94 results on '"Lund SP"'
Search Results
2. The risk of tinnitus following occupational noise exposure in workers with hearing loss or normal hearing
- Author
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Rubak, Tine, Koch, S, Koefoed-Nielsen, B, Lund, SP, Bonde, Jens Peter, and Kolstad, Henrik
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- 2008
3. Støj fra menneskelig aktivitet - et udredningsarbejde
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Lund, SP, Kristiansen, J, Shibuya, H, Clausen, T, Pejtersen, JH, Nielsen, PM, Kolstad, Henrik, Poulsen, T, Rindel, JH, and Christensen-Dalsgaard, J
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- 2006
4. Hearing loss and cochlear damage in experimental pneumococcal meningitis, with special reference to the role of neutrophil granulytes
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Brandt, CT, Caye-Thomsen, P, Lund, SP, Worsøe, L, Østergaard, C, Frimodt-Møller, N, Espersen, F, Thomsen, J, Lundgren, Jens Dilling, Brandt, CT, Caye-Thomsen, P, Lund, SP, Worsøe, L, Østergaard, C, Frimodt-Møller, N, Espersen, F, Thomsen, J, and Lundgren, Jens Dilling
- Abstract
Hearing loss is a well-known sequelae from meningitis, affecting up to 25% of survivors. However, the principal components of the infectious and inflammatory reaction responsible for the sensorineural hearing loss remain to be identified. The present study aimed to investigate the impact of an augmented neutrophil response on the development of hearing loss and cochlear damage in a model of experimental pneumococcal meningitis in rats. Hearing loss and cochlear damage were assessed by distortion product oto-acoustic emissions (DPOAE), auditory brainstem response (ABR) and histopathology in rats treated with ceftriaxone 28 h after infection. Rats were treated with Granulocyte Colony Stimulating Factor (G-CSF) initiated prior to infection, 28 h after infection or with ceftriaxone only. Rats were followed for 7 days, and assessment of hearing was performed before infection and 24 h and day 8 after infection. Pretreatment with G-CSF increased hearing loss 24 h after infection and on day 8 compared to untreated rats (Mann-Whitney, P = 0.012 and P = 0.013 respectively). The increased sensorineural hearing loss at day 8 was associated with significantly decreased spiral ganglion cell counts (P = 0.0006), increased damage to the organ of Corti (P = 0.007), increased areas of inflammatory infiltrates (P = 0.02) and increased white blood cell (WBC) counts in cerebrospinal fluid on day 8 after infection (P = 0.0084). Initiation of G-CSF 28 h after infection did not significantly affect hearing loss or cochlear pathology compared to controls. In conclusion, the inflammatory host reaction contributes significantly to the development of hearing loss in experimental meningitis.
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- 2006
5. Attenuation of the blood bacterial load by pre-treatment with G-CSF protects from fatal outcome and brain damage in Streptococcus pneumoniae meningitis in rats.
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Brandt, CT, Lundgren, Jens Dilling, Lund, SP, Frimodt-Møller, N, Christensen, T, Benfield, Thomas, Espersen, F, Hougaard, DM, Østergaard, C, Brandt, CT, Lundgren, Jens Dilling, Lund, SP, Frimodt-Møller, N, Christensen, T, Benfield, Thomas, Espersen, F, Hougaard, DM, and Østergaard, C
- Abstract
Udgivelsesdato: Aug
- Published
- 2004
6. Toxic encephalopathy and noise-induced hearing loss
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Lund, SP, primary, Brun, B, additional, Rosenberg, T, additional, Lykke, J, additional, Sorensen, AM, additional, and Shapiro, A.U.C, additional
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- 2006
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7. Intratympanic steroid prevents long-term spiral ganglion neuron loss in experimental meningitis.
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Worsøe L, Brandt CT, Lund SP, Ostergaard C, Thomsen J, and Cayé-Thomasen P
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- 2010
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8. Smoking and height as risk factors for prevalence and 5-year incidence of hearing loss. A questionnaire-based follow-up study of employees in Denmark aged 18-59 years exposed and unexposed to noise.
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Burr H, Lund SP, Sperling BB, Kristensen TS, and Poulsen OM
- Abstract
This paper investigated whether smoking and short stature in adulthood were independent risk factors for hearing loss. We reanalyzed data from the Danish Work Environment Cohort Study (an existing cohort study), on prevalence of self-reported hearing loss among 7,221 employees and on five-year incidence among 4,610 employees. We found that smoking predicted hearing loss incidence and prevalence. Smoking did not predict incidence at noise exposure during half or more of a worker's hours. Very short stature predicted prevalence in the total adult population only weakly, but strongly among employees born before 1951. These prospective findings indicate that smoking is an independent risk factor for incidence of hearing loss. Very short stature predicted prevalence of hearing loss only in a subpopulation. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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9. Establishing a reference focal plane using convolutional neural networks and beads for brightfield imaging.
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Chalfoun J, Lund SP, Ling C, Peskin A, Pierce L, Halter M, Elliott J, and Sarkar S
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Repeatability of measurements from image analytics is difficult, due to the heterogeneity and complexity of cell samples, exact microscope stage positioning, and slide thickness. We present a method to define and use a reference focal plane that provides repeatable measurements with very high accuracy, by relying on control beads as reference material and a convolutional neural network focused on the control bead images. Previously we defined a reference effective focal plane (REFP) based on the image gradient of bead edges and three specific bead image features. This paper both generalizes and improves on this previous work. First, we refine the definition of the REFP by fitting a cubic spline to describe the relationship between the distance from a bead's center and pixel intensity and by sharing information across experiments, exposures, and fields of view. Second, we remove our reliance on image features that behave differently from one instrument to another. Instead, we apply a convolutional regression neural network (ResNet 18) trained on cropped bead images that is generalizable to multiple microscopes. Our ResNet 18 network predicts the location of the REFP with only a single inferenced image acquisition that can be taken across a wide range of focal planes and exposure times. We illustrate the different strategies and hyperparameter optimization of the ResNet 18 to achieve a high prediction accuracy with an uncertainty for every image tested coming within the microscope repeatability measure of 7.5 µm from the desired focal plane. We demonstrate the generalizability of this methodology by applying it to two different optical systems and show that this level of accuracy can be achieved using only 6 beads per image., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)
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- 2024
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10. Effects of DNA template preparation on variability in cell-free protein production.
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Romantseva E, Alperovich N, Ross D, Lund SP, and Strychalski EA
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DNA templates for protein production remain an unexplored source of variability in the performance of cell-free expression (CFE) systems. To characterize this variability, we investigated the effects of two common DNA extraction methodologies, a postprocessing step and manual versus automated preparation on protein production using CFE. We assess the concentration of the DNA template, the quality of the DNA template in terms of physical damage and the quality of the DNA solution in terms of purity resulting from eight DNA preparation workflows. We measure the variance in protein titer and rate of protein production in CFE reactions associated with the biological replicate of the DNA template, the technical replicate DNA solution prepared with the same workflow and the measurement replicate of nominally identical CFE reactions. We offer practical guidance for preparing and characterizing DNA templates to achieve acceptable variability in CFE performance., (Published by Oxford University Press 2022. This work is written by (a) US Government employee(s) and is in the public domain in the US.)
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- 2022
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11. Developmental exposure to the brominated flame retardant DE-71 reduces serum thyroid hormones in rats without hypothalamic-pituitary-thyroid axis activation or neurobehavioral changes in offspring.
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Ramhøj L, Svingen T, Mandrup K, Hass U, Lund SP, Vinggaard AM, Hougaard KS, and Axelstad M
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- Animals, Female, Halogenated Diphenyl Ethers toxicity, Humans, Pregnancy, Rats, Thyroid Gland, Thyroid Hormones pharmacology, Thyroxine, Flame Retardants toxicity
- Abstract
Polybrominated diphenyl ethers (PBDEs) are legacy flame retardants for which human exposure remains ubiquitous. This is of concern since these chemicals can perturb development and cause adverse health effects. For instance, DE-71, a technical mixture of PBDEs, can induce liver toxicity as well as reproductive and developmental toxicity. DE-71 can also disrupt the thyroid hormone (TH) system which may induce developmental neurotoxicity indirectly. However, in developmental toxicity studies, it remains unclear how DE-71 exposure affects the offspring's thyroid hormone system and if this dose-dependently relates to neurodevelopmental effects. To address this, we performed a rat toxicity study by exposing pregnant dams to DE-71 at 0, 40 or 60 mg/kg/day during perinatal development from gestational day 7 to postnatal day 16. We assessed the TH system in both dams and their offspring, as well as potential hearing and neurodevelopmental effects in prepubertal and adult offspring. DE-71 significantly reduced serum T4 and T3 levels in both dams and offspring without a concomitant upregulation of TSH, thus inducing a hypothyroxinemia-like effect. No discernible effects were observed on the offspring's brain function when assessed in motor activity boxes and in the Morris water maze, or on offspring hearing function. Our results, together with a thorough review of the literature, suggest that DE-71 does not elicit a clear dose-dependent relationship between low serum thyroxine (T4) and effects on the rat brain in standard behavioral assays. However, low serum TH levels are in themselves believed to be detrimental to human brain development, thus we propose that we lack assays to identify developmental neurotoxicity caused by chemicals disrupting the TH system through various mechanisms., Competing Interests: The authors have declared that no competing interests exist.
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- 2022
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12. Quantitative evaluation of footwear evidence: Initial workflow for an end-to-end system.
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Venkatasubramanian G, Hegde V, Lund SP, Iyer H, and Herman M
- Abstract
In the United States, footwear examiners make decisions about the sources of crime scene shoe impressions using subjective criteria. This has raised questions about the accuracy, repeatability, reproducibility, and scientific validity of footwear examinations. Currently, most footwear examiners follow a workflow that compares a questioned and test impression with regard to outsole design, size, wear, and randomly acquired characteristics (RACs). We augment this workflow with computer algorithms and statistical analysis so as to improve in the following areas: (1) quantifying the degree of correspondence between the questioned and test impressions with respect to design, size, wear, and RACs, (2) reducing the potential for cognitive bias, and (3) providing an empirical basis for examiner conclusions by developing a reference database of case-relevant pairs of impressions containing known mated and known nonmated impressions. Our end-to-end workflow facilitates all three of these points and is directly relatable to current practice. We demonstrate the workflow, which includes obtaining and interpreting outsole pattern scores, RAC comparison scores, and final scores, on two scenarios-a pristine example (involving very high quality Everspry EverOS scanner impressions) and a mock crime scene example that more closely resembles real casework. These examples not only demonstrate the workflow but also help identify the algorithmic, computational, and statistical challenges involved in improving the system for eventual deployment in casework., (© 2021 American Academy of Forensic Sciences. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)
- Published
- 2021
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13. Establishing a reference focal plane using beads for trypan-blue-based viability measurements.
