| 1. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
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| 3. |
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- 2019
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Journal article (peer-reviewed)
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| 4. |
- Klionsky, Daniel J., et al.
(author)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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In: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Research review (peer-reviewed)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 6. |
- Sampson, Joshua N., et al.
(author)
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Analysis of Heritability and Shared Heritability Based on Genome-Wide Association Studies for 13 Cancer Types
- 2015
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In: Journal of the National Cancer Institute. - : Oxford University Press (OUP). - 0027-8874 .- 1460-2105. ; 107:12
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Journal article (peer-reviewed)abstract
- Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, h(l)(2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (rho = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (rho = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (rho = 0.51, SE = 0.18), and bladder and lung (rho = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.
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| 7. |
- Pan, Xiong-Fei, et al.
(author)
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Circulating fatty acids and risk of gestational diabetes mellitus : prospective analyses in China
- 2021
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In: European Journal of Endocrinology. - : Bioscientifica. - 0804-4643 .- 1479-683X. ; 185:1, s. 87-97
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Journal article (peer-reviewed)abstract
- Objective: We aimed to examine prospective associations between circulating fatty acids in early pregnancy and incident gestational diabetes mellitus (GDM) among Chinese pregnant women.Methods: Analyses were based on two prospective nested case-control studies conducted in western China (336 GDM cases and 672 matched controls) and central China (305 cases and 305 matched controls). Fasting plasma fatty acids in early pregnancy (gestational age at enrollment: 10.4 weeks(s.d., 2.0)) and 13.2 weeks (1.0), respectively) were determined by gas chromatography-mass spectrometry, and GDM was diagnosed based on the International Association of Diabetes in Pregnancy Study Groups criteria during 24-28 weeks of gestation. Multiple metabolic biomarkers (HOMA-IR (homeostatic model assessment for insulin resistance), HbA1c, c-peptide, high-sensitivity C-reactive protein, adiponectin, leptin, and blood lipids) were additionally measured among 672 non-GDM controls at enrollment.Results: Higher levels of saturated fatty acids (SFAs) 14:0 (pooled odds ratio, 1.41 for each 1-s.d. increase; 95% CI: 1.25, 1.59) and 16:0 (1.19; 1.05, 1.35) were associated with higher odds of GDM. Higher levels of n-6 polyunsaturated fatty acid (PUFA) 18:2n-6 were strongly associated with lower odds of GDM (0.69; 0.60, 0.80). In non-GDM pregnant women, higher SFAs 14:0 and 16:0 but lower n-6 PUFA 18:2n-6 were generally correlated with unfavorable metabolic profiles.Conclusions: We documented adverse associations of 14:0 and 16:0 but a protective association of 18:2n-6 with GDM among Chinese pregnant women. Our findings highlight the distinct roles of specific fatty acids in the onset of GDM.
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| 9. |
- Lv, Yi Qing, et al.
(author)
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Long-term hyperglycemia aggravates α-synuclein aggregation and dopaminergic neuronal loss in a Parkinson’s disease mouse model
- 2022
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In: Translational Neurodegeneration. - : Springer Science and Business Media LLC. - 2047-9158. ; 11
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Journal article (peer-reviewed)abstract
- Background: Growing evidence suggests an association between Parkinson’s disease (PD) and diabetes mellitus (DM). At the cellular level, long-term elevated levels of glucose have been shown to lead to nigrostriatal degeneration in PD models. However, the underlying mechanism is still unclear. Previously, we have elucidated the potential of type 2 diabetes mellitus (T2DM) in facilitating PD progression, involving aggregation of both alpha-synuclein (α-syn) and islet amyloid polypeptide in the pancreatic and brain tissues. However, due to the complicated effect of insulin resistance on PD onset, the actual mechanism of hyperglycemia-induced dopaminergic degeneration remains unknown. Methods: We employed the type 1 diabetes mellitus (T1DM) model induced by streptozotocin (STZ) injection in a transgenic mouse line (BAC-α-syn-GFP) overexpressing human α-syn, to investigate the direct effect of elevated blood glucose on nigrostriatal degeneration. Results: STZ treatment induced more severe pathological alterations in the pancreatic islets and T1DM symptoms in α-syn-overexpressing mice than in wild-type mice, at one month and three months after STZ injections. Behavioral tests evaluating motor performance confirmed the nigrostriatal degeneration. Furthermore, there was a marked decrease in dopaminergic profiles and an increase of α-syn accumulation and Serine 129 (S129) phosphorylation in STZ-treated α-syn mice compared with the vehicle-treated mice. In addition, more severe neuroinflammation was observed in the brains of the STZ-treated α-syn mice. Conclusion: Our results solidify the potential link between DM and PD, providing insights into how hyperglycemia induces nigrostriatal degeneration and contributes to pathogenic mechanisms in PD.
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| 10. |
- Pan, Zijun, et al.
(author)
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Influence of SiC/Epoxy Coating on Surface Charging Phenomenon at DC Voltage - Part I: Charge Accumulation
- 2022
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In: IEEE Transactions on Dielectrics and Electrical Insulation. - 1558-4135 .- 1070-9878. ; 29:4, s. 1333-1342
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Journal article (peer-reviewed)abstract
- Surface charge accumulation on SiC/epoxy coatings with different contents of SiC filler, 3, 5, 7, 10 wt%, is investigated using flat samples of epoxy substrate. In the experiments, a pair of finger-shaped electrodes was attached to the samples surface using direct pressing and conductive adhesive providing two different types of contacts and, respectively, surface charging methods. The electrodes were energized by applying DC voltage for various time intervals and resulted surface charge distributions between the electrodes were measured. It was found that depending on the contact type, charging duration and filler content, different patterns of homo- or hetero-charge appeared on the material surface. Physical reasons for the observed effects are analyzed based on the calculated electric field distributions in the experimental setup, results of the auxiliary tests on material charging in a limited air volume and surface trap energy distributions measured utilizing the isothermal surface potential decay (ISPD) method. Application of SiC/epoxy coating for controlling surface charge accumulation is discussed.
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