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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. |
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| 4. |
- Asayama, Kei, et al.
(författare)
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Setting Thresholds to Varying Blood Pressure Monitoring Intervals Differentially Affects Risk Estimates Associated With White-Coat and Masked Hypertension in the Population
- 2014
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Ingår i: Hypertension. - 0194-911X .- 1524-4563. ; 64:5, s. 935-942
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Tidskriftsartikel (refereegranskat)abstract
- Outcome-driven recommendations about time intervals during which ambulatory blood pressure should be measured to diagnose white-coat or masked hypertension are lacking. We cross-classified 8237 untreated participants (mean age, 50.7 years; 48.4% women) enrolled in 12 population studies, using >= 140/>= 90, >= 130/>= 80, >= 135/>= 85, and >= 120/>= 70 mm Hg as hypertension thresholds for conventional, 24-hour, daytime, and nighttime blood pressure. White-coat hypertension was hypertension on conventional measurement with ambulatory normotension, the opposite condition being masked hypertension. Intervals used for classification of participants were daytime, nighttime, and 24 hours, first considered separately, and next combined as 24 hours plus daytime or plus nighttime, or plus both. Depending on time intervals chosen, white-coat and masked hypertension frequencies ranged from 6.3% to 12.5% and from 9.7% to 19.6%, respectively. During 91 046 person-years, 729 participants experienced a cardiovascular event. In multivariable analyses with normotension during all intervals of the day as reference, hazard ratios associated with white-coat hypertension progressively weakened considering daytime only (1.38; P=0.033), nighttime only (1.43; P=0.0074), 24 hours only (1.21; P=0.20), 24 hours plus daytime (1.24; P=0.18), 24 hours plus nighttime (1.15; P=0.39), and 24 hours plus daytime and nighttime (1.16; P=0.41). The hazard ratios comparing masked hypertension with normotension were all significant (P<0.0001), ranging from 1.76 to 2.03. In conclusion, identification of truly low-risk white-coat hypertension requires setting thresholds simultaneously to 24 hours, daytime, and nighttime blood pressure. Although any time interval suffices to diagnose masked hypertension, as proposed in current guidelines, full 24-hour recordings remain standard in clinical practice.
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| 5. |
- Brguljan-Hitij, Jana, et al.
(författare)
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Risk Stratification by Ambulatory Blood Pressure Monitoring Across JNC Classes of Conventional Blood Pressure
- 2014
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Ingår i: American Journal of Hypertension. - : Oxford University Press (OUP). - 0895-7061 .- 1941-7225. ; 27:7, s. 956-965
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Guidelines propose classification of conventional blood pressure (CBP) into normotension (<120/<80 mm Hg), prehypertension (120-139/80-89 mm Hg), and hypertension (>140/>90 mm Hg). METHODS To assess the potential differential contribution of ambulatory blood pressure (ABP) in predicting risk across CBP strata, we analyzed outcomes in 7,826 untreated people recruited from 11 populations. RESULTS During an 11.3-year period, 809 participants died (276 cardiovascular deaths) and 639, 383, and 225 experienced a cardiovascular, cardiac, or cerebrovascular event. Compared with normotension (n = 2,639), prehypertension (n = 3,076) carried higher risk (P <= 0.015) of cardiovascular (+ 41%) and cerebrovascular (+ 92%) endpoints; compared with hypertension (n = 2,111) prehypertension entailed lower risk (P <= 0.005) of total mortality (-14%) and cardiovascular mortality (-29%) and of cardiovascular (-34%), cardiac (-33%), or cerebrovascular (-47%) events. Multivariable-adjusted hazard ratios (HRs) for stroke associated with 24-hour and daytime diastolic ABP (+ 5 mm Hg) were higher (P <= 0.045) in normotension than in prehypertension and hypertension (1.98 vs. 1.19 vs. 1.28 and 1.73 vs. 1.09 vs. 1.24, respectively) with similar trends (0.03 <= P <= 0.11) for systolic ABP (+10 mm Hg). However, HRs for fatal endpoints and cardiac events associated with ABP did not differ significantly (P >= 0.13) across CBP categories. Of normotensive and prehypertensive participants, 7.5% and 29.3% had masked hypertension (daytime ABP >= 135/>= 85 mm Hg). Compared with true normotension (P <= 0.01), HRs for stroke were 3.02 in normotension and 2.97 in prehypertension associated with masked hypertension with no difference between the latter two conditions (P = 0.93). CONCLUSION ABP refines risk stratification in normotension and prehypertension mainly by enabling the diagnosis of masked hypertension.