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Peskin A, Lund SP, Pierce L, Kurbanov F, Chan LL, Halter M, Elliott J, Sarkar S, and Chalfoun J
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- Signal-To-Noise Ratio, Image Processing, Computer-Assisted, Trypan Blue
- Abstract
Trypan blue dye exclusion-based cell viability measurements are highly dependent upon image quality and consistency. In order to make measurements repeatable, one must be able to reliably capture images at a consistent focal plane, and with signal-to-noise ratio within appropriate limits to support proper execution of image analysis routines. Imaging chambers and imaging systems used for trypan blue analysis can be inconsistent or can drift over time, leading to a need to assure the acquisition of images prior to automated image analysis. Although cell-based autofocus techniques can be applied, the heterogeneity and complexity of the cell samples can make it difficult to assure the effectiveness, repeatability and accuracy of the routine for each measurement. Instead of auto-focusing on cells in our images, we add control beads to the images, and use them to repeatedly return to a reference focal plane. We use bead image features that have stable profiles across a wide range of focal values and exposure levels. We created a predictive model based on image quality features computed over reference datasets. Because the beads have little variation, we can determine the reference plane from bead image features computed over a single-shot image and can reproducibly return to that reference plane with each sample. The achieved accuracy (over 95%) is within the limits of the actuator repeatability. We demonstrate that a small number of beads (less than 3 beads per image) is needed to achieve this accuracy. We have also developed an open-source Graphical User Interface called Bead Benchmarking-Focus And Intensity Tool (BB-FAIT) to implement these methods for a semi-automated cell viability analyser., (© 2021 Royal Microscopical Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)
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- 2021
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14. Comparison of bias and resolvability in single-cell and single-transcript methods.
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Rammohan J, Lund SP, Alperovich N, Paralanov V, Strychalski EA, and Ross D
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- Bacterial Proteins genetics, Bias, Bioengineering, Escherichia coli genetics, Flow Cytometry, Gene Expression Profiling standards, Gene Expression Profiling statistics & numerical data, In Situ Hybridization methods, In Situ Hybridization standards, In Situ Hybridization statistics & numerical data, In Situ Hybridization, Fluorescence methods, In Situ Hybridization, Fluorescence standards, In Situ Hybridization, Fluorescence statistics & numerical data, Luminescent Proteins genetics, Microscopy, RNA, Bacterial analysis, Reproducibility of Results, Single-Cell Analysis standards, Single-Cell Analysis statistics & numerical data, Gene Expression Profiling methods, Single-Cell Analysis methods
- Abstract
Single-cell and single-transcript measurement methods have elevated our ability to understand and engineer biological systems. However, defining and comparing performance between methods remains a challenge, in part due to the confounding effects of experimental variability. Here, we propose a generalizable framework for performing multiple methods in parallel using split samples, so that experimental variability is shared between methods. We demonstrate the utility of this framework by performing 12 different methods in parallel to measure the same underlying reference system for cellular response. We compare method performance using quantitative evaluations of bias and resolvability. We attribute differences in method performance to steps along the measurement process such as sample preparation, signal detection, and choice of measurand. Finally, we demonstrate how this framework can be used to benchmark different methods for single-transcript detection. The framework we present here provides a practical way to compare performance of any methods.
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- 2021
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15. Development and interlaboratory evaluation of a NIST Reference Material RM 8366 for EGFR and MET gene copy number measurements.
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He HJ, Das B, Cleveland MH, Chen L, Camalier CE, Liu LC, Norman KL, Fellowes AP, McEvoy CR, Lund SP, Almeida J, Steffen CR, Karlovich C, Williams PM, and Cole KD
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- DNA, Neoplasm genetics, ErbB Receptors genetics, ErbB Receptors standards, Gene Dosage, Humans, Polymerase Chain Reaction, Proto-Oncogene Mas, Proto-Oncogene Proteins c-met standards, Reference Standards, Tumor Cells, Cultured, High-Throughput Nucleotide Sequencing standards, Proto-Oncogene Proteins c-met genetics
- Abstract
Background The National Institute of Standards and Technology (NIST) Reference Material RM 8366 was developed to improve the quality of gene copy measurements of EGFR (epidermal growth factor receptor) and MET (proto-oncogene, receptor tyrosine kinase), important targets for cancer diagnostics and treatment. The reference material is composed of genomic DNA prepared from six human cancer cell lines with different levels of amplification of the target genes. Methods The reference values for the ratios of the EGFR and MET gene copy numbers to the copy numbers of reference genes were measured using digital PCR. The digital PCR measurements were confirmed by two additional laboratories. The samples were also characterized using Next Generation Sequencing (NGS) methods including whole genome sequencing (WGS) at three levels of coverage (approximately 1 ×, 5 × and greater than 30 ×), whole exome sequencing (WES), and two different pan-cancer gene panels. The WES data were analyzed using three different bioinformatic algorithms. Results The certified values (digital PCR) for EGFR and MET were in good agreement (within 20%) with the values obtained from the different NGS methods and algorithms for five of the six components; one component had lower NGS values. Conclusions This study shows that NIST RM 8366 is a valuable reference material to evaluate the performance of assays that assess EGFR and MET gene copy number measurements.
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- 2019
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16. Cell-based reference samples designed with specific differences in microRNA biomarkers.
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Pine PS, Lund SP, Stass SA, Kukuruga D, Jiang F, Sorbara L, Srivastava S, and Salit M
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- Analysis of Variance, Cell Line, Tumor, Gene Expression, Humans, Reference Standards, Reproducibility of Results, Reverse Transcriptase Polymerase Chain Reaction methods, Reverse Transcriptase Polymerase Chain Reaction standards, Biomarkers, Tumor genetics, Clinical Laboratory Techniques standards, MicroRNAs genetics, RNA, Small Untranslated genetics
- Abstract
Background: We demonstrate the feasibility of creating a pair of reference samples to be used as surrogates for clinical samples measured in either a research or clinical laboratory setting. The reference sample paradigm presented and evaluated here is designed to assess the capability of a measurement process to detect true differences between two biological samples. Cell-based reference samples can be created with a biomarker signature pattern designed in silico. Clinical laboratories working in regulated applications are required to participate in proficiency testing programs; research laboratories doing discovery typically do not. These reference samples can be used in proficiency tests or as process controls that allow a laboratory to evaluate and optimize its measurement systems, monitor performance over time (process drift), assess changes in protocols, reagents, and/or personnel, maintain standard operating procedures, and most importantly, provide evidence for quality results., Results: The biomarkers of interest in this study are microRNAs (miRNAs), small non-coding RNAs involved in the regulation of gene expression. Multiple lung cancer associated cell lines were determined by reverse transcription (RT)-PCR to have sufficiently different miRNA profiles to serve as components in mixture designs as reference samples. In silico models based on the component profiles were used to predict miRNA abundance ratios between two different cell line mixtures, providing target values for profiles obtained from in vitro mixtures. Two reference sample types were tested: total RNA mixed after extraction from cell lines, and intact cells mixed prior to RNA extraction. MicroRNA profiling of a pair of samples composed of extracted RNA derived from these cell lines successfully replicated the target values. Mixtures of intact cells from these lines also approximated the target values, demonstrating potential utility as mimics for clinical specimens. Both designs demonstrated their utility as reference samples for inter- or intra-laboratory testing., Conclusions: Cell-based reference samples can be created for performance assessment of a measurement process from biomolecule extraction through quantitation. Although this study focused on miRNA profiling with RT-PCR using cell lines associated with lung cancer, the paradigm demonstrated here should be extendable to genome-scale platforms and other biomolecular endpoints.
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- 2018
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17. Summarizing performance for genome scale measurement of miRNA: reference samples and metrics.
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Pine PS, Lund SP, Parsons JR, Vang LK, Mahabal AA, Cinquini L, Kelly SC, Kincaid H, Crichton DJ, Spira A, Liu G, Gower AC, Pass HI, Goparaju C, Dubinett SM, Krysan K, Stass SA, Kukuruga D, Van Keuren-Jensen K, Courtright-Lim A, Thompson KL, Rosenzweig BA, Sorbara L, Srivastava S, and Salit ML
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- Female, Gene Expression Profiling methods, High-Throughput Nucleotide Sequencing methods, Humans, Pregnancy, Reference Standards, Brain metabolism, Gene Expression Profiling standards, Genome, Human, Liver metabolism, MicroRNAs genetics, Placenta metabolism
- Abstract
Background: The potential utility of microRNA as biomarkers for early detection of cancer and other diseases is being investigated with genome-scale profiling of differentially expressed microRNA. Processes for measurement assurance are critical components of genome-scale measurements. Here, we evaluated the utility of a set of total RNA samples, designed with between-sample differences in the relative abundance of miRNAs, as process controls., Results: Three pure total human RNA samples (brain, liver, and placenta) and two different mixtures of these components were evaluated as measurement assurance control samples on multiple measurement systems at multiple sites and over multiple rounds. In silico modeling of mixtures provided benchmark values for comparison with physical mixtures. Biomarker development laboratories using next-generation sequencing (NGS) or genome-scale hybridization assays participated in the study and returned data from the samples using their routine workflows. Multiplexed and single assay reverse-transcription PCR (RT-PCR) was used to confirm in silico predicted sample differences. Data visualizations and summary metrics for genome-scale miRNA profiling assessment were developed using this dataset, and a range of performance was observed. These metrics have been incorporated into an online data analysis pipeline and provide a convenient dashboard view of results from experiments following the described design. The website also serves as a repository for the accumulation of performance values providing new participants in the project an opportunity to learn what may be achievable with similar measurement processes., Conclusions: The set of reference samples used in this study provides benchmark values suitable for assessing genome-scale miRNA profiling processes. Incorporation of these metrics into an online resource allows laboratories to periodically evaluate their performance and assess any changes introduced into their measurement process.
