Kinetic Components Research Articles

Targeting the Red Nucleus for Cerebellar Tremor

Deep brain stimulation of the thalamus (and especially the ventral intermediate nucleus) does not significantly improve a drug-resistant, disabling cerebellar tremor. The dentato-rubro-olivary tract (Guillain-Mollaret triangle, including the red nucleus) is a subcortical loop that is critically involved in tremor genesis. We report the case of a 48-year-old female patient presenting with generalized cerebellar tremor caused by alcohol-related cerebellar degeneration. Resistance to pharmacological treatment and the severity of the symptoms prompted us to investigate the effects of bilateral deep brain stimulation of the red nucleus. Intra-operative microrecordings of the red nucleus revealed intense, irregular, tonic background activity but no rhythmic components that were synchronous with upper limb tremor. The postural component of the cerebellar tremor disappeared during insertion of the macro-electrodes and for a few minutes after stimulation, with no changes in the intentional (kinetic) component. Stimulation per se did not reduce postural or intentional tremor and was associated with dysautonomic symptoms (the voltage threshold for which was inversed related to the stimulation frequency). Our observations suggest that the red nucleus is (1) an important centre for the genesis of cerebellar tremor and thus (2) a possible target for drug-refractory tremor. Future research must determine how neuromodulation of the red nucleus can best be implemented in patients with cerebellar degeneration.

Hammond Energy Shifts Reveal Sequence of Conformational Changes in N- and C-Type Inactivation of Kv1.4

C-type inactivation is sensitive to mutation on extra- and intracellular side of the channel, indicating it may involve conformational changes at both extracellular and intracellular mouth of the channel. This movement is critical in determining the allosteric coupling between N-type and C-type inactivation. X-ray crystallography has provided insights into the structure of low-energy stable states in inactivation. In order to investigate the path connecting two stable end states and the sequence of movement over the energy landscape of the critical domains involved in C-type inactivation of Kv1.4 channel, we applied ϕ value analysis to this channel. We chose the V561 at intracellular side of S6. Mutations:[V561A], [V561C], [V561Q], [V561S] and [V561T] were made in N-terminal deleted and N-terminal intact channels. In the N-terminal deleted constructs a ϕ of 0.49 was observed for C-type inactivation. With N-terminal binding, the inactivation process became more complex, but analysis of kinetic components revealed a ϕ value of 0.88 for N-terminal binding, indicating an early interaction with the open pore and a ϕ value of 0.64 was obtained C-type inactivation, indicating facilitation of this step to earlier in the total process. Extracellular function was probed by titration of H508. The slopes of Hammond energy plot for pH titration of H508 from all different mutants are consistent with an average ϕ value of 0.218 (range from 0.20 to 0.23), which indicates the movement of extracellular region near selectivity filter is after the movement of intracellular side of S6. Our results reveal that C-type inactivation can be accelerated by binding of N-terminal to the intracellular mouth of the pore, followed by conformational change at intracellular portion of S6 which is transduced to the extracellular mouth region through an allosteric mechanism.

The Functional Heterogeneity of the Human CaV1.2 Voltage Sensors

Voltage-dependent Ca2+ channels (CaV) are the principal pathway of excitation-evoked Ca2+ entry. Their pore-forming α1C subunit encodes four homologous, but non-identical, concatenated repeats, each including a voltage-sensing domain (VSD). The four VSDs confer voltage dependence to the ion-conductive pore. A potential consequence of the independent evolution of each VSD is that the strength and timing of Ca2+ influx are governed by up to four VSDs with distinct voltage-sensing properties and contributions to channel opening. To test this hypothesis, and resolve the voltage dependent conformational rearrangements that initiate excitation-coupled Ca2+ signaling, we used voltage-clamp fluorometry, tracking the activation of each VSD in human CaV1.2 (L-type) channels coexpressed with β3 and α2δ subunits. We found that each VSD possesses distinct voltage-sensitivity, as estimated by fitting normalized fluorescence deflections from each VSD to Boltzmann distributions: VSD-I: V0.5= 8.3±2.7mV; z=2.0±0.090e0; VSD-II: V0.5=-27±1.8mV; z=2.4±0.17e0; VSD-III: V0.5=-18±2.1mV; z=1.4±0.085e0; VSD-IV: V0.5=-61±2.3mV; z=1.3±0.18e0. Upon depolarization to 0mV, VSDs I-III activate with a similar time course to channel opening (τON≈2-4ms), while VSD-IV is significantly slower (τON=17±2.3ms). Upon repolarization, VSD-II deactivates with a kinetic component practically synchronous to the tail current (τOFF=0.57±0.22ms), while other VSDs were several fold slower: VSD-I τOFF=3.7±0.69ms; VSD-III τOFF=6.6±1.0ms; VSD-IV τOFF=28±5.3ms. How do the disparate voltage dependences and kinetics of the four VSDs associate with open probability and global charge displacement? All experimental data were fit by an allosteric model comprising five “gating particles” representing the four VSDs and the pore. This model revealed that the pore Closed/Open transition in the α1C-β3-α2δ channel is primarily regulated by VSD-II and -III, which stabilize the Open state by ∼-37meV and ∼-68meV, respectively. This finding sets CaV1.2 channels apart from KV and NaV channels, where activation is governed by four and three VSDs, respectively. Funded by: NIH,AHA,FONDECYT,ACT.

