Range Of Dynamic Changes Research Articles

Application of early warning signs to physiological contexts: a comparison of multivariate indices in patients on long-term hemodialysis.

Early warnings signs (EWSs) can anticipate abrupt changes in system state, known as "critical transitions," by detecting dynamic variations, including increases in variance, autocorrelation (AC), and cross-correlation. Numerous EWSs have been proposed; yet no consensus on which perform best exists. Here, we compared 15 multivariate EWSs in time series of 763 hemodialyzed patients, previously shown to present relevant critical transition dynamics. We calculated five EWSs based on AC, six on variance, one on cross-correlation, and three on AC and variance. We assessed their pairwise correlations, trends before death, and mortality predictive power, alone and in combination. Variance-based EWSs showed stronger correlations (r = 0.663 ± 0.222 vs. 0.170 ± 0.205 for AC-based indices) and a steeper increase before death. Two variance-based EWSs yielded HR95 > 9 (HR95 standing for a scale-invariant metric of hazard ratio), but combining them did not improve the area under the receiver-operating curve (AUC) much compared to using them alone (AUC = 0.798 vs. 0.796 and 0.791). Nevertheless, the AUC reached 0.825 when combining 13 indices. While some indicators did not perform overly well alone, their addition to the best performing EWSs increased the predictive power, suggesting that indices combination captures a broader range of dynamic changes occurring within the system. It is unclear whether this added benefit reflects measurement error of a unified phenomenon or heterogeneity in the nature of signals preceding critical transitions. Finally, the modest predictive performance and weak correlations among some indices call into question their validity, at least in this context.

Design of Smart Antibody Mimetics with Photosensitive Switches.

As two prominent examples of intracellular single-domain antibodies or antibody mimetics derived from synthetic protein scaffolds, monobodies and nanobodies are gaining wide applications in cell biology, structural biology, synthetic immunology, and theranostics. Herein, a generally applicable method to engineer light-controllable monobodies and nanobodies, designated as moonbody and sunbody, respectively, is introduced. These engineered antibody-like modular domains enable rapid and reversible antibody-antigen recognition by utilizing light. By the paralleled insertion of two light-oxygen-voltage domain 2 modules into a single sunbody and the use of bivalent sunbodies, the range of dynamic changes of photoswitchable sunbodies is substantially enhanced. Furthermore, the use of moonbodies or sunbodies to precisely control protein degradation, gene transcription, and base editing by harnessing the power of light is demonstrated.

Using Formal Methods to Improve Home-Use Medical Device Safety

Using Formal Methods to Improve Home-Use Medical Device Safety

How do Three Proteins Generate Circadian Rhythms? The Detailed Timing Mechanism of the Cyanobacterial Circadian Oscillator

Virtually all organisms contain a circadian clock that regulates gene expression, metabolic pathway and cell division. These regulations enhance the fitness of organisms by anticipating daily changes. To generate a clock, a stable oscillation must be maintained. Thus, we focus on understanding how molecular components form an oscillator which drives a biological clock.To study clock mechanism in detail, we use the cyanobacterial oscillator because it is the only system that can be functionally reconstituted in a test tube. Mixing three clock proteins, KaiA, KaiB, and KaiC, and ATP produces a robust 24-hour rhythm of KaiC phosphorylation/dephosphorylation. All other oscillators are difficult to study at the mechanistic level because they cannot be isolated from the complex milieu of living cells.This oscillator has two distinct phases: 1) in Phosphorylation Phase, KaiA binds to the C-terminal residues of KaiC known as the A-loop and stimulates KaiC phosphorylation; 2) in Dephosphorylation Phase, KaiA is inhibited from binding to A-loop by KaiB, then KaiC dephosphorylates.Our central hypothesis is that the KaiA binding site on KaiC (i.e. A-loop) experiences a range of dynamic changes that drive preferential KaiA-KaiC interaction which is critical to the rhythm. Here we will present our latest findings of this unique oscillator to gain a deep mechanistic insight into how these three proteins form transient and time-dependent interactions that are central to the function of this oscillator.

Changing Land Use in Recent Decades and Its Impact on Plant Cover in Agricultural and Forest Landscapes in Poland

The objective of this paper is to present the effects of general changes in land use in recent decades on plant cover structure in Poland. The paper is focused on spontaneous processes that occur in agricultural and forest areas being no longer under human pressure. Studies carried out in different geobotanical regions of Poland demonstrated that the directions and range of dynamic changes in plant cover are similar across the country. The formation of secondary forest phytocenoses, on the lands delivered from human activity is a common ecological process observed today in the agricultural landscape. In the dynamics of forest vegetation the basic process is regeneration after ceased use, and the introduction of legal protection.

