Not just binary: embracing the complexity of nuclear division dynamics.

Cell division presents a challenge for eukaryotic cells: how can chromosomes effectively segregate within the confines of a membranous nuclear compartment? Different organisms have evolved diverse solutions by modulating the degree of nuclear compartmentalization, ranging from complete nuclear envelope breakdown to complete maintenance of nuclear compartmentalization via nuclear envelope expansion. Many intermediate forms exist between these extremes, suggesting that nuclear dynamics during cell division are surprisingly plastic. In this review, we highlight the evolutionary diversity of nuclear divisions, focusing on two defining characteristics: (1) chromosome compartmentalization and (2) nucleocytoplasmic transport. Further, we highlight recent evidence that nuclear behavior during division can vary within different cellular contexts in the same organism. The variation observed within and between organisms underscores the dynamic evolution of nuclear divisions tailored to specific contexts and cellular requirements. In-depth investigation of diverse nuclear divisions will enhance our understanding of the nucleus, both in physiological and pathological states.

Meiotic nuclear pore complex remodeling provides key insights into nuclear basket organization.

Nuclear pore complexes (NPCs) are large proteinaceous assemblies that mediate nuclear compartmentalization. NPCs undergo large-scale structural rearrangements during mitosis in metazoans and some fungi. However, our understanding of NPC remodeling beyond mitosis remains limited. Using time-lapse fluorescence microscopy, we discovered that NPCs undergo two mechanistically separable remodeling events during budding yeast meiosis in which parts or all of the nuclear basket transiently dissociate from the NPC core during meiosis I and II, respectively. Meiosis I detachment, observed for Nup60 and Nup2, is driven by Polo kinase-mediated phosphorylation of Nup60 at its interface with the Y-complex. Subsequent reattachment of Nup60-Nup2 to the NPC core is facilitated by a lipid-binding amphipathic helix in Nup60. Preventing Nup60-Nup2 reattachment causes misorganization of the entire nuclear basket in gametes. Strikingly, meiotic nuclear basket remodeling also occurs in the distantly related fission yeast, Schizosaccharomyces pombe. Our study reveals a conserved and developmentally programmed aspect of NPC plasticity, providing key mechanistic insights into the nuclear basket organization.

Evaluation of a self-cleaning portable dust collector for reducing worker exposures to silica at hydraulic-fracturing sites.

National Institute for Occupational Safety and Health (NIOSH) researchers continue to study worker exposure to respirable crystalline silica (RCS) and develop interventions to reduce these exposures. Occupational overexposures to RCS continue to cause illness and deaths in many industries and RCS has been identified as a serious exposure risk associated with hydraulic- fracturing operations during oil and gas extraction. In 2016 the Occupational Safety and Health Administration (OSHA) reduced the permissible exposure limit (PEL) to 0.05 milligrams of silica per cubic meter of air, averaged over an 8-hour day. This mandate requires hydraulic-fracturing operations to implement dust controls and safer work methods to protect workers from silica exposures above this PEL by June 23, 2021. At hydraulic-fracturing sites utilizing sand movers, pneumatic transfer of fracking sand is the primary source of aerosolized RCS. Currently, there are limited commercially available engineering controls for the collection of dust emitted from thief hatches on sand movers. The goal of this research is to develop a robust, cost-effective, weather resistant, portable, self-cleaning dust collection system that can be retrofitted onto sand mover thief hatches. A prototype was designed, built, and tested, and it was determined that the system could handle flows in the range of 600 to 1300 cfm with loading/cleaning cycle times of 40 and 5 minutes respectively and demonstrated operating efficiencies of 97-99%. Further development of this NIOSH prototype is being done in collaboration with an industry partner with the goal of developing a commercially viable, cost-effective solution to reduce RCS at hydraulic-fracturing sites around the world.Implications: This research has verified that airborne dust created by pneumatic transfer of fracking sand can be effectively collected using a passive cartridge filter system, and that the filters can be cleaned using blasts of air. Mounting these units to the thief hatches of sand movers will significantly reduce dust emissions from sand movers on hydraulic fracturing sites. Thus, this system offers the Oil and Gas Industry a method to reduce worker exposure to RCS on hydraulic fracturing sites that utilize sand movers. The success of this prototype has led researchers to devise a modified version for collecting dust at conveyor transfer points.

Impact analysis of expanding narrow-spectrum antibiotic use for children with ear, sinus and throat infections.

