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The hydrodynamic cell splitter splits single-cell ciliate Stentor coeruleus using a microfluidic cross junction at a high throughput of 500 cells min−1. Fragment viability decreases with increasing hydrodynamic stress and decreasing fragment size.

Inanimate objects or surfaces contaminated with infectious agents, referred to as fomites, play an important role in the spread of viruses, including SARS-CoV-2, the virus responsible for the COVID-19 pandemic. The long persistence of viruses (hours to days) on surfaces calls for an urgent need for effective surface disinfection strategies to intercept virus transmission and the spread of diseases. Elucidating the physicochemical processes and surface science underlying the adsorption and transfer of virus between surfaces, as well as their inactivation, is important for understanding how diseases are transmitted and for developing effective intervention strategies. This review summarizes the current knowledge and underlying physicochemical processes of virus transmission, in particular via fomites, and common disinfection approaches. Gaps in knowledge and the areas in need of further research are also identified. The review focuses on SARS-CoV-2, but discussion of related viruses is included to provide a more comprehensive review given that much remains unknown about SARS-CoV-2. Our aim is that this review will provide a broad survey of the issues involved in fomite transmission and intervention to a wide range of readers to better enable them to take on the open research challenges.

Stentor coeruleus, a single-cell ciliated protozoan, is a model organism for wound healing and regeneration studies. Despite Stentor’s large size (up to 2 mm in extended state), microdissection of Stentor remains challenging. In this work, we describe a hydrodynamic cell splitter, consisting of a cross junction, capable of splitting Stentor cells in a non-contact manner at a high throughput of ∼500 cells/min under continuous operation. Introduction of asymmetry in the flow field at the cross junction leads to asymmetric splitting of the cells to generate cell fragments as small as ∼8.5 times the original cell size. Characterization of cell fragment viability shows reduced 5-day survival as fragment size decreases and as the extent of hydrodynamic stress imposed on the fragments increases. Our results suggest that cell fragment size and composition, as well as mechanical stress, play important roles in the long-term repair of Stentor cells and warrant further investigations. Nevertheless, the hydrodynamic splitter can be useful for studying phenomena immediately after cell splitting, such as the closure of wounds in the plasma membrane which occurs on the order of 100 – 1000 seconds in Stentor.

Background The goal of this study was to evaluate efficacy and safety of 90Y radioembolization for neuroendocrine liver metastases (NELM) in a multicenter registry. Methods One hundred-seventy patients with NELM were enrolled in the registry (NCT 02685631). Prior treatments included hepatic resection (n = 23, 14%), arterial therapy (n = 62, 36%), octreotide (n = 119, 83%), cytotoxic chemotherapy (n = 58, 41%), biologic therapy (n = 49, 33%) and immunotherapy (n = 10, 6%). Seventy-seven (45%) patients had extrahepatic disease. Seventy-eight (48%), 61 (37%), and 25 (15%) patients were Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or ≥ 2. Tumor grade was known in 81 (48%) patients: 57 (70%) were well-, 12 (15%) moderate-, and 12 (15%) poorly-differentiated. Kaplan-Meier analysis and log rank tests were performed to compare overall and progression-free survival (OS/PFS) by tumor location and grade. Toxicities were reported using Common Terminology Criteria for Adverse Events v.5. Cox Proportional Hazards were calculated for pancreatic primary, performance status, extrahepatic disease at treatment, unilobar treatment, baseline ascites, and > 25% tumor burden. Results One, 2, and 3-year OS rates were 75, 62 and 46%, respectively. Median OS was 33 months [(95% CI: 25-not reached (NR)]. The longest median OS was in patients with pancreatic (42 months, 95% CI: 33-NR) and hindgut 41 months, 95% CI: 12-NR) primaries. The shortest OS was in foregut primaries (26 months; 95% CI: 23-NR; X2 = 7, p = 0.1). Median OS of well-differentiated tumors was 36 months (95% CI: 10-NR), compared to 44 (95% CI: 7-NR) and 25 (95% CI: 3-NR) months for moderate and poorly differentiated tumors. Median progression-free survival (PFS) was 25 months with 1, 2, and 3-year PFS rates of 70, 54, and 35%, respectively. Thirteen patients (7.6%) developed grade 3 hepatic toxicity, most commonly new ascites (n = 8, 5%) at a median of 5.5 months. Performance status of ≥2 (HR 2.7, p = 0.01) and baseline ascites (HR 2.8, P = 0.049) predicted shorter OS. Discussion In a population with a high incidence of extrahepatic disease, 90Y was effective and safe in treatment of NELM, with median OS of 41 months for well differentiated tumors. Grade 3 or greater hepatic toxicity was developed in 7.6% of patients. Trial registration NCT 02685631.

