Acta biochimica et biophysica Hungarica最新文献

In recombinant mouse strains the elements of the major histocompatibility complex gene cluster are composed of those of the parental strains. The origin of elements except the S region was previously determined by immunological and biochemical typing methods. For determination of the origin of the S region and the possible location of the recombination event around the S region, Southern blot analysis was performed. By the detection of genetic polymorphic patterns of complement C4 gene in 2 of the 5 recombinant strains the recombination was localized down-stream of the C4 gene and before the D gene region.

Plasminogen activator activity and plasmin-like amidolytic activity were investigated in two experimental rat tumours, using human plasminogen and chromogenic peptide substrate, S-2251. The invasive hepatocarcinoma and non-invasive nephroma were induced with the same chemical carcinogen, dimethylnitrosamine, in F-344 rats and they were continuously transplanted under the renal capsule. While there was no difference in plasmin-like activities of the tumours, the plasminogen activator activity was very low in the nephroma, but high in the hepatocarcinoma. Since the activator activity was completely inhibited by amiloride, it was considered to be of urokinase-type. These results were in accordance with the assumed role of urokinase in the invasion. However, of the respective control organ, kidney was rich in both activities but rat liver contained only very low activities. Therefore the comparison of the plasminogen activator activity of a tumour to the control organ probably does not provide information concerning the malignant transformation as it is suggested in the literature.

As an extension of our studies on simple and macromolecules, the optical polarizabilities of some biomolecules (Glycine, L-alanine and folic acid) have been studied using new dispersion relation. Diamagnetic susceptibilities and electron ionization cross sections for these biomolecules have also been evaluated. The relative merits, feasibility and the limitations of the dispersion relation in relation to other reported methods are discussed critically. The use of the studies in this direction are also cited briefly.

The effect of ethanol on the fractionation of gliadin by cellulose-based ion exchange column chromatography was studied. Ten peaks have been separated on DEAE- and 12 peaks on CM-cellulose column using a complex elution technique. By SDS-polyacrylamide gel electrophoresis of the separated fractions, it was observed that ethanol incorporated into the eluent improved the resolution of some fractions. Some of the peaks gave only 2 or 3 protein bands in electrophoregrams. Since ethanol does not affect the reproducibility in the two types of chromatographic medium, the method seems to be suitable for purification of gliadin fractions in large quantities.

Murine peritoneal macrophages were treated in vitro with L-leucine methyl ester (0.25-5.0 mM). This treatment resulted in an inhibition of the amino acid incorporation into the cells both at 4 degrees C and 37 degrees C during a relatively short incubation period. The adherence of macrophages was not changed by the treatment. Bacterial phagocytosis was partly influenced: Leu-OMe did not change the binding but the engulfment of opsonized bacteria was blocked. Damage of the plasma membrane caused by Leu-OMe was not so serious as that produced by specific anti-PEC antiserum. Leu-OMe is a lysosomotropic agent accumulated preferentially by lysosomes. The vacuolization of the cells and the dilatation of the vacuoles are evidences for the intracellular damage. In the early phase this damage is characterized only by the leakage of the cytoplasm, later the damage of the plasma membrane can also be demonstrated.

Magnetic Resonance Imaging (MRI) is a powerful new diagnostic tool in medicine. In MRI there is a great need to improve the specific identification of different tissues i.e. to enhance the contrast between them. This review tries to cover most of the approaches known for solving this problem.

A new family of tricyclic compounds, the dibenzodioxazocines were synthesized. These compounds were the following: 2-chloro-12-(2-piperidino-ethyl)-dibenzo d,g 1,3,6 dioxazocine hydrochloride: EGYT-2347, 2-chloro-12-(3-dimethylamino-2-methyl-propyl)-dibenzo [d,g] [1,3,6]-dibenzodioxazocine hydrochloride: EGYT-2509, 2-chloro-12-(3-dimethylamino-propyl)-dibenzo [d,g] [1,3,6] dioxazocine-maleate: EGYT-2474 and 2-chloro-12-2-(4-methyl-piperazino)-ethyl-dibenzo [d,g] [1,3,6]-dioxazocine-dihydrochloride: EGYT-2541. These compounds are inhibitors of both butyryl- and acetylcholinesterase to and they exhibited relatively good anticholinergic properties in receptor binding experiments. The most selective inhibitor of butyrylcholinesterase is the compound EGYT-2347 (Ki = 1.5 x 10(-7) M) which strongly binds to rat brain muscarinic cholinergic receptor (KD = 4.1 x 10(-8) M).

Monovalent cations such as Na+, K+ and Li+ at 100 mM concentration inhibit the binding of mu and delta opioid agonists (e.g. (3H) dihydromorphine and (3H) D-Ala2-Leu5-enkephalin), enhance opioid antagonist [(3H) naloxone] binding in rat brain membranes. Divalent cations have an opposite effect: Mg2+ or Mn2+ (2mM) increase both mu and delta agonist binding, and decrease the antagonist binding. The effect of guanosine 5'-triphosphate and its non-hydrolysable analogue 5'-guanylyl-imidodiphosphate at micromolar concentrations is similar to that of sodium ion. In kinetic experiments, guanine nucleotides promote the dissociation of radiolabelled agonists from their binding sites by increasing the rate of dissociation. Equilibrium saturation binding studies show that only binding of the opioid agonist ligands are significantly inhibited by 5'-guanylyl-imidodiphosphate.

Plasma membrane vesicles were purified from roots of winter wheat seedlings (Triticum aestivum L. cv. Marton-vásári-8) by aqueous polymer two-phase partitioning. The ATPase activity of vesicles in the presence of Ca was independent of but in the presence of Mg depended on the EDTA concentration in the ATPase assay. The potassium stimulation and vanadate inhibition of the MgATPase also depended on the EDTA concentration. Consequences of these results are briefly discussed.