Aim: Estimate the impacts treating acute respiratory tract infections (ARTIs) in children aged 6 months through 12 years with narrow-spectrum antibiotics. Materials & methods: Decision-tree model to estimate children's health, healthcare utilization and costs, and caregiver's time and costs for using narrow-spectrum antibiotics in eligible children with an ARTI, compared with current use of narrow- and broad-spectrum antibiotics. Results: Reduced adverse drug reactions by 35,750 (14%) cases) and 4750 (12%) fewer emergency department visits, 300 (12%) fewer hospitalizations, and 50,500 (10%) avoided outpatient visits. Annual healthcare costs fell by US$120 million (22%). Total societal costs declined by US$131 million (20%). Conclusion: National implementation of narrow-spectrum antibiotics to treat ARTIs in children improves patient outcomes and reduces caregiver burden and annual healthcare costs.

An economic evaluation of reducing colorectal cancer surveillance intensity.

Aim: Analyze the impact of national implementation of 'low intensity' post-treatment colorectal cancer surveillance compared with current practices. Materials & methods: Create a population-level Markov model to estimate impacts of expansion of low versus high intensity surveillance post-treatment on healthcare utilization, costs and caregiver time loss. Results: Shifting to low intensity colorectal cancer surveillance would reduce patient burden by 301,830 h per patient annually over 5 years. Cost reductions over 5 years were US$43.5 million for Medicare and US$4.2 million for Medicaid. Total societal cost savings equaled US$104.2 million. Conclusion: National implementation of low intensity post-treatment colorectal cancer surveillance has the potential to significantly reduce burden and costs on patients and their caregivers with no added risks to health.

Cellular quality control during gametogenesis.

A hallmark of aging is the progressive accumulation of cellular damage. Age-induced damage arises due to a decrease in organelle function along with a decline in protein quality control. Although somatic tissues deteriorate with age, the germline must maintain cellular homeostasis in order to ensure the production of healthy progeny. While germline quality control has been primarily studied in multicellular organisms, recent evidence suggests the existence of gametogenesis-specific quality control mechanisms in unicellular eukaryotes, highlighting the evolutionary conservation of meiotic events beyond chromosome morphogenesis. Notably, budding yeast eliminates age-induced damage during meiotic differentiation, employing novel organelle and protein quality control mechanisms to produce young and healthy gametes. Similarly, organelle and protein quality control is present in metazoan gametogenesis; however, whether and how these mechanisms contribute to cellular rejuvenation requires further investigation. Here, we summarize recent findings that describe organelle and protein quality control in budding yeast gametogenesis, examine similar quality control mechanisms in metazoan development, and identify research directions that will improve our understanding of meiotic cellular rejuvenation.

The dynamic nuclear periphery as a facilitator of gamete health and rejuvenation.

The nuclear periphery is a hotspot for the accumulation of age-induced damage in eukaryotic cells. The types of damage that occur at the periphery and their phenotypic consequences have begun to be characterized; however, the mechanisms by which cells repair or eliminate nuclear damage remain poorly understood. Using budding yeast meiosis as a natural system to study cellular rejuvenation, we recently discovered a novel nuclear quality control event, in which age-induced damage is sequestered away from dividing chromosomes to a discarded nuclear compartment that we term the GUNC (for "Gametogenesis Uninherited Nuclear Compartment"). Interestingly, extensive nuclear remodeling occurs even in young cells, including a surprising modularity of the nuclear pore complex, suggesting a general contribution to gamete fitness. In this review, we discuss these findings in the context of recent evidence that the nuclear periphery is a highly dynamic region critical for cellular health.

Spatial Release from Masking Using Clinical Corpora: Sentence Recognition in a Colocated or Spatially Separated Speech Masker.

BACKGROUND: Speech recognition in complex multisource environments is challenging, particularly for listeners with hearing loss. One source of difficulty is the reduced ability of listeners with hearing loss to benefit from spatial separation of the target and masker, an effect called spatial release from masking (SRM). Despite the prevalence of complex multisource environments in everyday life, SRM is not routinely evaluated in the audiology clinic. PURPOSE: The purpose of this study was to demonstrate the feasibility of assessing SRM in adults using widely available tests of speech-in-speech recognition that can be conducted using standard clinical equipment. RESEARCH DESIGN: Participants were 22 young adults with normal hearing. The task was masked sentence recognition, using each of five clinically available corpora with speech maskers. The target always sounded like it originated from directly in front of the listener, and the masker either sounded like it originated from the front (colocated with the target) or from the side (separated from the target). In the real spatial manipulation conditions, source location was manipulated by routing the target and masker to either a single speaker or to two speakers: one directly in front of the participant, and one mounted in an adjacent corner, 90° to the right. In the perceived spatial separation conditions, the target and masker were presented from both speakers with delays that made them sound as if they were either colocated or separated. RESULTS: With real spatial manipulations, the mean SRM ranged from 7.1 to 11.4 dB, depending on the speech corpus. With perceived spatial manipulations, the mean SRM ranged from 1.8 to 3.1 dB. Whereas real separation improves the signal-to-noise ratio in the ear contralateral to the masker, SRM in the perceived spatial separation conditions is based solely on interaural timing cues. CONCLUSIONS: The finding of robust SRM with widely available speech corpora supports the feasibility of measuring this important aspect of hearing in the audiology clinic. The finding of a small but significant SRM in the perceived spatial separation conditions suggests that modified materials could be used to evaluate the use of interaural timing cues specifically.