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- 2018
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18. Counting Caenorhabditis elegans: Protocol Optimization and Applications for Population Growth and Toxicity Studies in Liquid Medium.
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Scanlan LD, Lund SP, Coskun SH, Hanna SK, Johnson ME, Sims CM, Brignoni K, Lapasset P, Petersen EJ, Elliott JT, and Nelson BC
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- Animals, Culture Media metabolism, Nematoda growth & development, Population Growth, Reproduction physiology, Caenorhabditis elegans growth & development
- Abstract
The nematode Caenorhabditis elegans is used extensively in molecular, toxicological and genetics research. However, standardized methods for counting nematodes in liquid culture do not exist despite the wide use of nematodes and need for accurate measurements. Herein, we provide a simple and affordable counting protocol developed to maximize count accuracy and minimize variability in liquid nematode culture. Sources of variability in the counting process were identified and tested in 14 separate experiments. Three variables resulted in significant effects on nematode count: shaking of the culture, priming of pipette tips, and sampling location within a microcentrifuge tube. Between-operator variability did not have a statistically significant effect on counts, even among differently-skilled operators. The protocol was used to assess population growth rates of nematodes in two different but common liquid growth media: axenic modified Caenorhabditis elegans Habitation and Reproduction medium (mCeHR) and S-basal complete. In mCeHR, nematode populations doubled daily for 10 d. S-basal complete populations initially doubled every 12 h, but slowed within 7 d. We also detected a statistically significant difference between embryo-to-hatchling incubation period of 5 d in mCeHR compared to 4 d in S-basal complete. The developed counting method for Caenorhabditis elegans reduces variability and allows for rigorous and reliable experimentation.
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- 2018
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19. Evaluating the quality of a cell counting measurement process via a dilution series experimental design.
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Sarkar S, Lund SP, Vyzasatya R, Vanguri P, Elliott JT, Plant AL, and Lin-Gibson S
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- Automation, Cell Count statistics & numerical data, Humans, Quality Control, Cell Count methods, Mesenchymal Stem Cells cytology
- Abstract
Background Aims: Cell counting measurements are critical in the research, development and manufacturing of cell-based products, yet determining cell quantity with accuracy and precision remains a challenge. Validating and evaluating a cell counting measurement process can be difficult because of the lack of appropriate reference material. Here we describe an experimental design and statistical analysis approach to evaluate the quality of a cell counting measurement process in the absence of appropriate reference materials or reference methods., Methods: The experimental design is based on a dilution series study with replicate samples and observations as well as measurement process controls. The statistical analysis evaluates the precision and proportionality of the cell counting measurement process and can be used to compare the quality of two or more counting methods. As an illustration of this approach, cell counting measurement processes (automated and manual methods) were compared for a human mesenchymal stromal cell (hMSC) preparation., Results: For the hMSC preparation investigated, results indicated that the automated method performed better than the manual counting methods in terms of precision and proportionality., Discussion: By conducting well controlled dilution series experimental designs coupled with appropriate statistical analysis, quantitative indicators of repeatability and proportionality can be calculated to provide an assessment of cell counting measurement quality. This approach does not rely on the use of a reference material or comparison to "gold standard" methods known to have limited assurance of accuracy and precision. The approach presented here may help the selection, optimization, and/or validation of a cell counting measurement process., (Published by Elsevier Inc.)
- Published
- 2017
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20. Likelihood Ratio as Weight of Forensic Evidence: A Closer Look.
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Lund SP and Iyer H
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The forensic science community has increasingly sought quantitative methods for conveying the weight of evidence. Experts from many forensic laboratories summarize their findings in terms of a likelihood ratio. Several proponents of this approach have argued that Bayesian reasoning proves it to be normative. We find this likelihood ratio paradigm to be unsupported by arguments of Bayesian decision theory, which applies only to personal decision making and not to the transfer of information from an expert to a separate decision maker. We further argue that decision theory does not exempt the presentation of a likelihood ratio from uncertainty characterization, which is required to assess the fitness for purpose of any transferred quantity. We propose the concept of a lattice of assumptions leading to an uncertainty pyramid as a framework for assessing the uncertainty in an evaluation of a likelihood ratio. We demonstrate the use of these concepts with illustrative examples regarding the refractive index of glass and automated comparison scores for fingerprints.
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- 2017
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21. Airway exposure to multi-walled carbon nanotubes disrupts the female reproductive cycle without affecting pregnancy outcomes in mice.
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Johansson HKL, Hansen JS, Elfving B, Lund SP, Kyjovska ZO, Loft S, Barfod KK, Jackson P, Vogel U, and Hougaard KS
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- Animals, Brain drug effects, Brain metabolism, Female, Gene Expression Regulation, Mice, Inbred C57BL, Ovulation drug effects, Pregnancy, Proof of Concept Study, Risk Assessment, Time Factors, Estrous Cycle drug effects, Inhalation Exposure, Nanotubes, Carbon toxicity, Pregnancy Outcome, Reproduction drug effects
- Abstract
Background: The use of multiwalled carbon nanotubes (MWCNT) is increasing due to a growing use in a variety of products across several industries. Thus, occupational exposure is also of increasing concern, particularly since airway exposure to MWCNTs can induce sustained pulmonary acute phase response and inflammation in experimental animals, which may affect female reproduction. This proof-of-principle study therefore aimed to investigate if lung exposure by intratracheal instillation of the MWCNT NM-400 would affect the estrous cycle and reproductive function in female mice., Results: Estrous cycle regularity was investigated by comparing vaginal smears before and after exposure to 67 μg of NM-400, whereas reproductive function was analyzed by measuring time to delivery of litters after instillation of 2, 18 or 67 μg of NM-400. Compared to normal estrous cycling determined prior to exposure, exposure to MWCNT significantly prolonged the estrous cycle during which exposure took place, but significantly shortened the estrous cycle immediately after the exposed cycle. No consistent effects were seen on time to delivery of litter or other gestational or litter parameters, such as litter size, sex ratio, implantations and implantation loss., Conclusion: Lung exposure to MWCNT interfered with estrous cycling. Effects caused by MWCNTs depended on the time of exposure: the estrous stage was particularly sensitive to exposure, as animals exposed during this stage showed a higher incidence of irregular cycling after exposure. Our data indicates that MWCNT exposure may interfere with events leading to ovulation.
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- 2017
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22. Occupational noise exposure, psychosocial working conditions and the risk of tinnitus.
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Frederiksen TW, Ramlau-Hansen CH, Stokholm ZA, Grynderup MB, Hansen ÅM, Lund SP, Kristiansen J, Vestergaard JM, Bonde JP, and Kolstad HA
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- Cross-Sectional Studies, Denmark epidemiology, Humans, Logistic Models, Stress, Psychological epidemiology, Surveys and Questionnaires, Workplace standards, Noise, Occupational adverse effects, Occupational Exposure adverse effects, Social Environment, Tinnitus epidemiology, Workplace psychology
- Abstract
Purpose: The purpose of this study was to evaluate the influence of occupational noise (current and cumulative doses) and psychosocial work factors (psychological demands and decision latitude) on tinnitus occurrence among workers, using objective and non-self-reported exposure measures to prevent reporting bias., Methods: In a cross-sectional study, we analyzed data from a Danish survey from 2009 to 2010 that included 534 workers from children day care units and 10 manufacturing trades. Associations between risk factors (current noise exposure, cumulative noise exposure and psychosocial working conditions) and tinnitus were analyzed with logistic regression., Results: We found no statistically significant associations between either current [OR 0.95 (95% CI 0.89; 1.01)] or cumulative [OR 0.93 (95% CI 0.81; 1.06)] occupational noise exposure and tinnitus. Likewise, results for psychosocial working conditions showed no statistically significant association between work place decision latitude [OR 1.06 (95% CI 0.94; 1.13)] or psychological demands [OR 1.07 (95% CI 0.90; 1.26)] and tinnitus., Conclusions: Our results suggest that current Danish occupational noise levels (in combination with relevant noise protection) are not associated with tinnitus. Also, results indicated that the psychosocial working conditions we observed in this cohort of mainly industrial workers were not associated with tinnitus. Therefore, psychosocial working conditions comparable to those observed in this study are probably not relevant to take into account in the evaluation of workers presenting with tinnitus.
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- 2017
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23. Fibronectin in Layer-by-Layer Assembled Films Switches Tumor Cells between 2D and 3D Morphology.
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Bhadriraju K, Hong JS, Lund SP, and Reyes DR
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Tumor cells showing a 3D morphology and in coculture with endothelial cells are a valuable in vitro model for studying cell-cell interactions and for the development of pharmaceuticals. Here, we found that HepG2 cells, unlike endothelial cells, show differences in adhesion to fibronectin alone, or in combination with poly(allylamine hydrochloride). This response allowed us to engineer micropatterned heterotypic cultures of the two cell types using microfluidics to pattern cell adhesion. The resulting cocultures exhibit spatially encoded and physiologically relevant cell function. Further, we found that the protrusive, migratory and 3D morphological responses of HepG2 are synergistically modulated by the constituents of the hybrid extracellular matrix. Treating the hybrid material with the cross-linking enzyme transglutaminase inhibited 3D morphogenesis of tumor cells. Our results extend previous work on the role of fibronectin in layer-by-layer assembled films, and demonstrate that cell-specific differences in adhesion to fibronectin can be used to engineer tumor cell cocultures., Competing Interests: Notes The authors declare no competing financial interest.
- Published
- 2017
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24. Ambient and at-the-ear occupational noise exposure and serum lipid levels.
