CTL responses of high functional avidity and broad variant cross-reactivity are associated with HIV control

Cytotoxic T lymphocyte (CTL) responses targeting specific HIV proteins, in particular Gag, have been associated with relative control of viral replication in vivo. However, Gag-specific CTL can also be detected in individuals who do not control the virus and it remains thus unclear how Gag-specific CTL may mediate the beneficial effects in some individuals but not in others. Here, we used a 10mer peptide set spanning HIV Gag-p24 to determine immunogen-specific T-cell responses and to assess functional properties including functional avidity and cross-reactivity in 25 HIV-1 controllers and 25 non-controllers without protective HLA class I alleles. Our data challenge the common belief that Gag-specific T cell responses dominate the virus-specific immunity exclusively in HIV-1 controllers as both groups mounted responses of comparable breadths and magnitudes against the p24 sequence. However, responses in controllers reacted to lower antigen concentrations and recognized more epitope variants than responses in non-controllers. These cross-sectional data, largely independent of particular HLA genetics and generated using direct ex-vivo samples thus identify T cell responses of high functional avidity and with broad variant reactivity as potential functional immune correlates of relative HIV control.     

Phosphorylation of fibrinogen by casein kinase 1

Casein kinase 1 phosphorylated human fibrinogen, in a reaction that did not use GTP as phosphoryl donor and was neither stimulated by cyclic AMP or Ca2+, nor inhibited by the cyclic AMP-dependent protein kinase inhibitor protein. Maximal incorporation averaged 4 mol of phosphate per mol of fibrinogen, most of it in the largest CNBr-fragment of the alpha-chain. Phosphoamino acid analysis revealed that phosphorylation occurred only at seryl residues. The phosphorylation of fibrinogen by casein kinase 1 was reverted by alkaline phosphatase.     

Effect of starvation, diabetes and insulin on the casein kinase 2 from rat liver cytosol.

Starvation, diabetes and insulin did not alter the concentration of casein kinases in rat liver cytosol. However, the Km for casein of casein kinase 2 from diabetic rats was about 2-fold lower than that from control animals. Administration of insulin to control rats did not alter this parameter, but increased the Km for casein of casein kinase 2 in diabetic rats. Starvation did not affect the kinetic constants of casein kinases. The effect of diabetes on casein kinase 2 persisted after partial purification of the enzyme by glycerol-density-gradient centrifugation and affected also its activity on other protein substrates such as phosvitin, high-mobility-group protein 14 and glycogen synthase. The results indicate that rat liver cytosol casein kinase 2 is under physiological control.     

Effect of bivalent cations on rat liver cytosol casein (glycogen synthase) kinases 1 and 2. Influence of the protein substrate.

Rat liver cytosol casein kinases 1 and 2 were stimulated by free Mg2+, but the optimal concentration of cation varied with both the casein kinase and the protein substrate used. Mn2+, but neither Ca2+ nor Zn2+, could efficiently substitute for Mg2+ in forming the bivalent-cation-ATP complex used as substrate, but free Mn2+ was inhibitory. The magnitude of these effects depended on the type of casein kinase and the protein substrate used. These results support the idea that, besides the effects of Mg2+ as a component of the Mg-ATP complex, or through interaction with the protein substrate, free Mg2+ is an allosteric effector of both casein kinases.     

Spatial root distribution of apricot trees in different soil tillage practices

Root and soil water distribution was studied in a mature drip-irrigated apricot (Prunus armeniaca L. cv. Búlida) orchard with different soil tillage practices, in a loamy textured soil with a 7% slope, located in Murcia (SE Spain). Three treatments were applied between tree rows:control (no-tillage), whereby, following the common practice in the area, weeds were cut back to ground level by a blade attached to a tractor; perforated treatment, where the soil surface was mechanically perforated with an adapted-plough; and mini-catchment treatment, consisting of mini-catchments with low banks manually raised perpendicular to the line of emitters. Almost all of the apricot root system was located in the first 0.75 m of soil depth, with 91% in the first 0.50 m. More than 75% of the roots corresponded to thin roots, with a diameter less than 0.2 mm. Both tillage treatments decreased runoff compared with the control treatment, while the mini-catchment treatment showed the highest change in soil water content after rainfall events. The mini-catchment treatment was performed in an attempt to reduce the rainwater running down the slope, leaving the accumulated water near plant roots, an effect which was responsible for the higher root length density (RLD) values found in this treatment. In addition, roots were distributed over a wider area, providing higher RLD values up to 1 m from the emitter, meaning that a higher soil volume was explored. For these reasons, the mini-catchment treatment was seen to be the most beneficial soil tillage treatment for optimising water use in semiarid conditions.     

Effects of clotrimazole on transport mediated by multidrug resistance associated protein 1 (MRP1) in human erythrocytes and tumour cells.

