109 research outputs found

    Duplication and Diversification of the Hypoxia-Inducible IGFBP-1 Gene in Zebrafish

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    Gene duplication is the primary force of new gene evolution. Deciphering whether a pair of duplicated genes has evolved divergent functions is often challenging. The zebrafish is uniquely positioned to provide insight into the process of functional gene evolution due to its amenability to genetic and experimental manipulation and because it possess a large number of duplicated genes.We report the identification and characterization of two hypoxia-inducible genes in zebrafish that are co-ortholgs of human IGF binding protein-1 (IGFBP-1). IGFBP-1 is a secreted protein that binds to IGF and modulates IGF actions in somatic growth, development, and aging. Like their human and mouse counterparts, in adult zebrafish igfbp-1a and igfbp-1b are exclusively expressed in the liver. During embryogenesis, the two genes are expressed in overlapping spatial domains but with distinct temporal patterns. While zebrafish IGFBP-1a mRNA was easily detected throughout embryogenesis, IGFBP-1b mRNA was detectable only in advanced stages. Hypoxia induces igfbp-1a expression in early embryogenesis, but induces the igfbp-1b expression later in embryogenesis. Both IGFBP-1a and -b are capable of IGF binding, but IGFBP-1b has much lower affinities for IGF-I and -II because of greater dissociation rates. Overexpression of IGFBP-1a and -1b in zebrafish embryos caused significant decreases in growth and developmental rates. When tested in cultured zebrafish embryonic cells, IGFBP-1a and -1b both inhibited IGF-1-induced cell proliferation but the activity of IGFBP-1b was significantly weaker.These results indicate subfunction partitioning of the duplicated IGFBP-1 genes at the levels of gene expression, physiological regulation, protein structure, and biological actions. The duplicated IGFBP-1 may provide additional flexibility in fine-tuning IGF signaling activities under hypoxia and other catabolic conditions

    Diminution of Voltage Threshold Plays a Key Role in Determining Recruitment of Oculomotor Nucleus Motoneurons during Postnatal Development

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    The size principle dictates the orderly recruitment of motoneurons (Mns). This principle assumes that Mns of different sizes have a similar voltage threshold, cell size being the crucial property in determining neuronal recruitment. Thus, smaller neurons have higher membrane resistance and require a lower depolarizing current to reach spike threshold. However, the cell size contribution to recruitment in Mns during postnatal development remains unknown. To investigate this subject, rat oculomotor nucleus Mns were intracellularly labeled and their electrophysiological properties recorded in a brain slice preparation. Mns were divided into 2 age groups: neonatal (1–7 postnatal days, n = 14) and adult (20–30 postnatal days, n = 10). The increase in size of Mns led to a decrease in input resistance with a strong linear relationship in both age groups. A well-fitted inverse correlation was also found between input resistance and rheobase in both age groups. However, input resistance versus rheobase did not correlate when data from neonatal and adult Mns were combined in a single group. This lack of correlation is due to the fact that decrease in input resistance of developing Mns did not lead to an increase in rheobase. Indeed, a diminution in rheobase was found, and it was accompanied by an unexpected decrease in voltage threshold. Additionally, the decrease in rheobase co-varied with decrease in voltage threshold in developing Mns. These data support that the size principle governs the recruitment order in neonatal Mns and is maintained in adult Mns of the oculomotor nucleus; but during postnatal development the crucial property in determining recruitment order in these Mns was not the modifications of cell size-input resistance but of voltage threshold

    Thoracic ultrasound: introduction

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    Pleural disease: introduction

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    Pleural diseases are common and associated with specialist procedures and a growing evidence base. This book, written by experts in the field, summarises up-to-date knowledge of the investigation, management and future directions of this exciting field

    Development of and gathering validity evidence for a theoretical test in thoracic ultrasound