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Arlien-Søborg MC, Schmedes AS, Stokholm ZA, Grynderup MB, Bonde JP, Jensen CS, Hansen ÅM, Frederiksen TW, Kristiansen J, Christensen KL, Vestergaard JM, Lund SP, and Kolstad HA
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- Adult, Cardiovascular Diseases etiology, Cholesterol blood, Cross-Sectional Studies, Denmark, Environmental Monitoring methods, Female, Humans, Lipoproteins, HDL blood, Lipoproteins, LDL blood, Male, Middle Aged, Occupational Diseases etiology, Occupational Exposure analysis, Risk Factors, Triglycerides blood, Lipids blood, Manufacturing Industry, Noise, Occupational adverse effects, Occupational Exposure adverse effects
- Abstract
Objectives: Occupational and residential noise exposure has been related to increased risk of cardiovascular disease. Alteration of serum lipid levels has been proposed as a possible causal pathway. The objective of this study was to investigate the relation between ambient and at-the-ear occupational noise exposure and serum levels of total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and triglycerides when accounting for well-established predictors of lipid levels., Methods: This cross-sectional study included 424 industrial workers and 84 financial workers to obtain contrast in noise exposure levels. They provided a serum sample and wore portable dosimeters that every 5-s recorded ambient noise exposure levels during a 24-h period. We extracted measurements obtained during work and calculated the full-shift mean ambient noise level. For 331 workers who kept a diary on the use of a hearing protection device (HPD), we subtracted 10 dB from every noise recording obtained during HPD use and estimated the mean full-shift noise exposure level at the ear., Results: Mean ambient noise level was 79.9 dB (A) [range 55.0-98.9] and the mean estimated level at the ear 77.8 dB (A) [range 55.0-94.2]. Ambient and at-the-ear noise levels were strongly associated with increasing levels of triglycerides, cholesterol-HDL ratio, and decreasing levels of HDL-cholesterol, but only in unadjusted analyses that did not account for HPD use and other risk factors., Conclusion: No associations between ambient or at-the-ear occupational noise exposure and serum lipid levels were observed. This indicates that a causal pathway between occupational and residential noise exposure and cardiovascular disease does not include alteration of lipid levels.
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- 2016
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25. Certified DNA Reference Materials to Compare HER2 Gene Amplification Measurements Using Next-Generation Sequencing Methods.
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Lih CJ, Si H, Das B, Harrington RD, Harper KN, Sims DJ, McGregor PM, Camalier CE, Kayserian AY, Williams PM, He HJ, Almeida JL, Lund SP, Choquette S, and Cole KD
- Subjects
- Cell Line, Tumor, Exome, Female, Gene Dosage, Genome, Human, Humans, Male, Neoplasms diagnosis, Neoplasms genetics, Real-Time Polymerase Chain Reaction, Gene Amplification, High-Throughput Nucleotide Sequencing methods, High-Throughput Nucleotide Sequencing standards, Receptor, ErbB-2 genetics, Reference Standards
- Abstract
The National Institute of Standards and Technology (NIST) Standard Reference Materials 2373 is a set of genomic DNA samples prepared from five breast cancer cell lines with certified values for the ratio of the HER2 gene copy number to the copy numbers of reference genes determined by real-time quantitative PCR and digital PCR. Targeted-amplicon, whole-exome, and whole-genome sequencing measurements were used with the reference material to compare the performance of both the laboratory steps and the bioinformatic approaches of the different methods using a range of amplification ratios. Although good reproducibility was observed in each next-generation sequencing method, slightly different HER2 copy numbers associated with platform-specific biases were obtained. This study clearly demonstrates the value of Standard Reference Materials 2373 as reference material and as a calibrator for evaluating assay performance as well as for increasing confidence in reporting HER2 amplification for clinical applications., (Published by Elsevier Inc.)
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- 2016
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26. Development of NIST standard reference material 2373: Genomic DNA standards for HER2 measurements.
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He HJ, Almeida JL, Lund SP, Steffen CR, Choquette S, and Cole KD
- Abstract
NIST standard reference material (SRM) 2373 was developed to improve the measurements of the HER2 gene amplification in DNA samples. SRM 2373 consists of genomic DNA extracted from five breast cancer cell lines with different amounts of amplification of the HER2 gene. The five components are derived from the human cell lines SK-BR-3, MDA-MB-231, MDA-MB-361, MDA-MB-453, and BT-474. The certified values are the ratios of the HER2 gene copy numbers to the copy numbers of selected reference genes DCK, EIF5B, RPS27A, and PMM1. The ratios were measured using quantitative polymerase chain reaction and digital PCR, methods that gave similar ratios. The five components of SRM 2373 have certified HER2 amplification ratios that range from 1.3 to 17.7. The stability and homogeneity of the reference materials were shown by repeated measurements over a period of several years. SRM 2373 is a well characterized genomic DNA reference material that can be used to improve the confidence of the measurements of HER2 gene copy number.
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- 2016
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27. Evaluation of microbial qPCR workflows using engineered Saccharomyces cerevisiae.
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Da Silva SM, Vang LK, Olson ND, Lund SP, Downey AS, Kelman Z, Salit ML, Lin NJ, and Morrow JB
- Abstract
Aims: We describe the development and interlaboratory study of modified Saccharomyces cerevisiae as a candidate material to evaluate a full detection workflow including DNA extraction and quantitative polymerase chain reaction (qPCR)., Methods and Results: S. cerevisiae NE095 was prepared by stable insertion of DNA sequence External RNA Control Consortium-00095 into S. cerevisiae BY4739 to convey selectivity. For the interlaboratory study, a binomial regression model was used to select three cell concentrations, high (4 × 10(7) cells ml(-1)), intermediate (4 × 10(5) cells ml(-1)) and low (4 × 10(3) cells ml(-1)), and the number of samples per concentration. Seven participants, including potential end users, had combined rates of positive qPCR detection (quantification cycle <37) of 100%, 40%, and 0% for high, intermediate, and low concentrations, respectively., Conclusions: The NE095 strain was successfully detected by all participants, with the high concentration indicating a potential target concentration for a reference material., Significance and Impact of the Study: The engineered yeast has potential to support measurement assurance for the analytical process of qPCR, encompassing the method, equipment, and operator, to increase confidence in results and better inform decision-making in areas of applied microbiology. This material can also support process assessment for other DNA-based detection technologies.
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- 2016
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28. The effects of acoustical refurbishment of classrooms on teachers' perceived noise exposure and noise-related health symptoms.
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Kristiansen J, Lund SP, Persson R, Challi R, Lindskov JM, Nielsen PM, Larsen PK, and Toftum J
- Subjects
- Adult, Disorders of Excessive Somnolence etiology, Facility Design and Construction, Fatigue etiology, Female, Humans, Male, Middle Aged, Noise, Occupational adverse effects, Occupational Exposure adverse effects, Perception, Schools, Sound Spectrography, Surveys and Questionnaires, Voice Disorders etiology, Acoustics, Noise, Occupational prevention & control, Occupational Exposure prevention & control, Teaching
- Abstract
Objectives: To investigate whether acoustical refurbishment of classrooms for elementary and lower secondary grade pupils affected teachers' perceived noise exposure during teaching and noise-related health symptoms., Methods: Two schools (A and B) with a total of 102 teachers were subjected to an acoustical intervention. Accordingly, 36 classrooms (20 and 16 in school A and school B, respectively) were acoustically refurbished and 31 classrooms (16 and 15 in school A and school B, respectively) were not changed. Thirteen classrooms in school A were interim "sham" refurbished. Control measurements of RT and activity sound levels were measured before and after refurbishment. Data on perceived noise exposure, disturbance attributed to different noise sources, voice symptoms, and fatigue after work were collected over a year in a total of six consecutive questionnaires., Results: Refurbished classrooms were associated with lower perceived noise exposure and lower ratings of disturbance attributed to noise from equipment in the class compared with unrefurbished classrooms. No associations between the classroom refurbishment and health symptoms were observed. Before acoustical refurbishment, the mean classroom reverberation time was 0.68 (school A) and 0.57 (school B) and 0.55 s in sham refurbished classrooms. After refurbishment, the RT was approximately 0.4 s in both schools. Activity sound level measurements confirmed that the intervention had reduced the equivalent sound levels during lessons with circa 2 dB(A) in both schools., Conclusion: The acoustical refurbishment was associated with a reduction in classroom reverberation time and activity sound levels in both schools. The acoustical refurbishment was associated with a reduction in the teachers' perceived noise exposure, and reports of disturbance from equipment in the classroom decreased. There was no significant effect of the refurbishment on the teachers' voice symptoms or fatigue after work.
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- 2016
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29. Auto-inflammatory challenge of the endolymphatic sac--Cochlear damage measured by distortion product oto-acoustic emissions.
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Larsen M, Friis M, Karlsen CV, Poulsen SS, Lund SP, and Qvortrup K
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- Acoustic Stimulation, Animals, Cochlea ultrastructure, Disease Models, Animal, Endolymphatic Sac physiopathology, Meniere Disease pathology, Meniere Disease physiopathology, Microscopy, Electron, Transmission, Rats, Rats, Inbred Lew, Autoimmunity, Endolymphatic Sac ultrastructure, Meniere Disease immunology, Otoacoustic Emissions, Spontaneous physiology
- Abstract
Conclusion: Twenty-five rats were challenged by an immunologic attack of the endolymphatic sac. After 6 months, distortion product oto-acoustic emissions (DPOAE) revealed a dysfunction of the outer hair cells and immunological active cells were observed in the endolymphatic sac. This information could contribute to the understanding of Ménière's disease., Objectives: This study investigated if an autoimmune challenge of the endolymphatic sac could affect DPOAE output measurements in rats. Also, a potential autoimmune cell infiltration of the endolymphatic sac was investigated., Methods: Eighteen Lewis rats were immunized with a crude endolymphatic sac extract in complete Freund's adjuvant. Seven control animals were injected with Freund's adjuvant in saline. Cochlear damage was estimated by DPOAE dynamics 3 weeks and 6 months after the immunization. Infiltrative cells in the endolymphatic sac were investigated with transmission electron microscopy., Results: The hearing assessment 6 months after immunization revealed a reduction of the DPOAE, on the full range of frequencies (2-63 kHz) in an average of the mean, of 2 dB ± 1.1 in the immunized group compared to the controls (p < 0.05). The same test showed a 2.5 dB decrease from 2 to 5 kHz (p < 0.01). Immunological active cells were observed in the endolymphatic sac in most of the immunized rats.
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- 2015
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30. Best practices for evaluating single nucleotide variant calling methods for microbial genomics.