Incidence, deaths, and lifetime costs of injury among American Indians and Alaska Natives.

BACKGROUND: In the United States, the mortality burden of injury is higher among American Indians and Alaska Natives (AI/AN) than any other racial/ethnic group, and injury contributes to considerable medical costs, years of potential life lost (YPLL), and productivity loss among AI/AN.This study assessed the economic burden of injuries for AI/AN who are eligible for services through Indian Health Service, analyzing direct medical costs of injury for Indian Health Service's users and years of potential life lost (YPLL) and the value of productivity losses from injury deaths for AI/AN in the Indian Health Service population. METHODS: Injury-related lifetime medical costs were estimated for Indian Health Service users with medically treated injuries using data from the 2011-2015 National Data Warehouse. Productivity costs and YPLL were estimated using data on injury-related deaths among AI/AN in Indian Health Service's 2008-2010 service population. Costs were reported in 2017 U.S. dollars. RESULTS: The total estimated costs of injuries per year, including injuries among Indian Health Service users and productivity losses from injury-related deaths, were estimated at $4.5 billion. Lifetime medical costs to treat annual injuries among Indian Health Service users were estimated at $549 million, with the largest share ($131 million) going toward falls, the most frequent injury cause. Total estimated YPLL from AI/AN injury deaths in Indian Health Service's service population were 106,400. YPLL from injury deaths for men (74,000) were 2.2 times YPLL for women (33,000). Productivity losses from all injury-related deaths were $3.9 billion per year. The highest combined lifetime medical and mortality costs were for motor vehicle/traffic injuries, with an estimated cost of $1.6 billion per year. CONCLUSIONS: Findings suggest that targeted injury prevention efforts by Indian Health Service likely contributed to lower rates of injury among AI/AN, particularly for motor vehicle/traffic injuries. However, because of remaining disparities in injury-related outcomes between AI/AN and all races in the United States, Indian Health Service should continue to monitor changes in injury incidence and costs over time, evaluate the impacts of previous injury prevention investments on current incidence and costs, and identify additional injury prevention investment needs.

Analysis of the profitability of adult vaccination in 13 private provider practices in the United States.

Vaccination coverage among adults remains low in the United States. Understanding the barriers to provision of adult vaccination is an important step to increasing vaccination coverage and improving public health. To better understand financial factors that may affect practice decisions about adult vaccination, this study sought to understand how costs compared with payments for adult vaccinations in a sample of U.S. physician practices. We recruited a convenience sample of 19 practices in nine states in 2017. We conducted a time-motion study to assess the time costs of vaccination activities and conducted a survey of practice managers to assess materials, management, and dose costs and payments for vaccination. We received complete cost and payment data from 13 of the 19 practices. We calculated annual income from vaccination services by comparing estimated costs with payments received for vaccine doses and vaccine administration. Median annual total income from vaccination services was $90,343 at family medicine practices (range: $3968-$249,628), $28,267 at internal medicine practices (-$32,659-$141,034) and $2886 at obstetrics and gynecology practices (-$73,451-$23,820). Adult vaccination was profitable at the median of our sample, but there is wide variation in profitability due to differences in costs and payment rates across practices. This study provides evidence on the financial viability of adult vaccination and supports actions for improving financial viability. These results can help inform practices' decisions whether to provide adult vaccines and contribute to keeping adults up-to-date with the recommended vaccination schedule.

Meiotic cellular rejuvenation is coupled to nuclear remodeling in budding yeast.