Micro-blade design is an important factor in the cutting of single cells and other biological structures. This paper describes the fabrication process of three dimensional (3D) micro-blades for the cutting of single cells in a microfluidic “guillotine” intended for fundamental wound repair and regeneration studies. Our microfluidic guillotine consists of a fixed 3D micro-blade centered in a microchannel to bisect cells flowing through. We show that the Nanoscribe two-photon polymerization direct laser writing system is capable of fabricating complex 3D micro-blade geometries. However, structures made of the Nanoscribe IP-S resin have low adhesion to silicon, and they tend to peel off from the substrate after at most two times of replica molding in poly(dimethylsiloxane) (PDMS). Our work demonstrates that the use of a secondary mold replicates Nanoscribe printed features faithfully for at least 10 iterations. Finally, we show that complex micro-blade features can generate different degrees of cell wounding and cell survival rates compared with simple blades possessing a vertical cutting edge fabricated with conventional 2.5D photolithography. Our work lays the foundation for future applications in single cell analyses, wound repair and regeneration studies, as well as investigations of the physics of cutting and the interaction between the micro-blade and biological structures.

Microscale surgery on single cells and small organisms have enabled major advances in fundamental biology and in engineering biological systems. Examples of applications range from wound healing and regeneration studies to the generation of hybridoma to produce monoclonal antibodies. Even today, these surgical operations are often performed manually, but they are labor-intensive and lack reproducibility. Microfluidics has emerged as a powerful technology to control and manipulate cells and multicellular systems at the micro- and nanoscale with high precision. Here, we review the physical and chemical mechanisms of microscale surgery, and the corresponding design principles, applications, and implementations in microfluidic systems. We consider four types of surgical operations: 1) Sectioning, which splits a biological entity into multiple parts, 2) ablation, which destroys part of an entity, 3) biopsy, which extracts materials from within a living cell, and 4) fusion, which joins multiple entities into one. For each type of surgery, we summarize the motivating applications and the microfluidic devices developed. Throughout the review, we highlight existing challenges and opportunities. We hope that this review will inspire scientists and engineers to continue to explore and improve microfluidic surgical methods.

Quantification of the simultaneous contributions of loci to multiple traits, a phenomenon called pleiotropy, is facilitated by the increased availability of high-throughput genotypic and phenotypic data. To understand the prevalence and nature of pleiotropy, the ability of multivariate and univariate genome-wide association study (GWAS) models to distinguish between pleiotropic and non-pleiotropic loci in linkage disequilibrium (LD) first need to be evaluated. Therefore, we used publicly available maize and soybean genotypic data to simulate multiple pairs of traits that were either i) controlled by quantitative trait nucleotides (QTNs) on separate chromosomes, ii) controlled by QTNs in various degrees of LD with each other, or iii) controlled by a single pleiotropic QTN. In addition to confirming that multivariate GWAS was either equal to or more powerful than univariate GWAS, we also showed that multivariate GWAS could not distinguish between QTNs in LD and a single pleiotropic QTN. In contrast, a unique QTN detection rate pattern was observed whenever the simulated QTNs were in high LD or pleiotropic. Collectively, these results suggest that multivariate and univariate GWAS should both be used to infer whether or not causal mutations underlying peak GWAS associations are pleiotropic. Therefore, we recommend that future studies use a combination of multivariate and univariate GWAS models, as both models could be useful for identifying and narrowing down candidate loci with potential pleiotropic effects for downstream biological experiments.

Wound healing is an essential biological process for maintaining homeostasis and, ultimately, for survival. Cells, such as skeletal muscles, are wounded regularly under physiological conditions. Understanding wound response at the single-cell level is critical for determining fundamental cellular functions needed for cell repair and survival, and ultimately, how wound-induced diseases such as muscular dystrophies develop. Key barriers to answering these questions are the lack of a tool that can introduce wounds reproducibly to a large number of cells and a quantitative assay to measure healing efficiency. We aim to develop a microfluidic platform to investigate the mechanisms underlying single-cell wound healing using Stentor coeruleus as a model organism.

AIM To develop an easily-administered metric to quantify gait impairment in children and to assess its use in children with cerebral palsy (CP). METHOD The Pediatric Temporal-spatial Deviation Index (TDI) was developed from gait data collected from 75 typically developing children (37 males, 38 females; mean age 9y 4mo; interquartile range [IQR] 8-10y) and 17 children diagnosed with spastic CP (nine males, eight females; mean age 9y 9mo; IQR 9-11y), in Gross Motor Function Classification System (GMFCS) levels I to III, aged 7 to 11 years. Children walked on a pressure-sensitive mat. Children with CP also completed 3D gait analysis. The Kaiser-Meyer-Olkin test of sampling adequacy was used for temporal-spatial feature selection. Principal components obtained from temporal-spatial gait parameters quantified deviation from typically developing gait. Deviation was normalized to a Pediatric TDI score mean (standard deviation [SD]) of 100 (10). The Pediatric TDI for children with CP was compared to 3D motion capture-based Gait Deviation Index (GDI). RESULTS The Pediatric TDI was significantly lower for children with CP compared to typically developing children (p

