Gut microbial ß-glucuronidases influence endobiotic homeostasis and are modulated by diverse therapeutics.

Hormones and neurotransmitters are essential to homeostasis, and their disruptions are connected to diseases ranging from cancer to anxiety. The differential reactivation of endobiotic glucuronides by gut microbial ß-glucuronidase (GUS) enzymes may influence interindividual differences in the onset and treatment of disease. Using multi-omic, in vitro, and in vivo approaches, we show that germ-free mice have reduced levels of active endobiotics and that distinct gut microbial Loop 1 and FMN GUS enzymes drive hormone and neurotransmitter reactivation. We demonstrate that a range of FDA-approved drugs prevent this reactivation by intercepting the catalytic cycle of the enzymes in a conserved fashion. Finally, we find that inhibiting GUS in conventional mice reduces free serotonin and increases its inactive glucuronide in the serum and intestines. Our results illuminate the indispensability of gut microbial enzymes in sustaining endobiotic homeostasis and indicate that therapeutic disruptions of this metabolism promote interindividual response variabilities.

pSK41/pGO1-family conjugative plasmids of Staphylococcus aureus encode a cryptic repressor of replication.

The majority of large multiresistance plasmids of Staphylococcus aureus utilise a RepA_N-type replication initiation protein, the expression of which is regulated by a small antisense RNA (RNAI) that overlaps the rep mRNA leader. The pSK41/pGO1-family of conjugative plasmids additionally possess a small (86 codon) divergently transcribed ORF (orf86) located upstream of the rep locus. The product of pSK41 orf86 was predicted to have a helix-turn-helix motif suggestive of a likely function in transcriptional repression. In this study, we investigated the effect of Orf86 on transcription of thirteen pSK41 backbone promoters. We found that Orf86 only repressed transcription from the rep promoter, and hence now redesignate the product as Cop. Over-expression of Cop in trans reduced the copy number of pSK41 mini-replicons, both in the presence and absence of rnaI. in vitro protein-DNA binding experiments with purified 6 × His-Cop demonstrated specific DNA binding, adjacent to, and partially overlapping the -35 hexamer of the rep promoter. The crystal structure of Cop revealed a dimeric structure similar to other known transcriptional regulators. Cop mRNA was found to result from "read-through" transcription from the strong RNAI promoter that escapes the rnaI terminator. Thus, PrnaI is responsible for transcription of two distinct negative regulators of plasmid copy number; the antisense RNAI that primarily represses Rep translation, and Cop protein that can repress rep transcription. Deletion of cop in a native plasmid did not appear to impact copy number, indicating a cryptic auxiliary role.

Mechanism-based inhibition of gut microbial tryptophanases reduces serum indoxyl sulfate.

Indoxyl sulfate is a microbially derived uremic toxin that accumulates in late-stage chronic kidney disease and contributes to both renal and cardiovascular toxicity. Indoxyl sulfate is generated by the metabolism of indole, a compound created solely by gut microbial tryptophanases. Here, we characterize the landscape of tryptophanase enzymes in the human gut microbiome and find remarkable structural and functional similarities across diverse taxa. We leverage this homology through a medicinal chemistry campaign to create a potent pan-inhibitor, (3S) ALG-05, and validate its action as a transition-state analog. (3S) ALG-05 successfully reduces indole production in microbial culture and displays minimal toxicity against microbial and mammalian cells. Mice treated with (3S) ALG-05 show reduced cecal indole and serum indoxyl sulfate levels with minimal changes in other tryptophan-metabolizing pathways. These studies present a non-bactericidal pan-inhibitor of gut microbial tryptophanases with potential promise for reducing indoxyl sulfate in chronic kidney disease.

Breast cancer detection with upstream data fusion, machine learning, and automated registration: initial results.