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    Background: Thoracic ultrasound (TUS) has a high diagnostic accuracy for many common pulmonary diseases, but theoretic knowledge in sonographic physics, thoracic anatomy and physiology, and sonopathologic patterns is required to develop competence. Objectives: The aims of the study were to develop and gather validity evidence for a theoretical test in TUS and to establish a pass/fail standard. Methods: Content was provided based on expert interviews, leading to the creation of 113 initial multiple-choice question (MCQ) items. Consensus was reached on 92 proceeding items through a Delphi process, and items were presented to physicians with different knowledge and experience in TUS. Answers were used for item statistics in order to select the items with the most optimal item discrimination and difficulty (i.e., level I items) to be included in the final test. Mean scores of the novice, intermediate and experienced groups were compared, and a pass/fail score was established using the contrasting groups’ standard setting method. Results: Item statistics revealed 38 level I items, of which 30 were selected to be included in the final test. The internal consistency was high (Cronbach’s alpha = 0.88). Differences in mean scores were 8.6 points (p < 0.001), 6.3 points (p = 0.01), and 14.9 points (p < 0.001) between novices and intermediates, intermediates and experienced, and novices and experienced, respectively. A pass/fail standard of 20 points was established. Conclusion: The established MCQ test can distinguish between physicians with different levels of competence in TUS and enables an objective, evidence-based approach for assessing the theoretical knowledge of trainees undergoing an educational programme in TUS

    Incidental pulmonary nodules may lead to a high proportion of early-stage lung cancer: but it requires more than a high CT volume to achieve this

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    ABSTRACTBackground The management of pulmonary nodules plays a critical role in early detection of lung cancer. Computed tomography (CT) has led to a stage-shift towards early-stage lung cancer, but regional differences in survival rates have been reported in Denmark. This study aimed to evaluate whether variations in nodule management among Danish health regions contributed to these differences.Material and Methods The Danish Health Data Authority and Danish Lung Cancer Registry provided data on CT usage and lung cancer stage distribution, respectively. Auditing of lung cancer stage IA patient referrals and nodule management of stage IV lung cancer patients was conducted in seven Danish lung cancer investigation centers, covering four of the five Danish health regions. CT scans were performed up to 2 years before the patients’ diagnosis from 2019 to 2021.Results CT usage has increased steadily in Denmark over the past decade, with a simultaneous increase in the proportion of early-stage lung cancers, particularly stage IA. However, one Danish health region, Region Zealand, exhibited lower rates of early-stage lung cancer and overall survival despite a CT usage roughly similar to that of the other health regions. The audit did not find significant differences in pulmonary nodule management or a higher number of missed nodules by radiologists in this region compared to others.Conclusion This study suggests that a high CT scan volume alone is not sufficient for the early detection of lung cancer. Factors beyond hospital management practices, such as patient-related delays in socioeconomically disadvantaged areas, may contribute to regional differences in survival rates. This has implications for future strategies for reducing these differences

    Inhaled Corticosteroids in Patients with Chronic Obstructive Pulmonary Disease and Risk of Acquiring Streptococcus pneumoniae Infection. A Multiregional Epidemiological Study

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    Background: Inhaled corticosteroids (ICS) are associated with an increased risk of clinical pneumonia among patients with chronic obstructive pulmonary disease (COPD). It is unknown whether the risk of microbiologically verified pneumonia such as pneumococcal pneumonia is increased in ICS users. Methods: The study population consists of all COPD patients followed in outpatient clinics in eastern Denmark during 2010-2017. ICS use was categorized into four categories based on accumulated use. A Cox proportional hazard regression model was used adjusting for age, body mass index, sex, airflow limitation, use of oral corticosteroids, smoking, and year of cohort entry. A propensity score matched analysis was performed for sensitivity analyses. Findings:  A total of 21,438 patients were included. Five hundred and eighty-two (2.6%) patients acquired a positive lower airway tract sample with S. pneumoniae during follow-up. In the multivariable analysis ICS-use was associated with a dose-dependent risk of S. pneumoniae as follows: low ICS dose: HR 1.11, 95% CI 0.84 to 1.45, p = 0.5; moderate ICS dose: HR 1.47, 95% CI 1.13 to 1.90, p = 0.004; high ICS dose: HR 1.77, 95% CI 1.38 to 2.29, p < 0.0001, compared to no ICS use. Sensitivity analyses confirmed these results. Interpretation: Use of ICS in patients with severe COPD was associated with an increased and dose-dependent risk of acquiring S. pneumoniae, but only for moderate and high dose. Caution should be taken when administering high dose of ICS to patients with COPD. Low dose of ICS seemed not to carry this risk
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