Alpha-crystallin, a molecular chaperone, forms a stable complex with carbonic anhydrase upon heat denaturation

Alpha-crystallin, a major eye lens protein of vertebrates has been characterized as a molecular chaperone based on its ability to inhibit the aggregation of proteins undergoing thermal denaturation (Horwitz, J., Proc. Natl. Acad. Sci. USA 1992, 89, 10449-10453). To understand the mechanisms underlying this chaperone-like activity, the present study addressed molecular interactions between alpha-crystallin and its target proteins. Using carbonic anhydrase as a model target protein, we demonstrate complex formation between the 2 proteins upon heating, as assessed by the criteria of agarose gel electrophoresis, immunoprecipitation, ultrafiltration and gel filtration chromatography. The complex of alpha-crystallin and carbonic anhydrase is stable, at room temperature and at 4 degrees C, for over 18 hours, and is non-covalent in nature. The results also indicate that alpha-crystallin binds the early non-native form of the target protein.     

31P magnetic resonance spectroscopy as predictor of clinical response in human extremity sarcomas treated by single dose TNF-alpha + melphalan isolated limb perfusion

Irresectable extremity sarcomas are large (grade II/III) tumors requiring amputation of the limb for local control. Limb salvage can be achieved by isolated limb perfusion (ILP) with tumor necrosis factor alpha (TNF-alpha), interferon-gamma and melphalan. To obtain insight into the effects of single dose ILP on extremity tumors, phosphate metabolism was monitored by 31P magnetic resonance spectroscopy (MRS) using the chemical shift imaging (CSI) technique. 2D CSI was used in combination with a slice select gradient in the third dimension to obtain true 3D localization. Spectral maps obtained prior to ILP revealed reductions in phosphocreatine (PCr) level and increases in phosphomonoester (PME) and phosphodiester (PDE) in tumor compared with muscle tissue. ILP treated tumors showed highly divergent changes in Pi while PME decreased in all cases (n = 11). Tumor volume, unchanged on day 8 after ILP, was decreased by 58 +/- 29% (mean +/- SD) at 2 months. Linear regression analysis revealed correlation between the changes in tumor metabolites measured on day 8, with percent volume decrease (Pi: r = -0.88, p < 0.001) and percent necrosis at resection (PME: r = -0.79, p -0.01). Correlation between pretreatment spectra and effectiveness of ILP treatment was not found. It is concluded that a single ILP with TNF-alpha + melphalan induced changes in tumor metabolite levels (measured on day 8) that reflect treatment efficacy. 31P MRS can thus provide information facilitating the decision as to when to remove tumor (residue) and, in the case where tumor remains inoperable, whether or not to apply additional therapy.     

Need-informational interaction of brain structures

The data presented deal with the role of four main brain structures in the development of emotional states and the organization of purposeful behavior. According to these data, the frontal neocortex orients behavior towards signals of highly probable events (reinforcement), whereas the hypothalamus is the basis for satisfaction of the dominant need. Unlike the neocortex, the hippocampus react to events of low probability, which is typical of emotionally stressed brain activity. Unlike the hypothalamus, the amygdala creates the balance, the dynamic coexistence, of competing needs (motivations) and emotions generated by such needs, which makes behavior more adequate. Individual characteristics of the interaction among the four brain structures is the basis for the individual types of higher nervous activity.     

Atherogenesis and the acute-phase reaction of the liver

Data from literature are given on the role of "acute phase" proteins in inflammation and their connection with lipoproteins. Intensive production of acute phase proteins is shown to take place in modelling of experimental atherosclerosis. The hypothesis is proposed that allows to consider the acute phase reaction of the liver as a very important condition of modified lipoproteins formation acquiring autoantigenic properties.     

Glutathione-dependent factors and inhibition of rat liver microsomal lipid peroxidation

The effects of reduced glutathione (GSH) and glutathione disulfide (GSSG) on lipid peroxidation were investigated in rat liver microsomes containing deficient or adequate amounts of alpha-tocopherol (alpha-TH). Rates of formation of thiobarbituric acid reactive substances (TBARS) as well as rates of consumption of alpha-TH and O2 were decreased by GSH and were more pronounced in the NADPH-dependent assay system than in the ascorbate-dependent system. The GSH-dependent inhibition of lipid peroxidation was potentiated by GSSG in the NADPH-dependent assay system, but it had no effect in the nonenzymatic system. Diphenyliodonium chloride, an inhibitor of NADPH cytochrome P-450 reductase, completely prevented lipid peroxidation in the NADPH-dependent assay system whereas it had no effect on the ascorbate-dependent system. This is further evidenced by the fact that purified rat liver microsomal NADPH cytochrome P-450 reductase (EC 1.6.2.4) was inhibited approximately 24% and 52% by 5 mM GSH and 5 mM GSH + 2.5 mM GSSG, respectively. Glutathione disulfide alone had no effect on reductase activity. Similarly, other disulfides such as cystine, cystamine and lipoic acid were without effect on reductase activity. These results clearly delineate different mechanisms underlying the combined effects of GSH and GSSG on microsomal lipid peroxidation in rat liver. One mechanism involves recycling of microsomal alpha-TH by GSH during oxidative stress via a labile protein, ostensibly associated with "free radical reductase" activity. A second glutathione-dependent mechanism appears to be mediated through the inhibition of NADPH cytochrome P-450 reductase. The enhanced inhibition by GSH + GSSG of microsomal lipid peroxidation in the NADPH-dependent assay system suggests suppression of the initiation phase at the level of NADPH cytochrome P-450 reductase which is independent of microsomal alpha-TH.     