Diurnal Changes in Mitochondrial Function Reveal Daily Optimization of Light and Dark Respiratory Metabolism in Arabidopsis

Biomass production by plants is often negatively correlated with respiratory rate, but the value of this rate changes dramatically during diurnal cycles, and hence, biomass is the cumulative result of complex environment-dependent metabolic processes. Mitochondria in photosynthetic plant tissues undertake substantially different metabolic roles during light and dark periods that are dictated by substrate availability and the functional capacity of mitochondria defined by their protein composition. We surveyed the heterogeneity of the mitochondrial proteome and its function during a typical night and day cycle in Arabidopsis shoots. This used a staged, quantitative analysis of the proteome across 10 time points covering 24 h of the life of 3-week-old Arabidopsis shoots grown under 12-h dark and 12-h light conditions. Detailed analysis of enzyme capacities and substrate-dependent respiratory processes of isolated mitochondria were also undertaken during the same time course. Together these data reveal a range of dynamic changes in mitochondrial capacity and uncover day- and night-enhanced protein components. Clear diurnal changes were evident in mitochondrial capacities to drive the TCA cycle and to undertake functions associated with nitrogen and sulfur metabolism, redox poise, and mitochondrial antioxidant defense. These data quantify the nature and nuances of a daily rhythm in Arabidopsis mitochondrial respiratory capacity.

Dynamic myocardial velocity changes between phases of the cardiac cycle.

The purpose of this study was 1. to define relationships between myocardial velocities according to phases and the range of dynamic phasic changes in controls using tissue Doppler echocardiography (TDE); 2. to compare the usefulness of dynamic changes vs. peak velocities alone on controls and patients. Peak velocity changes between phases were studied by colour M-mode TDE in the posterior wall from pre-ejection to systole (ejectional wall velocity increase) and from ejection to early diastole (early diastolic wall velocity increase) in 17 age-matched controls and a group of 30 patients with dilated cardiomyopathies (CMy) consisting of ischaemic (14) and nonischaemic (16) CMy with similar clinical and echocardiographic presentations. Systolic were correlated with early diastolic peak velocities (r = 0.79 p < 0.0001). Velocity values were significantly lower in patients than in controls (p < 0.001) as well as dynamic ejectional (p = 0.02) and early diastolic (0.03) increases. Dynamic changes were closely similar to controls (74 +/- 7%, 46 +/- 14%) in nonischaemic CMy (66 +/- 18%, 39 +/- 10% NS, respectively), but markedly reduced in ischaemic CMy (28 +/- 59%, and 26 +/- 31%, p = 0.005 and p = 0.06 vs. nonischaemic CMy, respectively). Of patients with ischaemic CMy, 78% had an ejectional increase < 40% and/or an early diastolic increase < 25%. Thus, correlation exists between systolic and early diastolic velocities. Normal range of dynamic changes was defined in an elderly population. Results suggest that velocity dynamics might be more informative than peak velocities alone to show left ventricular dysfunction.

Activity-dependent sensitivity of proprioceptive sensory neurons in the stick insect femoral chordotonal organ.

Mechanosensory neurons exhibit a wide range of dynamic changes in response, including rapid and slow adaptation. In addition to mechanical factors, electrical processes may also contribute to sensory adaptation. We have investigated adaptation of afferent neurons in the stick insect femoral chordotonal organ (fCO). The fCO contains sensory neurons that respond to position, velocity, and acceleration of the tibia. We describe the influence of random mechanical stimulation of the fCO on the response of fCO afferent neurons. The activity of individual sensory neurons was recorded intracellularly from their axons in the main leg nerve. Most fCO afferents (93%) exhibited a marked decrease in response to trapezoidal stimuli following sustained white noise stimulation (bandwidth = 60 Hz, amplitudes from +/-5 to +/-30 degrees ). Concurrent decreases in the synaptic drive to leg motoneurons and interneurons were also observed. Electrical stimulation of spike activity in individual fCO afferents in the absence of mechanical stimulation also led to a dramatic decrease in response in 15 of 19 afferents tested. This indicated that electrical processes are involved in the regulation of the generator potential or encoding of action potentials and partially responsible for the decreased response of the afferents. Replacing Ca(2+) with Ba(2+) in the saline surrounding the fCO greatly reduced or blocked the decrease in response elicited by electrically induced activity or mechanical stimulation when compared with control responses. Our results indicate that activity of fCO sensory neurons strongly affects their sensitivity, most likely via Ca(2+)-dependent processes.