ATP transport through VDAC and the VDAC-tubulin complex probed by equilibrium and nonequilibrium MD simulations.

Voltage-dependent anion channel (VDAC), the major channel of the mitochondrial outer membrane, serves as a principal pathway for ATP, ADP, and other respiratory substrates across this membrane. Using umbrella-sampling simulations, we established the thermodynamic and kinetic components governing ATP transport across the VDAC1 channel. We found that there are several low-affinity binding sites for ATP along the translocation pathway and that the main barrier for ATP transport is located around the center of the channel and is formed predominantly by residues in the N-terminus. The binding affinity of ATP to an open channel was found to be in the millimolar to micromolar range. However, we show that this weak binding increases the ATP translocation probability by about 10-fold compared with the VDAC pore in which attractive interactions were artificially removed. Recently, it was found that free dimeric tubulin induces a highly efficient, reversible blockage of VDAC reconstituted into planar lipid membranes. It was proposed that by blocking VDAC permeability for ATP/ADP and other mitochondrial respiratory substrates tubulin controls mitochondrial respiration. Using the Rosetta protein-protein docking algorithm, we established a tentative structure of the VDAC-tubulin complex. An extensive set of equilibrium and nonequilibrium (under applied electric field) molecular dynamics (MD) simulations was used to establish the conductance of the open and blocked channel. It was found that the presence of the unstructured C-terminal tail of tubulin in the VDAC pore decreases its conductance by more than 40% and switches its selectivity from anionic to cationic. The subsequent 1D potential of mean force (PMF) computations for the VDAC-tubulin complex show that the state renders ATP transport virtually impossible. A number of residues pivotal for tubulin binding to the channel were identified that help to clarify the molecular details of VDAC-tubulin interaction and to provide new insight into the mechanism of the control of mitochondria respiration by VDAC.

AMMONIA THERMOMETRY OF STAR-FORMING GALAXIES

With a goal toward deriving the physical conditions in external galaxies, we present a study of the ammonia (NH$_3$) emission and absorption in a sample of star forming systems. Using the unique sensitivities to kinetic temperature afforded by the excitation characteristics of several inversion transitions of NH$_3$, we have continued our characterization of the dense gas in star forming galaxies by measuring the kinetic temperature in a sample of 23 galaxies and one galaxy offset position selected for their high infrared luminosity. We derive kinetic temperatures toward 13 galaxies, 9 of which possess multiple kinetic temperature and/or velocity components. Eight of these galaxies exhibit kinetic temperatures $>100$ K, which are in many cases at least a factor of two larger than kinetic temperatures derived previously. Furthermore, the derived kinetic temperatures in our galaxy sample, which are in many cases at least a factor of two larger than derived dust temperatures, point to a problem with the common assumption that dust and gas kinetic temperatures are equivalent. As previously suggested, the use of dust emission at wavelengths greater than 160 $\mu$m to derive dust temperatures, or dust heating from older stellar populations, may be skewing derived dust temperatures in these galaxies to lower values. We confirm the detection of high-excitation OH $^2\Pi_{3/2}$ J=9/2 absorption toward Arp220 (Ott et. al. 2011). We also report the first detections of non-metastable NH$_3$ inversion transitions toward external galaxies in the (2,1) (NGC253, NGC660, IC342, and IC860), (3,1), (3,2), (4,3), (5,4) (all in NGC660) and (10,9) (Arp220) transitions.

