Relationship between trinitrophenol and H-2 antigens on trinitrophenyl-modified spleen cells. III. Quantitative aspects of trinitrophenol binding on cells treated with trinitrobenzene sulfonic acid

Splenic lymphoblasts or normal spleen cells were treated with varying concentrations of TNBS in order to assess whether cell membrane H-2 molecules were derivatized with TNP. Cells treated with high concentrations of TNBS had their cell membrane H-2 molecules derivatized and functioned antigenically as inhibitors in a cold target TNP-CML competition assay. In contrast, cells derivatized with lower concentrations of TNBS had a significant proportion of their membrane proteins derivatized with TNP but did not have their H-2 molecules derivatized. These latter cells were unable to block anti-TNP cytotoxic effector cells in the competition assay. When cells were treated with 3H-TNBS, it was observed that TNP couples to cell membrane H-2, Ia and Ig molecules, and an estimate of the number of TNP molecules bound per cell at varying concentrations of TNBS was determined. The data obtained are consistent with there being a requirement for TNP to directly derivatize H-2 molecules on the cell membrane in order to create antigenic determinants that can be recognized by cytotoxic anti-TNP effector cells. As an alternative, there may be a requirement for the presence of a high density of TNP molecules per cell rather than direct H-2 derivatization by TNP in order to account for activity.     

Studies on rat liver catalase. X. Effect of hemin and an inhibitor on the translation of catalase messenger RNA1.

Rat liver catalase mRNA was translated in a rabbit reticulocyte lysates and wheat germ cell-free system in the presence or absence of hemin and/or a translational inhibitor prepared from reticulocytes, liver cells, and wheat germs. Failure to add hemin to the lysates, or the addition of a hemin-regulated translational inhibitor (HRI) to the hemin-supplemented lysates caused a repressed translation. A preparation of inhibitor from rat liver showed activity similar to that of HRI for this translating system. The translation repression by rat liver inhibitor was reversed by eIF-2 (initiation factor) or GTP, but ATP enhanced the repression. The translation of catalase mRNA in the wheat germ system was not affected by the addition of hemin. An inhibitor prepared from wheat germ extracts, as well as the rat liver inhibitor, markedly decreased the rate of translation. eIF-2, GTP, and ATP behaved in the manner described above. Catalase synthesis in a cell-free system derived from rat liver (using endogenous mRNA) was not influenced by either hemin or the inhibitor. The possibilities are discussed that the synthesis of catalase in liver cells is controlled by a translational inhibitor at the level of chain initiation, and that the formation of the inhibitor from its inactive proinhibitor is regulated by the amount of heme.     

Effect of treatment with hemin on rat liver catalase.

Rats were injected with a single or repeated doses of hemin intraperitoneally, and the effect on liver catalase [EC 1.11.1.6] was studied. A single administration of hemin caused a reduction in the concentration of liver catalase, both in enzymatic activity and in catalase protein determined immunochemically. The reduction occurred a few hours after the hemin injection, and is probably due to stimulated degradation. Disappearance of radioactivity from liver catalase prelabelled with [14C]leucine was enhanced following the administration of hemin. No evidence for a repression in vivo incorporation of [14C]leucine and [3H]sigma-aminolevulinic acid into liver catalase was obtained with hemin-treated rats. When the hemin was given repeatedly at 12-h intervals, the level of liver catalase decreased considerably. However, the impairment in catalase-synthesizing activity of liver cells of rats thus treated was rather slight, when examined in a cell-free system. Some differences were noted between the results in the present study and those in previous investigations with Sedormid-treated rats.     

Synthesis and properties on some 2-, 4- and 5-aminopyrimidines. Effect of -NH2 and ortho-C methylation on protolytic equilibria and electronic absorption spectra.

A number of new 2-, 4- and 5-aminopyrimidines with sterical hindrance to the amino group rotation were synthesized. The pKa values and u.v. absorption spectra of the aminopyrimidines were measured in order to elucidate the conformation of the amino group depending on the place of substitution.     

Effect of C111T polymorphism in exon 9 of the catalase gene on blood catalase activity in different types of diabetes mellitus

Hydrogen peroxide plays a major role in the pathomechanism of diabetes mellitus and its main regulator is enzyme catalase.

The blood catalase and the C111T polymorphism in exon 9 was examined in type 1, type 2 and gestational diabetes mellitus.

