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Publication
Journal: Advanced Functional Materials
November/29/2020
Abstract
Injectable colloids that self-assemble into three-dimensional networks are promising materials for applications in regenerative engineering, as they create open systems for cellular infiltration, interaction, and activation. However, most injectable colloids have spherical morphologies, which lack the high material-biology contact areas afforded by higher aspect ratio materials. To address this need, injectable high aspect ratio particles (HARPs) were developed that form three-dimensional networks to enhance scaffold assembly dynamics and cellular interactions. HARPs were functionalized for tunable surface charge through layer-by-layer electrostatic assembly. Positively charged Chitosan-HARPs had improved particle suspension dynamics when compared to spherical particles or negatively charged HARPs. Chit-HARPs were used to improve the suspension dynamics and viability of MIN6 cells in three-dimensional networks. When combined with negatively charged gelatin microsphere (GelMS) porogens, Chit-HARPs reduced GelMS sedimentation and increased overall network suspension, due to a combination of HARP network formation and electrostatic interactions. Lastly, HARPs were functionalized with fibroblast growth factor 2 (FGF2) to highlight their use for growth factor delivery. FGF2-HARPs increased fibroblast proliferation through a combination of 3D scaffold assembly and growth factor delivery. Taken together, these studies demonstrate the development and diverse uses of high aspect ratio particles as tunable injectable scaffolds for applications in regenerative engineering.
Keywords: assembly; biointerface; colloids; growth factors; nanomaterials; regenerative engineering; scaffolds.
Publication
Journal: Environmental Pollution
June/27/2001
Abstract
Levels of tris (4-chlorophenyl) methanol (TCPM) and its presumed precursor tris (4-chlorophenyl) methane (TCPMe) are reported in marine mammals from the Estuary and Gulf of St. Lawrence, Canada. These compounds were measured in blubber samples of seals and whales using ion trap mass spectrometry (MS/MS) detection. Detectable concentrations of both TCPM and TCPMe were observed in all of the samples analysed. Concentrations of these compounds varied with species ranging from 1.7 to 153 and from 1.3 to 50.6 ng/g lipid wt. for TCPM and TCPMe, respectively. TCPM was from 1.3 to 10 times more concentrated than TCPMe. The highest levels of both TCPM and TCPMe were observed in adult male beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, while adult female beluga whales from the same area showed levels similar to those in the seals examined. Among the four seal species investigated, TCPM and TCPMe levels were the highest in grey (Halichoerus grypus) and hooded (Cystophora cristata) seals, and lowest in harp seals (Phoca groenlandica). Intermediate levels were found in harbour seals (Phoca vitulina); however, their concentrations might be underestimated considering the younger mean age of these animals. Ratios of both 4,4'-DDE/sigma DDT and TCPM/sigma TCP were very similar between animals from the same species. Strong correlations between sigma TCP and sigma DDT were also observed for each species of mammals, most likely indicating that both sigma TCP and sigma DDT are bioaccumulated in marine mammals. The relationships between sigma DDT and sigma TCP also demonstrate that sigma TCP are less bioaccumulated than sigma DDT by the marine mammal species examined.
Publication
Journal: Plant Disease
November/22/2020
Abstract
Anthracnose fruit rot caused by various Colletotrichum spp. is a serious disease for pepper (Capsicum annuum) growers, resulting in extensive fruit loss (Harp et al. 2008). Samples of five pepper fruits were obtained from two commercial farms in Lexington and Pickens counties, South Carolina, in August and September 2019, respectively. All fruits had two or more soft, sunken lesions covered with salmon-colored spore masses. Pieces of diseased tissue cut from the margins of lesions were surface disinfested in 0.6% sodium hypochlorite, rinsed in sterile deionized water, blotted dry, and placed on one-quarter-strength potato dextrose agar (PDA/4) amended with 100 mg chloramphenicol, 100 mg streptomycin sulfate, and 60.5 mg mefenoxam (0.25 ml Ridomil Gold EC) per liter. Two isolates of Colletotrichum sp. per fruit were preserved on dried filter paper and stored at 10º C. One additional isolate of Colletotrichum sp. had been collected from a jalapeño pepper fruit on a farm in Charleston County, South Carolina, in 1997. Colony morphology of three isolates, one per county, on Spezieller Nährstoffarmer Agar (SNA) was pale grey with a faint orange tint. All isolates readily produced conidia on SNA with an average length of 16.4 μm (std. dev. = 1.8 μm) and a width of 2.2 μm (std. dev. = 0.2 μm). Conidia were hyaline, smooth, straight, aseptate, cylindrical to fusiform with one or both ends slightly acute or round, matching the description of C. scovillei (Damm et al. 2012). The glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and beta-tubulin (TUB2) genes from three isolates were