Production of healthy gametes in meiosis relies on the quality control and proper distribution of both nuclear and cytoplasmic contents. Meiotic differentiation naturally eliminates age-induced cellular damage by an unknown mechanism. Using time-lapse fluorescence microscopy in budding yeast, we found that nuclear senescence factors - including protein aggregates, extrachromosomal ribosomal DNA circles, and abnormal nucleolar material - are sequestered away from chromosomes during meiosis II and subsequently eliminated. A similar sequestration and elimination process occurs for the core subunits of the nuclear pore complex in both young and aged cells. Nuclear envelope remodeling drives the formation of a membranous compartment containing the sequestered material. Importantly, de novo generation of plasma membrane is required for the sequestration event, preventing the inheritance of long-lived nucleoporins and senescence factors into the newly formed gametes. Our study uncovers a new mechanism of nuclear quality control and provides insight into its function in meiotic cellular rejuvenation.

Provider time and costs to vaccinate adult patients: Impact of time counseling without vaccination.

Amid provider reports of financial barriers as an impediment to adult immunization, this study explores the time and costs of vaccination in adult provider practices. Both a Vaccination Time-Motion Study and Vaccine Practice Management Survey were conducted (March - October 2017) in a convenience sample of 19 family medicine (FM), internal medicine (IM), and obstetrician-gynecology (OBGYN) practices, in nine states. Practices were directly observed during a one week period; estimates were collected of time spent on activities that could not be directly observed. Cost estimates were calculated by converting staff time for performed activities. In the time-motion study, FM and IM practices spent similar time conducting vaccination activities (median = 5 min per vaccination), while OBGYN practices spent more time (median = 29 min per vaccination). Combining results from the time-motion study and the practice management survey, the median costs of vaccination remained similar for FM practices and IM practices at $7 and $8 per vaccination, respectively, but was substantially higher for OBGYN practices at $43 per vaccination. Factors that contributed to higher costs among OBGYN practices were the increased time to counsel patients, administer vaccines, and to plan and manage vaccine supplies. In addition, 68% of OBGYN patients who were offered and counseled to receive vaccines declined to receive them. Counseling patients who ultimately do not go on to receive a vaccine may be an important cost factor. Lower costs of vaccination services may be achieved by increasing efficiencies in workflow or the volume of vaccinations.

Predicted glycosyltransferases promote development and prevent spurious cell clumping in the choanoflagellate S. rosetta.

In a previous study we established forward genetics in the choanoflagellate Salpingoeca rosetta and found that a C-type lectin gene is required for rosette development (Levin et al., 2014). Here we report on critical improvements to genetic screens in S. rosetta while also investigating the genetic basis for rosette defect mutants in which single cells fail to develop into orderly rosettes and instead aggregate promiscuously into amorphous clumps of cells. Two of the mutants, Jumble and Couscous, mapped to lesions in genes encoding two different predicted glycosyltransferases and displayed aberrant glycosylation patterns in the basal extracellular matrix (ECM). In animals, glycosyltransferases sculpt the polysaccharide-rich ECM, regulate integrin and cadherin activity, and, when disrupted, contribute to tumorigenesis. The finding that predicted glycosyltransferases promote proper rosette development and prevent cell aggregation in S. rosetta suggests a pre-metazoan role for glycosyltransferases in regulating development and preventing abnormal tumor-like multicellularity.

Pivotal roles of PCNA loading and unloading in heterochromatin function.

In Saccharomyces cerevisiae, heterochromatin structures required for transcriptional silencing of the HML and HMR loci are duplicated in coordination with passing DNA replication forks. Despite major reorganization of chromatin structure, the heterochromatic, transcriptionally silent states of HML and HMR are successfully maintained throughout S-phase. Mutations of specific components of the replisome diminish the capacity to maintain silencing of HML and HMR through replication. Similarly, mutations in histone chaperones involved in replication-coupled nucleosome assembly reduce gene silencing. Bridging these observations, we determined that the proliferating cell nuclear antigen (PCNA) unloading activity of Elg1 was important for coordinating DNA replication forks with the process of replication-coupled nucleosome assembly to maintain silencing of HML and HMR through S-phase. Collectively, these data identified a mechanism by which chromatin reassembly is coordinated with DNA replication to maintain silencing through S-phase.

Preventing fatal winch entanglements in the US southern shrimp fleet: A research to practice approach.

