Another cellulose membrane containing the seventeen peptides were

Another cellulose membrane containing the seventeen peptides were prepared, blocked and probed with LmmAbB2D4 (10 μg/ml). As shown in Fig. 2B, the peptides recognized by LmmAbB2D4 were peptide 4 (QCTMDQGRLRCR), Cytoskeletal Signaling inhibitor peptide 7 (TCATDQGRLRCT), peptide 8 (HCFHDQGRVRCA), peptide 14 (HCTMDQGRLRCR) and peptide 15 (SCMLDQGRSRCR). Analysis of these sequences revealed no obvious homology between the mimotopes and the mut-II sequence. Based on the results of immunoassay with cellulose-bound peptides, the peptides (QCTMDQGRLRCR, TCATDQGRLRCT, HCFHDQGRVRCA and HCTMDQGRLRCR) were synthesized in a soluble form, trapped

in liposomes and used as immunogens in rabbits. One week after the sixth injection, sera from rabbits were tested in an indirect ELISA for their reactivity toward the peptides, the L. muta whole venom and the cognate mut-II protein. The sera from rabbits immunized with peptides show marginal reactivity against the peptides coated to plates, likely due to low adsorption of peptides to the microtiter plates (data find more not shown). However, ELISA reactivity was observed when the

antigens were L. muta crude venom and mut-II ( Fig. 3A and B). The strongest reactivity toward Mut-II was obtained with the serum of rabbits immunized with peptides TCATDQGRLRCT and QCTMDQGRLRCR ( Fig. 3B). The serum of rabbits immunized with the peptides HCFHDQGRVRCA and HCTMDQGRLRCR reacted poorly with the Mut-II protein, even lower that the serum of mock-liposomes immunized rabbits. The neutralizing properties of the anti-peptide antibodies raised in rabbits were assessed in vivo by testing the hemorrhagic inducing activity

of L. muta venom in animals immunized with the four target peptides. The rabbits immunized with the peptide-mimotopes TCATDQGRLRCT and QCTMDQGRLRCR were completely protected ( Fig. 4A and B). The rabbits immunized with the HCFHDQGRVRCA and HCTMDQGRLRCR peptides were partially protected (about 62% and 37% protection, respectively). The animal from the group that received the empty liposome (without peptides) as negative control liposome was not protected. Snake venoms are a cocktail of biologically active molecules, including toxins with enzymatic and non-enzymatic activities that have evolved to assist in the capture and digestion Branched chain aminotransferase of prey, as well as defense against predators. Human systemic envenomation is associated with a number of adverse effects, the nature and severity of which depends on the species of snake, the quantity of venom injected and the time period between envenomation and the administration of appropriate medical treatment. These effects may include paralysis, myolysis, blood coagulation disturbances and renal damage [7] and [41]. Bushmaster snake envenomation is characterized by serious hemorrhage, blood coagulation disorders, and renal failure; hemorrhage is the major complication resulting from envenomation by the pit vipers Bothrops and Lachesis snakebites [22].

Plasma creatine kinase activity was determined using the CK-UV Ki

Plasma creatine kinase activity was determined using the CK-UV Kit (Bioclin, Brazil). Activity was expressed in units/L, with one unit corresponding to the production of 1 μmol of NADH per min at 30 °C. Negative controls received 50 μL of 1% DMSO-PBS alone. The control group for each sesquiterpene lactone compound received an intramuscular PD-1 antibody inhibitor injection of 50 μL of a solution containing

just 20 μg of each sesquiterpene lactone derivative compound, dissolved in 1% DMSO in PBS (pH 7.2) ( Souza et al., 2008 and Da Silva et al., 2008a). The measurement of the enzymatic activity using the micellar substrate, 1-hexadecanoyl-2-(1-pyrenedecanoyl)-sn-glycero-3-phosphoglycerol (HPGP), was performed through the microtiter plate assay. Each sesquiterpene lactone derivative compound was tested in final concentrations of 0.0, 1.0, 2.0, 3.0 and 4.0 μM. Seven wells of a 96-well microtiter plate were used for each assay, resulting in six measurement repetitions of the enzymatic activity for each final concentration of the inhibitor. Thus, for each assay with different concentrations of the inhibitor, 100 μL of solution A in assay buffer (27 μM bovine serum albumin, 50 mM KCl, 1 mM CaCl2, 50 mM Tris– HCl, pH 8.0) was added to seven wells, followed by the addition of a volume of lactone find more derivative compound (the volume used was according to the assay concentration,

