis. After injury, systemic inflammatory response syndrome (SIRS) and compensatory anti-inflammatory response syndrome (CARS) are related to the prognosis of trauma patients. We aimed to evaluate the associations between the immune response and prognosis in trauma patients. Patients who admitted to the Trauma Intensive Care Unit (ICU) were eligible. Whole blood samples were collected at admission, and then 6, 12, 24, 48 and 72 h after admission. Natural killer (NK) cells, lymphocyte subset population and cytokines release were identified using flow cytometry. We grouped patients by their ISS (≤ 25 and > 25 as very severe injury) and ICU stay (≤ 10 days as a short ICU stay and > 10 days as a long ICU stay) for evaluation. Fifty-three patients were enrolled. ICU stay but not ISS was close correlated with activity daily living (ADL) at discharge. Patients with a long ICU stay had an immediate increase in NK cells followed by lymphopenia which persisted for 48 h. Immediate activation of CD8+ T cells and then exhaustion with a higher programmed cell death-1 (PD-1) expression and suppression of CD4+ T cells with a shift to an anti-inflammatory Th2 phenotype were also observed in the patients with a long ICU stay. When the patients were grouped by ISS, the dynamics of immune responses were inconsistent to those when the patients were grouped by ICU stay. Immune responses are associated with the prognosis of trauma patients, however the currently used clinical parameters may not accurately reflect immune responses. Further investigations are needed to identify accurate predictors of prognosis in trauma patients.

Retinopathy of prematurity: risk stratification by gestational age.

OBJECTIVE: To identify gestational age (GA) specific risk factors for severe ROP (sROP). STUDY DESIGN: Single-center cohort stratified by GA into <24 weeks, 24-26 weeks and ≥27 weeks. RESULTS: 132/1106 (11.9%) developed sROP. Time to full feeds was the only risk factor [HR 1.003 (1.001-1.006), p = 0.04] for infants<24 weeks GA. For infants 24-26 weeks GA, a higher GA was protective [HR 0.66 (0.51-0.85), p < 0.01], whereas steroids for bronchopulmonary dysplasia (BPD) [HR 2.21 (1.28-3.26), p < 0.01], patent ductus arteriosus (PDA) ligation [HR 1.99 (1.25-3.11), p < 0.01] and use of nitric oxide [HR 1.96 (1.11-3.30), p = 0.01] increased the hazard of sROP. Increasing birthweight was protective [HR 0.70 (0.54-0.89), p < 0.01] in infants ≥27 weeks GA. Cumulative hazard of sROP reached 1.0 by fifteen weeks for <24 weeks GA, 0.4 by twenty weeks for 24-26 weeks GA, and 0.05 by twenty weeks after birth for ≥27 weeks GA. CONCLUSIONS: Risk factors, cumulative hazard, and time to sROP vary by GA.

Formation of multicellular colonies by choanoflagellates increases susceptibility to capture by amoeboid predators.

Many heterotrophic microbial eukaryotes are size-selective feeders. Some microorganisms increase their size by forming multicellular colonies. We used choanoflagellates, Salpingoeca helianthica, which can be unicellular or form multicellular colonies, to study the effects of multicellularity on vulnerability to predation by the raptorial protozoan predator, Amoeba proteus, which captures prey with pseudopodia. Videomicrography used to measure the behavior of interacting S. helianthica and A. proteus revealed that large choanoflagellate colonies were more susceptible to capture than were small colonies or single cells. Swimming colonies produced larger flow fields than did swimming unicellular choanoflagellates, and the distance of S. helianthica from A. proteus when pseudopod formation started was greater for colonies than for single cells. Prey size did not affect the number of pseudopodia formed and the time between their formation, pulsatile kinematics and speed of extension by pseudopodia, or percent of prey lost by the predator. S. helianthica did not change swimming speed or execute escape maneuvers in response to being pursued by pseudopodia, so size-selective feeding by A. proteus was due to predator behavior rather than prey escape. Our results do not support the theory that the selective advantage of becoming multicellular by choanoflagellate-like ancestors of animals was reduced susceptibility to protozoan predation.