Purpose: To develop an artificial intelligence algorithm for the detection of breast cancer by combining upstream data fusion (UDF), machine learning (ML), and automated registration, using digital breast tomosynthesis (DBT) and breast ultrasound (US). Approach: Our retrospective study included examinations from 875 women obtained between April 2013 and January 2019. Included patients had a DBT mammogram, breast US, and biopsy proven breast lesion. Images were annotated by a breast imaging radiologist. An AI algorithm was developed based on ML for image candidate detections and UDF for fused detections. After exclusions, images from 150 patients were evaluated. Ninety-five cases were used for training and validation of ML. Fifty-five cases were included in the UDF test set. UDF performance was evaluated with a free-response receiver operating characteristic (FROC) curve. Results: Forty percent of cases evaluated with UDF (22/55) yielded true ML detections in all three images (craniocaudal DBT, mediolateral oblique DBT, and US). Of these, 20/22 (90.9%) produced a UDF fused detection that contained and classified the lesion correctly. FROC analysis for these cases showed 90% sensitivity at 0.3 false positives per case. In contrast, ML yielded an average of 8.0 false alarms per case. Conclusions: An AI algorithm combining UDF, ML, and automated registration was developed and applied to test cases, showing that UDF can yield fused detections and decrease false alarms when applied to breast cancer detection. Improvement of ML detection is needed to realize the full benefit of UDF.

Microbial ß-glucuronidases drive human periodontal disease etiology.

Periodontitis is a chronic inflammatory disease associated with persistent oral microbial dysbiosis. The human ß-glucuronidase (GUS) degrades constituents of the periodontium and is used as a biomarker for periodontitis severity. However, the human microbiome also encodes GUS enzymes, and the role of these factors in periodontal disease is poorly understood. Here, we define the 53 unique GUSs in the human oral microbiome and examine diverse GUS orthologs from periodontitis-associated pathogens. Oral bacterial GUS enzymes are more efficient polysaccharide degraders and processers of biomarker substrates than the human enzyme, particularly at pHs associated with disease progression. Using a microbial GUS-selective inhibitor, we show that GUS activity is reduced in clinical samples obtained from individuals with untreated periodontitis and that the degree of inhibition correlates with disease severity. Together, these results establish oral GUS activity as a biomarker that captures both host and microbial contributions to periodontitis, facilitating more efficient clinical monitoring and treatment paradigms for this common inflammatory disease.

Induced defenses as a management tool: Shaping individuals to their environment.

Many prey species can adjust morphology to reduce predation risk in response to predator cues. Enhancing prey defenses using predator cues may improve survival of cultivated species and enhance species restoration efforts, but assessment of such benefits at industrially relevant scales is needed. We examined how raising a model foundation species, oysters (Crassostrea virginica), under commercial hatchery conditions with cues from two common predator species can improve survival across a variety of predator regimes and environmental conditions. Oysters responded to predators by growing stronger shells than controls, but had subtle variations in shell characteristics depending on the predator species. Predator-induced changes significantly increased oyster survival up to 600% and survivorship was maximized when cue source was matched with local predator regime. Overall, our findings demonstrate the utility of using predator cues to enhance the survival of target species across landscapes and highlight the opportunity to employ nontoxic methods to control pest-based mortality.

Survival and growth of triploid eastern oysters, Crassostrea virginica, produced from wild diploids collected from low-salinity areas.

Triploid Eastern oysters have been reported to suffer greater mortalities than diploids when exposed to low-salinity (<5) conditions in the U.S. Gulf of Mexico and Atlantic estuaries. As such, the effect of broodstock parentage was investigated on the low-salinity tolerance of triploid progeny produced by mating diploid females (collected from three Louisiana estuaries differing in salinity regimes) with male tetraploids at two hatcheries. Diploid crosses were also produced using the wild broodstocks to verify expected differences in low-salinity tolerance among diploid progeny and between ploidy levels. All progeny were deployed at low and moderate-salinity (averages of 9.3 and 19.4) field sites to monitor monthly growth and mortality. Sex ratio, gametogenic stage, gonad-to-body ratio, condition index, and Perkinsus marinus infection were also measured periodically at both field sites Although high triploid mortality at the low-salinity site prevented complete analysis, results indicated that diploid parentage had little effect on triploid survival at low salinity. Broodstock parentage affected diploid mortality and growth, although results did not match with predictions made based on historical salinity at broodstock collection sites. Ploidy level had the largest effect on triploid survival and growth followed by the hatchery site where the oysters were produced.