Rest and other types of tremor in adult-onset primary dystonia

IntroductionKnowledge regarding tremor prevalence and phenomenology in patients with adult-onset primary dystonia is limited. Dystonic tremor is presumably under-reported, and we aimed to assess the prevalence and the clinical correlates...

Watching Photoactivation in a Ru(II) Chromophore–Catalyst Assembly on TiO2 by Ultrafast Spectroscopy

This paper examines the ultrafast dynamics of the initial photoactivation step in a molecular assembly consisting of a chromophore (denoted [RuaII]2+) and a water-splitting catalyst (denoted [RubII]2+) anchored to TiO2. Photoexcitation of the chromophore is followed by rapid electron injection from the Ru(II) metal-to-ligand charge-transfer (MLCT) excited state. The injection process was followed via the decay of the bpy radical anion absorption at 375 nm. Injection is ∼95% efficient and exhibits multiple kinetic components with decay times ranging from <250 fs to 250 ps. Electron injection is followed by the transfer of the oxidative equivalent from the chromophore to the catalyst (ΔG = −0.28 eV) with a transfer time of 145 ps. In the absence of subsequent photoexcitation events, the charge-separated state undergoes electron-transfer recombination on the microsecond time scale.

The molecular mechanism of ion-dependent gating in secondary transporters.

LeuT-like fold Na-dependent secondary active transporters form a large family of integral membrane proteins that transport various substrates against their concentration gradient across lipid membranes, using the free energy stored in the downhill concentration gradient of sodium ions. These transporters play an active role in synaptic transmission, the delivery of key nutrients, and the maintenance of osmotic pressure inside the cell. It is generally believed that binding of an ion and/or a substrate drives the conformational dynamics of the transporter. However, the exact mechanism for converting ion binding into useful work has yet to be established. Using a multi-dimensional path sampling (string-method) followed by all-atom free energy simulations, we established the principal thermodynamic and kinetic components governing the ion-dependent conformational dynamics of a LeuT-like fold transporter, the sodium/benzyl-hydantoin symporter Mhp1, for an entire conformational cycle. We found that inward-facing and outward-facing states of Mhp1 display nearly the same free energies with an ion absent from the Na2 site conserved across the LeuT-like fold transporters. The barrier separating an apo-state from inward-facing or outward-facing states of the transporter is very low, suggesting stochastic gating in the absence of ion/substrate bound. In contrast, the binding of a Na2 ion shifts the free energy stabilizing the outward-facing state and promoting substrate binding. Our results indicate that ion binding to the Na2 site may also play a key role in the intracellular thin gate dynamics modulation by altering its interactions with the transmembrane helix 5 (TM5). The Potential of Mean Force (PMF) computations for a substrate entrance displays two energy minima that correspond to the locations of the main binding site S1 and proposed allosteric S2 binding site. However, it was found that substrate's binds to the site S1 ∼5 kcal/mol more favorable than that to the site S2 for all studied bound combinations of ions and a substrate.

New Vector Description of Kinetic Pressures on Shaft Bearings of a Rigid Body Nonlinear Dynamics with Coupled Rotations around No Intersecting Axes

New vector description of kinetic pressures on shaft bearings of a rigid body nonlinear dynamics with coupled rotations around no intersecting axes is first main result presented in this paper. Mass moment vectors and vector rotators coupled for pole and oriented axes, defined by K. Hedrih in 1991, are used for obtaining vector expressions for kinetic pressures on the shaft bearings of a rigid body dynamics with coupled rotations around no intersecting axes. A complete analysis of obtained vector expressions for kinetic pressures on shaft bearings give us a series of the kinematical vectors rotators around both directions determined by axes of the rigid body coupled rotations around no intersecting axes. As an example of defined dynamics, we take into consideration a heavy gyro-rotor- disk with one degree of freedom and coupled rotations when one component of rotation is programmed by constant angular velocity. For this system with nonlinear dynamics, series of graphical presentation transformations in realizations with changes of eccentricity and angle of inclination (skew position) of heavy rigid body-disk in relation to self rotation axis are presented, as well as in realization with changing orthogonal distance between axes of coupled rotations. Angular velocity of kinetic pressures components in vector form are expressed by using angular acceleration and angular velocity of component coupled rotations of gyrorotor-disk.