amplified and sequenced with the primer pairs GDF1/GDR1 and T1/Bt2b, respectively. Species within the C. acutatum clade can be readily distinguished with GAPDH or TUB2 (Cannon et al. 2012). The GAPDH and TUB2 sequences for all three isolates were 100% similar to each other and strain CBS 126529 (GAPDH accession number JQ948597; TUB2 accession number JQ949918) of C. scovillei (Damm et al. 2012). GAPDH and TUB2 sequences for each isolate were deposited in GenBank under the accessions MT826948-MT926950 and MT826951-MT86953, respectively. A pathogenicity test was conducted on jalapeño pepper fruits by placing a 10-ul droplet of a 5 x 105 conidial suspension of each isolate onto a wound made with a sterile toothpick. Control peppers were mock inoculated with 10 ul sterile distilled water. A humid chamber was prepared by placing moist paper towels on the bottom of a sealed crisper box. Inoculated peppers were placed on upside-down 60 ml plastic condiment cups. Three replicate boxes each containing all four treatments were prepared. The experiment was repeated once. After 7 days in the humid chamber at 26ºC, disease did not develop on control fruits, whereas soft, sunken lesions covered with salmon-colored spores developed on inoculated fruits. Lesions were measured and C. scovillei was re-isolated onto amended PDA/4 as previously described. Lesion length averaged 15.6 mm (std dev. = 4.1 mm) by 11.5 mm (std dev. = 2.0 mm). Colletotrichum sp. resembling the original isolate were recovered from all inoculated fruit, but not from non-inoculated fruit. C. scovillei has been reported in Brazil in South America and in China, Indonesia, Japan, Malaysia, South Korea, Taiwan, and Thailand in Asia (Farr and Rossman 2020). This is the first report of C. scovillei as the casual organism of anthracnose fruit rot on pepper in South Carolina and the United States.
Keywords: Anthracnose; Capsicum annum; Colletotrichum scovillei; pepper.
Publication
Journal: Pharmaceuticals
February/19/2017
Abstract
RNA interference (RNAi) allows the specific knockdown of tumor relevant genes. To induce RNAi, the delivery of small interfering RNAs (siRNAs) is of crucial importance. This is particularly challenging for their therapeutic applications in vivo. Low molecular weight branched polyethylenimine (PEI) is safe and efficient for nucleic acid delivery including small RNA molecules, based on its ability to electrostatically complex siRNA molecules, thereby protecting them from nuclease degradation. The nanoscale PEI/siRNA complexes are endocytosed by cells prior to intracellular complex release from the lysosome and cytoplasmic release of the siRNAs from the complexes. Chemical modification and ligand decoration of the complexes aim at introducing target tissue specificity and further increased efficacy of PEI-mediated siRNA delivery. CRM197 is a mutated, non-toxic diphtheria toxin (DT) that binds to the membrane-bound precursor of HB-EGF-like growth factor/diphtheria toxin receptor highly expressed in glioblastoma cells. Likewise, the growth factor pleiotrophin (PTN/HB-GAM/HARP) is overexpressed in glioblastoma and is rate limiting for tumor growth, thus representing an attractive target gene for therapeutic knockdown approaches. PEGylation of PEI was performed to reduce the surface charge, and by CRM197 coupling we prepared a modified PEI for siRNA delivery into glioblastoma cells. The novel PEI conjugates were analyzed for their complexation efficiency and optimal mixing ratios, and complexes were physicochemically characterized regarding stability, size and zeta potential. The biological activity of the complexes was confirmed in cell culture by reporter gene knockdown. For the therapeutic treatment of subcutaneous human gliobastoma xenografts in athymic nude mice, we systemically injected the modified PEI/siRNA complexes targeting PTN. Antitumor effects based on PTN knockdown demonstrated the advantage of tumor-targeted CRM197-PEG-PEI/siRNA over untargeted PEG-PEI polyplexes. Thus, we establish targeted CRM197-PEG-PEI-based complexes for siRNA delivery in vivo, and show therapeutic effects of CRM197-PEG-PEI/siRNA-mediated knockdown of PTN.
Publication
Journal: Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery
January/10/2011
Authors
Publication
Journal: Marine Pollution Bulletin
April/16/2021
Abstract
Plastic debris is globally found around the world and the remote Arctic is no exception. Arctic true seals are sentinel species of marine pollution and represent the link between marine food webs and Arctic apex predators like polar bears and humans. With regard to true seals, ingested macroplastics have never been reported in an Arctic species. We harvested 10 harp seals Pagophilus groenlandicus and 8 hooded seals Cystophora cristata from the breeding grounds in the pack ice of the Greenland Sea. The digestive tract was inspected exclusively for the presence of macroplastics (>5 mm). Two pieces of single-use plastic were found in the stomach of a weaned hooded seal pup. This study indicates that young Arctic marine predators may ingest macroplastics, and therefore may be at risk during their early stages of life due to human caused plastic pollution even in the remote Arctic pack ice.