Diverse MarR bacterial regulators of auxin catabolism in the plant microbiome.

Chemical signalling in the plant microbiome can have drastic effects on microbial community structure, and on host growth and development. Previously, we demonstrated that the auxin metabolic signal interference performed by the bacterial genus Variovorax via an auxin degradation locus was essential for maintaining stereotypic root development in an ecologically relevant bacterial synthetic community. Here, we dissect the Variovorax auxin degradation locus to define the genes iadDE as necessary and sufficient for indole-3-acetic acid (IAA) degradation and signal interference. We determine the crystal structures and binding properties of the operon's MarR-family repressor with IAA and other auxins. Auxin degradation operons were identified across the bacterial tree of life and we define two distinct types on the basis of gene content and metabolic products: iac-like and iad-like. The structures of MarRs from representatives of each auxin degradation operon type establish that each has distinct IAA-binding pockets. Comparison of representative IAA-degrading strains from diverse bacterial genera colonizing Arabidopsis plants show that while all degrade IAA, only strains containing iad-like auxin-degrading operons interfere with auxin signalling in a complex synthetic community context. This suggests that iad-like operon-containing bacterial strains, including Variovorax species, play a key ecological role in modulating auxins in the plant microbiome.

Expectant Management of Blunt Grade III Renal Injuries: Early Discharge Outcomes From a Level I Trauma Center.

OBJECTIVES: To determine whether patients with American Association for the Surgery of Trauma (AAST) grade III blunt renal injuries discharged within 48 hours of admission have increased rates of readmission for renal-related complications compared to patients observed for over 48 hours. METHODS: Renal trauma patients from 2005 through 2020 were identified from our institutional trauma registry. Patients with AAST III blunt renal injuries who survived beyond 48 hours of admission were included. Univariable analysis was used to identify variables associated with discharge within 48 hours. Reasons for readmission were compared between patients discharged before and after 48 hours of admission. RESULTS: Of the 1751 renal trauma patients, 377 (21.5%) met inclusion criteria. Sixty-five of 377 (17.2%) AAST III injuries were discharged within 48 hours of admission. Forty (10.6%) patients required readmission, 3 in the early discharge group and 37 in the standard discharge group. No patient required readmission for renal-related complications. CONCLUSION: Patients with AAST grade III blunt renal injuries are not at increased risk for early renal-related complications if discharged within 48 hours of admission and should be considered for early discharge. The very low rate of renal-related complications for AAST III blunt renal injuries supports their categorization as "low-grade" renal trauma.

Automated Registration for Dual-View X-Ray Mammography Using Convolutional Neural Networks.

OBJECTIVE: Automated registration algorithms for a pair of 2D X-ray mammographic images taken from two standard imaging angles, namely, the craniocaudal (CC) and the mediolateral oblique (MLO) views, are developed. METHODS: A fully convolutional neural network, a type of convolutional neural network (CNN), is employed to generate a pixel-level deformation field, which provides a mapping between masses in the two views. Novel distance-based regularization is employed, which contributes significantly to the performance. RESULTS: The developed techniques are tested using real 2D mammographic images, slices from real 3D mammographic images, and synthetic mammographic images. Architectural variations of the neural network are investigated and the performance is characterized from various aspects including image resolution, breast density, lesion size, lesion subtlety, and lesion Breast Imaging-Reporting and Data System (BI-RADS) category. Our network outperformed the state-of-the-art CNN-based and non-CNN-based registration techniques, and showed robust performance across various tissue/lesion characteristics. CONCLUSION: The proposed methods provide a useful automated tool for co-locating lesions between the CC and MLO views even in challenging cases. SIGNIFICANCE: Our methods can aid clinicians to establish lesion correspondence quickly and accurately in the dual-view X-ray mammography, improving diagnostic capability.