0.0–4.0 μM) dissolved in DMSO. For control reactions, the same volume of DMSO was used Morin Hydrate alone. Solution B had the same composition as that of Solution A, but contained PLA2 (0.5 μg/mL) and was delivered in 100 μL volumes to seven wells, except for the first well. Instead of Solution B, an additional

100 μL-portion of Solution A was added to the first of the seven wells in the assay. Solution B was prepared immediately before each set of assays to avoid loss of enzymatic activity. Quickly, after the addition of Solution B, the assay was initiated by the addition of 0.5–50 μL of Solution C to the seven wells (53 mM HPGP vesicles in assay buffer), with a repeating pipette. The final concentration of HPGP varied from 0.125 to 10 mM. The final volume of the assay was 265 μL and, when necessary, the wells received an extra volume of solution A in order to complete this volume. The fluorescence (excitation = 342 nm, emission = 395 nm) was read with a microtiter plate spectrophotometer (Fluorocount, Packard Instruments). Control reactions without enzyme or inhibitor were run for all assays and the initial velocity was calculated from the initial slope of fluorescence versus time, for each concentration of the substrate used. The significance of differences between groups was evaluated using the Student’s t-test. A P-value <0.05 was considered to be significant ( Da Silva et al., 2008b). The structures of each sesquiterpene lactone derivative compound were submitted to ab initio quantum calculations. In order to select the best conformations, the HyperChem 7.51 software was utilized.

The steady-state Richardson number can still be predicted by line

The steady-state Richardson number can still be predicted by linear theory, however. Finding the predicted value amounts to moving right along the λλ-axis in Fig. 4 to the point where λ=3Δxλ=3Δx. At this point, which corresponds to the grid cutoff scale, the maximal value of Ri   with σ>0σ>0 is the

predicted restratification potential of the resolved SI modes. In simulation A6A6 linear theory predicts the flow to become SI-neutral at Ri≈0.56Ri≈0.56, matching the simulated value to within 1%1%. The prediction for simulation C6C6 again did not perform DAPT research buy as well due to entrainment from the thermocline, yielding a steady Ri≈0.41Ri≈0.41 compared with a predicted value of Ri≈0.47Ri≈0.47. This outcome represents the most likely scenario that would occur in an ocean model, where some combination of coarse grid spacing and viscosity NU7441 would limit the presence of

SI modes and thereby limit restratification of the mixed layer. Note, however, that in the general case of an ocean model where mixed layer depth, forcing, viscosity, and stratification are all varying in time and space the restratification potential will not be easily predictable. Nonetheless, the cases here demonstrate that the grid spacing can affect restratification by making some of the SI modes unresolvable. The third outcome is perhaps the most interesting, and occurs when the horizontal and vertical viscosities are small enough to permit a full restratification by the SI modes but are anisotropic (Sets B and D). In finely-resolved simulations with isotropic viscosity and nearly-isotropic grid spacing secondary Kelvin–Helmholtz instabilities form in the shear zones between SI cells (Taylor and Ferrari, 2009), which serve to mix potential vorticity across density surfaces. Simulations with coarse horizontal resolution develop these shear zones between cells 17-DMAG (Alvespimycin) HCl as well, but the anisotropic

viscosity does not permit fully realized shear instability to form at these locations. The resulting flow features localized regions of vigorous, small-scale noise (Fig. 6(d)) that act as a nonphysical source of mixing, after which the steady-state flow is characterized by strong inertial oscillations with Ri>1Ri>1 and q>0q>0. This overturning penetrates deep into the thermocline and entrains a large amount of high-PV fluid, which is then rapidly mixed up into the interior of the mixed layer and causes the overshoot in Ri and q. Some entrainment is to be expected in all scenarios since the SI overturning cells extend into the thermocline ( Fig. 3(a)), but in Sets B and D strong mixing occurs in the interior of the thermocline and persists even after the majority of the mixed layer restratification is complete, suggesting that this mechanism is nonphysical ( Fig. 6(b) and (d)).