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Olson ND, Lund SP, Colman RE, Foster JT, Sahl JW, Schupp JM, Keim P, Morrow JB, Salit ML, and Zook JM
- Abstract
Innovations in sequencing technologies have allowed biologists to make incredible advances in understanding biological systems. As experience grows, researchers increasingly recognize that analyzing the wealth of data provided by these new sequencing platforms requires careful attention to detail for robust results. Thus far, much of the scientific Communit's focus for use in bacterial genomics has been on evaluating genome assembly algorithms and rigorously validating assembly program performance. Missing, however, is a focus on critical evaluation of variant callers for these genomes. Variant calling is essential for comparative genomics as it yields insights into nucleotide-level organismal differences. Variant calling is a multistep process with a host of potential error sources that may lead to incorrect variant calls. Identifying and resolving these incorrect calls is critical for bacterial genomics to advance. The goal of this review is to provide guidance on validating algorithms and pipelines used in variant calling for bacterial genomics. First, we will provide an overview of the variant calling procedures and the potential sources of error associated with the methods. We will then identify appropriate datasets for use in evaluating algorithms and describe statistical methods for evaluating algorithm performance. As variant calling moves from basic research to the applied setting, standardized methods for performance evaluation and reporting are required; it is our hope that this review provides the groundwork for the development of these standards.
- Published
- 2015
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31. International interlaboratory study comparing single organism 16S rRNA gene sequencing data: Beyond consensus sequence comparisons.
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Olson ND, Lund SP, Zook JM, Rojas-Cornejo F, Beck B, Foy C, Huggett J, Whale AS, Sui Z, Baoutina A, Dobeson M, Partis L, and Morrow JB
- Abstract
This study presents the results from an interlaboratory sequencing study for which we developed a novel high-resolution method for comparing data from different sequencing platforms for a multi-copy, paralogous gene. The combination of PCR amplification and 16S ribosomal RNA gene (16S rRNA) sequencing has revolutionized bacteriology by enabling rapid identification, frequently without the need for culture. To assess variability between laboratories in sequencing 16S rRNA, six laboratories sequenced the gene encoding the 16S rRNA from Escherichia coli O157:H7 strain EDL933 and Listeria monocytogenes serovar 4b strain NCTC11994. Participants performed sequencing methods and protocols available in their laboratories: Sanger sequencing, Roche 454 pyrosequencing(®), or Ion Torrent PGM(®). The sequencing data were evaluated on three levels: (1) identity of biologically conserved position, (2) ratio of 16S rRNA gene copies featuring identified variants, and (3) the collection of variant combinations in a set of 16S rRNA gene copies. The same set of biologically conserved positions was identified for each sequencing method. Analytical methods using Bayesian and maximum likelihood statistics were developed to estimate variant copy ratios, which describe the ratio of nucleotides at each identified biologically variable position, as well as the likely set of variant combinations present in 16S rRNA gene copies. Our results indicate that estimated variant copy ratios at biologically variable positions were only reproducible for high throughput sequencing methods. Furthermore, the likely variant combination set was only reproducible with increased sequencing depth and longer read lengths. We also demonstrate novel methods for evaluating variable positions when comparing multi-copy gene sequence data from multiple laboratories generated using multiple sequencing technologies.
- Published
- 2015
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32. Evaluation of two mitochondrial DNA biomarkers for prostate cancer detection.
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Maragh S, Veltri RW, Lund SP, Mangold L, Isharwal S, Christudass CS, Partin AW, Humphreys EB, Sorbara L, Srivastava S, and Wagner PD
- Subjects
- Aged, Aged, 80 and over, Case-Control Studies, DNA, Mitochondrial blood, DNA, Mitochondrial urine, Female, Follow-Up Studies, Humans, Male, Middle Aged, Neoplasm Grading, Neoplasm Staging, Paraffin Embedding, Prognosis, Prospective Studies, Prostate pathology, Prostatic Neoplasms blood, Prostatic Neoplasms pathology, Prostatic Neoplasms urine, ROC Curve, Real-Time Polymerase Chain Reaction, Urinalysis, DNA, Mitochondrial genetics, Genetic Markers, Prostate metabolism, Prostatic Neoplasms genetics
- Abstract
Background: A 3.4kb deletion (3.4kbΔ ) in mitochondrial DNA (mtDNA) found in histologically normal prostate biopsy specimens has been reported to be a biomarker for the increased probability of prostate cancer. Increased mtDNA copy number is also reported as associated with cancer., Objective: Independent evaluation of these two potential prostate cancer biomarkers using formalin-fixed paraffin-embedded (FFPE) prostate tissue and matched urine and serum from a high risk cohort of men with and without prostate cancer., Methods: Biomarker levels were detected via qPCR., Results: Both 3.4kbΔ and mtDNA levels were significantly higher in cancer patient FFPE cores (p= 0.045 and p= 0.070 respectively at > 90% confidence). Urine from cancer patients contained significantly higher levels of mtDNA (p= 0.006, 64.3% sensitivity, 86.7% specificity). Combining the 3.4kbΔ and mtDNA gave better performance of detecting prostate cancer than either biomarker alone (FFPE 73.7% sensitivity, 65% specificity; urine 64.3% sensitivity, 100% specificity). In serum, there was no difference for any of the biomarkers., Conclusions: This is the first report on detecting the 3.4kbΔ in urine and evaluating mtDNA levels as a prostate cancer biomarker. A confirmation study with increased sample size and possibly with additional biomarkers would need to be conducted to corroborate and extend these observations.
- Published
- 2015
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33. Nonparametric estimates of drift and diffusion profiles via Fokker-Planck algebra.
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Lund SP, Hubbard JB, and Halter M
- Subjects
- Biological Transport, Computer Simulation, Diffusion, Electricity, Energy Transfer, Motion, Time Factors, Lipid Bilayers chemistry, Models, Statistical
- Abstract
Diffusion processes superimposed upon deterministic motion play a key role in understanding and controlling the transport of matter, energy, momentum, and even information in physics, chemistry, material science, biology, and communications technology. Given functions defining these random and deterministic components, the Fokker-Planck (FP) equation is often used to model these diffusive systems. Many methods exist for estimating the drift and diffusion profiles from one or more identifiable diffusive trajectories; however, when many identical entities diffuse simultaneously, it may not be possible to identify individual trajectories. Here we present a method capable of simultaneously providing nonparametric estimates for both drift and diffusion profiles from evolving density profiles, requiring only the validity of Langevin/FP dynamics. This algebraic FP manipulation provides a flexible and robust framework for estimating stationary drift and diffusion coefficient profiles, is not based on fluctuation theory or solved diffusion equations, and may facilitate predictions for many experimental systems. We illustrate this approach on experimental data obtained from a model lipid bilayer system exhibiting free diffusion and electric field induced drift. The wide range over which this approach provides accurate estimates for drift and diffusion profiles is demonstrated through simulation.
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- 2014
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34. A study of classroom acoustics and school teachers' noise exposure, voice load and speaking time during teaching, and the effects on vocal and mental fatigue development.
- Author
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Kristiansen J, Lund SP, Persson R, Shibuya H, Nielsen PM, and Scholz M
- Subjects
- Adult, Female, Humans, Male, Middle Aged, Schools standards, Teaching statistics & numerical data, Acoustics, Faculty statistics & numerical data, Fatigue etiology, Noise, Occupational adverse effects, Occupational Diseases etiology, Schools statistics & numerical data, Speech physiology
- Abstract
Objectives: The study investigated the noise exposure in a group of Danish school teachers. The aims were to investigate if noise posed a risk of impairment of hearing and to study the association between classroom acoustical conditions, noise exposure, vocal symptoms, and cognitive fatigue., Methods: Background noise levels, vocal load and speaking time were measured on 35 teachers during actual classroom teaching. The classrooms were characterized acoustically by measurements of reverberation time. Before and after the workday, the teachers answered a questionnaire on fatigue symptoms and carried out two cognitive test tasks sensitive to mental fatigue., Results: The average noise level during the lessons was 72 dB(A), but during indoor sports activities the average noise level increased 6.6 dB(A). Room reverberation time (range 0.39-0.83 s) had no significant effect on the noise level. The teachers were talking with a raised voice in 61% of the time, and the vocal load increased 0.65 dB(A) per dB(A) increase in the average lesson noise level. An increase in voice symptoms during the workday correlated significantly with individual average noise exposure, and a decrease in performance in the two-back test correlated significantly with individual average vocal load., Conclusions: Noise exposure in general classrooms posed no risk of noise-induced hearing impairment in school teachers. However, the results provide evidence for an association between noise exposure and vocal load and development of vocal symptoms and cognitive fatigue after work.
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- 2014
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35. Assessing technical performance in differential gene expression experiments with external spike-in RNA control ratio mixtures.
- Author
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Munro SA, Lund SP, Pine PS, Binder H, Clevert DA, Conesa A, Dopazo J, Fasold M, Hochreiter S, Hong H, Jafari N, Kreil DP, Łabaj PP, Li S, Liao Y, Lin SM, Meehan J, Mason CE, Santoyo-Lopez J, Setterquist RA, Shi L, Shi W, Smyth GK, Stralis-Pavese N, Su Z, Tong W, Wang C, Wang J, Xu J, Ye Z, Yang Y, Yu Y, and Salit M
- Subjects
- Gene Expression Profiling standards, Humans, Reference Standards, Reproducibility of Results, Gene Expression Profiling methods, RNA, Messenger genetics
- Abstract
There is a critical need for standard approaches to assess, report and compare the technical performance of genome-scale differential gene expression experiments. Here we assess technical performance with a proposed standard 'dashboard' of metrics derived from analysis of external spike-in RNA control ratio mixtures. These control ratio mixtures with defined abundance ratios enable assessment of diagnostic performance of differentially expressed transcript lists, limit of detection of ratio (LODR) estimates and expression ratio variability and measurement bias. The performance metrics suite is applicable to analysis of a typical experiment, and here we also apply these metrics to evaluate technical performance among laboratories. An interlaboratory study using identical samples shared among 12 laboratories with three different measurement processes demonstrates generally consistent diagnostic power across 11 laboratories. Ratio measurement variability and bias are also comparable among laboratories for the same measurement process. We observe different biases for measurement processes using different mRNA-enrichment protocols.
- Published
- 2014
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36. Transcriptional analysis of the global regulatory networks active in Pseudomonas syringae during leaf colonization.