UbCadet: detection of compromised accounts in twitter based on user behavioural profiling

Multimedia Tools and Applications - Online Social Networks(OSNs) are generally at the risk of many potential dangers. Malicious attackers use compromised OSN accounts to spread fake news, to send...     

Mutational analysis of candidate genes in psychiatric disorders

A genetic hypothesis for a disease presupposes the existence of variation in the DNA sequences of affected individuals. A series of techniques known together as "mutational analysis" can be applied towards identifying new sequence variations in selected genes. These techniques can screen a large series of individuals for mutations efficiently, so it is not necessary to determine the nucleotide sequence in every DNA sample. DNA samples suspected of harboring sequence variants are then sequenced. Denaturing gradient gel electrophoresis techniques, single stranded conformation polymorphism paradigms, and chemical cleavage of mismatches are 3 procedures widely used for the molecular screening of mutations today. We discuss each of these techniques for mutation screening.     

Ligands of the histamine H3-receptor: new potent antagonists of the 2-thioimidazole type

INTRODUCTION AND OBJECTIVES: The temporal stability of the positive and negative symptoms in schizophrenia deserves a special interest due to its consequences in the outcome and the treatment of the disease. This study determines the temporal stability of positive/negative subtypes in schizophrenia during the acute phase. MATERIAL AND METHODS: This is a clinical, observational and prospective study of a dynamic cohort of patients with acute exacerbation of schizophrenia defined by DSM III-R criteria. Patients with severe and unstable organic pathology, substance dependence, mental organic disorder, mental retardation, depression, or medicamentous parkinsonism were excluded. Clinical assessment was performed with the PANSS scale. Schizophrenic subtypes were established according to inclusive and restrictive criteria of PANSS. All patients were treated with new antipsycotics and biperiden if necessary. RESULTS: 51 patients were assessed for 8 weeks. In the baseline, the negative subtype (63.3% and 52.5% by inclusive and restrictive system respectively) and paranoid form (45.1%) were predominant. Three types of analysis were performed to determine the temporal stability: 1. Concordance (Kappa index). The concordance of the inclusive and restrictive System, regarding to the baseline assessment, indicated that both criteria had a low temporal stability. 2. Mc Nemar Ji Square. This test showed that these changes were bi-directional except for the first visit, which was significant through the restrictive system (higher change from the negative to other subtypes). 3. Transition analysis among groups by First Order Morkov Chains analysis indicated that this change was stationary (the change was the same in all phases). CONCLUSIONS: 1o The variable "time" has to be considered for the definition of subtypes in schizophrenia. 2o The restrictive system is more specific. It allows to identify a subgroup of patients with "Negative" schizophrenia with a high specificity and validity in clinical and epidemiological studies. 3o The use of the baseline visit as a reference (gold standard) is recommended because it exits a higher concordance among criteria and a more florid psychopathology.     

Cytotoxic potential of the preparations from Solanum trilobatum and the effect of sobatum on tumour reduction in mice

Madin Darby canine kidney cells transformed by alkaline stress (MDCK-F cells) constitutively migrate at a rate of about 1 microm.min-1. Migration depends on the intermittent activity of a Ca2+-stimulated, 53-pS K+ channel (KCa channel) that is inhibitable by charybdotoxin. In the present study we examined whether this intermittent KCa channel activity results in a significant K+ loss across the plasma membrane. K+ efflux from MDCK-F cells should result in a transient increase of extracellular K+ ([K+]e) in the close vicinity of a migrating cell. However, due to the rapid diffusion of K+ ions into the virtually infinite extracellular space, such a transient increase in [K+]e was too small to be detected by conventional K+-selective electrodes. Therefore, we developed a "shielded ion-sensitive microelectrode" (SIM) that limited diffusion to a small compartment, formed by a shielding pipette which surrounded the tip of the K+-sensitive microelectrode. The SIM improved the signal to noise ratio by a factor of at least three, thus transient increases of [K+]e in the vicinity of MDCK-F cells became detectable. They occurred at a rate of 1.3 min-1. The cell releases 40 fmol K+ during each burst of intermittent KCa channel activity, which corresponds to about 15% of the total cellular K+ content. Since transmembrane K+ loss must be accompanied by anion loss and therefore leads to a decrease of cell volume, these findings support the hypothesis that intermittent volume changes are a prerequisite for the migration of MDCK-F cells.