Loops were optimized using MODLOOP ( Fiser and Sali, 2003b) based

Loops were optimized using MODLOOP ( Fiser and Sali, 2003b) based on the satisfaction of spatial restraints, without relying Staurosporine cell line on a database of known protein structures. The DOPE potential was evaluated for all models, and the model with the lowest global score was selected for explicit solvent molecular dynamics simulation using the GROMACS package (

Lindahl et al., 2001) and the GROMOS-96 (43a1) force field to check its stability and consistency. The overall and local quality of the final model was assessed by VERIFY3D ( Eisenberg et al., 1997), PROSA ( Wiederstein and Sippl, 2007) and VADAR ( Willard et al., 2003). Three-dimensional structures were analyzed and compared using the program PyMoL ( The results obtained were expressed as the mean ± standard deviation (SD) and statistically analyzed by applying a one-way ANOVA, followed by the Tukey method. Differences with p < 0.05 were considered

statistically significant. A new proteinase isolated from the venom of Bothrops MK-2206 datasheet atrox, which is a snake native to the state of Pará in Brazil, was obtained by two chromatographic procedures. The first step consisted of gel filtration on a Sephadex G-75 column under alkaline conditions (pH 8.0). The chromatogram shown in Fig. 1A illustrates the five major fractions obtained (Ba I to Ba V). Fraction Ba III presented hemorrhagic activity. The SDS-PAGE analysis of the fraction content under reduced conditions ( Fig. 1A insert) shows that Ba III contained two proteins, with one main band presenting a molecular mass of approximately 27 kDa and the second band presenting a molecular mass of approximately 17 kDa. Ba III was submitted to a second purification procedure using anion exchange chromatography ( Fig. 1B). Unbound material was eluted in 50 mM ambic pH 7.4, whereas the bound proteins were

eluted with a linear gradient of increasing concentrations of ambic pH 7.4, up to 500 mM. The resulting fractions (ES I and ES II) were assayed for hemorrhagic activity, Edoxaban and fraction ES I was able to induce dorsal skin hemorrhage in mice. SDS-PAGE ( Fig. 1B insert) shows that ES I produced a single protein band of approximately 27 kDa under reducing conditions. To confirm the purity of the fraction, ES I was submitted to reverse phase chromatography on HPLC, which revealed a single homogenous peak ( Fig. 1C). In addition, isoelectric focusing produced a single protein band with a pI of 7.5 ( Fig. 1D). The MALDI-TOF mass spectrometry analysis, based on a single charged molecule, identified a protein with a molecular mass of 22.9 kDa (data not shown). Taken together, these results confirm the isolation of Batroxase, a new protein from Bothrops atrox snake venom. Batroxase was able to induce hemorrhaging after intradermal injection in the dorsal skin of mice, with a DMH of 10 μg (Fig. 2A).

In spite of the subsequent decrease in the depth of sleep, MFV de

In spite of the subsequent decrease in the depth of sleep, MFV decreased further from stages IVa to IIc preceding the REM period. MFVs in stage IIa of the second and last sleep cycles were significantly (p < 0.01) lower than those in stage IIa during the first NREM cycle. A special pattern in the MFV profile was seen during passage through the second and subsequent NREM sleep cycles. MFV values were low during sleep stages

IIa and IVa following REM sleep, increased moderately during intermediate sleep stage IIb and decreased again gradually with consecutive sleep stages IIIb, IVb and IIc. The decrease in MFV values was less during the second and last NREM sleep stages than during the first sleep cycle. MFV values in all sleep stages did not differ significantly during the NREM sleep stages in the second and last NREM sleep cycles CHIR 99021 studied. The beginning of REM sleep was accompanied by a marked increase in MFV. MFV values markedly exceeded values of the preceding sleep stages II and IV but did not reach waking values in the first, second and last sleep cycle. The MFV during alpha-frequency wakefulness that follows NREM sleep was lower than waking values preceding sleep onset (Fig. 3). After morning awakening, patients lying awake often required more than half an hour to reach MFV values Trametinib corresponding to the waking state of the previous evening.