Keywords: Arctic; Cystophora cristata; FTIR; Macroplastic; Pagophilus groenlandicus; Pinnipeds.
Publication
Journal: Journal of the American Medical Directors Association
November/8/2020
Abstract
Objectives: To evaluate the effect of Hospital Admission Risk Program (HARP) on unplanned hospitalization, bed days, and mortality of enrolled individuals and to evaluate the cost-effectiveness of HARP.
Design: A retrospective longitudinal analysis of hospital administrative data.
Intervention: Individuals at risk of hospitalization were provided with multidisciplinary, community-based care support managed by care coordinators including integrated care planning, education, monitoring, service linkages, and general practitioner liaison over 6-9 months.
Setting and participants: Individuals who were enrolled into 1 of 8 HARP chronic disease management programs between July 1, 2017, and June 30, 2018, at the Royal Melbourne Hospital, Australia.
Methods: Hospital admissions between 18 months before and 18 months after HARP enrollment were analyzed. Total hospital costs were compared between 18 months before and 12 months after HARP enrollment.
Results: A total of 1553 individuals with a median age of 71 years (interquartile range 60-81), 63.4% males, were admitted to HARP. Both unplanned hospitalizations and bed days were reduced during the HARP intervention compared to within 3 months before enrollment in each of the HARP management programs. After the HARP intervention, cardiac coach, cardiac heart failure, chronic respiratory, diabetes comanagement, and medication management programs had higher hospitalizations and bed days than individuals' baseline of at least 3 months before HARP enrollment. Individuals in cardiac heart failure and chronic respiratory management programs had a higher mortality rate than other HARP chronic disease management programs. Individuals in cardiac coach, diabetes comanagement, and medication management programs had lower hospital costs during the HARP intervention compared to within 3 months before HARP enrollment.
Conclusions and implications: HARP reduced unplanned hospitalization and bed days but did not return individuals' hospital use to baseline before the intervention. The variations in mortality between HARP chronic disease management programs implies that condition-specific goals between programs is preferable.
Keywords: Outcome and process assessment; aged; chronic disease; health care; hospital costs; mortality; patient readmission.
Publication
Journal: Journal of Zoo and Wildlife Medicine
July/23/2009
Abstract
An adult, wild-collected, male harp seal (Phoca groenlandica) was transferred from a rehabilitation center to a display facility because of unilateral phthisis bulbi and decreased use of the right forelimb, which precluded its release. In quarantine, the animal demonstrated limited use of the right forelimb, which acutely progressed to complete disuse of the limb accompanied by intermittent lethargy. One month after transfer, the animal was found dead on exhibit. Necropsy showed septic arthritis of the right scapulohumeral joint, valvular endocarditis with systemic bacterial thromboembolism, and infarction of the cerebrum and myocardium. Culture of the blood and affected joint space revealed Staphylococcus aureus. Bacterial polymerase chain reaction of formalin-fixed tissues from the heart and brain were also positive for S. aureus. Staphylococcus aureus infection should be considered as an additional cause of endocarditis and embolic encephalitis in seals.
Publication
Journal: Homeopathy
October/4/2018
Abstract
BACKGROUND
Practice-based registration could identify 'general' and 'homeopathic' prognostic factors for therapeutic success in patients who seek complementary and alternative medicine (CAM)/homeopathic treatment. Identification of 'best homeopathic cases' within a database could inform clinical research and improve homeopathic practice.
OBJECTIVE
To investigate the feasibility of registration in daily CAM/homeopathic practice, evaluate patient-reported outcome measures and tools for identifying 'best homeopathic cases' and to make recommendations for an electronic database.
METHODS
In 2015 and 2016, 25 homeopathic doctors registered details of a maximum of 20 patients each, with 6 months of follow-up (extended follow-up for 'best homeopathic cases'), in Excel or in the Homeopathic Administration and Registration Program (HARP) database. Informed consent was obtained from each patient. Patient-perceived change of main complaint was measured by a 7-point Likert scale. Best homeopathic cases were defined by treatment with one homeopathic medicine, ≥ 2 months of follow-up, result score +2 to +4 on a 9-point Likert scale by the doctor, and by changes that could be attributed to the homeopathic medicine. Association between scores for change of main complaint and scores for 'best homeopathic case' was analysed by the Kruskal gamma test.
RESULTS
Three-hundred and ninety-nine patients were included. In 49.1%, the main complaint was present for ≥ 2 years. The most common diagnosis was 'fatigue' (N = 56; 14%). Major improvement in the main complaint (score +3) was reported by 22 to 26% at consecutive follow-up visits. One-hundred and ninety-six patients were treated with a single homeopathic medicine, among whom 66 'best homeopathic cases' were identified. The correlation between patient-reported changes of main complaint and assessment by the doctor was significant (gamma = 0.832; p < 0.001).