Sperm Repository for a Breeding Program of the Eastern Oyster Crassostrea virginica: Sample Collection, Processing, Cryopreservation, and Data Management Plan.

The Eastern oyster Crassostrea virginica (Family Ostreidae) is one of the most important fishery and aquaculture species in the U.S. and is a keystone species for coastal reefs. A breeding program was initiated in 2019 to support the fast-growing aquaculture industry culturing this species in the Gulf of Mexico. Oysters from 17 wild populations in embayment along the U.S. Gulf of Mexico coast from southwest Florida to the Matagorda Bay, Texas were used as broodstock for the program to maximize genetic diversity in the base population. A sperm repository of the broodstock was established to support the breeding project. The goal of this study was to demonstrate the sperm sample collection, processing, cryopreservation, and the data management plan involved in the establishment of a sperm germplasm repository of base populations. The supporting objectives were to: (1) develop a data management plan for the sperm repository; (2) streamline the procedure for sample collection, processing, and cryopreservation; (3) incorporate sperm quality analysis into the procedure, and (4) archive the cryopreserved samples as a repository for future use in the breeding program. This sperm repository included a total of 102 male oysters from the 17 collection sites (six oysters per site). A data management plan was developed with six categories, including sample collection, phenotype, fresh sperm, genotype, cryopreservation, and post-thaw sperm, as guide for data collection. Sperm collection was accomplished by strip spawn, and fresh sperm production, motility, and fertility were recorded for quality analysis. Cryopreserved sperm samples were sorted, labelled, archived, and stored in liquid nitrogen for future use. Post-thaw motility (1-30%) and plasm membrane integrity (15.34-70.36%) were recorded as post-thaw quality parameters. Overall, this study demonstrated a streamlined procedure of oyster sperm collection, processing, and cryopreservation for establishing a sperm repository that can serve as a template for construction of oyster germplasm repositories for breeding programs.

Tolerance of northern Gulf of Mexico eastern oysters to chronic warming at extreme salinities.

The eastern oyster, Crassostrea virginica, provides critical ecosystem services and supports valuable fishery and aquaculture industries in northern Gulf of Mexico (nGoM) subtropical estuaries where it is grown subtidally. Its upper critical thermal limit is not well defined, especially when combined with extreme salinities. The cumulative mortalities of the progenies of wild C. virginica from four nGoM estuaries differing in mean annual salinity, acclimated to low (4.0), moderate (20.0), and high (36.0) salinities at 28.9 °C (84 °F) and exposed to increasing target temperatures of 33.3 °C (92 °F), 35.6 °C (96 °F) or 37.8 °C (100 °F), were measured over a three-week period. Oysters of all stocks were the most sensitive to increasing temperatures at low salinity, dying quicker (i.e., lower median lethal time, LT50) than at the moderate and high salinities and resulting in high cumulative mortalities at all target temperatures. Oysters of all stocks at moderate salinity died the slowest with high cumulative mortalities only at the two highest temperatures. The F1 oysters from the more southern and hypersaline Upper Laguna Madre estuary were generally more tolerant to prolonged higher temperatures (higher LT50) than stocks originating from lower salinity estuaries, most notably at the highest salinity. Using the measured temperatures oysters were exposed to, 3-day median lethal Celsius degrees (LD50) were estimated for each stock at each salinity. The lowest 3-day LD50 (35.1-36.0 °C) for all stocks was calculated at a salinity of 4.0, while the highest 3-day LD50 (40.1-44.0 °C) was calculated at a salinity of 20.0.

Effects of Farm Location on Vibrio parahaemolyticus and Vibrio vulnificus Levels in Oysters after Desiccation and Resubmersion in the Northern Gulf of Mexico.