- Author
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Yu X, Lund SP, Greenwald JW, Records AH, Scott RA, Nettleton D, Lindow SE, Gross DC, and Beattie GA
- Subjects
- Bacterial Proteins metabolism, DNA-Binding Proteins genetics, DNA-Binding Proteins metabolism, Gene Deletion, Gene Expression Profiling, Gene Regulatory Networks, Genes, Regulator, Plant Diseases microbiology, Pseudomonas syringae growth & development, RNA, Bacterial genetics, RNA, Bacterial isolation & purification, Sigma Factor genetics, Sigma Factor metabolism, Stress, Physiological, Bacterial Proteins genetics, Gene Expression Regulation, Bacterial, Plant Leaves microbiology, Pseudomonas syringae genetics, Quorum Sensing genetics, Regulon genetics
- Abstract
Unlabelled: The plant pathogen Pseudomonas syringae pv. syringae B728a grows and survives on leaf surfaces and in the leaf apoplast of its host, bean (Phaseolus vulgaris). To understand the contribution of distinct regulators to B728a fitness and pathogenicity, we performed a transcriptome analysis of strain B728a and nine regulatory mutants recovered from the surfaces and interior of leaves and exposed to environmental stresses in culture. The quorum-sensing regulators AhlR and AefR influenced few genes in planta or in vitro. In contrast, GacS and a downstream regulator, SalA, formed a large regulatory network that included a branch that regulated diverse traits and was independent of plant-specific environmental signals and a plant signal-dependent branch that positively regulated secondary metabolite genes and negatively regulated the type III secretion system. SalA functioned as a central regulator of iron status based on its reciprocal regulation of pyoverdine and achromobactin genes and also sulfur uptake, suggesting a role in the iron-sulfur balance. RetS functioned almost exclusively to repress secondary metabolite genes when the cells were not on leaves. Among the sigma factors examined, AlgU influenced many more genes than RpoS, and most AlgU-regulated genes depended on RpoN. RpoN differentially impacted many AlgU- and GacS-activated genes in cells recovered from apoplastic versus epiphytic sites, suggesting differences in environmental signals or bacterial stress status in these two habitats. Collectively, our findings illustrate a central role for GacS, SalA, RpoN, and AlgU in global regulation in B728a in planta and a high level of plasticity in these regulators' responses to distinct environmental signals., Importance: Leaves harbor abundant microorganisms, all of which must withstand challenges such as active plant defenses and a highly dynamic environment. Some of these microbes can influence plant health. Despite knowledge of individual regulators that affect the fitness or pathogenicity of foliar pathogens, our understanding of the relative importance of various global regulators to leaf colonization is limited. Pseudomonas syringae strain B728a is a plant pathogen and a good colonist of both the surfaces and interior of leaves. This study used global transcript profiles of strain B728a to investigate the complex regulatory network of putative quorum-sensing regulators, two-component regulators, and sigma factors in cells colonizing the leaf surface and leaf interior under stressful in vitro conditions. The results highlighted the value of evaluating these networks in planta due to the impact of leaf-specific environmental signals and suggested signal differences that may enable cells to differentiate surface versus interior leaf habitats., (Copyright © 2014 Yu et al.)
- Published
- 2014
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37. Recent and long-term occupational noise exposure and salivary cortisol level.
- Author
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Stokholm ZA, Hansen ÅM, Grynderup MB, Bonde JP, Christensen KL, Frederiksen TW, Lund SP, Vestergaard JM, and Kolstad HA
- Subjects
- Adult, Female, Humans, Hypothalamo-Hypophyseal System physiopathology, Male, Middle Aged, Pituitary-Adrenal System physiopathology, Stress, Psychological physiopathology, Workplace, Hydrocortisone analysis, Noise, Occupational adverse effects, Saliva chemistry, Stress, Psychological etiology
- Abstract
Environmental and occupational noise exposure have been related to increased risk of cardiovascular disease, hypothetically mediated by stress-activation of the hypothalamic-pituitary-adrenal (HPA) axis. The objective of this study was to investigate the relation between recent and long-term occupational noise exposure and cortisol level measured off work to assess a possible sustained HPA-axis effect. We included 501 industrial, finance, and service workers who were followed for 24h during work, leisure, and sleep. Ambient occupational noise exposure levels were recorded every 5s by personal dosimeters and we calculated the full-shift LAEq value and estimated duration and cumulative exposure based on their work histories since 1980. For 332 workers who kept a log-book on the use of hearing protection devices (HPD), we subtracted 10 dB from every noise recording obtained during HPD use and estimated the noise level at the ear. Salivary cortisol concentration was measured at 20.00 h, the following day at awakening, and 30 min after awakening on average 5, 14 and 14.5h after finishing work. The mean ambient noise exposure level was 79.9 dB(A) [range: 55.0-98.9] and the mean estimated level at the ear 77.7 dB(A) [range: 55.0-94.2]. In linear and mixed regression models that adjusted for age, sex, current smoking, heavy alcohol consumption, personal income, BMI, leisure-time noise exposure level, time since occupational noise exposure ceased, awakening time, and time of saliva sampling, we observed no statistically significant exposure response relation between recent, or long-term ambient occupational noise exposure level and any cortisol parameter off work. This was neither the case for recent noise level at the ear. To conclude, neither recent nor long-term occupational noise exposure levels were associated with increased cortisol level off work. Thus, our results do not indicate that a sustained activation of the HPA axis, as measured by cortisol, is involved in the causal pathway between occupational noise exposure and cardiovascular disease., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2014
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38. Atherogenic risk factors and hearing thresholds.
- Author
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Frederiksen TW, Ramlau-Hansen CH, Stokholm ZA, Brødsgaard Grynderup M, Hansen ÅM, Lund SP, Medom Vestergaard J, Kristiansen J, Bonde JP, and Kolstad HA
- Subjects
- Adult, Aged, Blood Pressure Monitoring, Ambulatory, Cholesterol, LDL blood, Cohort Studies, Cross-Sectional Studies, Denmark epidemiology, Diabetes Mellitus metabolism, Female, Glycated Hemoglobin metabolism, Hearing Loss, Sensorineural physiopathology, Humans, Hyperlipidemias blood, Male, Middle Aged, Risk Factors, Triglycerides blood, Young Adult, Atherosclerosis epidemiology, Auditory Threshold physiology, Diabetes Mellitus epidemiology, Hearing Loss, Sensorineural epidemiology, Hyperlipidemias epidemiology, Hypertension epidemiology, Noise, Occupational statistics & numerical data, Obesity epidemiology, Smoking epidemiology
- Abstract
The objective of this study was to evaluate the influence of atherogenic risk factors on hearing thresholds. In a cross-sectional study we analyzed data from a Danish survey in 2009-2010 on physical and psychological working conditions. The study included 576 white- and blue-collar workers from children's day care units, financial services and 10 manufacturing trades. Associations between atherogenic risk factors (blood lipids, glycosylated hemoglobin, smoking habits, body mass index (BMI), and ambulatory blood pressure) and hearing thresholds were analyzed using multiple linear regression models. Adjusted results suggested associations between smoking, high BMI and triglyceride level and low high-density lipoprotein level and increased low-frequency hearing thresholds (average of pure-tone hearing thresholds at 0.25, 0.5 and 1 kHz). Furthermore, an increasing load of atherogenic risk factors seemed associated with increased low-frequency hearing thresholds, but only at a borderline level of statistical significance. Associations were generally strongest with hearing levels of the worst hearing ear. We found no statistically significant associations between atherogenic risk factors and high-frequency hearing thresholds (average of pure-tone hearing thresholds at 4, 6 and 8 kHz)., (© 2014 S. Karger AG, Basel.)
- Published
- 2014
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39. Classroom acoustics and hearing ability as determinants for perceived social climate and intentions to stay at work.
- Author
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Persson R, Kristiansen J, Lund SP, Shibuya H, and Nielsen PM
- Subjects
- Adult, Auditory Threshold, Denmark, Female, Humans, Intention, Job Satisfaction, Male, Psychoacoustics, Attitude, Faculty, Interprofessional Relations, Noise, Occupational adverse effects, Personnel Turnover
- Abstract
Background noise and room acoustics may impede social interactions by interfering with oral communication and other cognitive processes. Accordingly, recent research in school environments has showed that social relationships with peers and teachers are described more negatively in rooms with long reverberation times (RT). The purpose of this study was to investigate how RT and hearing ability (i.e., hearing thresholds [HT] and distortion product oto-acoustic emissions) were associated with school teachers' perceptions of the social climate at work and their intentions to stay on the job. School teachers (n = 107) from 10 schools that worked in classrooms classified by acoustical experts as "short RT" (3 schools, mean RT 0.41-0.47 s), "medium RT" (3 schools, mean RT 0.50-0.53 s), and "long RT" (4 schools, mean RT 0.59-0.73 s) were examined. Teachers who worked in classrooms with long RT perceived their social climate to be more competitive, conflict laden, and less relaxed and comfortable. They were more doubtful about staying on the job. Even if the teachers were generally satisfied with their work the results suggest that the comfort at work may have been further improved by acoustical interventions that focus on reducing sound reflections in the classrooms. Yet, due the study design and the novelty of the findings the potential practical significance of our observations remains to be evaluated.
- Published
- 2013
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40. Boltzmann's H-function and diffusion processes.
- Author
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Hubbard JB, Lund SP, and Halter M
- Subjects
- Diffusion, Markov Chains, Thermodynamics, Models, Chemical
- Abstract
There exists a generalization of Boltzmann's H-function that allows for nonuniformly populated stationary states, which may exist far from thermodynamic equilibrium. Here we describe a method for obtaining a generalized or collective diffusion coefficient D directly from this H-function, the only constraints being that the relaxation process is Markov (short memory), continuous in the reaction coordinate, and local in the sense of a flux/force relationship. As an application of this H-function method, we simulate the self-consistent extraction of D via Langevin/Fokker-Planck (L/FP) dynamics on various potential energy landscapes. We observe that the initial epoch of relaxation, which is far removed from the stationary state, provides the most reliable estimates of D. The construction of an H-function that guarantees conformity with the second law of thermodynamics has been generalized to allow for diffusion coefficients that may depend on both the reaction coordinate and time, and the extension to an arbitrary number of reaction coordinates is straightforward. For this multidimensional case, the diffusion tensor must be positive definite in the sense that its eigenvalues must be real and positive. To illustrate the behavior of the proposed collective diffusion coefficient, we simulate the H-function for a variety of Langevin systems. In particular, the impacts on H and D of landscape shape, sample size, selection of an initial distribution, finite dynamic observation range, stochastic correlations, and short/long-term memory effects are examined.