CONCLUSIONS
Registration of (co-)diagnoses, chronicity, treatments and outcomes in homeopathic practice with identification of 'best homeopathic cases' is feasible, using the tools provided. A user-friendly electronic database for efficient recording is recommended.
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Publication
Journal: Health Services Research
April/19/2021
Abstract
Objective: To evaluate the impact of the Health and Recovery Plan (HARP), a capitated special needs Medicaid managed care product that fully integrates physical and behavioral health delivery systems in New York State.
Data sources: 2013-2019 claims and encounters data on continuously enrolled individuals from the New York State Medicaid data system.
Study design: We used a difference-in-difference approach with inverse probability of exposure weights to compare service use outcomes in individuals enrolled in the HARP versus HARP eligible comparison group in two regions, New York City (NYC) pre- (2013-2015) versus post- (2016-2018) intervention periods, and rest of the state (ROS) pre- (2014-2016) versus post- (2017-2019) intervention periods.
Data collection/extraction methods: Not applicable.
Principal findings: HARPs were associated with a relative decrease in all-cause (RR = 0.78, 95% CI 0.68-0.90), behavioral health-related (RR = 0.76, 95% CI 0.60-0.96), and nonbehavioral-related (RR = 0.87, 95% CI 0.78-0.97) stays in the NYC region. In the ROS region, HARPs were associated with a relative decrease in all-cause (RR = 0.87, 95% CI 0.80-0.94) and behavioral health-related (RR = 0.80, 95% CI 0.70-0.91) stays. Regarding outpatient visits, the HARPs benefit package were associated with a relative increase in behavioral health (RR = 1.21, 95% CI 1.13-1.28) and nonbehavioral health (RR = 1.08, 95% CI 1.01-1.15) clinic visits in the NYC region. In the ROS region, the HARPs were associated with relative increases in behavioral health (RR = 1.47, 95% CI 1.32-1.64) and nonbehavioral health (RR = 1.17, 95% CI 1.11-1.25) clinic visits.
Conclusions: Compared to patients with similar clinical needs, HARPs were associated with a relative increase in services used and led to a better engagement in the HARPs group regardless of the overall decline in services used pre- to postperiod.
Keywords: Medicaid Managed Care; health care access and use; health care reform; health policy research; mental health.
Publication
Journal: Basic and Clinical Pharmacology and Toxicology
March/6/2013
Abstract
Pleiotrophin, also known as heparin affin regulatory peptide (HARP), is a growth factor expressed in various tissues and cell lines. In this work, HARP was tested for its capacity to modulate the anticoagulant activity of heparin and heparan sulphate mimetics (OTR4120). We used both in vitro and in vivo assays. HARP was found to be differently effective for neutralization of the anticoagulant activity of the mimetic heparan sulphate (OTR4120) and heparin in purified system and human plasma. HARP was shown to compete with both antithrombin and thrombin for binding to heparin and to OTR4120, respectively. In the presence of OTR4120, the V(max) was constant and the calculated maximum velocity was 1.56 U/min; the thrombin Km value (0.011 nM) was affected by HARP concentrations. The Km (HARP) value was 0.085 nM, which is consistent with high affinity of HARP to OTR4120. Under the same conditions, initial velocity patterns for antithrombin-heparin were determined in the presence or in the absence of HARP. The antithrombin value Km (0.022 nM) was affected by HARP (0.077 nM). HARP exhibits efficacy equivalent to or greater than protamine. Interestingly, intraperitoneally administered HARP decreased the anticoagulant activity of heparin and of OTR4120 in mice. Taken together, these data provide the first evidence for a physiological role of HARP in the modulation of anticoagulant activity of heparin and heparin-like material.
Publication
Journal: Journal of Experimental Biology
May/17/2021
Abstract
Assessment of the compressibility of marine mammal airways at depth is crucial to understanding vital physiologic processes such as gas exchange during diving. Very few studies have directly assessed changes in cetacean and pinniped trachea-bronchial shape, and none have quantified changes in volume with increasing pressure. A freshly deceased harbor seal, grey seal, harp seal, harbor porpoise, and common dolphin were imaged post mortem via CT in a radiolucent hyperbaric chamber as previously described in Moore et al (2011). Volume reconstructions were performed of segments of the trachea and bronchi of the pinnipeds and bronchi of the cetaceans for each pressure treatment. All specimens examined demonstrated significant decreases in volume with increasing pressure, with the harbor seal and common dolphin nearing complete collapse at the highest pressures. The common dolphin bronchi demonstrated distinctly different compression dynamics between 50% and 100% lung inflation treatments, indicating the importance of air in maintaining patent airways, and collapse occurred caudally to cranially in the 50% treatment. Dynamics of the harbor seal and grey seal airways indicated that the trachea was less compliant than the bronchi. These findings indicate potential species-specific variability in airway compliance, and cessation of gas exchange may occur at greater depths than those predicted in models assuming rigid airways. This may potentially increase the likelihood of decompression sickness in these animals during diving.
