Preparation of the myristoylated and nonmyristoylated form of recombinant recoverin in E. coli cells and comparison of their functional activity]

Numerous data strongly suggest the involvement of cytokines and the matrix metalloproteinase collagenase (MMP-1) in the pathogenesis of periodontitis. Recently, we have demonstrated that, upon culturing under the influence of IL-1 alpha + EGF, a large amount of inactive procollagenase (MMP-1) is stored in the extracellular matrix of periosteal tissue. We now show that this endogenous reservoir of proenzyme can be operative after activation with plasmin and is able to induce a rapid and almost complete breakdown of the collagenous extracellular matrix. The level of collagen degradation following activation showed a strong correlation with the amount of proenzyme that was incorporated in the tissue. The highest level of degradation (70% of the total amount of collagenous proteins) was found with the IL-1 alpha + EGF-treated explants, followed by those treated with IL-1 alpha alone (35%). Explants cultured with EGF or in the absence of cytokines, containing only small amounts of procollagenase, showed little collagen breakdown following plasmin activation (7%). Inhibition of metalloproteinases by EDTA, or blockage of plasmin by PMSF, prevented the degradation in all explants irrespective of the amount of proenzyme present in the tissue. Our findings demonstrate that endogenous proenzyme stored in a native connective tissue matrix can be activated at a later time interval which results in a massive breakdown of the tissue. This study shows a possible pathway of collagenase-induced breakdown without recent de novo synthesis of the enzyme. Such a sequence may be operative in chronic inflammatory diseases, such as periodontitis, where production of procollagenase under the influence of cytokines spans a longer time period, whereas breakdown is often characterized by a cyclic behaviour.     

The forensic medical assessment of the mechanisms of trauma to the large joints of the upper extremity

Glycogen synthesis and degradation were studied in cultured rat hepatocytes prelabeled by incubation with [14C]glucose or [14C]galactose. During prelabeling about 75% of the accumulated glycogen was synthesized from glucose and about 25% from gluconeogenic precursors. Following the labeling period, glycogen synthesis and degradation were estimated at 5 and 12.5 mM glucose and varying concentrations of insulin and glucagon. At 12.5 mM glucose and 10 nM insulin the accumulation of glycogen was comparable to in vivo values, whereas the level of radioactivity in prelabeled glycogen remained constant. Further addition of 0.1 nM glucagon resulted in constant values of both content and radioactivity of glycogen. Increasing the concentration of glucagon to 10 nM resulted in a parallel decrease of content and radioactivity in glycogen. At 5 mM glucose, 10 nM insulin, and 0.1 nM glucagon both the content and the radioactivity of glycogen were constant, whereas addition of 10 nM glucagon resulted in a parallel decrease of content and radioactivity of glycogen, which was 64% higher than that observed with 12.5 mM glucose. In the absence of insulin, prostaglandin D2 had effects similar to those of 10 nM glucagon, whereas no effects was observed in the presence of insulin. From these results and from calculated rates of glucose 6-phosphate formation, it is concluded that the rate of glycogen degradation is less than 10% of the rate of synthesis under conditions favoring glycogen accumulation. At conditions favoring glycogen degradation (10 nM insulin plus 10 nM glucagon or prostaglandin in the absence of insulin) no synthesis could be detected. Results from cells prelabeled with [14C]galactose suggested that glycogen degradation is not an absolutely ordered process, but that some random degradation takes place.     

Karyological, biochemical, and physiological aspects of Callophysus macropterus (Siluriformes, Pimelodidae) from the Solim?es and Negro Rivers (central Amazon)

Karyological characteristics, i.e., diploid number, chromosome morphology and nucleolus organizer regions (NORs), biochemical characteristics, i.e., electrophoretic analysis of blood hemoglobin and the tissue enzymes lactate dehydrogenase (LDH), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), and phosphoglucose isomerase (PGI), and physiological characteristics, i.e., relative concentration of hemoglobin and intraerythrocytic concentrations of organic phosphates were analyzed for the species Callophysus macropterus collected from Marchantaria Island (white water system--Solim?es River) and Anavilhanas Archipelago (black water system--Negro River). Karyological and biochemical data did not reveal significant differences between specimens collected at the two sites. However, the relative distribution of hemoglobin bands I and III (I = 16.33 +/- 1.05 and III = 37.20 +/- 1.32 for Marchantaria specimens and I = 6.33 +/- 1.32 and III = 48.05 +/- 1.55 for Anavilhanas specimens) and levels of intraerythrocytic GTP (1.32 +/- 0.16 and 2.76 +/- 0.18 for Marchantaria and Anavilhanas specimens, respectively), but not ATP or total phosphate, were significantly different, indicating a physiological adaptation to the environmental conditions of these habitats. It is suggested that C. macropterus specimens from the two collecting sites belong to a single population, and that they adjusted some physiological characteristics to adapt to local environmental conditions.     

Radiation experiments with hydrogen-containing materials on the URAM-2 cryogenic irradiation facility at the IBR-2 reactor

The URAM-2 irradiation system facility at the IBR-2 reactor is described. The results of experiments performed with this facility to study the behavior of water ice, solid methane, aromatic hydrocarbons, and other materials exposed to fast neutrons and rays are presented. The rate of energy accumulation in these materials under irradiation and the amount of accumulated hydrogen and the temperature at which the hydrogen leaves the material matrices are determined. Recommendations are made for the working temperature of these materials for use in cold neutron moderators.Translated from Atomnaya Énergiya, Vol. 97, No. 3, pp. 183–189, September, 2004.