MFV profiles were occasionally interrupted by movement artifacts in all healthy subjects (Fig. 3). Rapid fluctuations in FV lasting seconds occurred during SWS as well as stage II and REM sleep. Fig. 4 shows the FV curve with corresponding sleep stages in a typical healthy

subject [39]. There were no major fluctuations of FV during stage IV. Moderate fluctuations appeared during sleep stage II. During REM sleep, the amplitude and the duration of fluctuations were markedly increased. Large fluctuations in FV lasting seconds were accompanied G protein-coupled receptor kinase by fluctuations in blood pressure. However, the changes in peripheral blood pressure and pulse were not always accompanied by corresponding changes in FV. Fluctuations in FV also occurred following sleep events such as K-complexes and arousal. Immediately after the sleep event there was a moderate increase followed by a pronounced decrease in MFV. During REM sleep, increases in velocity that appeared during phases of rapid eye movements (phasic REM) often persisted for several minutes. Fig. 5, showing a typical recording of about 6 min duration during sleep stage II, illustrates FV fluctuations that correlated with cardiovascular and respiratory parameters. K-complexes and arousal initiated the observed alterations in FV, MFV, blood pressure and CO2. Blood pressure increased in the subsequent cardiac cycles, reaching a maximum after about 5 s, then returned to normal during the next 5–15 s. Increases in MFV did not always occur despite rising blood pressure in stage II but were usually found with greater rises of blood pressure in REM sleep.

These factors mean that different antigens would be protective ag

These factors mean that different antigens would be protective against different stages of infection. A good example of this is malaria, where the Plasmodium parasite undergoes several stages of development, each of which is antigenically distinct from other stages, and which occur in different anatomical locations. This makes it difficult to target all of the critical phases of the infective process using the whole pathogen from any single stage of selleck compound development. This is one of the key challenges to producing an effective malaria vaccine. (It is not the only

challenge as the immunodominant antigenic site is also subject to ‘segment’ mutation as different protein ‘cassettes’ are inserted at this site.) Some pathogens exist in a latent state within the host, often for the life of the host, or may be protected or hidden from the immune system and are, therefore, not available to the vaccine-induced immune response. Latency is a feature of bacteria, such as Mycobacterium tuberculosis (the causative agent of tuberculosis), and herpesviruses, such as cytomegalovirus (CMV), varicella zoster and herpes simplex viruses. In addition, some pathogens produce virulence factors that actively suppress or subvert

SB203580 mw host immunity, for example CMV produces proteins that can subvert or evade killing of infected cells by natural killer cells. In this case, vaccine formulation should consider alternative options to a whole-pathogen approach, to try to improve on nature. Research in antigen development has been driven by the reduced immunogenicity sometimes observed with highly attenuated or killed pathogen antigens. The procedure for attenuation or inactivation of the pathogen may remove vital defensive triggers, but could also remove/alter essential protective immunogenic components (epitopes) present in the intact pathogen, in which case the remaining antigens may not induce immune responses that protect the vaccine recipient against the live pathogen. An example of this is the live attenuated Towne vaccine Miconazole strain of CMV which, although

providing some protection against CMV disease in certain settings, is actually less protective than immunity that is acquired naturally following recovery from CMV infection (natural immunity). This strain may have been over-attenuated by multiple (>125) passages through human cell culture, rendering it suboptimally efficacious as a vaccine. Overall, however, when used in vaccines, whole live, attenuated pathogens are highly immunogenic, since both antigenic structures and defensive triggers, which activate the innate immune system (see Chapter 2 – Vaccine immunology) are present. Some of the relative advantages and disadvantages associated with live, attenuated and killed/inactivated vaccines are summarised in Table 3.1.


Regional Y-27632 chemical structure algorithms, based on data measured in situ in a given area, are needed ( Such measurements were carried out in the expeditions organised by the Russian State Hydrometeorological University (RSHU) in the summers of 2012 and 2013. The field studies were carried out on the yacht CENTAURUS II during 21–28 July 2012 and 20 July–02 August 2013; 15 stations were set up in 2012 and 26 in 2013. The positions of the station are given on

maps showing the spatial distributions of Chl concentration from MODIS-Aqua data on 22 July 2012 and 27 July 2013 derived by a standard MODIS algorithm (Figure 1a,b). According to these maps, Chl values on the most of stations were < 10 and even 20 mg m−3. In fact, the Chl concentration, directly measured in the study area, varied from 1.2 to 23.7 mg m0−3 in 2012 and from 1.6 to 18.6 mg m−3 in 2013. The Secchi depth varied from 1.8 m in the eastern part of the Gulf of Finland near the Neva Bay to 4.0 m in the open part of the Gulf. Station M2 of 26 July 2013 (Figure 1b) was rejected owing to the inconsistency of the measured Chl value with other values on that day; the remaining 40 stations were used for the derivation of the Chl regional algorithm. The spectral radiance reflectance was measured, the surface irradiance at 554 nm for controlling the illumination conditions continuously recorded and photographs of clouds taken at each station. Some of the stations were located directly selleck kinase inhibitor under the