Clotrimazole has been shown to have potent anti-malarial activity in vitro, one possible mechanism being inhibition of oxidized glutathione (GSSG) export from the infected human red blood cells or from the parasite itself. Efflux of GSSG from normal erythrocytes is mediated by a high affinity glutathione S-conjugate transporter. This paper shows that transport of the model substrate, 3 microm dinitrophenyl S-glutathione, across erythrocyte membranes is inhibited by multidrug resistance-associated protein 1 (MRP1)-specific antibody, QCRL-3, strongly suggesting that the high affinity transport is mediated by MRP1. The rates of transport observed with membrane vesicles prepared from erythrocytes or from multidrug resistant tumour cells show a similar pattern of responses to applied reduced glutathione, GSSG and MRP1 inhibitors (indomethacin, MK571) further supporting the conclusion that the high affinity transporter is MRP1. In both erythrocytes and MRP1-expressing tumour cells, MRP1-associated transport is inhibited by clotrimazole over the range 2-20 microm, and the inhibitory effect leads to increases in accumulation of MRP1 substrates, vincristine and calcein, and decreases in calcein efflux from intact MRP1-expressing human tumour cells. It also results in increased sensitivity to daunorubicin of the multidrug resistant cells, L23/R but not the sensitive parent L23/P cells. These results demonstrate that clotrimazole can inhibit the MRP1 which is present in human erythrocytes, an effect that may contribute to, though not fully account for, its anti-malarial action.     

The interaction of hydralazine with a semicarbazide-sensitive amine oxidase in brown adipose tissue of the rat. Its use as a radioactive ligand for the enzyme.

Hydralazine is a potent irreversible inhibitor of the semicarbazide-sensitive amine oxidase (SSAO) found in brown fat. Initially it may act on the enzyme as a competitive inhibitor, but irreversible inhibition occurs rapidly in a concentration- and temperature-dependent manner. The presence of primary amines known to be substrates for the enzyme, but not of secondary amines, which are not metabolized by SSAO, diminishes this rate of inactivation, whereas removal of O2 is without effect. The kinetic pattern of inactivation of SSAO by hydralazine is consistent with an active-site-directed site-saturable binding followed by the development of an irreversible enzyme-inhibitor complex. [3H]Hydralazine, used as an affinity label for SSAO, shows saturable binding to brown-fat membranes. This binding is inhibited by other inhibitors of SSAO. The rate of binding to membrane pellets containing SSAO is not affected by substrates for the enzyme. However, if solubilized partially purified SSAO preparations are used instead, the rate of binding is lowered in the presence of the SSAO substrate benzylamine. 3H-labelled material solubilized from [3H]hydralazine-treated membrane pellets by Triton X-100 at that detergent/protein ratio which releases SSAO from membranes shows the same gel-filtration characteristics as SSAO and appears by lentil lectin-agarose affinity chromatography to contain similar carbohydrate moieties. 3H-labelled material, partially purified by gel filtration and affinity chromatography, produces predominantly a single band of radioactivity on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The position of this band corresponds to an Mr of about 94 000, almost exactly half the Mr already estimated for the functional unit of SSAO. Radiolabelled hydralazine may thus be used as a label for purified SSAO, but it is not specific enough to be suitable as a ligand in vivo.     

Surface fitting of 2D diffusion-edited 1H NMR spectroscopy data for the characterisation of human plasma lipoproteins

Determining the concentration and size of lipoprotein complexes is very important due to their role in cardiovascular diseases and metabolic disorders. However, standard methods for lipoprotein fractionation are manual and time consuming and cannot be used as standard diagnostic tools. Because different subclasses of lipoproteins have different radii and, hence, different diffusion velocities, we propose a fast and reliable method that uses 2D diffusion-edited ¹H NMR spectroscopy to acquire a set of 2D spectra of plasma samples, followed by a surface fitting algorithm based on Lorentzian functions to estimate the sizes and the relative proportions of different lipoprotein subclasses. We were able to demonstrate that the derived sizes and positions related to the Lorentzian functions follow an exponential relationship for normolipidaemic and dislipaemic samples with coefficients of determination (r ²) of 0.85 and 0.81, respectively. Moreover, we found a linear relationship between the width and size of the Lorentzian functions for normolipidaemic samples (r ² = 0.88) while for dislipaemic samples this relation was nonlinear (r ² = 0.62). Dividing our samples set into four different lipoprotein profiles (normal lipid values, low HDL/LDL ratio, high triglycerides values and both risk factors) and using principal component analysis (PCA) followed by multivariate analysis of variance (MANOVA), our method was able to statistically discriminate between those groups, with p-values of 0.0016, 0.0006, <1e⁻⁴ and 0.0035, respectively. These parameters are characteristic and indicative of different lipoprotein profiles and can be used to distinguish between normolipidaemic, hypercholesterolaemic, hypertriglyceridaemic and chylomicronaemic profiles.