Compared to the control group (104.7 ± 18.5 MU/l) significantly decreased (p < 0.001) blood catalase activities were detected in type 2 (71.2 ± 14.6 MU/l), gestational (68.5 ± 12.2 MU/l) diabetes mellitus and without change in type 1 (102.5 ± 26.9 MU/l). The blood catalase decreased (p = 0.043) with age for type 2 diabetics and did not change (p>0.063) for type 1, gestational diabetic patients and controls. Blood catalase showed a weak association with hemoglobin A1c for type 1 diabetic patients (r = 0.181, increasing).

The mutant T allele was increased in type 1 and gestational diabetes mellitus, and CT+TT genotypes showed decreased blood catalase activity for type 1 and increased activities for type 2 diabetic patients.

The C111T polymorphism may implicate a very weak effect on blood catalase activity in different types of diabetes mellitus.     

Effect of the in vivo catalase inhibition on aminonucleoside nephrosis.

Reactive oxygen species have been involved in the pathophysiology of puromycin aminonucleoside (PAN)-nephrosis. The role of H2O2 in these rats may be studied modulating the amount or activity of catalase, which breakdowns H2O2 to water and oxygen. To explore the role of H2O2 in this experimental model, we studied the effect of the in vivo catalase inhibiton with 3-amino-1,2,4-triazole (ATZ) on the course of PAN-nephrosis. Four groups of rats were studied: control rats (CT group), PAN-injected rats (PAN group), ATZ-injected rats (ATZ group), and ATZ- and PAN-injected rats (ATZPAN group). Rats were placed in metabolic cages to collect 24 h urine along the study, ATZ (1 g/kg) was given 24 h before PAN injection (75 mg/kg), and the proteinuria was measured on days 0, 2, 4, 6, 8, and 10. Proteinuria started before (day 4) and was significantly higher on days 6, 8, and 10 in the ATZPAN group than in the PAN group. On day 10, hypercholesterolemia was significantly higher in the ATZPAN group than in the PAN group. These data indicate that the in vivo catalase inhibition magnifies PAN-nephrosis, suggesting that H2O2 is produced in vivo and involved in the renal damage in this experimental disease.     

Effect of C111T polymorphism in exon 9 of the catalase gene on blood catalase activity in different types of diabetes mellitus

Hydrogen peroxide plays a major role in the pathomechanism of diabetes mellitus and its main regulator is enzyme catalase. The blood catalase and the C111T polymorphism in exon 9 was examined in type 1, type 2 and gestational diabetes mellitus. Compared to the control group (104.7 +/- 18.5 MU/l) significantly decreased (p < 0.001) blood catalase activities were detected in type 2 (71.2 +/- 14.6 MU/l), gestational (68.5 +/- 12.2 MU/l) diabetes mellitus and without change in type 1 (102.5 +/- 26.9 MU/l). The blood catalase decreased (p = 0.043) with age for type 2 diabetics and did not change (p>0.063) for type 1, gestational diabetic patients and controls. Blood catalase showed a weak association with hemoglobin A1c for type 1 diabetic patients (r = 0.181, increasing). The mutant T allele was increased in type 1 and gestational diabetes mellitus, and CT+TT genotypes showed decreased blood catalase activity for type 1 and increased activities for type 2 diabetic patients. The C111T polymorphism may implicate a very weak effect on blood catalase activity in different types of diabetes mellitus.     

Effect of corticoliberin fragment CRF4-6 on blood glucose level and body temperature of rats

The effects of tripeptide corticoliberin fragment CRF4-6 (Pro-Pro-Ile) on blood glucose level and the rat body temperatire were investigated. Intracerebroventricularly injected CRF4-6 (6, 30, 150 nmol/head) causes a dosedependent hyperglycemia and hyperthermia in anaesthetized animals. Corticotropin releasing factor antagonist alpha-helical CRF4-6 (6.5 nmol/head) abolishes the influence of tripeptide CRF4-6 (6 nmol/head) on blood glucose level and body temperature of rats. Bilateral adrenalectomy has no effect on tripeptide-induced hyperglycemia and hyperthemia. This result indicates that hyperglycemic and hyperthermal effects of tripeptide occur independently of adrenal gland catecholamines. In addition, non-pituitary corticoliberin receptors are involved in CRF4-6 influences on blood glucose level and body temperature.