passing MODIS-Aqua and VIIRS satellite scanners. Such measurements provided us with data for evaluating the atmospheric correction errors. This instrument measures the spectral upwelling radiance just beneath the sea surface and the spectral downwelling irradiance just above the sea surface (Artemiev et al. 2000). The spectral range is 390–700 nm, spectral resolution – 2 nm, the scan time – 15 s. The accuracy of measurement of absolute values of the radiance and irradiance is about 5%. Figure 2 shows the spectroradiometer during measurements. The measurements are taken at ever drift stations. The device drifts with the drogue at

a distance of 30–50 m from the ship to avoid the influence of the ship’s hull, and 20–30 scans are run during 15–20 min. The measurement data are processed with a specially developed computer program. The subsurface radiance reflectance p(λ) is calculated from equation(1) ρ(λ)=πLu(λ)/Ed(λ),ρ(λ)=πLu(λ)/Ed(λ),where Lu(λ)and Ed(λ), are the upwelling radiance and downwelling irradiance just beneath the sea surface. The calculated values of ρ(λ) were used to develop bio-optical algorithms and also to validate of the atmospheric correction algorithms if the measurements were performed simultaneously with satellite observations. Chlorophyll concentration was measured by a spectrophotometric method with 90% aqueous acetone solution. For calculating the chlorophyll aconcentration, data for the wavelengths of 630, 645, 663 and 750 nm were used ( Report 1966).

“Celiac disease (CD) affects approximately 1% of the popul

“Celiac disease (CD) affects approximately 1% of the population in North America and Western Europe,1, 2 and 3 of whom 0.2% are clinically diagnosed, with women constituting approximately 60%–70% of the clinically diagnosed population.4 The literature reports

several mechanisms through which CD potentially could affect a woman’s fertility such as the presence of abnormal villous structure in the intestine and malabsorption of the nutrients leading to nutritional deficiencies (eg, in zinc, iron, folate, and selenium).5 These nutritional deficiencies are said to selleck affect fertility, however, there is no conclusive evidence on the extent to which this may cause fertility problems in CD.6 A lower Pembrolizumab ic50 level of ghrelin and leptin in women with CD also has been reported to play a role in fertility problems.7 In addition,

a shortened reproductive period with delayed menarche and early menopause also has been cited as an explanation for the reported increase in fertility problems related to CD.8 On the contrary, a study based on 99 women being evaluated for infertility in Sardinia found no delay in the age of menarche in women with diagnosed CD (mean age at menarche, 11.8 y).9 Based on these explanations, several small studies over the years have assessed the link between CD and fertility problems, with some reporting a higher

prevalence of CD in women seeking fertility treatments10 and 11 and some showing no increase compared with the general population.9, 12 and 13 Some of these studies found that although the prevalence of CD was not higher in women with infertility, when restricted to only women with unexplained infertility, the prevalence of CD was significantly higher than in the general population,9, 10 and 14 whereas others did not find any significant association even with unexplained infertility.12 and 13 These studies all were conducted on a very small number of women (the largest study included 535 women) primarily attending infertility specialist services, which represents a very selective group of women in the general ADAM7 population. In addition, these studies did not distinguish the burden of fertility problems in women with diagnosed from undiagnosed CD. Despite these inconsistent findings from small studies, a wide variety of reviews highlight infertility as one of the key nongastrointestinal manifestations in CD.15, 16 and 17 We therefore performed a large population-based study to compare the rates of new clinically recorded fertility problems in a group of women with and without celiac disease that are representative of the UK population.