Keywords: Airway compression; Bronchi; Computed Tomography; Marine mammal; Trachea.
Publication
Journal: Research
May/16/2021
Abstract
Polymeric particles with intricate morphologies and properties have been developed based on bioinspired designs for applications in regenerative medicine, tissue engineering, and drug delivery. However, the fabrication of particles with asymmetric functionalities remains a challenge. Janus polymeric particles are an emerging class of material with asymmetric functionalities; however, they are predominantly spherical in morphology, made from non-biocompatible materials, and made using specialized fabrication techniques. We therefore set out to fabricate nonspherical Janus particles inspired by high aspect ratio filamentous bacteriophage using polycaprolactone polymers and standard methods. Janus high aspect ratio particles (J-HARPs) were fabricated with a nanotemplating technique to create branching morphologies selectively at one edge of the particle. J-HARPs were fabricated with maleimide handles and modified with biomolecules such as proteins and biotin. Regioselective modification was observed at the tips of J-HARPs, likely owing to the increased surface area of the branching regions. Biotinylated J-HARPs demonstrated cancer cell biotin receptor targeting, as well as directional crosslinking with spherical particles via biotin-streptavidin interactions. Lastly, maleimide J-HARPs were functionalized during templating to contain amines exclusively at the branching regions and were dual-labeled orthogonally, demonstrating spatially separated bioconjugation. Thus, J-HARPs represent a new class of bioinspired Janus material with excellent regional control over biofunctionalization.
Keywords: Janus; bioconjugation; bioinspired materials; biotin; nanotechnology; particle; polymer.
Publication
Journal: Advances in Colloid and Interface Science
December/25/2021
Abstract
Water shortages are currently becoming more and more serious due to complicated factors such as the development of the economy, environmental pollution, and climate deterioration. And it is the best solution to the problems faced by people in today's world to investigate the bionic structure of nature and explore effective methods for fog collection. Herein, we've illustrated the bionic structures of the Namib desert beetle, cactus spines, and spider silk, and we imitate and further modify the respective bionic structures, as well as construct multifunctional bionic structures to improve fog collection. In addition, we also expound the fog collection behavior of a large fog collector, and an excellent fog capture effect was achieved through studying the mesh structure, the surface modification of the mesh, and the construction of the fog collector. The advantages and limitations of fog collection by a harp fog collector were also explored. We hope that through this review, relevant researchers can have a deeper understanding of this field and thus promote the development of fog collection.
Keywords: Biomimetics; Fog collection; Raschel mesh; fog harp.
Publication
Journal: Sensors
April/2/2021
Abstract
Cameras are widely adopted for high image quality with the rapid advancement of complementary metal-oxide-semiconductor (CMOS) image sensors while offloading vision applications' computation to the cloud. It raises concern for time-critical applications such as autonomous driving, surveillance, and defense systems since moving pixels from the sensor's focal plane are expensive. This paper presents a hardware architecture for smart cameras that understands the salient regions from an image frame and then performs high-level inference computation for sensor-level information creation instead of transporting raw pixels. A visual attention-oriented computational strategy helps to filter a significant amount of redundant spatiotemporal data collected at the focal plane. A computationally expensive learning model is then applied to the interesting regions of the image. The hierarchical processing in the pixels' data path demonstrates a bottom-up architecture with massive parallelism and gives high throughput by exploiting the large bandwidth available at the image source. We prototype the model in field-programmable gate array (FPGA) and application-specific integrated circuit (ASIC) for integrating with a pixel-parallel image sensor. The experiment results show that our approach achieves significant speedup while in certain conditions exhibits up to 45% more energy efficiency with the attention-oriented processing. Although there is an area overhead for inheriting attention-oriented processing, the achieved performance based on energy consumption, latency, and memory utilization overcomes that limitation.
Keywords: ASIC; CNN; FPGA; computation at sensor; computer vision; image relevance.
Publication
Journal: PLoS ONE
March/24/2021
Abstract
Introduction: This study estimated the costs and incremental cost per case detected of screening strategies for high-grade cervical intraepithelial neoplasia (CIN2+) in women living with HIV (WLHIV) attending HIV clinics in Burkina Faso.
Methods: The direct healthcare provider costs of screening tests (visual inspection with acetic acid (VIA), VIA combined visual inspection with Lugol's iodine (VIA/VILI), cytology and a rapid HPV DNA test (careHPV)) and confirmatory tests (colposcopy, directed biopsy and systematic four-quadrant (4Q) biopsy) were collected alongside the HPV in Africa Research Partnership (HARP) study. A model was developed for a hypothetical cohort of 1000 WLHIV using data on CIN2+ prevalence and the sensitivity of the screening tests. Costs are reported in USD (2019).