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| 6. |
- Conen, David, et al.
(författare)
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Age-Specific Differences Between Conventional and Ambulatory Daytime Blood Pressure Values
- 2014
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Ingår i: Hypertension. - 0194-911X .- 1524-4563. ; 64:5, s. 1073-1079
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Tidskriftsartikel (refereegranskat)abstract
- Mean daytime ambulatory blood pressure (BP) values are considered to be lower than conventional BP values, but data on this relation among younger individuals <50 years are scarce. Conventional and 24-hour ambulatory BP were measured in 9550 individuals not taking antihypertensive treatment from 13 population-based cohorts. We compared individual differences between daytime ambulatory and conventional BP according to 10-year age categories. Age-specific prevalences of white coat and masked hypertension were calculated. Among individuals aged 18 to 30, 30 to 40, and 40 to 50 years, mean daytime BP was significantly higher than the corresponding conventional BP (6.0, 5.2, and 4.7 mm Hg for systolic; 2.5, 2.7, and 1.7 mm Hg for diastolic BP; all P<0.0001). In individuals aged 60 to 70 and >= 70 years, conventional BP was significantly higher than daytime ambulatory BP (5.0 and 13.0 mm Hg for systolic; 2.0 and 4.2 mm Hg for diastolic BP; all P<0.0001). The prevalence of white coat hypertension exponentially increased from 2.2% to 19.5% from those aged 18 to 30 years to those aged >= 70 years, with little variation between men and women (8.0% versus 6.1%; P=0.0003). Masked hypertension was more prevalent among men (21.1% versus 11.4%; P<0.0001). The age-specific prevalences of masked hypertension were 18.2%, 27.3%, 27.8%, 20.1%, 13.6%, and 10.2% among men and 9.0%, 9.9%, 12.2%, 11.9%, 14.7%, and 12.1% among women. In conclusion, this large collaborative analysis showed that the relation between daytime ambulatory and conventional BP strongly varies by age. These findings may have implications for diagnosing hypertension and its subtypes in clinical practice.
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| 7. |
- Gu, Yu-Mei, et al.
(författare)
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Outcome-Driven Thresholds for Ambulatory Pulse Pressure in 9938 Participants Recruited From 11 Populations
- 2014
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Ingår i: Hypertension. - 0194-911X .- 1524-4563. ; 63:2, s. 229-237
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Tidskriftsartikel (refereegranskat)abstract
- Evidence-based thresholds for risk stratification based on pulse pressure (PP) are currently unavailable. To derive outcome-driven thresholds for the 24-hour ambulatory PP, we analyzed 9938 participants randomly recruited from 11 populations (47.3% women). After age stratification (<60 versus >= 60 years) and using average risk as reference, we computed multivariable-adjusted hazard ratios (IIRs) to assess risk by tenths of the PP distribution or risk associated with stepwise increasing (+1 mm Hg) PP levels. All adjustments included mean arterial pressure. Among 6028 younger participants (68 853 person-years), the risk of cardiovascular (HR, 1.58; P=0.011) or cardiac (HR, 1.52; P=0.056) events increased only in the top PP tenth (mean, 60.6 mm Hg). Using stepwise increasing PP levels, the lower boundary of the 95% confidence interval of the successive thresholds did not cross unity. Among 3910 older participants (39 923 person-years), risk increased (P <= 0.028) in the top PP tenth (mean, 76.1 mm Hg). HRs were 1.30 and 1.62 for total and cardiovascular mortality, and 1.52, 1.69, and 1.40 for all cardiovascular, cardiac, and cerebrovascular events. The lower boundary of the 95% confidence interval of the HRs associated with stepwise increasing PP levels crossed unity at 64 mm Hg. While accounting for all covariables, the top tenth of PP contributed less than 0.3% (generalized R-2 statistic) to the overall risk among the elderly. Thus, in randomly recruited people, ambulatory PP does not add to risk stratification below age 60; in the elderly, PP is a weak risk factor with levels below 64 mm Hg probably being innocuous.