Interaction between avoidance of photon absorption, excess energy dissipation and zeaxanthin synthesis against photooxidative stress in Arabidopsis

Plants evolved photoprotective mechanisms in order to counteract the damaging effects of excess light in oxygenic environments. Among them, chloroplast avoidance and non-photochemical quenching concur in reducing the concentration of chlorophyll excited states in the photosynthetic apparatus to avoid photooxidation. We evaluated their relative importance in regulating excitation pressure on photosystem II. To this aim, genotypes were constructed carrying mutations impairing the chloroplast avoidance response (phot2) as well as mutations affecting the biosynthesis of the photoprotective xanthophyll zeaxanthin (npq1) or the activation of non-photochemical quenching (npq4), followed by evaluation of their photosensitivity in vivo. Suppression of avoidance response resulted in oxidative stress under excess light at low temperature, while removing either zeaxanthin or PsbS had a milder effect. The double mutants phot2 npq1 and phot2 npq4 showed the highest sensitivity to photooxidative stress, indicating that xanthophyll cycle and qE have additive effects over the avoidance response. The interactions between non-photochemical quenching and avoidance responses were studied by analyzing the kinetics of fluorescence decay and recovery at different light intensities. phot2 fluorescence decay lacked a component, here named as qM. This kinetic component linearly correlated with the leaf transmittance changes due to chloroplast relocation induced by white light and was absent when red light was used as actinic source. On these basis we conclude that a decrease in leaf optical density affects the apparent non-photochemical quenching (NPQ) rise kinetic. Thus, excess light-induced fluorescence decrease is in part due to avoidance of photon absorption rather than to a genuine quenching process.

Sub-grid drag models for horizontal cylinder arrays immersed in gas-particle multiphase flows

Immersed cylindrical tube arrays often are used as heat exchangers in gas-particle fluidized beds. In multiphase computational fluid dynamics (CFD) simulations of large fluidized beds, explicit resolution of small cylinders is computationally infeasible. Instead, the cylinder array may be viewed as an effective porous medium in coarse-grid simulations. The cylinders’ influence on the suspension as a whole, manifested as an effective drag force, and on the relative motion between gas and particles, manifested as a correction to the gas-particle drag, must be modeled via suitable sub-grid constitutive relationships. In this work, highly-resolved unit-cell simulations of flow around an array of horizontal cylinders, arranged in a staggered configuration, are filtered to construct sub-grid, or ‘filtered’, drag models, which can be implemented in coarse-grid simulations. The force on the suspension exerted by the cylinders is composed of, as expected, a buoyancy contribution, and a kinetic component analogous to fluid drag on a single cylinder. Furthermore, the introduction of tubes also is found to enhance segregation at the scale of the cylinder size, which, in turn, leads to a reduction in the filtered gas-particle drag.

Protein misfolding and aggregation research: Some thoughts on improving quality and utility

Once misfolded and aggregated proteins were as interesting as yesterday's trash, just a bothersome byproduct of productive activities. Today, they attract sustained interest from both basic researchers and practicing engineers. In the burgeoning biopharmaceutical industry, protein misfolding and aggregation pose significant challenges to the economic manufacture of safe and effective protein products. In the clinic, protein aggregates are believed to be pathological agents in a number of serious neurodegenerative disorders, such as Alzheimer's and Parkinson's. Over the past few years, the quantity of research into biotechnological aspects of protein misfolding and aggregation has skyrocketed. However, the quality of the published work is quite variable. In this brief opinion piece, we describe what we believe are some key features of high-quality publications in protein aggregation. We focus on experimental studies that may also have a kinetic modeling component.

The Carboxyl Terminal Residues 220–283 Are Not Required for Voltage Gating of a Chimeric Connexin32 Hemichannel