- Published
- 2013
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41. Transcriptional responses of Pseudomonas syringae to growth in epiphytic versus apoplastic leaf sites.
- Author
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Yu X, Lund SP, Scott RA, Greenwald JW, Records AH, Nettleton D, Lindow SE, Gross DC, and Beattie GA
- Subjects
- Bacterial Proteins classification, Bacterial Proteins genetics, Bacterial Proteins metabolism, Cell Wall metabolism, Cell Wall microbiology, Cluster Analysis, Ecosystem, Extracellular Space metabolism, Extracellular Space microbiology, Flagella metabolism, Flagella physiology, Genes, Bacterial genetics, Host-Pathogen Interactions, Movement, Nitrogen metabolism, Oligonucleotide Array Sequence Analysis, Peptides, Cyclic metabolism, Phenylalanine metabolism, Plant Epidermis metabolism, Plant Epidermis microbiology, Plant Leaves microbiology, Pseudomonas syringae pathogenicity, Pseudomonas syringae physiology, Virulence genetics, Water metabolism, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Plant Leaves metabolism, Pseudomonas syringae genetics
- Abstract
Some strains of the foliar pathogen Pseudomonas syringae are adapted for growth and survival on leaf surfaces and in the leaf interior. Global transcriptome profiling was used to evaluate if these two habitats offer distinct environments for bacteria and thus present distinct driving forces for adaptation. The transcript profiles of Pseudomonas syringae pv. syringae B728a support a model in which leaf surface, or epiphytic, sites specifically favor flagellar motility, swarming motility based on 3-(3-hydroxyalkanoyloxy) alkanoic acid surfactant production, chemosensing, and chemotaxis,indicating active relocation primarily on the leaf surface. Epiphytic sites also promote high transcript levels for phenylalanine degradation, which may help counteract phenylpropanoid-based defenses before leaf entry. In contrast, intercellular, or apoplastic,sites favor the high-level expression of genes for GABA metabolism (degradation of these genes would attenuate GABA repression of virulence) and the synthesis of phytotoxins, two additional secondary metabolites, and syringolin A. These findings support roles for these compounds in virulence, including a role for syringolin A in suppressing defense responses beyond stomatal closure. A comparison of the transcriptomes from in planta cells and from cells exposed to osmotic stress, oxidative stress, and iron and nitrogen limitation indicated that water availability, in particular,was limited in both leaf habitats but was more severely limited in the apoplast than on the leaf surface under the conditions tested. These findings contribute to a coherent model of the adaptations of this widespread bacterial phytopathogen to distinct habitats within its host.
- Published
- 2013
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42. Detecting differential expression in RNA-sequence data using quasi-likelihood with shrunken dispersion estimates.
- Author
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Lund SP, Nettleton D, McCarthy DJ, and Smyth GK
- Subjects
- Base Sequence, Databases, Genetic, Gene Expression Profiling methods, Likelihood Functions, RNA, Messenger metabolism, Gene Expression Profiling statistics & numerical data, Sequence Analysis, RNA methods
- Abstract
Next generation sequencing technology provides a powerful tool for measuring gene expression (mRNA) levels in the form of RNA-sequence data. Method development for identifying differentially expressed (DE) genes from RNA-seq data, which frequently includes many low-count integers and can exhibit severe overdispersion relative to Poisson or binomial distributions, is a popular area of ongoing research. Here we present quasi-likelihood methods with shrunken dispersion estimates based on an adaptation of Smyth's (2004) approach to estimating gene-specific error variances for microarray data. Our suggested methods are computationally simple, analogous to ANOVA and compare favorably versus competing methods in detecting DE genes and estimating false discovery rates across a variety of simulations based on real data.
- Published
- 2012
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43. An experimental protocol for maternal pulmonary exposure in developmental toxicology.
- Author
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Jackson P, Lund SP, Kristiansen G, Andersen O, Vogel U, Wallin H, and Hougaard KS
- Subjects
- Anesthetics, Inhalation adverse effects, Animals, Animals, Newborn, Animals, Suckling, Body Weight drug effects, Bronchoalveolar Lavage Fluid cytology, Bronchoalveolar Lavage Fluid immunology, DNA Damage drug effects, Female, Inhalation Exposure adverse effects, Isoflurane adverse effects, Liver drug effects, Liver growth & development, Liver metabolism, Male, Mice, Mice, Inbred C57BL, Pregnancy, Fetal Development drug effects, Lactation drug effects, Maternal Exposure adverse effects, Prenatal Exposure Delayed Effects, Sexual Maturation drug effects, Toxicity Tests methods
- Abstract
To establish a protocol for studying effects of pulmonary exposure in developmental toxicity studies, the effects of intratracheal sham instillation under short-term isoflurane anaesthesia were evaluated with a protocol including multiple instillations during gestation. Twelve time-mated mice (C57BL/6BomTac) were anaesthetized with isoflurane and intratracheally instilled with saline containing 10% bronchoalveolar lavage (BAL) on gestation days 8, 11, 15 and 18. In addition, the early effects of the procedure were assessed in naive female mice. Control animals were not handled. Dams were followed until weaning, and the offspring were observed from birth to sexual maturation. The cell composition of BAL was examined in the females early after treatment (3 days) and in the dams at weaning (25 days). DNA damage in BAL and liver cells was determined by the comet assay. The procedure did not affect gestation or viability, growth and sexual maturation of the offspring. Lung markers of inflammation and DNA damage were comparable in control and treated dams. Livers of the anaesthetized and instilled females, dams and their offspring displayed no induction of DNA damage. Intratracheal instillation under isoflurane anaesthesia did not induce observable effects in pregnant mice or their offspring. We suggest that this procedure can be used as a means of exposure through the airways in studies of developmental toxicity., (© 2010 The Authors. Basic & Clinical Pharmacology & Toxicology © 2010 Nordic Pharmacological Society.)
- Published
- 2011
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44. Effects of pre- and postnatal exposure to the UV-filter octyl methoxycinnamate (OMC) on the reproductive, auditory and neurological development of rat offspring.
- Author
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Axelstad M, Boberg J, Hougaard KS, Christiansen S, Jacobsen PR, Mandrup KR, Nellemann C, Lund SP, and Hass U
- Subjects
- Animals, Cinnamates administration & dosage, Dose-Response Relationship, Drug, Endocrine Disruptors administration & dosage, Estradiol blood, Female, Growth drug effects, Lactation metabolism, Male, Maze Learning drug effects, Organ Size drug effects, Pregnancy, Prenatal Exposure Delayed Effects pathology, Prenatal Exposure Delayed Effects physiopathology, Progesterone blood, Rats, Rats, Wistar, Reflex, Startle drug effects, Semen drug effects, Sexual Maturation drug effects, Sunscreening Agents administration & dosage, Testosterone blood, Thyroxine blood, Behavior, Animal drug effects, Cinnamates toxicity, Endocrine Disruptors toxicity, Hearing drug effects, Maternal Exposure adverse effects, Prenatal Exposure Delayed Effects chemically induced, Sunscreening Agents toxicity
- Abstract
Octyl Methoxycinnamate (OMC) is a frequently used UV-filter in sunscreens and other cosmetics. The aim of the present study was to address the potential endocrine disrupting properties of OMC, and to investigate how OMC induced changes in thyroid hormone levels would be related to the neurological development of treated offspring. Groups of 14-18 pregnant Wistar rats were dosed with 0, 500, 750 or 1000 mg OMC/kg bw/day during gestation and lactation. Serum thyroxine (T(4)), testosterone, estradiol and progesterone levels were measured in dams and offspring. Anogenital distance, nipple retention, postnatal growth and timing of sexual maturation were assessed. On postnatal day 16, gene expression in prostate and testes, and weight and histopathology of the thyroid gland, liver, adrenals, prostate, testes, epididymis and ovaries were measured. After weaning, offspring were evaluated in a battery of behavioral and neurophysiological tests, including tests of activity, startle response, cognitive and auditory function. In adult animals, reproductive organ weights and semen quality were investigated. Thyroxine (T(4)) levels showed a very marked decrease during the dosing period in all dosed dams, but were less severely affected in the offspring. On postnatal day 16, high dose male offspring showed reduced relative prostate and testis weights, and a dose-dependent decrease in testosterone levels. In OMC exposed female offspring, motor activity levels were decreased, while low and high dose males showed improved spatial learning abilities. The observed behavioral changes were probably not mediated solely by early T(4) deficiencies, as the observed effects differed from those seen in other studies of developmental hypothyroxinemia. At eight months of age, sperm counts were reduced in all three OMC-dosed groups, and prostate weights were reduced in the highest dose group. Taken together, these results indicate that perinatal OMC-exposure can affect both the reproductive and neurological development of rat offspring, which may be a cause of concern, as humans are systematically exposed to the compound through usage of sunscreens and other cosmetics., (Copyright © 2010 Elsevier Inc. All rights reserved.)
- Published
- 2011
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45. Systemic steroid reduces long-term hearing loss in experimental pneumococcal meningitis.
- Author
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Worsøe L, Brandt CT, Lund SP, Østergaard C, Thomsen J, and Cayé-Thomasen P
- Subjects
- Animals, Cochlea drug effects, Cochlea pathology, Hearing Loss, Sensorineural pathology, Injections, Intramuscular, Male, Meningitis, Pneumococcal pathology, Neurons drug effects, Neurons pathology, Rats, Rats, Wistar, Spiral Ganglion pathology, Anti-Inflammatory Agents pharmacology, Betamethasone pharmacology, Evoked Potentials, Auditory, Brain Stem drug effects, Hearing Loss, Sensorineural drug therapy, Meningitis, Pneumococcal drug therapy, Otoacoustic Emissions, Spontaneous drug effects, Spiral Ganglion drug effects
- Abstract
Objectives/hypothesis: Sensorineural hearing loss is a common complication of pneumococcal meningitis. Treatment with corticosteroids reduces inflammatory response and may thereby reduce hearing loss. However, both experimental studies and clinical trials investigating the effect of corticosteroids on hearing loss have generated conflicting results. The objective of the present study was to determine whether systemic steroid treatment had an effect on hearing loss and cochlear damage in a rat model of pneumococcal meningitis., Study Design: Controlled animal study of acute bacterial meningitis., Methods: Adult rats were randomly assigned to two experimental treatment groups: a group treated with systemic steroid (n = 13) and a control group treated with saline (n = 13). Treatment was initiated 21 hours after infection and repeated once a day for three days. Hearing loss and cochlear damage were assessed by distortion product otoacoustic emissions (DPOAE), auditory brainstem response (ABR) at 16 kHz, and spiral ganglion neuron density., Results: Fifty-six days after infection, steroid treatment significantly reduced hearing loss assessed by DPOAE (P < .05; Mann-Whitney) and showed a trend toward reducing loss of viable neurons in the spiral ganglion (P = .0513; Mann-Whitney). After pooling data from day 22 with data from day 56, we found that systemic steroid treatment significantly reduced loss of spiral ganglion neurons (P = .0098; Mann-Whitney test)., Conclusions: Systemic steroid treatment reduces long-term hearing loss and loss of spiral ganglion neurons in experimental pneumococcal meningitis in adult rats. The findings support a beneficial role of anti-inflammatory agents in reducing hearing loss and cochlear damage in meningitis.
