| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)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. |
- Hao, Xiaojin, et al.
(författare)
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Angiogenic effects of sequential release of VEGF-A(165) and PDGF-BB with alginate hydrogels after myocardial infarction
- 2007
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 0008-6363 .- 1755-3245. ; 28, s. 612-612
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study investigates whether local sequential delivery of vascular endothelial growth factor-A(165) (VEGF-A(165)) followed by platelet-derived growth factor-BB (PDGF-BB) with alginate hydrogels could induce an angiogenic effect and functional improvement greater than single factors after myocardial infarction. Methods: Alginate hydrogels were prepared by combining high and low molecular weight alginate. Growth factor release rates were monitored over time in vitro with I-125-labelled VEGF-A(165) and PDGF-BB included in the gels. One week after myocardial infarction was induced in Fisher rats, gels with VEGF-A(165), PDGF-BB, or both were given intra-myocardially along the border of the myocardial infarction. Vessel density was analysed in hearts and cardiac function was determined by Tissue Doppler Echocardiography. In addition, the angiogenic effect of sequenced delivery was studied in vitro in aortic rings from C57B1/6 mice. Results: Alginate gets were capable of delivering VEGF-A(165) and PDGF-BB in a sustainable manner, and PDGF-BB was released more slowly than VEGF-A(165). Sequential growth factor administration led to a higher density of alpha-actin positive vessels than single factors, whereas no further increment was found in capillary density. Sequential protein delivery increased the systolic velocity-time integral and displayed a superior effect than single factors. In the aortic ring model, sequential delivery led to a higher angiogenic effect than single factor administration. Conclusions: The alginate hydrogel is an effective and promising injectable delivery system in a myocardial infarction model. Sequential growth factor delivery of VEGF-A(165) and PDGF-BB induces mature vessels and improves cardiac function more than each factor singly. This may indicate clinical utility.
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| 3. |
- Hao, Xiaojin
(författare)
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Experimental therapeutic angiogenesis after myocardial infarction : efficacy of different angiogenic factors and delivery methods
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Angiogenesis, the stimulation of vessel growth, is a promising therapy in ischemic heart disease. A wealth of evidence has shown that several growth factors can induce neovascularization in ischemic models. However, the optimal application of growth factors and delivery method requires further exploration. VEGF, the most investigated therapeutic agent was used to study angiogenic efficacy and safety. In addition, as the angiogenic process is complex with multiple growth factors involved, different combinations of growth factors and with different delivery modalities were also studied. A rat myocardial infarction model was used to investigate angiogenic effects up to 4 weeks after delivery that was performed one week after the myocardial infarction. VEGFA165, bFGF and PDGF-BB were administered into the myocardial infarction border zone as gene in plasmid or in adenoviral vector or as protein in a slow release alginate formulation. The amount of delivered growth factor was detected as protein, mRNA or by radiolabelling. Myocardial capillary and arteriolar densities were quantitatively detected by immunohistochemistry. Apoptosis analysis was done using TUNEL staining. Left ventricular function was determined by echocardiography. While AdhVEGF-A165 expressed VEGF-A in the myocardium to a considerably higher extent than PhVEGF-A165, both vectors increased arteriolar and capillary densities and left ventricular function to the same extent. AdhVEGF-A165 induced apoptosis and induced higher ectopic expression of VEGF-A than PhVEGF-A165. The combined growth factor delivery of PhPDGF-BB+PhbFGF or PhpDGF-BB+PhVEGF did not show any angiogenic advantage over single growth factor delivery However, when dual growth factor of PDGF-BB and VEGF-A165 were given as protein in alginate gel, more arterioles but not capillaries were observed with the dual protein transfer. Dual protein delivery increased left ventricular function better than single factor delivery. The findings indicate that at least in the myocardial infarction model used, AdhVEGFA165 has no obvious angiogenic advantage over PhVEGF-A165 but more side effects. Combined growth factor delivery for angiogenic therapy might benefit the ischemic tissue more than single growth factor administration. However, the angiogenic effect is dependent not only on growth factors but also on delivery modality and alginate gel might be a promising utility.
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| 4. |
- Hao, Xiaojin, et al.
(författare)
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Myocardial angiogenesis after plasmid or adenoviral VEGF-A(165) gene transfer in rat myocardial infarction model
- 2007
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 0008-6363 .- 1755-3245. ; 73:3, s. 481-487
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To compare gene transfer of plasmid (P) and adenovirus (Ad) encoding human vascular endothelial growth factor-A(165) (hVEGF-A(165)) angiogenic efficacy and adverse effects as regards apoptosis and ectopic expression of the transgene in a rat myocardial infarction model. Methods: Myocardial infarction was provoked in Fisher rats. One week later, PhVEGF-A(165), PLacZ, AdhVEGF-A(165), or AdLacZ was transferred intramyocardially along the border of the myocardial infarction. hVEGF-A expression was detected with ELISA. Myocardial vessel density was analyzed 1 and 4 weeks after gene transfer. Apoptosis was detected by TUNEL staining. Cardiac function was assessed with Tissue Doppler Velocity Imaging. Results: Although AdhVEGF-A(165) had substantially higher myocardial hVEGF-A expression than PhVEGF-A(165), AdhVEGF-A(165) and PhVEGF-A(165) induced angiogenic effects to a similar extent with maintained increased arteriolar density after 4 weeks of gene transfer (p < 0.05). The two treatments also improved left ventricular function similarly. Adenoviral gene transfer induced a higher number of TUNEL positive cells than plasmid (p < 0.02). Ectopic expression of the transgene was present with both vectors but substantially higher after adenoviral gene transfer. Conclusions: AdhVEGF-A165 has no obvious angiogenic advantage over PhVEGF-A165 but more side effects at least in a rat myocardial infarction model. This indicates that PhVEGF-A(165) might be more applicable for therapeutic angiogenesis than AdhVEGF-A(165).
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