Connexin hemichannels display two distinct forms of voltage-dependent gating, corresponding to the operation of Vj- or fast gates and loop- or slow gates. The carboxyl terminus (CT) of connexin 32 has been reported to be required for the operation of the Vj (fast) gates, but this conclusion was inferred from the loss of a fast kinetic component in macroscopic currents of CT-truncated intercellular channels elicited by transjunctional voltage. Such inferences are complicated by presence of both fast and slow gates in each hemichannel and the serial head-to-head arrangement of these gates in the intercellular channel. Examination of voltage gating in undocked hemichannels and Vj gate polarity reversal by a negative charge substitution (N2E) in the amino terminal domain allow unequivocal separation of the two gating processes in a Cx32 chimera (Cx32∗43E1). This chimera expresses currents as an undocked hemichannel in Xenopus oocytes and provides a model system to study the molecular determinants and mechanisms of Cx32 voltage gating. Here, we demonstrate that both Vj- and loop gates are operational in a truncation mutation that removes all but the first four CT residues (ACAR219) of the Cx32∗43E1 hemichannel. We conclude that an operational Cx32 Vj (fast) gate does not require CT residues 220–283, as reported previously by others.

The point kinetic component of neutron noise in an MSR

The point kinetic approximation, and the calculation of the point kinetic component of the neutron noise in Molten Salt Reactors (MSR) is revisited. First, the derivation of the point kinetic equations in an MSR, found in the literature, is discussed. It is shown that to make the equations solvable, some simplifications need to be made whose validity is not justified. Then the point kinetic component of the noise is derived from the full space-frequency dependent solution in an analytical form by a projection to the static adjoint. The solution of the simplified point kinetic equations and the linearly exact point kinetic component obtained by the projection technique are compared quantitatively and it is shown that the solution of the simplified point kinetic equations cannot reconstruct some important features of the true solution.

A combined INS and DINS study of proton quantum dynamics of ice and water across the triple point and in the supercritical phase

We report new results of a combined analysis of previous Inelastic Neutron Scattering (INS) and Deep Inelastic Neutron Scattering (DINS) experiments on ice at T=271K and water at T=285K and T=673K. Proton quantum dynamics is discussed in terms of the total mean kinetic energy, 〈EK〉, and its three principal direction components, 〈EK〉α (with α=x,y,z), the lineshape momentum distribution, n(p), and its harmonic lineshape components, nh(p). The results show that the single proton dynamics is ground-state dominated and that 〈EK〉x,〈EK〉y and 〈EK〉z consist mainly of weighted averages of a mix of bending and librational, librational and stretching mean kinetic energy components, respectively. The stretching component 〈EK〉z is redshifted respect to its harmonic component due to additional network mode contributions and softening caused by anharmonicity. The n(p) lineshapes derived at the investigated temperature reflect the anisotropy and quasi-harmonic nature of proton motion in ice and water.

Trapped one-dimensional ideal Fermi gas with a single impurity

Ground-state properties of a single impurity in a one-dimensional Fermi gas are investigated in uniform and trapped geometries. The energy of a trapped system is obtained (i) by generalizing the McGuire expression from a uniform to trapped system (ii) within the local density approximation (iii) using the perturbative approach in the case of a weakly interacting impurity and (iv) diffusion Monte Carlo method. We demonstrate that there is a closed formula based on the exact solution of the homogeneous case which provides a precise estimation for the energy of a trapped system even for a small number of fermions and arbitrary coupling constant of the impurity. Using this expression, we analyze energy contributions from kinetic, interaction, and potential components, as well as spatial properties such as the system size and the pair-correlation function. Finally, we calculate the frequency of the breathing mode. Our analysis is directly connected and applicable to the recent experiments in microtraps.

Low absorption state of phycocyanin from Acaryochloris marina antenna system: On the interplay between ionic strength and excitonic coupling

This paper studies the excitonic factor in the excited state energy transfer of phycobilisome (PBS) by using a polarized time-resolved pump-probe and by changing the ionic strength of the cofactors' medium in the PBS of Acaryochloris marina (A. marina). As a result, the interplay between the surrounding medium and the closely excited adjacent cofactors is shown to be a negligible factor of the excitonic decay kinetics at 618 nm of the phycocyanin (PC), while it appears as a driving factor of an increase in excitonic delocalization at 630 nm. The obtained anisotropy values are consistent with the contribution of ionic strength in the excitonic mechanism in PBS. These values were 0.38 in high ionic strength and 0.4 in low ionic strength at 618 nm, and 0.52 in high ionic strength and 0.4 in low ionic strength at 630-635 nm. The anisotropy value of 0.52 in high phosphate is similar at 630 nm and 635 nm, which is consistent with an excitonic delocalization band at 635 nm. The 635 nm band is suggested to show the true low energy level of PC in A. marina PBS. The anisotropy decay kinetic at 630 nm suggests that the excited state population of PC is not all equilibrated in 3 ps because of the existence of the 10 ps decay kinetic component. The presence of the slow kinetic decay component in high, and low ionic strength, is consistent with a 10 and 14 ps energy transfer pathway, while the 450 fs kinetic decay component is consistent with the presence of an additional excitation energy transfer pathway between adjacent α84 and β84. Furthermore, the 450 fs decay kinetic is suggested to be trapped in the trimer, while the 400 fs decay kinetic rules out an excitonic flow from low energy level PC to allophycoyanin. This excitonic flow may occur between β84 in adjacent trimers, towards the low energy state of the PBS rod.