The Billups–Birch Reduction chemistry has been shown to functionalize single-walled carbon nanotubes (SWCNTs) without damaging the sidewalls, but has challenges in scalability. Currently published work uses a large mole ratio of Li to carbon atoms in the SWCNT (Li:C) to account for lithium amide formation, however this increases the cost and hazard of the reaction. We report here the systematic understanding of the effect of various parameters on the extent of functionalization using resonant Raman spectroscopy. Addition of 1-iodododecane yielded alkyl-functionalized SWCNTs, which were isolated by solvent extraction and evaporation, and purified by a hydrocarbon wash. The presence of SWCNT growth catalyst residue (Fe) was shown to have a strong adverse effect on SWCNT functionalization. Chlorination-based SWCNT purification reduced the amount of residual Fe, and achieve a maximum ID/IG ratio using a Li:C ratio of 6:1 in a reaction time of 30 min. This result is consistent with published literature requiri...

A prototype design of a reactor for scalable functionalization of SWCNTs by the reaction of alkyl halides with Billups-Birch reduced SWCNTs is described. The Hauge apparatus is designed to allow for the safe handling of all the reagents and products under an inert atmosphere at controlled temperatures. The extent of reaction of Li/NH3 solution with the SWCNTs is measured in-situ by solution conduction, while homogenous mixing is ensured by the use of a homogenizer, and thermocouple are placed at different heights within the reactor flask. Addition of an alkyl halide yield alkyl-functionalized SWCNTs, which may be isolated by solvent extraction leaving a solid sample that is readily purified by hydrocarbon extraction. As an example, reaction of SWCNT/Li/NH3 with 1-iododecane yields dodecane-functionalized SWCNTs (C12-SWCNTs), which have been characterized by TG/DTA, XPS, and Raman spectroscopy. Sample extraction during the reaction allows for probing of the rate of the reaction in order to determine the end point of the reaction, which for C12-SWCNTs (at −78 °C) is 30 min.

PURPOSE To describe the outcome of surgical bleb revision for late-onset bleb leaks after trabeculectomy. PATIENTS AND METHODS Appropriate cases were identified. Qualified and complete success required intraocular pressure of 21 mm Hg or less with and without glaucoma medication use, respectively. Bleb survival was determined using Kaplan-Meier survival analysis, and overall success rate was defined as qualified success at last follow-up. Preoperative and postoperative ocular parameters were compared using the signed-rank test. Age, sex, ethnicity, time between leak and revision, and surgeon type (attending vs. surgeons in training) were entered into a logistic regression analysis to assess the impact on surgical outcome. RESULTS Seventy-eight eyes of 75 patients were included. The overall rate of successful bleb revision was 77%, and qualified and complete success at 24 months was 71% and 34%, respectively. Postoperative complications included early and late bleb leaks in 6% and 9% of the eyes, respectively; bleb-related infections in 4% of the eyes; and the need for additional glaucoma surgery in 10% of the eyes. There was no difference in preoperative and postoperative visual acuity (P=0.34) but there was an increase in intraocular pressure (P

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome or drug-induced hypersensitivity is a potentially life-threatening drug hypersensitivity syndrome most commonly associated with anticonvulsants, allopurinol, long-acting sulfonamides, dapsone, and minocycline. In the setting of HIV infection, the antiretroviral medicines abacavir, nevirapine, and efavirenz have all shown well-documented associations with DRESS syndrome. There has only been one case (in a poster presentation) of this syndrome in a patient who was taking raltegravir.

Purpose To describe a series of cases of orbital inflammatory disorders in children. Design Retrospective case series. Methods The medical records of pediatric patients diagnosed with orbital inflammation between September 1, 2002, and December 31, 2008, at Texas Children's Hospital were reviewed. Data collected included age at presentation, final diagnosis, treatment, workup and evaluation, need for biopsy and biopsy results, and involvement of lacrimal gland and muscles. Results Twelve cases were identified. Six cases were males and 6 were females with age at presentation ranging from 1.3 to 16.2 years (mean, 11.9 years). The most common presentation was lacrimal gland enlargement, which was bilateral in 3 cases. Other common presenting signs were proptosis, extraocular motility limitation, and pain on eye movement. Half of our patients had systemic complaints at presentation, the most common of which was fever. Four patients were diagnosed as having a systemic cause and 2 of these patients had systemic symptoms. Conclusions Idiopathic orbital inflammatory conditions in children are uncommon, but can be associated with systemic conditions. Patients typically have lacrimal gland involvement, pain with eye movement, proptosis, and motility deficits at presentation. Bilateral cases may have a higher incidence of systemic disease.