Publications by authors named "Alexander Chen"

Coronary-pulmonary artery fistulas (CPAFs) are rare entities that can cause significant left-to-right shunting and complicate routine coronary artery bypass grafting. There are no best practice guidelines and a scarcity of reports regarding concomitant treatment of CPAF with coronary artery disease. We present a case of bilateral CPAFs in a 60-year-old man with symptomatic coronary artery disease treated successfully with coronary artery bypass, epicardial ligation, and transpulmonary closure of CPAF with patch reconstruction.

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Background: Testing for targeting programmed death ligand 1 (PD-L1) is standard of care for patients with newly diagnosed non-small cell lung cancer (NSCLC) but is only approved for use with core biopsy specimens. Endobronchial ultrasound guided miniforceps biopsy (EBUS-MFB) is an approach to obtain core biopsy material but data assessing the ability of EBUS-MFB to adequately test for PD-L1 is lacking. We evaluate the feasibility of EBUS-MFB to acquire adequate tissue for PD-L1 testing and look to compare the quality of specimens between EBUS-MFB and endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) using a standard method of tissue analysis.

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  • The research highlights significant racial and ethnic disparities in excess mortality during the COVID-19 pandemic, revealing a concerning trend concerning minoritized populations who faced greater mortality rates compared to pre-pandemic disparities.!* -
  • A comprehensive analysis of over 10.6 million death certificates from March 2020 to May 2023 indicated that more than 1.38 million excess deaths occurred, representing around 23 million years of potential life lost.!* -
  • The findings emphasize the need for further investigation into the age-specific impact of COVID-19 on various racial and ethnic groups to better understand and address these health disparities moving forward.!*
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The root parasitic weed has a devastating effect on sorghum and other cereal crops in Sub-Saharan Africa. Available Striga management strategies are rarely sufficient or not widely accessible or affordable. Identification of soil- or plant-associated microorganisms that interfere in the Striga infection cycle holds potential for development of complementary biological control measures.

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 Virtual reality (VR) is an increasingly valuable teaching tool, but current simulators are not typically clinically scalable due to their reliance on inefficient manual segmentation. The objective of this project was to leverage a high-throughput and accurate machine learning method to automate data preparation for a patient-specific VR simulator used to explore preoperative sinus anatomy.  An endoscopic VR simulator was designed in to enable interactive exploration of sinus anatomy.

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  • Recent studies show that GPT-4V outperforms human doctors in medical tasks, but mostly focused on multi-choice question accuracy.
  • Our research expands this by analyzing GPT-4V's reasoning skills and image comprehension in NEJM Image Challenges, finding its multi-choice accuracy is similar to human physicians (81.6% vs. 77.8%).
  • Despite high accuracy, GPT-4V frequently offers flawed explanations (35.5%) for its correct answers, highlighting the need for deeper evaluations before using AI in clinical settings.
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We performed a systematic review and meta-analysis of hypertension in people living with human immunodeficiency virus (HIV) in sub-Saharan Africa (SSA). We searched the PubMed, Google Scholar, African Index Medicus, and Embase databases to identify studies published from January 1, 2010, to December 31, 2021. We used a random-effects model to estimate the pooled prevalence of hypertension and mean SBP/DBP level on a sex-specific basis.

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Durable and conductive interfaces that enable chronic and high-resolution recording of neural activity are essential for understanding and treating neurodegenerative disorders. These chronic implants require long-term stability and small contact areas. Consequently, they are often coated with a blend of conductive polymers and are crosslinked to enhance durability despite the potentially deleterious effect of crosslinking on the mechanical and electrical properties.

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  • The study highlights the lack of data on adolescents in sub-Saharan Africa with elevated blood pressure (BP) and its long-term cardiovascular risks.
  • Using meta-analysis from over 37,000 adolescents, it found that 7.2% of 10-14 year-olds and 13.0% of 15-19 year-olds in SSA have elevated BP.
  • The research estimates that between 201,000 to 503,000 excess cardiovascular events could be linked to hypertension in those transitioning from adolescence to adulthood.
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Electrotactile stimulus is a form of sensory substitution in which an electrical signal is perceived as a mechanical sensation. The electrotactile effect could, in principle, recapitulate a range of tactile experience by selective activation of nerve endings. However, the method has been plagued by inconsistency, galvanic reactions, pain and desensitization, and unwanted stimulation of nontactile nerves.

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Single-line-defect (W1) photonic crystal waveguides hold significant promise for various applications in integrated photonics due to their ability to induce slow light across wide photonic band ranges. Ensuring the manufacturing reliability of these devices is paramount for their practical implementation, as they tend to be highly sensitive to fabrication deviations. In this study, we investigated the manufacturing reliability of photonic crystal waveguides fabricated at the Albany Nanotech Complex foundry by comparing the consistency of band-edge locations and group indices across 14 chips.

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Introduction And Objectives: Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and can progress to non-alcoholic steatohepatitis (NASH) and, ultimately, cirrhosis. Clostridioides difficile is the most common nosocomial cause of diarrhea and is associated with worse clinical outcomes in other liver diseases, including cirrhosis, but has not been extensively evaluated in concomitant NAFLD/NASH.

Materials And Methods: We conducted a retrospective cohort study using the National Inpatient Sample database from 2015 to 2017.