INTRODUCTION: During 2000-2011, 35 injuries (8 fatal) involving winches were reported to the Coast Guard in the Southern shrimp fleet. Injuries involving the main winch drums had a higher risk for fatal outcomes compared to injuries involving the winch cathead (RR=7.5; 1.1-53.7). The objective of this study was to design effective solutions to protect deckhands from entanglement hazards posed by winches found on the vessels in the Southern shrimp fleet. METHODS: Based on injury characteristics, site visit observations, and input from vessel owners, NIOSH determined that the design and implementation of effective main-winch guarding was a feasible first-step in mitigating the entanglement hazard. Design considerations for stationary guards favor systems that are simple, affordable, durable, unobtrusive, and will not interfere with normal fishing operations. In addition, an auxiliary-stop method was tested to prevent entanglements in try-net winches. RESULTS: Standardized passive guards were designed for three commonly found main winch models. Initial prototype guards have been sea-tested. The design of six additional guards is underway, for a total of three iterations for each winch model identified. These will incorporate features found to be valued by fishermen, will be more efficient, and will reduce the overall cost of fabrication and maintenance. Sea testing of these iterations continues. The auxiliary-stop circuit control prototype system was designed to prevent entanglements in the try-net winch and is currently being sea tested. DISCUSSION: NIOSH has completed initial designs for stationary-winch guards. Through collaborations with shrimper associations and safety groups, the successfully tested winch guard and auxiliary stop designs will be made available to qualified welders and craftsmen to use. This approach has proven effective in preventing other types of winch injuries. PRACTICAL APPLICATIONS: Injury epidemiologic methods and industry input are an effective way to identify workplace hazards and to design effective safety interventions to control hazards.

An outbreak of multiple serotypes of salmonella in New Zealand linked to consumption of contaminated tahini imported from Turkey.

A widespread salmonellosis outbreak linked to consumption of hummus made from contaminated tahini imported from Turkey occurred in New Zealand in November 2012. This article summarizes the outbreak detection, investigation, and control. The New Zealand Enteric Reference Laboratory alerted public health units regarding a cluster of 11 persons with Salmonella Montevideo infection identified from different regions of the North Island of New Zealand. A multiagency outbreak investigation commenced to determine the source of illness and prevent further transmission. Salmonellosis is a notifiable disease in New Zealand. Outbreak cases were identified through routine salmonellosis notifications, and interviewed using a standardized questionnaire to identify common exposures. Clinical and food isolates were initially characterized by serotyping and then further typed by pulsed-field gel electrophoresis (PFGE). PFGE profiles were sent to PulseNet and international alerts were posted. The scope of the investigation widened to include persons with either Salmonella Maastricht and Salmonella Mbandaka infection following detection of these serotypes in tahini epidemiologically linked to laboratory-confirmed cases. All three of the tahini-associated serotypes were detected in people who had consumed tahini, and these were found to have PFGE profiles indistinguishable from the tahini isolates. Twenty-seven salmonellosis cases infected with at least one of the three tahini-associated Salmonella serotypes were detected between September 1 and December 31, 2012; of these, 16 (59%) cases (12 with Salmonella Montevideo, 3 with Salmonella Mbandaka, and 1 with Salmonella Maastricht infection) had PFGE patterns indistinguishable from the outbreak profile. The investigation led to a trade withdrawal and consumer recall for tahini sesame paste from the consignment and products containing this tahini. The outbreak ceased following the recall. The importer of the implicated tahini was reminded of his duties as a food importer, including ensuring appropriate product testing. Changes to New Zealand legislation strengthened food safety responsibilities of food importers.

Design Optimization of a Portable Thermophoretic Precipitator Nanoparticle Sampler.

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are developing methods for characterizing diesel particulate matter in mines. Introduction of novel engine and exhaust after treatment technologies in underground mines is changing the nature of diesel emissions, and metrics alternative to the traditional mass-based measurements are being investigated with respect to their ability to capture changes in the properties of diesel aerosols. The emphasis is given to metrics based on measurement of number and surface area concentrations, but analysis of collected particles using electron microscopy (EM) is also employed for detailed particle characterization. To collect samples for EM analysis at remote workplaces, including mining and manufacturing facilities, NIOSH is developing portable particle samplers capable of collecting airborne nano-scale particles. This paper describes the design, construction, and testing of a prototype thermophoretic precipitator (TP) particle sampler optimized for collection of particles in the size range of 1-300 nm. The device comprises heated and cooled metal plates separated by a 0.8 mm channel through which aerosol is drawn by a pump. It weighs about 2 kg, has a total footprint of 27 × 22 cm, and the collection plate size is approximately 4 × 8 cm. Low power consumption and enhanced portability were achieved by using moderate flow rates (50-150 cm3/min) and temperature gradients (10-50 K/mm with ΔT between 8 K and 40 K). The collection efficiency of the prototype, measured with a condensation particle counter using laboratory-generated polydisperse submicrometer NaCl aerosols, ranged from 14-99%, depending on temperature gradient and flow rate. Analysis of transmission electron microscopy images of samples collected with the TP confirmed that the size distributions of collected particles determined using EM are in good agreement with those determined using a Fast Mobility Particle Sizer.