Hypertension is the most common cause of vessel injury Hypertens

Hypertension is the most common cause of vessel injury. Hypertension or high blood pressure is a major risk factor in stroke. It has a stepping gradient in inducing vessel damage that lead to the vessels becoming stiff. In the process of hypertension-induced atherosclerosis,

blood vessels become smaller in size, rigid and lose compliance. Elevated blood pressure increases blood flow through the vessels. CP 868596 This induces shear stress elevation that leads to an increase in endothelial-derived relaxing factor (EDRF) production from endothelial cells. This includes nitric oxide, prostaglandin E and prostacyclin. These vasomotor activators induce the superoxide production and reduce the vessels permeability. The endothelial cells in the process of injury will release increased amounts of pro-inflammatory cytokines that will activate the leukocyte. This further induces

the elevation of vaso-active substances such as prostacycline and nitric oxide which eventually induce complete endothelial injury. The increase in intravascular pressure induces stress on the vessel wall in hypertension. This alters the vessel wall thickness through a process called vascular remodeling. Vascular remodeling as a response to high blood pressure leads to the reduction of the diameter of the blood vessel through hypertrophy (hypertrophic outer remodeling or hypertrophic inner remodeling) or through a eutrophic inner remodeling process. Change PD0325901 manufacturer in the common-carotid-artery intima–media thickness is believed to be an indicator of generalized atherosclerosis. It has also been adopted as an intermediate end point for determining cardiovascular morbidity and also as a surrogate end point to evaluate the success of lipid

lowering drug interventions [4] and [5]. High-resolution carotid ultrasonography has been used to obtain measurements of the thickness of the tunica intima and media of the carotid arteries. Studies in the western countries have shown not only cross-sectional correlations but also prospective correlations between common-carotid-artery intima–media thickness and the prevalence of cardiovascular and cerebrovascular disease science [1], [2] and [3]. There are still few studies showing an association between increased carotid-artery intima–media thickness and stroke in Asia, especially in Indonesia. In this study, we investigated the hypothesis that carotid-artery intima–media thickness is directly correlated with the incidence of stroke. The study subjects were patients in the Cipto Mangunkusumo National Hospital, Jakarta, Indonesia with age ranging from 31 to 75 years old. The patients were categorized into 2 groups, stroke and non stroke groups. There were 131 patients in the stroke group and 128 patients in the non-stroke group. The carotid arteries of all patients were evaluated using high-resolution B-mode ultrasonography using a cross-sectional methodology.

As the acquisition starts immediately, a

center out, non-

As the acquisition starts immediately, a

center out, non-Cartesian, sampling of k-space is required as there is no time for a phase encode gradient or de-phasing read check details gradient [24]. Typically k-space is sampled radially however, spiral sampling has also been used for samples with a somewhat longer signal lifetime [6]. A center out sampling pattern is desirable as it minimizes the echo time and ensures maximum signal sampled at the center of k-space. A drawback of non-Cartesian sampling is that it prevents the use of the fast Fourier transform (FFT), and therefore image reconstruction becomes prohibitively time consuming for many images. To overcome this limitation, “re-gridding” techniques have been developed to interpolate the measured signal onto a regular Cartesian grid which can then be transformed using the FFT [27]. It is important to choose the convolution function for this interpolation process accurately. Theoretically, a sinc function of infinite extent should be used, however, this is not practical. Common alternative convolution functions include truncated sinc interpolation, Kaiser–Bessel interpolation

and min–max interpolation [28] and [29]. Such re-gridding techniques permit image reconstruction in almost the same time as with Cartesian sampling. Linsitinib supplier Non-Cartesian sampling, especially radial sampling, acquires data non-uniformly throughout k-space. In the case of radial sampling, many more points are acquired at the center of k-space (i.e. in the low spatial frequency region). If all data points are weighted equally, the Fourier transform would be biased to these low frequency data resulting in a low spatial resolution, or heavily blurred, image. Density compensation is used to overcome this limitation [30]. Density compensation considers the sampling density throughout k-space

and uses a weighting function to correct for this. For radial sampling the weighting function will increase the contribution of the points around the edge of k-space prior to re-gridding and Fourier transformation. Re-gridding with density compensation alone can produce blurring and artifacts in the reconstructed image, especially if the number of lines in the radial sampling pattern is small. An alternative approach is to iteratively reconstruct the image based on the a priori assumption that the unknown spin proton density image is sparse with respect to a specific representation. This assumption results in nonlinear optimization methods such as CS [3], [16], [17], [18] and [19]. All experiments were performed using a Bruker, AV400 spectrometer, operating at a 1H resonance frequency of 400.23 MHz. A three-axis, shielded gradient system with a maximum strength of 146 G cm−1 was used for gradient encoding, and a 25 mm diameter birdcage r.f. coil was used for excitation and signal detection.