ABSTRACT: Desiccation is a routine farming practice used in off-bottom oyster aquaculture to reduce biofouling organisms and improve shell quality. This practice can increase Vibrio parahaemolyticus and Vibrio vulnificus levels, leading to increased risk of illness for raw oyster consumers. Previous resubmersion studies were performed in geographic proximity to one another, so to better understand the broader applicability of resubmersion, the next step was to perform concurrent studies in multiple geographic locations within a region. This study evaluated the effect of variations in geographic location on the recovery time needed for elevated vibrio levels to return to ambient levels in desiccated oysters after resubmersion at Gulf Coast farms. Two trials were performed between May and August 2019 at sites spanning ∼100 km: three in Alabama and one in Florida. Oysters were deployed in OysterGro cages at each location, 2 weeks before each trial, and then either were desiccated for 24 h or remained submersed as controls. Triplicate samples were taken before and immediately following the desiccation period, as well as 7 and 14 days after resubmersion. Total and pathogenic V. parahaemolyticus and V. vulnificus levels were determined using most-probable-number (MPN) real-time PCR. Vibrio levels increased by 0.23 to 3.50 log MPN/g after desiccation. Recovery times varied among geographic locations by trial and Vibrio spp., with all vibrio counts recovering to levels not significantly higher than those in control oysters within 7 to 14 days of resubmersion (P ≥ 0.06). These results suggest a 14-day resubmersion period of cultured oysters allowed vibrio levels, elevated because of routine handling, to return to ambient levels at all farm sites studied.

Divergence in salinity tolerance of northern Gulf of Mexico eastern oysters under field and laboratory exposure.

The eastern oyster, Crassostrea virginica, is a foundation species within US Gulf of Mexico (GoM) estuaries that has experienced substantial population declines. As changes from management and climate are expected to continue to impact estuarine salinity, understanding how local oyster populations might respond and identifying populations with adaptations to more extreme changes in salinity could inform resource management, including restoration and aquaculture programs. Wild oysters were collected from four estuarine sites from Texas [Packery Channel (PC): 35.5, annual mean salinity, Aransas Bay (AB): 23.0] and Louisiana [Calcasieu Lake (CL): 16.2, Vermilion Bay (VB): 7.4] and spawned. The progeny were compared in field and laboratory studies under different salinity regimes. For the field study, F1 oysters were deployed at low (6.4) and intermediate (16.5) salinity sites in Alabama. Growth and mortality were measured monthly. Condition index and Perkinsus marinus infection intensity were measured quarterly. For the laboratory studies, mortality was recorded in F1 oysters that were exposed to salinities of 2.0, 4.0, 20.0/22.0, 38.0 and 44.0 with and without acclimation. The results of the field study and laboratory study with acclimation indicated that PC oysters are adapted to high-salinity conditions and do not tolerate very low salinities. The AB stock had the highest plasticity as it performed as well as the PC stock at high salinities and as well as Louisiana stocks at the lowest salinity. Louisiana stocks did not perform as well as the Texas stocks at high salinities. Results from the laboratory studies without salinity acclimation showed that all F1 stocks experiencing rapid mortality at low salinities when 3-month oysters collected at a salinity of 24 were used and at both low and high salinities when 7-month oysters collected at a salinity of 14.5 were used.

The Impact of Delayed-Phase Imaging at Admission on the Management of Urinary Extravasation in High-Grade Renal Trauma.