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This study evaluates the effectiveness of myocardial matrix (MM) hydrogels in mitigating negative right ventricular (RV) remodeling in a rat model of RV heart failure. The goal was to assess whether a hydrogel derived from either the right or left ventricle could promote cardiac repair. Injured rat right ventricles were injected with either RV-or left ventricular-derived MM hydrogels.

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Hepatic encephalopathy (HE) is a neuropsychiatric syndrome that is observed primarily in patients with liver disease. The pathophysiology is complex and involves many factors including ammonia toxicity, dysregulation of central nervous system activity, and excess inflammatory cytokines. Symptoms of HE range from subclinical to debilitating.

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Sorghum bicolor is among the most important cereals globally and a staple crop for smallholder farmers in sub-Saharan Africa. Approximately 20% of sorghum yield is lost annually in Africa due to infestation with the root parasitic weed Striga hermonthica. Existing Striga management strategies are not singularly effective and integrated approaches are needed.

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Superlattice formation afforded by metal halide perovskite nanocrystals has been a phenomenon of interest due to the high structural order induced in these self-assemblies, an order that is influenced by the surface chemistry and particle morphology of the starting building block material. In this work, we report on the formation of superlattices from aluminum oxide shelled CsPbBr perovskite nanocrystals where the oxide shell is grown by colloidal atomic layer deposition. We demonstrate that the structural stability of these superlattices is preserved over 25 days in an inert atmosphere and that colloidal atomic layer deposition on colloidal perovskite nanocrystals yields structural protection and an enhancement in photoluminescence quantum yields and radiative lifetimes as opposed to gas phase atomic layer deposition on pre-assembled superlattices or excess capping group addition.

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  • SARS-CoV-2, the virus responsible for COVID-19, was identified in 2019 and has led to a significant global health crisis.
  • The study evaluated the effectiveness of various serological tests for detecting SARS-CoV-2 specific antibodies, including in-house ELISA and commercial assays, using samples from confirmed COVID-19 patients and a control group.
  • All tests showed high sensitivity (95.4-96.6%) and diagnostic accuracy, but the researchers emphasized the need for independent evaluations to enhance the interpretation of serological test results.
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Current rates of reported pediatric femoral hernias remain exceedingly low, with their incidence reported to be <1%. The mainstay of repair has traditionally been through an open approach, and pediatric surgeons remain reluctant to repair otherwise. Owing to its rarity, consensus regarding management remains absent.

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Recent studies indicate that Generative Pre-trained Transformer 4 with Vision (GPT-4V) outperforms human physicians in medical challenge tasks. However, these evaluations primarily focused on the accuracy of multi-choice questions alone. Our study extends the current scope by conducting a comprehensive analysis of GPT-4V's rationales of image comprehension, recall of medical knowledge, and step-by-step multimodal reasoning when solving (NEJM) Image Challenges - an imaging quiz designed to test the knowledge and diagnostic capabilities of medical professionals.

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Background: Radial probe endobronchial ultrasound (R-EBUS) is often utilized in guided bronchoscopy for the diagnosis of peripheral pulmonary lesions. R-EBUS probe positioning has been shown to correlate with diagnostic yield, but overall diagnostic yield with this technology has been inconsistent across the published literature. Currently there is no standardization for R-EBUS image interpretation, which may result in variability in grading concentricity of lesions and subsequently procedure performance.

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  • Wine tasting involves a complex interplay of sensory perception, language, and memory, and this process is distinctly different between trained sommeliers and casual wine drinkers.
  • Research using advanced brain imaging techniques shows that sommeliers have a unique brain structure and function that allows them to process flavors and articulate their experiences better than non-experts.
  • The study highlights how sommelier training improves their ability to recognize wine complexity by enhancing the connections between sensory processing and semantic network areas in the brain.
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  • The COVID-19 pandemic has led to extensive global data collection on nasal swabs, showing significant variations in viral loads among positive test results.
  • The study explores if this variability is specific to SARS-CoV-2 or typical of viral respiratory infections by using a detailed computational model of nasal infections.
  • By simulating factors like individual physiological differences and immune responses, researchers create a "virtual population database" that illustrates the distribution of viral titers during the first 48 hours post-infection.
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  • The incidence of colorectal cancer in patients under 50 has increased significantly, now representing up to 25% of total cases, raising concerns about early-onset CRC and the need for timely detection.
  • A retrospective study analyzed claims data from 2007 to 2017 to identify risk factors in different age groups, highlighting that younger patients (18-50) were more likely to be female and obese, especially morbidly obese.
  • Common symptoms in the younger cohort included abdominal pain, hematochezia, weight loss, and anemia, indicating specific clinical features that could aid in early diagnosis.
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Background: Inflammatory pseudotumor (IPT) is a rare and benign lesion that mimics malignancy and can develop in any part of the body. The pathophysiology and etiology of these quasineoplastic lesions remain unclear.

Case Summary: We report a case of a 65-year-old male who presented with fevers, night sweats, and unintentional weight loss following an influenza infection and was found to have multiple hepatic IPT's following an extensive work up.

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Nanosized particles of liquid metals are emerging materials that hold promise for applications spanning from microelectronics to catalysis. Yet, knowledge of their chemical reactivity is largely unknown. Here, we study the reactivity of liquid Ga and Cu nanoparticles under the application of a cathodic voltage.

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