Human Fc Receptor–Like 5 Binds Intact IgG via Mechanisms Distinct from Those of Fc Receptors

Fc receptor-like (FCRL) 5 regulates B cell Ag receptor signaling and has been reported to bind aggregated IgG. Using surface plasmon resonance, we analyzed the interaction of native IgG samples with FCRL5, revealing a complex binding mechanism, where isotype is just one factor. FCRL5 bound IgG1 and IgG4 with ~1 μM KD, whereas the interaction with IgG3 was a magnitude weaker. However, IgG2 samples displayed a wide range of affinities, indicating that additional factors affect binding. We used a panel of 19 anti-FCRL5 mAbs with defined reactivity to identify domains involved in ligand binding. Six mAbs blocked IgG binding, indicating critical roles of FCRL5 domains 1 and 3, as well as epitopes at the domain 1/2 and domain 2/3 boundaries. We found that only glycosylated IgG containing both Fab arms and the Fc region bound with high affinity. Furthermore, the presence of sialic acid in the IgG carbohydrate altered FCRL5 binding. The interaction of IgG and FCRL5 consisted of two kinetic components, suggesting a complex binding mechanism. We established that the IgG-Fc and IgG-F(ab')2 fragments bind FCRL5 independently but with low affinity, revealing the mechanism behind the two-step binding of whole IgG. This complex binding mechanism is distinct from that of Fc receptors, which bind through the Fc. We propose that FCRL5 is a new type of receptor that recognizes intact IgG, possibly enabling B cells to sense Ig quality. Recognition of undamaged IgG molecules by FCRL5 could allow B cells to engage recently produced Abs.

Seismic Response of Squat Rigid Bodies on Inclined Planes with Rigid Boundaries

AbstractA planar rigid-body dynamics formulation describing the seismic behavior of a squat rectangular rigid body initially resting on an inclined rigid plane is presented. The downslope motion of the body is limited by a rigid boundary perpendicular to the inclined plane. This type of problem appears in several practical applications. Coulomb and hysteretic friction with velocity- and pressure-dependent properties are considered at the body-to-ground interface. The weaknesses of hysteretic friction models incorporating static and kinetic velocity-dependent components are identified and remedied. Impact models for collision of the body with the rigid boundary and the inclined plane are also derived. The formulation is embodied in a numerical model through a dedicated computer code. A comparative study is conducted to demonstrate the effects on the body response of major model characteristics, including the rigid boundary; inclination angle; Coulomb, hysteretic, and combined Coulomb-hysteretic friction; a...

SAKE: A new quantification tool for positron emission tomography studies

In dynamic positron emission tomography (PET) studies, spectral analysis (SA) refers to a data-driven quantification method, based on a single-input single-output model for which the transfer function is described by a sum of exponential terms. SA allows to quantify numerosities, amplitudes and eigenvalues of the transfer function allowing, in this way, to separate kinetic components of the tissue tracer activity with minimal model assumptions. The SA model can be solved with a linear estimator alone or with numerical filters, resulting in different types of SA approaches. Once estimated the number, amplitudes and eigenvalues of the transfer function, one can distinguish the presence in the system of irreversible and/or reversible components as well as derive parameters of physiological significance.These characteristics make it an appealing alternative method to compartmental models which are widely used for the quantitative analysis of dynamic studies acquired with PET. However, despite its applicability to a large number of PET tracers, its implementation is not straightforward and its utilization in the nuclear medicine community has been limited especially by the lack of an user-friendly software application.In this paper we proposed SAKE, a computer program for the quantitative analysis of PET data through the main SA methods. SAKE offers a unified pipeline of analysis usable also by people with limited computer knowledge but with high interest in SA.