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| 8. |
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| 9. |
- Li, Yan, et al.
(författare)
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Ambulatory Hypertension Subtypes and 24-Hour Systolic and Diastolic Blood Pressure as Distinct Outcome Predictors in 8341 Untreated People Recruited From 12 Populations
- 2014
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Ingår i: Circulation. - 0009-7322 .- 1524-4539. ; 130:6, s. 466-474
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Tidskriftsartikel (refereegranskat)abstract
- Background-Data on risk associated with 24-hour ambulatory diastolic (DBP24) versus systolic (SBP24) blood pressure are scarce. Methods and Results-We recorded 24-hour blood pressure and health outcomes in 8341 untreated people (mean age, 50.8 years; 46.6% women) randomly recruited from 12 populations. We computed hazard ratios (HRs) using multivariable-adjusted Cox regression. Over 11.2 years (median), 927 (11.1%) participants died, 356 (4.3%) from cardiovascular causes, and 744 (8.9%) experienced a fatal or nonfatal cardiovascular event. Isolated diastolic hypertension (DBP24 >= 80 mm Hg) did not increase the risk of total mortality, cardiovascular mortality, or stroke (HRs <= 1.54; P >= 0.18), but was associated with a higher risk of fatal combined with nonfatal cardiovascular, cardiac, or coronary events (HRs >= 1.75; P <= 0.0054). Isolated systolic hypertension (SBP24 >= 130 mm Hg) and mixed diastolic plus systolic hypertension were associated with increased risks of all aforementioned end points (P <= 0.0012). Below age 50, DBP24 was the main driver of risk, reaching significance for total (HR for 1-SD increase, 2.05; P=0.0039) and cardiovascular mortality (HR, 4.07; P=0.0032) and for all cardiovascular end points combined (HR, 1.74; P=0.039) with a nonsignificant contribution of SBP24 (HR <= 0.92; P >= 0.068); above age 50, SBP24 predicted all end points (HR >= 1.19; P <= 0.0002) with a nonsignificant contribution of DBP24 (0.96 <= HR <= 1.14; P >= 0.10). The interactions of age with SBP24 and DBP24 were significant for all cardiovascular and coronary events (P <= 0.043). Conclusions-The risks conferred by DBP24 and SBP24 are age dependent. DBP24 and isolated diastolic hypertension drive coronary complications below age 50, whereas above age 50 SBP24 and isolated systolic and mixed hypertension are the predominant risk factors.
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| 10. |
- Zhang, Xiao-Jie, et al.
(författare)
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Auto-suppression of Tet dioxygenases protects the mouse oocyte genome from oxidative demethylation
- 2024
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Ingår i: Nature Structural & Molecular Biology. - : NATURE PORTFOLIO. - 1545-9993 .- 1545-9985. ; 31:1
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Tidskriftsartikel (refereegranskat)abstract
- DNA cytosine methylation plays a vital role in repressing retrotransposons, and such derepression is linked with developmental failure, tumorigenesis and aging. DNA methylation patterns are formed by precisely regulated actions of DNA methylation writers (DNA methyltransferases) and erasers (TET, ten-eleven translocation dioxygenases). However, the mechanisms underlying target-specific oxidation of 5mC by TET dioxygenases remain largely unexplored. Here we show that a large low-complexity domain (LCD), located in the catalytic part of Tet enzymes, negatively regulates the dioxygenase activity. Recombinant Tet3 lacking LCD is shown to be hyperactive in converting 5mC into oxidized species in vitro. Endogenous expression of the hyperactive Tet3 mutant in mouse oocytes results in genome-wide 5mC oxidation. Notably, the occurrence of aberrant 5mC oxidation correlates with a consequent loss of the repressive histone mark H3K9me3 at ERVK retrotransposons. The erosion of both 5mC and H3K9me3 causes ERVK derepression along with upregulation of their neighboring genes, potentially leading to the impairment of oocyte development. These findings suggest that Tet dioxygenases use an intrinsic auto-regulatory mechanism to tightly regulate their enzymatic activity, thus achieving spatiotemporal specificity of methylome reprogramming, and highlight the importance of methylome integrity for development. Here the authors show that TET dioxygenases, the erasers of DNA methylation, use a self-limiting mechanism via their LCD domain to ensure adaptable methylome status and protect the genome from excessive oxidative methylation.
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