1,069 research outputs found

    The role of microtubule movement in bidirectional organelle transport

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    We study the role of microtubule movement in bidirectional organelle transport in Drosophila S2 cells and show that EGFP-tagged peroxisomes in cells serve as sensitive probes of motor induced, noisy cytoskeletal motions. Multiple peroxisomes move in unison over large time windows and show correlations with microtubule tip positions, indicating rapid microtubule fluctuations in the longitudinal direction. We report the first high-resolution measurement of longitudinal microtubule fluctuations performed by tracing such pairs of co-moving peroxisomes. The resulting picture shows that motor-dependent longitudinal microtubule oscillations contribute significantly to cargo movement along microtubules. Thus, contrary to the conventional view, organelle transport cannot be described solely in terms of cargo movement along stationary microtubule tracks, but instead includes a strong contribution from the movement of the tracks.Comment: 24 pages, 5 figure

    Studying the Salt Dependence of the Binding of σ70 and σ32 to Core RNA Polymerase Using Luminescence Resonance Energy Transfer

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    The study of protein-protein interactions is becoming increasingly important for understanding the regulation of many cellular processes. The ability to quantify the strength with which two binding partners interact is desirable but the accurate determination of equilibrium binding constants is a difficult process. The use of Luminescence Resonance Energy Transfer (LRET) provides a homogeneous binding assay that can be used for the detection of protein-protein interactions. Previously, we developed an LRET assay to screen for small molecule inhibitors of the interaction of σ70 with theβ' coiled-coil fragment (amino acids 100–309). Here we describe an LRET binding assay used to monitor the interaction of E. coli σ70 and σ32 with core RNA polymerase along with the controls to verify the system. This approach generates fluorescently labeled proteins through the random labeling of lysine residues which enables the use of the LRET assay for proteins for which the creation of single cysteine mutants is not feasible. With the LRET binding assay, we are able to show that the interaction of σ70 with core RNAP is much more sensitive to NaCl than to potassium glutamate (KGlu), whereas the σ32 interaction with core RNAP is insensitive to both salts even at concentrations >500 mM. We also find that the interaction of σ32 with core RNAP is stronger than σ70 with core RNAP, under all conditions tested. This work establishes a consistent set of conditions for the comparison of the binding affinities of the E.coli sigma factors with core RNA polymerase. The examination of the importance of salt conditions in the binding of these proteins could have implications in both in vitro assay conditions and in vivo function

    Versatile single-molecule multi-color excitation and detection fluorescence setup for studying biomolecular dynamics

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98644/1/RevSciInstrum_82_113702.pd

    Iterative Outlier Removal: A Method for Identifying Outliers in Laboratory Recalibration Studies

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    Extreme values that arise for any reason, including through non-laboratory measurement procedure-related processes (inadequate mixing, evaporation, mislabeling), lead to outliers and inflate errors in recalibration studies. We present an approach termed iterative outlier removal (IOR) for identifying such outliers

    Glycemic Control, Complications, and Death in Older Diabetic Patients: The Diabetes and Aging Study

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    OBJECTIVE—To identify the range of glycemic levels associated with the lowest rates of complications and mortality in older diabetic patients. RESEARCH DESIGN AND METHODS—We conducted a retrospective cohort study (2004–2008) of 71,092 patients with type 2 diabetes, aged 60years,enrolledinKaiserPermanenteNorthernCalifornia.WespecifiedCoxproportionalhazardsmodelstoevaluatetherelationshipsbetweenbaselineglycatedhemoglobin(A1C)andsubsequentoutcomes(nonfatalcomplications[acutemetabolic,microvascular,andcardiovascularevents]andmortality).RESULTSThecohort(aged71.067.4years[means6SD])hadameanA1Cof7.061.260 years, enrolled in Kaiser Per-manente Northern California. We specified Cox proportional hazards models to evaluate the relationships between baseline glycated hemoglobin (A1C) and subsequent outcomes (nonfatal complications [acute metabolic, microvascular, and cardiovascular events] and mortality). RESULTS—The cohort (aged 71.06 7.4 years [means6 SD]) had a mean A1C of 7.06 1.2%. The risk of any nonfatal complication rose monotonically for levels of A1C.6.0 % (e.g., adjusted hazard ratio 1.09 [95 % CI 1.02–1.16] for A1C 6.0–6.9 % and 1.86 [1.63–2.13] for A1C 11.0%). Mortality had a U-shaped relationship with A1C. Compared with the risk with A1C,6.0%, mortality risk was lower for A1C levels between 6.0 and 9.0 % (e.g., 0.83 [0.76–0.90] for A1C 7.0–7.9%) and higher at A1C11.011.0 % (1.31 [1.09–1.57]). Risk of any end point (compli-cation or death) became significantly higher at A1C 8.0%. Patterns generally were consistent across age-groups (60–69, 70–79, and $80 years). CONCLUSIONS—Observed relationships between A1C and combined end points suppor

    Ankle-brachial index and physical function in older individuals: The Atherosclerosis Risk in Communities (ARIC) study

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    Most prior studies investigating the association of lower extremity peripheral artery disease (PAD) with physical function were small or analyzed selected populations (e.g., patients at vascular clinics or persons with reduced function), leaving particular uncertainty regarding the association in the general community

    The impact of diabetes on multiple avoidable admissions: a cross-sectional study

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    Background Multiple admissions for ambulatory care sensitive conditions (ACSC) are responsible for an important proportion of health care expenditures. Diabetes is one of the conditions consensually classified as an ACSC being considered a major public health concern. The aim of this study was to analyse the impact of diabetes on the occurrence of multiple admissions for ACSC. Methods We analysed inpatient data of all public Portuguese NHS hospitals from 2013 to 2015 on multiple admissions for ACSC among adults aged 18 or older. Multiple ACSC users were identified if they had two or more admissions for any ACSC during the period of analysis. Two logistic regression models were computed. A baseline model where a logistic regression was performed to assess the association between multiple admissions and the presence of diabetes, adjusting for age and sex. A full model to test if diabetes had no constant association with multiple admissions by any ACSC across age groups. Results Among 301,334 ACSC admissions, 144,209 (47.9%) were classified as multiple admissions and from those, 59,436 had diabetes diagnosis, which corresponded to 23,692 patients. Patients with diabetes were 1.49 times (p < 0,001) more likely to be admitted multiple times for any ACSC than patients without diabetes. Younger adults with diabetes (18–39 years old) were more likely to become multiple users. Conclusion Diabetes increases the risk of multiple admissions for ACSC, especially in younger adults. Diabetes presence is associated with a higher resource utilization, which highlights the need for the implementation of adequate management of chronic diseases policies.NOVASaudeinfo:eu-repo/semantics/publishedVersio
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