Results: The study enrolled 554 WLHIV with median age 36 years (inter-quartile range, 31-41) and CIN2+ prevalence of 5.8%. The average cost per screening test ranged from US$3.2 for VIA to US$24.8 for cytology. Compared to VIA alone, the incremental cost per CIN2+ case detected was US$48 for VIA/VILI and US$814 for careHPV. Despite higher costs, careHPV was more sensitive for CIN2+ cases detected compared to VIA/VILI (97% and 56%, respectively). The cost of colposcopy was US$6.6 per person while directed biopsy was US$33.0 and 4Q biopsy was US$48.0.
Conclusion: Depending on the willingness to pay for the detection of a case of cervical cancer, decision makers in Burkina Faso can consider a variety of cervical cancer screening strategies for WLHIV. While careHPV is more costly, it has the potential to be cost-effective depending on the willingness to pay threshold. Future research should explore the lifetime costs and benefits of cervical cancer screening to enable comparisons with interventions for other diseases.
Publication
Journal: International Journal of Infectious Diseases
February/28/2021
Abstract
Objectives: Our study aimed to identify the factors influencing the delay in SARS-CoV-2 RNA negative conversion.
Methods: A cohort study including COVID-19 patients admitted to the Tunisian national containment center was conducted. The follow-up consisted of a weekly RT-PCR test. Multivariate Cox regression analysis was performed to determine independent predictors associated to negative RNA conversion.
Results: Among 264 patients included, the median duration of viral clearance was 20 days (IQR (Interquartile Range), 17-32). The shortest and longest durations were nine and 58 days, respectively. Associated factors to negative conversion of viral RNA, were symptoms such as fatigue, fever and shortness of breath (HR (Hazard Ratio): 0.600; 95% CI: 0.401-0.897) and face masks use when exposed to COVID-19 cases (HR: 2.006; 95%CI:1.247-3.228). The median time to RNA viral conversion was 18 days (IQR, 16-21) when using masks vs 23 days (IQR, 17-36) without wearing masks, and 24 days (IQR, 18-36) for symptomatic patients vs 20 days (IQR, 16-30) for asymptomatic ones.
Conclusion: Our results revealed that during SARS-CoV-2 infection, having symptoms delayed viral clearance, while wearing masks accelerated this conversion. These factors should be harp on consideration for the strategy of isolating infected patients.
Keywords: Coronavirus disease 2019 (COVID-19); SARS-CoV-2; Tunisia; negative conversion; viral shedding.
Publication
Journal: Heliyon
March/3/2021
Abstract
Background: Hippocampus segmentation on magnetic resonance imaging is of key importance for the diagnosis, treatment decision and investigation of neuropsychiatric disorders. Automatic segmentation is an active research field, with many recent models using deep learning. Most current state-of-the art hippocampus segmentation methods train their methods on healthy or Alzheimer's disease patients from public datasets. This raises the question whether these methods are capable of recognizing the hippocampus on a different domain, that of epilepsy patients with hippocampus resection. New Method: In this paper we present a state-of-the-art, open source, ready-to-use, deep learning based hippocampus segmentation method. It uses an extended 2D multi-orientation approach, with automatic pre-processing and orientation alignment. The methodology was developed and validated using HarP, a public Alzheimer's disease hippocampus segmentation dataset. Results and Comparisons: We test this methodology alongside other recent deep learning methods, in two domains: The HarP test set and an in-house epilepsy dataset, containing hippocampus resections, named HCUnicamp. We show that our method, while trained only in HarP, surpasses others from the literature in both the HarP test set and HCUnicamp in Dice. Additionally, Results from training and testing in HCUnicamp volumes are also reported separately, alongside comparisons between training and testing in epilepsy and Alzheimer's data and vice versa. Conclusion: Although current state-of-the-art methods, including our own, achieve upwards of 0.9 Dice in HarP, all tested methods, including our own, produced false positives in HCUnicamp resection regions, showing that there is still room for improvement for hippocampus segmentation methods when resection is involved.
Keywords: Alzheimer's disease; Convolutional neural networks; Deep learning; Epilepsy; Hippocampus segmentation.
