| 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. |
- Ma, Fei, et al.
(författare)
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Association of Leukocyte Telomere Length with Mild Cognitive Impairment and Alzheimer's Disease : Role of Folate and Homocysteine
- 2019
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Ingår i: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 48:1-2, s. 56-67
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Tidskriftsartikel (refereegranskat)abstract
- Background: Leukocyte telomere length (LTL) is associated with the aging process and age-related degenerative diseases. The relation of peripheral blood LTL to mild cognitive impairment (MCI) and Alzheimer's disease (AD) and the role of folate and homocysteine (Hcy) in this relation remain unclear.Objectives: We aimed to investigate the association between LTL and the risks of MCI/AD, and to explore whether folate and Hcy may play a role in this association.Methods: This case-control study included 129 MCI subjects, 131 AD patients and 134 healthy controls. LTL was assessed using real-time polymerase chain reaction assay. Serum folate levels were tested by chemiluminescence enzyme immunoassay, and serum Hcy levels were measured using the enzymatic cycling method. Data were analyzed using multivariate logistic regression and multivariable linear regression with adjustment for potential confounders.Results: The mean LTL was 1.56 +/- 0.25 in controls, 1.44 +/- 0.23 in MCI, and 1.28 +/- 0.28 in AD patients (p< 0.01). In multivariate logistic regression, subjects in the longest LTL tertile had lower OR for MCI (OR 0.246; 95% CI 0.101-0.597) and AD (OR 0.123; 95% CI 0.044-0.345) in comparison to subjects in the shortest tertile. Shorter LTL was dose-dependently related to the ORs of MCI and AD. Further, serum folate concentration was positively associated with LTL (p < 0.01), while serum Hcy level was negatively associated with LTL (p < 0.05). In stratified analyses, LTL-MCI/AD association varied by serum folate and Hcy level. Conclusions: Shorter LTL is associated with the risks of MCI/AD. Folate and Hcy might play an important role in this association.
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| 3. |
- Ma, Fei, et al.
(författare)
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Effects of Folic Acid and Vitamin B-12, Alone and in Combination on Cognitive Function and Inflammatory Factors in the Elderly with Mild Cognitive Impairment : A Single-blind Experimental Design
- 2019
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Ingår i: Current Alzheimer Research. - : Bentham Science Publishers Ltd.. - 1567-2050 .- 1875-5828. ; 16:7, s. 622-632
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Tidskriftsartikel (refereegranskat)abstract
- Background: Folate and vitamin B-12 are well-known as essential nutrients that play key roles in the normal functions of the brain. Inflammatory processes play at least some role in the pathology of AD. Effective nutritional intervention approaches for improving cognitive deficits that reduce the peripheral inflammatory cytokine levels have garnered special attention. Objective: The present study aimed to determine whether supplementation with folic acid and vitamin B-12, alone and in combination improves cognitive performance via reducing levels of peripheral inflammatory cytokines. Methods: 240 participants with MCI were randomly assigned in equal proportion to four treatment groups: folic acid alone, vitamin B-12 alone, folic acid plus vitamin B-12 or control without treatment daily for 6 months. Cognition was measured with WAIS-RC. The levels of inflammatory cytolcines were measured using ELISA. Changes in cognitive function or blood biomarkers were analyzed by repeated-measure analysis of variance or mixed-effects models. This trial has been registered with trial number ChiCTR-ROC-16008305. Results: Compared with control group, the folic acid plus vitamin B-12 group had significantly greater improvements in serum folate, homocysteine, vitamin B(1)(2 )and IL-6, TNF-alpha, MCP-1. The folic acid plus vitamin B-12 supplementation significantly changed the Full Scale IQ (effect size d = 0.169; P = 0.024), verbal IQ (effect size d= 0.146; P= 0.033). Information (d= 0.172; P= 0.019) and Digit Span (d= 0.187; P = 0.009) scores. Post hoc Turkey tests found that folic acid and vitamin B-12 supplementation was significantly more effective than folic acid alone for all endpoints. Conclusions: The combination of oral folic acid plus vitamin B-12 in MCI elderly for six months can significantly improve cognitive performance and reduce the levels of inflammatory cytokines in human peripheral blood. The combination of folic acid and vitamin B-12 was significantly superior to either folic acid or vitamin B-12 alone.
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| 4. |
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| 5. |
- Ma, Fei, et al.
(författare)
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Folic acid supplementation improves cognitive function by reducing the levels of peripheral inflammatory cytokines in elderly Chinese subjects with MCI
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to evaluate whether folic acid supplementation would improve cognitive performance by reducing serum inflammatory cytokine concentrations. This RCT was performed in Tianjin, China. Participants with mild cognitive impairment (MCI) were randomly assigned to the folic acid (400 mu g/day) or conventional treatment groups. Neuropsychological tests were administered, and folate, homocysteine, vitamin B-12, IL-6, TNF-alpha, A beta-42, and A beta-40 were measured at baseline and at 6- and 12-month time points. 152 participants (folic acid: 77, conventional: 75) completed the trial. Significant improvements in folate (eta p(2) = 0.703, P = 0.011), homocysteine (eta p(2) = 0.644, P = 0.009), A beta-42 (eta p(2) = 0.687, P = 0.013), peripheral IL-6 (eta p(2) = 0.477, P = 0.025), TNF-alpha (eta p(2) = 0.709, P = 0.009) levels were observed in folic acid group compared with conventional group. Folic acid supplementation improved the Full Scale Intelligence Quotient (P = 0.028; effect size d = 0.153), Information (P = 0.031; d = 0.157) and Digit Span (P = 0.009; d = 0.172) scores at 12 months compared with conventional treatment. Based on these findings, daily oral administration of a 400-mu g folic acid supplement to MCI subjects for 12 months can significantly improve cognitive performance and reduce peripheral inflammatory cytokine levels.
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