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| 2. |
- 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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| 3. |
- Ferrando, Carlos, et al.
(författare)
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Effects of oxygen on post-surgical infections during an individualised perioperative open-lung ventilatory strategy : a randomised controlled trial
- 2020
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Ingår i: British Journal of Anaesthesia. - : ELSEVIER SCI LTD. - 0007-0912 .- 1471-6771. ; 124:1, s. 110-120
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Tidskriftsartikel (refereegranskat)abstract
- Background: We aimed to examine whether using a high fraction of inspired oxygen (FIO2) in the context of an individualised intra- and postoperative open-lung ventilation approach could decrease surgical site infection (SSI) in patients scheduled for abdominal surgery. Methods: We performed a multicentre, randomised controlled clinical trial in a network of 21 university hospitals from June 6, 2017 to July 19, 2018. Patients undergoing abdominal surgery were randomly assigned to receive a high (0.80) or conventional (0.3) FIO2 during the intraoperative period and during the first 3 postoperative hours. All patients were mechanically ventilated with an open-lung strategy, which included recruitment manoeuvres and individualised positive end-expiratory pressure for the best respiratory-system compliance, and individualised continuous postoperative airway pressure for adequate peripheral oxyhaemoglobin saturation. The primary outcome was the prevalence of SSI within the first 7 postoperative days. The secondary outcomes were composites of systemic complications, length of intensive care and hospital stay, and 6-month mortality. Results: We enrolled 740 subjects: 371 in the high FIO2 group and 369 in the low FIO2 group. Data from 717 subjects were available for final analysis. The rate of SSI during the first postoperative week did not differ between high (8.9%) and low (9.4%) FIO2 groups (relative risk [RR]: 0.94; 95% confidence interval [CI]: 0.59-1.50; P=0.90]). Secondary outcomes, such as atelectasis (7.7% vs 9.8%; RR: 0.77; 95% CI: 0.48-1.25; P=0.38) and myocardial ischaemia (0.6% [n=2] vs 0% [n=0]; P=0.47) did not differ between groups. Conclusions: An oxygenation strategy using high FIO2 compared with conventional FIO2 did not reduce postoperative SSIs in abdominal surgery. No differences in secondary outcomes or adverse events were found.
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- de la Rosa, Andrés
(författare)
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Design, expression, and analysis of antibody-based blood-brain barrier shuttles
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibody therapeutics, with their strong and highly selective target binding, are now used to treat various diseases. However, to enable their use to treat brain disorders, they must be delivered across the blood-brain barrier (BBB), as without active transport, only around 0.01% of intravenously injected doses reach the brain. Brain delivery can be done by BBB shuttles capable of binding receptors that naturally transport proteins, e.g., the Transferrin receptor (TfR). This thesis has studied strategies for designing TfR-binding shuttles and how to enhance the protein expression of antibody therapeutics. In Paper I, we shared our updated transient gene expression (TGE) protocol and developed a small-scale version to surmount the cost limitations of testing many conditions. Large variations of protein expression were observed for both protocols, prompting future studies investigating its cause(s). In paper II, we investigated if binding to the glycosaminoglycan heparan sulfate (HS) present at the BBB could improve brain delivery. Our results indicate that the BBB shuttle scFv8D3 is not dependent on the HS-binding sites identified, and adding new HS-binding sites did not enhance delivery. However, further studies are required due to HS's complexity and heterogeneity. Decreasing the TfR affinity of BBB shuttles has been shown to boost the delivery of therapeutic doses of high affinity anti-TfR antibodies, e.g., bivalent 8D3 antibodies. In Paper III, we applied the strategy to a monovalent single-chain fragment variable (scFv) of 8D3 (scFv8D3) based BBB shuttle. Our affinity mutants exhibited lowered TfR affinity, longer blood half-life, and higher brain concentration. Using our In-Cell BBB Trans assay, we concluded that the increased brain concentration is likely due to extended blood half-life. In paper IV, we fused the TfR ligand holo-transferrin to the TfR binding arms of the partly bivalent RmAb158-scFv8D3 antibody. Our results indicate that the TfR binding shifted from partly to fully bivalent, resulting in markedly decreased in vitro transcytosis. The potential transcytosis-promoting effect of the fused holoTf was absent and/or counteracted by the bivalent binding of the design. However, the strategy may still prove useful for monovalent TfR binders. In conclusion, monovalent and low-to-moderate affinity are likely beneficial binding properties for TfR-mediated brain delivery at therapeutic doses. However, whether it is possible to enhance brain delivery with HS-binding or holoTf-fusion requires further study.
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| 5. |
- de la Rosa, Andres, et al.
(författare)
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Introducing or removing heparan sulfate binding sites does not alter brain uptake of the blood-brain barrier shuttle scFv8D3
- 2022
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The blood-brain barrier (BBB) greatly limits the delivery of protein-based drugs into the brain and is a major obstacle for the treatment of brain disorders. Targeting the transferrin receptor (TfR) is a strategy for transporting protein-based drugs into the brain, which can be utilized by using TfR-binding BBB transporters, such as the TfR-binding antibody 8D3. In this current study, we investigated if binding to heparan sulfate (HS) contributes to the brain uptake of a single chain fragment variable of 8D3 (scFv8D3). We designed and produced a scFv8D3 mutant, engineered with additional HS binding sites, HS(+)scFv8D3, to assess whether increased HS binding would improve brain uptake. Additionally, a mutant with a reduced number of HS binding sites, HS(-)scFv8D3, was also engineered to see if reducing the HS binding sites could also affect brain uptake. Heparin column chromatography showed that only the HS(+)scFv8D3 mutant bound HS in the experimental conditions. Ex vivo results showed that the brain uptake was unaffected by the introduction or removal of HS binding sites, which indicates that scFv8D3 is not dependent on the HS binding sites for brain uptake. Conversely, introducing HS binding sites to scFv8D3 decreased its renal excretion while removing them had the opposite effect.
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| 6. |
- Giannisis, Andreas, et al.
(författare)
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Brain integrity is altered by hepatic APOE ε4 in humanized-liver mice
- 2022
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Ingår i: Molecular Psychiatry. - : Springer Science and Business Media LLC. - 1359-4184 .- 1476-5578. ; 27:8, s. 3533-3543
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Tidskriftsartikel (refereegranskat)abstract
- Liver-generated plasma apolipoprotein E (apoE) does not enter the brain but nonetheless correlates with Alzheimer’s disease (AD) risk and AD biomarker levels. Carriers of APOEε4, the strongest genetic AD risk factor, exhibit lower plasma apoE and altered brain integrity already at mid-life versus non-APOEε4 carriers. Whether altered plasma liver-derived apoE or specifically an APOEε4 liver phenotype promotes neurodegeneration is unknown. Here we investigated the brains of Fah−/−, Rag2−/−, Il2rg−/− mice on the Non-Obese Diabetic (NOD) background (FRGN) with humanized-livers of an AD risk-associated APOE ε4/ε4 versus an APOE ε2/ε3 genotype. Reduced endogenous mouse apoE levels in the brains of APOE ε4/ε4 liver mice were accompanied by various changes in markers of synaptic integrity, neuroinflammation and insulin signaling. Plasma apoE4 levels were associated with unfavorable changes in several of the assessed markers. These results propose a previously unexplored role of the liver in the APOEε4-associated risk of neurodegenerative disease.
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