Publication
Journal: ACS Applied Materials & Interfaces
August/2/2021
Abstract
It has recently been demonstrated that harps harvest substantively more fog water than conventional mesh nets, but the optimal design for fog harps remains unknown. Here, we systematically vary key parameters of a scale-model fog harp, the wire material, wire pitch, and wire length, to find the optimal combination. We found stainless steel to not only be the best hydrophilic wire material but also nearly be as effective as Teflon-coated wires. The best choice for the wire pitch was coupled to the wire length, as the smallest pitch collected the most water for short harps but was hampered by tangling for taller harps. Accordingly, we use an elastocapillary wire tangling model to successfully predict the onset of tangling beyond a critical length for any given wire pitch. Combining what we learned, we achieved a water harvesting efficiency of 17% with an optimized stainless-steel harp, over three times higher than that of the current standard of a Raschel mesh. These results suggest that an optimal fog harp should feature high-tension, uncoated wires within a large aspect ratio frame to avoid tangling and promote efficient and reliable fog harvesting.
Keywords: anticlogging; elastocapillarity; fog harp; fog harvesting; wire tangling.
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Publication
Journal: Neural Networks
October/14/2021
Abstract
In stochastic optimization problems where only noisy zeroth-order (ZO) oracles are available, the Kiefer-Wolfowitz algorithm and its randomized counterparts are widely used as gradient estimators. Existing algorithms generate the random perturbations from certain distributions with a zero mean and an isotropic (either identity or scalar) covariance matrix. In contrast, this work considers the generalization where the perturbations may have an anisotropic covariance based on the ZO oracle history. We propose to feed the second-order approximation into the covariance matrix of the random perturbation, so it is dubbed as Hessian-aided random perturbation (HARP). HARP collects two or more (depending on the specific estimator form) ZO oracle calls per iteration to construct the gradient and the Hessian estimators. We prove HARP's almost-surely convergence and derive its convergence rate under standard assumptions. We demonstrate, with theoretical guarantees and numerical experiments, that HARP is less sensitive to ill-conditioning and more query-efficient than other gradient approximation schemes whose random perturbations have an isotropic covariance.
Authors
Publication
Journal: Journal of Wildlife Diseases
August/18/2021
Abstract
Influenza viruses have been reported from marine mammals worldwide, particularly in pinnipeds, and have caused mass mortalities of seals in North America and Europe. Because influenza viruses in marine mammals can be zoonotic, our objective was to examine Canadian phocids for exposure to influenza A and B viruses in order to understand health risks to wild populations as well as to humans who consume or handle these animals. Blood was collected from 394 seals in eastern Canada from 1994 to 2005. Sera were screened for exposure to influenza viruses in three resident species of seals: harbour, Phoca vitulina (n=66); grey, Halichoerus grypus (n=82); ringed, Phoca hispida (n=2), and two migrant species: harp, Pagophilus groenlandica (n=206) and hooded, Cystophora cristata (n=38). Included were samples from captive grey (n=1) and harbour seals (n=8) at two aquaria. Sera were prescreened using indirect enzyme-linked immunosorbent assay (ELISA), and antibodies against influenza A virus were confirmed using a commercial competitive ELISA (IDEXX Europe B.V., Hoofddorp, the Netherlands). A subset of influenza A virus positive sera was used to determine common virus subtypes recognized by sera using reference strains. All positive sera in the indirect ELISA reacted with influenza A virus subtypes H3, H4, and H10 using a hemagglutination inhibition (HI) assay. Sera from harbour, grey, harp, and hooded seals had antibodies against influenza A and influenza B viruses (some cross-reactivity occurred). Overall, 33% (128/385) of wild seals were seropositive to influenza viruses, with the highest seroprevalence in harp (42%) followed by harbour (33%), grey (23%), and hooded (11%) seals. Antibodies were detected in both sexes and most age classes of wild seals. Two of eight captive harbour seals were seropositive to influenza B virus and four had cross-reactions to influenza A and B viruses. This study reports antibodies against influenza A and B viruses in four seal species from the same geographic area in eastern Canada.
Keywords: Canada; influenza viruses; seals; serology.
Publication
Journal: BioImpacts
November/26/2021
Abstract
Regional soft tissue mechanical strain offers crucial insights into tissue's mechanical function and vital indicators for different related disorders. Tagging magnetic resonance imaging (tMRI) has been the standard method for assessing the mechanical characteristics of organs such as the heart, the liver, and the brain. However, constructing accurate artifact-free pixelwise strain maps at the native resolution of the tagged images has for decades been a challenging unsolved task. In this work, we developed an end-to-end deep-learning framework for pixel-to-pixel mapping of the two-dimensional Eulerian principal strains [Formula: see text] and [Formula: see text] directly from 1-1 spatial modulation of magnetization (SPAMM) tMRI at native image resolution using convolutional neural network (CNN). Four different deep learning conditional generative adversarial network (cGAN) approaches were examined. Validations were performed using Monte Carlo computational model simulations, and in-vivo datasets, and compared to the harmonic phase (HARP) method, a conventional and validated method for tMRI analysis, with six different filter settings. Principal strain maps of Monte Carlo tMRI simulations with various anatomical, functional, and imaging parameters demonstrate artifact-free solid agreements with the corresponding ground-truth maps. Correlations with the ground-truth strain maps were R = 0.90 and 0.92 for the best-proposed cGAN approach compared to R = 0.12 and 0.73 for the best HARP method for [Formula: see text] and [Formula: see text], respectively. The proposed cGAN approach's error was substantially lower than the error in the best HARP method at all strain ranges. In-vivo results are presented for both healthy subjects and patients with cardiac conditions (Pulmonary Hypertension). Strain maps, obtained directly from their corresponding tagged MR images, depict for the first time anatomical, functional, and temporal details at pixelwise native high resolution with unprecedented clarity. This work demonstrates the feasibility of using the deep learning cGAN for direct myocardial and liver Eulerian strain mapping from tMRI at native image resolution with minimal artifacts.