PURPOSE: American Urological Association Urotrauma guidelines recommend delayed-phase imaging on presentation for all renal injuries, although data to support it are anecdotal. Forgoing delays risks unrecognized collecting system injuries. We hypothesized that renal trauma patients without admission delays have more complications from urinary extravasation. MATERIALS AND METHODS: From 2005 through 2020, 1,751 renal trauma patients were identified from our institutional trauma registry. Included patients had an estimated American Association for the Surgery of Trauma renal injury grade of III-V and a perinephric fluid collection. Propensity scores for receipt of delayed-phase imaging were calculated based on Injury Severity Score, arrival condition, admission systolic blood pressure, sex and renal injury grade. Propensity score-adjusted logistic regression was used to compare clinical outcomes between those with and without admission delays. RESULTS: Ninety (28.6%) of 315 included patients had delays on presentation. Patients without delays had higher Injury Severity Scores (29 vs 23, p=0.002), fewer isolated renal injuries (27.6% vs 38.9%, p=0.05) and lower grade renal injuries (56.9% vs 41.1% grade 3, p=0.03). After propensity score adjustment, patients with delays were more likely to undergo immediate interventions (OR 11.75, 95% CI 2.99-78.10) and interval stent placement for urinary extravasation (OR 6.86, 95% CI 1.56-47.64) without a difference in urological complications (OR 5.07, 95% CI 0.25-766.16). CONCLUSIONS: Delayed-phase imaging was associated with an increased odds of undergoing immediate and asymptomatic interval urological interventions without a difference in the odds of a complication after high-grade renal trauma. Post-trauma urinary extravasation requires further research to determine which patients require imaging and intervention.

Discordant Pleistocene population size histories in a guild of hymenopteran parasitoids.

Signatures of past changes in population size have been detected in genome-wide variation in many species. However, the causes of such demographic changes and the extent to which they are shared across co-distributed species remain poorly understood. During Pleistocene glacial maxima, many temperate European species were confined to southern refugia. While vicariance and range expansion processes associated with glacial cycles have been widely documented, it is unclear whether refugial populations of co-distributed species have experienced shared histories of population size change. We analyse whole-genome sequence data to reconstruct and compare demographic histories during the Quaternary for Iberian refuge populations in a single ecological guild (seven species of chalcid parasitoid wasps associated with oak cynipid galls). For four of these species, we find support for large changes in effective population size (Ne ) through the Pleistocene that coincide with major climate events. However, there is little evidence that the timing, direction and magnitude of demographic change are shared across species, suggesting that demographic histories in this guild are largely idiosyncratic, even at the scale of a single glacial refugium.

Plant "helper" immune receptors are Ca2+-permeable nonselective cation channels.

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) regulate immunity and cell death. In Arabidopsis, a subfamily of "helper" NLRs is required by many "sensor" NLRs. Active NRG1.1 oligomerized, was enriched in plasma membrane puncta, and conferred cytoplasmic calcium ion (Ca2+) influx in plant and human cells. NRG1.1-dependent Ca2+ influx and cell death were sensitive to Ca2+ channel blockers and were suppressed by mutations affecting oligomerization or plasma membrane enrichment. Ca2+ influx and cell death mediated by NRG1.1 and ACTIVATED DISEASE RESISTANCE 1 (ADR1), another helper NLR, required conserved negatively charged N-terminal residues. Whole-cell voltage-clamp recordings demonstrated that Arabidopsis helper NLRs form Ca2+-permeable cation channels to directly regulate cytoplasmic Ca2+ levels and consequent cell death. Thus, helper NLRs transduce cell death signals directly.

Identification of Chemicals Associated Gambusia affinis (Cyprinodontiformes: Poeciliidae), and Their Effect on Oviposition Behavior of Culex tarsalis (Diptera: Culicidae) in the Laboratory.

The western mosquitofish, Gambusia affinis (Baird & Girard), has been used worldwide for the control of larval mosquitoes for more than 100 yr. We found that the western encephalitis mosquito, Culex tarsalis Coquillett (Diptera: Culicidae), can detect the presence of G. affinis in oviposition sites based on associated chemicals, leading to a decrease in the number of egg rafts laid. Three volatile chemical compounds were identified in the headspace above the water where G. affinis had been held for 24 h. Oviposition bioassays conducted using standards of the volatile compounds identified (dimethyl disulfide [DMDS], dimethyl trisulfide [DMTS], and S-methyl methanethiosulphonate) found that females reduced oviposition only when low concentrations of DMTS were present, but this response was not consistent across all trials and concentrations tested. DMDS, DMTS, and S-methyl methanethiosulphonate are known bacterial metabolic waste products and may be the source of the compounds. Two nonvolatile compounds of interest were found to be present in the Gambusia-exudate water. After tasting Cx. tarsalis were deterred from ovipositing onto Gambusia-treated water from which the bacteria had been removed by filtration, indicating that the kairomone may consist of nonvolatile compound(s). One of the nonvolatile compounds isolated from the Gambusia-treated water has a benzene ring structure similar to that of cholesterol but the structure of the two nonvolatile deterrents remains to be fully characterized. Our research shows that three volatile compounds and two nonvolatile compounds are present in water associated with G. affinis (Poeciliidae: Gambusia) and affect the oviposition behavior of Cx. tarsalis in laboratory bioassays.