- Published
- 2010
- Full Text
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46. Prenatal and adult stress interplay--behavioral implications.
- Author
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Kjaer SL, Wegener G, Rosenberg R, Lund SP, and Hougaard KS
- Subjects
- Acoustic Stimulation, Age Factors, Analysis of Variance, Animals, Corticosterone blood, Estrous Cycle physiology, Female, Neuropsychological Tests, Pregnancy, Random Allocation, Rats, Rats, Wistar, Prenatal Exposure Delayed Effects, Reflex, Startle physiology, Stress, Psychological blood, Stress, Psychological physiopathology
- Abstract
The origin of adult behavior and the possible pathogenesis of psychiatric disorders remain elusive, but extensive research indicates that interaction of genes and environment play a crucial role for adult phenotype. Differences in susceptibility may arise by earlier experiences and genomic variables, either alone or in combination. The acoustic startle response (ASR) has been shown to be altered in patients with several psychiatric diseases, a change that could result from a persistent sensitization caused by chronic arousal secondary to a traumatic incident. The current work hypothesized that a single aversive procedure would induce long-term hyperactivity in the HPA-axis of rats that had become vulnerable by prenatal stress, and thereby change reactivity in the ASR. Prenatal stress was achieved by maternal gestational exposure to Chronic Mild Stress (CMS). At age 3 months, the offspring were blood sampled by a stressful procedure, and subsequently tested in the acoustic startle paradigm. Prenatal CMS strongly reduced prepulse inhibition (PPI) whereas postnatal blood sampling under restraint generally increased PPI. Our data demonstrate interplay between pre- and postnatal stressful events, but also that this interaction is complex and could influence the interplay between PPI and basal startle. Our results suggest that circumstances dating back to early development may have implications for adult life behavior, and based on this we propose a new theory of a threshold in the induction of a stress response in the ASR test, which influences whether the PPI or basal startle response will be affected., (Copyright 2010 Elsevier B.V. All rights reserved.)
- Published
- 2010
- Full Text
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47. Non-auditory health effects among air force crew chiefs exposed to high level sound.
- Author
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Jensen A, Lund SP, Lücke TH, Clausen OV, and Svendsen JT
- Subjects
- Adult, Denmark, Environmental Exposure adverse effects, Health Status, Humans, Male, Middle Aged, Aircraft statistics & numerical data, Military Personnel statistics & numerical data, Noise, Occupational adverse effects, Noise, Transportation adverse effects, Occupational Exposure adverse effects
- Abstract
The possibility of non-auditory health effects in connection with occupational exposure to high level sound is supposed by some researchers, but is still debated. Crew chiefs on airfields are exposed to high-level aircraft sound when working close to aircraft with running engines. We compared their health status with a similar control group who were not subject to this specific sound exposure. Health records of 42 crew chiefs were compared to health records of 42 aircraft mechanics and 17 former crew chiefs. The specific sound exposure of crew chiefs was assessed. The number of reported disease cases was generally small, but generally slightly higher among mechanics than among crew chiefs. Diseases of the ear were more frequent among crew chiefs (not significant). Former crew chiefs reported fewer diseases of the ear and more airways infections (both significant). The sound exposure during launch was up to 144 dB (peak) and 124 dB (L(eq) ), but for limited time. The study did not reveal a higher disease frequency in general among crew chiefs. However, it did reveal a tendency to ear diseases, possibly due to their exposure to high-level sound.
- Published
- 2009
- Full Text
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48. Stress reactions to cognitively demanding tasks and open-plan office noise.
- Author
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Kristiansen J, Mathiesen L, Nielsen PK, Hansen AM, Shibuya H, Petersen HM, Lund SP, Skotte J, Jørgensen MB, and Søgaard K
- Subjects
- Adult, Affective Symptoms physiopathology, Affective Symptoms psychology, Blood Pressure physiology, Electromyography, Female, Heart physiopathology, Heart Rate physiology, Humans, Hydrocortisone analysis, Middle Aged, Muscle Contraction physiology, Muscle, Skeletal physiopathology, Physical Exertion physiology, Saliva chemistry, Stress, Psychological physiopathology, Stress, Psychological psychology, Task Performance and Analysis, Cognition physiology, Noise, Occupational adverse effects, Stress, Psychological etiology
- Abstract
Objectives: To investigate the effects of cognitively demanding work tasks and office noise on heart rate variability (HRV), cardiovascular responses and electromyography (EMG) activity in the trapezius muscles., Methods: Ten female volunteers were exposed to simulated open-plan office noise for 35 min (Leq 65 dBA), while engaged in cognitively demanding tasks. Task performance, self-rated stress and energy, affective state, perceived exertion in the shoulders and in the head, EMG in the left and right trapezius muscle, blood pressure, heart period length, HRV, and salivary cortisol were measured., Results: Cognitively demanding work tasks were associated with changes in HRV, systolic blood pressure and EMG that reflects increased sympathetic activity in the autonomic nervous system. No effect of noise was observed, except for a higher rating of perceived exertion in the head and, contrary to expectations, a 4% lower diastolic blood pressure in the noise conditions., Conclusions: Psychophysiological measures reflected the mental load imposed by cognitive work tasks. Short-term exposure to office noise resulted in increased ratings of perceived exertion in the head, but not in physiological stress reactions.
- Published
- 2009
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49. Developmental neurotoxicity of propylthiouracil (PTU) in rats: relationship between transient hypothyroxinemia during development and long-lasting behavioural and functional changes.
- Author
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Axelstad M, Hansen PR, Boberg J, Bonnichsen M, Nellemann C, Lund SP, Hougaard KS, and Hass U
- Subjects
- Age Factors, Animals, Animals, Newborn, Antithyroid Agents, Auditory Threshold, Body Weight, Disease Models, Animal, Dose-Response Relationship, Drug, Female, Gestational Age, Hearing, Hypothyroidism chemically induced, Hypothyroidism metabolism, Hypothyroidism physiopathology, Male, Maze Learning, Motor Activity, Nervous System growth & development, Nervous System metabolism, Neurotoxicity Syndromes metabolism, Neurotoxicity Syndromes physiopathology, Organ Size, Pregnancy, Propylthiouracil, Rats, Rats, Wistar, Thyroid Gland pathology, Thyroxine blood, Behavior, Animal, Hypothyroidism complications, Nervous System physiopathology, Neurotoxicity Syndromes etiology, Prenatal Exposure Delayed Effects, Thyroid Gland metabolism, Thyroxine deficiency
- Abstract
Markedly lowered thyroid hormone levels during development may influence a child's behaviour, intellect, and auditory function. Recent studies, indicating that even small changes in the mother's thyroid hormone status early in pregnancy may cause adverse effects on her child, have lead to increased concern for thyroid hormone disrupting chemicals in the environment. The overall aim of the study was therefore to provide a detailed knowledge on the relationship between thyroid hormone levels during development and long-lasting effects on behaviour and hearing. Groups of 16-17 pregnant rats (HanTac:WH) were dosed with PTU (0, 0.8, 1.6 or 2.4 mg/kg/day) from gestation day (GD) 7 to postnatal day (PND) 17, and the physiological and behavioural development of rat offspring was assessed. Both dams and pups in the higher dose groups had markedly decreased thyroxine (T(4)) levels during the dosing period, and the weight and histology of the thyroid glands were severely affected. PTU exposure caused motor activity levels to decrease on PND 14, and to increase on PND 23 and in adulthood. In the adult offspring, learning and memory was impaired in the two highest dose groups when tested in the radial arm maze, and auditory function was impaired in the highest dose group. Generally, the results showed that PTU-induced hypothyroxinemia influenced the developing rat brain, and that all effects on behaviour and loss of hearing in the adult offspring were significantly correlated to reductions in T(4) during development. This supports the hypothesis that decreased T(4) may be a relevant predictor for long-lasting developmental neurotoxicity.
- Published
- 2008
- Full Text
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50. The risk of tinnitus following occupational noise exposure in workers with hearing loss or normal hearing.
- Author
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Rubak T, Kock S, Koefoed-Nielsen B, Lund SP, Bonde JP, and Kolstad HA
- Subjects
- Adult, Audiometry, Pure-Tone, Cross-Sectional Studies, Female, Humans, Male, Middle Aged, Noise, Occupational statistics & numerical data, Occupational Diseases epidemiology, Risk Assessment, Surveys and Questionnaires, Time Factors, Hearing Loss, Noise-Induced complications, Noise, Occupational adverse effects, Occupational Exposure adverse effects, Tinnitus epidemiology, Tinnitus etiology
- Abstract
The purpose was to investigate the relationship between noise exposure and tinnitus among workers with normal hearing and hearing loss, respectively. We conducted a cross-sectional survey of 752 workers employed at 91 workplaces, that were investigated by means of full work-shift noise levels, questionnaire data, and bilateral pure-tone audiometry. Tinnitus was not associated with the present noise level, the duration of noise exposure, or the cumulative noise exposure if participants had normal hearing. As expected, such trends were demonstrated if participants had a hearing handicap. Based on these data, we will be cautious in ascribing tinnitus to noise exposure in our patients' workplaces if they have a normal audiogram. Furthermore our data indicates no risk of noise-induced tinnitus at exposure levels where no hearing loss would be expected, e.g. as usually encountered in non-industrial workplaces.
- Published
- 2008
- Full Text
- View/download PDF
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