Publication
Journal: Computers in Biology and Medicine
November/26/2021
Abstract
Background: Assessment of regional myocardial function at native pixel-level resolution can play a crucial role in recognizing the early signs of the decline in regional myocardial function. Extensive data processing in existing techniques limits the effective resolution and accuracy of the generated strain maps. The purpose of this study is to compute myocardial principal strain maps εp1 and εp2 from tagged MRI (tMRI) at the native image resolution using deep-learning local patch convolutional neural network (CNN) models (DeepStrain).
Methods: For network training, validation, and testing, realistic tMRI datasets were generated and consisted of 53,606 cine images simulating the heart, the liver, blood pool, and backgrounds, including ranges of shapes, positions, motion patterns, noise, and strain. In addition, 102 in-vivo image datasets from three healthy subjects, and three Pulmonary Arterial Hypertension patients, were acquired and used to assess the network's in-vivo performance. Four convolutional neural networks were trained for mapping input tagging patterns to corresponding ground-truth principal strains using different cost functions. Strain maps using harmonic phase analysis (HARP) were obtained with various spectral filtering settings for comparison. CNN and HARP strain maps were compared at the pixel level versus the ground-truth and versus the least-loss in-vivo maps using Pearson correlation coefficients (R) and the median error and Inter-Quartile Range (IQR) histograms.
Results: CNN-based local patch DeepStrain maps at a phantom resolution of 1.1mm × 1.1 mm and in-vivo resolution of 2.1mm × 1.6 mm were artifact-free with multiple fold improvement with εp1 ground-truth median error of 0.009(0.007) vs. 0.32(0.385) using HARP and εp2 ground-truth error of 0.016(0.021) vs. 0.181(0.08) using HARP. CNN-based strain maps showed substantially higher agreement with the ground-truth maps with correlation coefficients R > 0.91 for εp1 and εp2 compared to R < 0.21 and R < 0.82 for HARP-generated maps, respectively.
Conclusion: CNN-generated Eulerian strain mapping permits artifact-free visualization of myocardial function at the native image resolution.
Keywords: Convolutional neural network; Deep learning; DeepStrain; Harmonic phase; Myocardial strain mapping; Tagging MRI.
Publication
Journal: Sensors
April/29/2021
Abstract
Hippocampus atrophy is an early structural feature that can be measured from magnetic resonance imaging (MRI) to improve the diagnosis of neurological diseases. An accurate and robust standardized hippocampus segmentation method is required for reliable atrophy assessment. The aim of this work was to develop and evaluate an automatic segmentation tool (DeepHarp) for hippocampus delineation according to the ADNI harmonized hippocampal protocol (HarP). DeepHarp utilizes a two-step process. First, the approximate location of the hippocampus is identified in T1-weighted MRI datasets using an atlas-based approach, which is used to crop the images to a region-of-interest (ROI) containing the hippocampus. In the second step, a convolutional neural network trained using datasets with corresponding manual hippocampus annotations is used to segment the hippocampus from the cropped ROI. The proposed method was developed and validated using 107 datasets with manually segmented hippocampi according to the ADNI-HarP standard as well as 114 multi-center datasets of patients with Alzheimer's disease, mild cognitive impairment, cerebrovascular disease, and healthy controls. Twenty-three independent datasets manually segmented according to the ADNI-HarP protocol were used for testing to assess the accuracy, while an independent test-retest dataset was used to assess precision. The proposed DeepHarp method achieved a mean Dice similarity score of 0.88, which was significantly better than four other established hippocampus segmentation methods used for comparison. At the same time, the proposed method also achieved a high test-retest precision (mean Dice score: 0.95). In conclusion, DeepHarp can automatically segment the hippocampus from T1-weighted MRI datasets according to the ADNI-HarP protocol with high accuracy and robustness, which can aid atrophy measurements in a variety of pathologies.
Keywords: ADNI harmonized hippocampal protocol; convolutional neural network; hippocampus; magnetic resonance imaging; segmentation.
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