Dynamics of Mud Blister Worm Infestation and Shell Repair by Oysters.

AbstractMud blister worms bore into oyster shells; and oysters respond to shell penetration by secreting new layers of shell, resulting in mud blisters on inner surfaces of oyster shells. We conducted two experiments in off-bottom oyster farms along Alabama's coast in summer 2017 to explore the dynamics of worm infestation, blister formation, and shell repair. Results support our hypothesis that only a small proportion of worms that bore into oysters cause blisters. Triploid oysters had fewer blisters than diploids, likely because of faster growth and shell repair. We treated oysters to remove mud blister worms, redeployed them at intertidal and subtidal sites for nine weeks, and found that reinfestation by worms occurred only in subtidal oysters. Intertidally deployed oysters showed no visible blister coverage, indicating recovery, whereas blister coverage increased in subtidal oysters. Reinfestation of subtidal oysters was correlated with previous burrow damage, visualized with X-ray images, thus supporting our hypothesis that worms preferentially settle in previously infested shells. Forces required to break blisters, measured with a custom-built shucking knife with an integrated force sensor, were low relative to forces required to shuck oysters, possibly because our experiment was conducted when worm infestation was increasing. Higher forces were required to break smaller, lighter-colored blisters, consistent with blister recovery; but results were highly variable and not consistent across sites and sampling times, suggesting that size and color of blisters alone did not explain shell strength. Our results indicate that oysters repair shells slowly relative to more dynamic patterns of worm infestation.

Complication to consider: delayed traumatic hemothorax in older adults.

BACKGROUND: Emerging evidence suggests older adults may experience subtle hemothoraces that progress over several days. Delayed progression and delayed development of traumatic hemothorax (dHTX) have not been well characterized. We hypothesized dHTX would be infrequent but associated with factors that may aid prediction. METHODS: We retrospectively reviewed adults aged ≥50 years diagnosed with dHTX after rib fractures at two level 1 trauma centers (March 2018 to September 2019). dHTX was defined as HTX discovered ≥48 hours after admission chest CT showed either no or 'minimal/trace' HTX. Two blinded, board-certified radiologists reviewed inpatient chest imaging and classified injury patterns according to Chest Wall Injury Society (CWIS) taxonomy. Descriptive analysis was performed for demographic and hospitalization characteristics. RESULTS: We identified 14 patients with pooled dHTX rate of 1.3%. After initial chest CT negative for concerning hemothoraces, the patients did not undergo follow-up imaging until new symptoms (shortness of breath, chest pain) developed: eight (57%) were not diagnosed until after discharge from initial hospitalization (mean (range): 9 (2-20) days after discharge). Aspirin and/or anticoagulants were involved in fewer than half of cases (43%). According to CWIS taxonomy, all patients had a series of posterolateral fractures with at least one offset or displaced fracture, and an average of six consecutive rib fractures. All patients underwent tube thoracostomy and six patients (42%)-all aged <65-underwent operative interventions. DISCUSSION: Preliminary data suggest older adults with rib fractures may be at risk of experiencing delayed progression of trace hemothoraces or a delayed presentation of hemothoraces. Asymptomatic progression or readmission to other services/hospitals likely occurs and true dHTX rates are likely higher. Our preliminary findings suggest a possible anatomic explanation for severe chest wall injury patterns' association with dHTX. Further characterization and capturing the true incidence of dHTX first requires wider recognition of this complication.