Sex differences in the response of rats to drugs affecting GABAergic transmission

The administration of diazepam 1.0 mg/kg decreased the level of plasma corticosterone in female but not in male Wistar rats. Picrotoxin, another drug affecting GABAergic transmission, also brought about an increase of plasma corticosterone in both sexes. However, in order to achieve a plasma corticosterone increase of similar magnitude (more than 500%) a threefold higher dose of picrotoxin had to be given to males. When the convulsive properties of picrotoxin were tested, it became evident that the dose of picrotoxin (2.5 mg/kg) which was subconvulsive in male was almost 100% convulsive in female rats. The existing sex differences in the response of rats to drugs affecting GABAergic transmission might have possible implications in the treatment of GABA system dysfunction.     

Streptomyces rimosus extracellular proteases 3. Isolation and characterization of leucine aminopeptidase

Summary A leucine aminopeptidase was purified to homogeneity fromStreptomyces rimosus culture filtrates, which are waste broth of oxytetracycline bioproduction process. Purification procedure includes ultrafiltration and chromatography on CM-Sephadex, AH-Sepharose and FPLC Mono S column. The enzyme is a monomer with molecular weight of 27,500 Daltons and pI of 7.3, stable in broad pH range and up to 70°C. It is a metallo enzyme dependent on Ca²⁺ ions for its full activity. By its specificity it is a true aminopeptidase active on amino acid amide, arylamide, peptide and ester bonds. The hydrolysing activity shows preference for leucine at the N-terminal position of substrates, also acts on aromatic acids and methionine, but does not release glycine, proline, acidic amino acids orD-amino acid residues.     

Ornithine decarboxylase, transglutaminase, diamine oxidase and total diamines and polyamines in maternal liver and kidney throughout rat pregnancy.

Ornithine decarboxylase (ODC; EC 4.1.1.17), transglutaminase (EC 2.3.2.13), diamine oxidase (DAO; EC 1.4.3.6) and total di- and poly-amines were studied in rat liver and kidney cortex throughout pregnancy. In liver, ODC activity exhibited two major peaks (4.5-5 times the control activities) on days 15 and 17. Also putrescine and spermidine increased biphasically (3-4-fold), but no variation in spermine content was observed. Transglutaminase activity showed slight variations only near the end of gestation. In kidney, ODC activity did not fluctuate significantly during pregnancy, whereas both transglutaminase activity and putrescine content showed three major increases, in very early, middle and late pregnancy. No significant variations in spermidine and spermine were observed. In both organs, DAO activity, very low or undetectable until day 10, dramatically increased (10- and 20-fold in kidney and liver respectively) in the second half of pregnancy, reaching maxima on days 16-17 and 19. The results obtained for transglutaminase, ODC and total di- and poly-amines are interpreted on the basis of hyperplastic and hypertrophic events in the liver and kidney respectively. The behaviour of DAO suggests that the enzyme plays an important role in the control of intracellular diamine concentration.     

Effect of the polysaccharide ofAgrobacterium radiobacter on the growth of plants and occurrence of damping-off in sugar beet

Agrobacterium radiobacter, strain B6 (a strain isolated in this laboratory, which limited the occurrence of damping-off of sugar beet and influenced growth of plants in hot-house and field experiments) was found to produce an acidic exopolysaccharide in a mineral medium with various carbon sources. Hydrolyzates of the polysaccharide contained glucose, galactose, glycerol, succinic acid and pyruvic acid, whose quantitative content varied according to the carbon source used. The polysaccharide isolated from the medium containing glucose exhibited the highest physiological activity. Seeds germinated best and sugar beet roots were found to grow most rapidly in a medium containing 0.2 % (W/W) of the polysaccharide. The roots exposed for 3 d in this medium grew 2.7-fold as compared with non-treated plants. Higher sumbers of microorganisms were detected on the surface of roots treated with the polysaccharide. Growth of roots was also stimulated when immersing the seeds (30 min) in a 0.2 –0.4 % solution of this polysaccharide. After a two-fold treatment the roots were less damaged by the fungusPythium ultimum. Plants from seeds treated with the polysaccharide grew in the field soil more rapidly than the non-treated plants but worse than after bacterization of the seeds byA. radiobacter B6 and were only partially protected against the damping-off of sugar beet.     

Preferential association of kappa IIIb light chains with monoclonal human IgM kappa autoantibodies

The predominance of the relatively uncommon V region subgroup isotype kappa III among the light chains of human monoclonal (IgM kappa) anti-IgG antibodies, (i.e., rheumatoid factors), was further documented through sequence analyses of ten such autoantibodies isolated from IgM-anti-IgG cold-insoluble immune complexes (mixed cryoglobulins). The amino-terminal sequence of all ten kappa-chains was characteristic for kappa III proteins and virtually identical to that of a prototype kappa III light chain. Similar sequence identity was found for kappa-chains isolated from three IgM kappa autoantibodies that formed cold-insoluble immune complexes with low-density lipoprotein (LDL). The thirteen light chains were found to be virtually identical in sequence for the first framework region (FR); ten of these proteins sequenced through the first complementarity-determining region (CDR) and into the second FR were markedly similar. The second CDR of five proteins was almost identical in sequence to that of the prototype kappa III-chain. Concordance was also demonstrated between the structural classification of the light chains as kappa III and their immunochemical classification as members of this V region subgroup. Serologic analyses of light chains isolated from seven IgM kappa autoantibodies (six anti-IgG, one anti-LDL) and of one intact IgM kappa anti-LDL antibody showed that each had antigenic determinants common to kappa II proteins. These light chains also expressed the antigenic determinant(s) of a V-region sub-subgroup of kappa III proteins designated kappa IIIb. Our studies confirm the preferential association of kappa III (and kappa IIIb) light chains with IgM kappa anti-IgG antibodies and demonstrate a similar association for IgM kappa anti-LDL antibodies. The finding that these and other types of IgM kappa autoantibodies, e.g., cold agglutinins, have remarkably similar light chains suggests an inherent restriction in the immune response to self-antigens.     

Regression analysis of the spontaneous spike activity of neurons in snail ganglia

Regression analysis of the spontaneous spike activity of neurons in Helix pomatia was carried out with the aim to establish the statistical parameters of this activity under constant experimental conditions and during longer time intervals. The activity of 38 randomly chosen neurons in visceral and parietal ganglia, penetrated by microelectrodes and activated either endogenously by pacemaker potentials or by synaptic inputs, was recorded during time intervals lasting from 20 min to 3 h. The main results of the statistical analyses are presented in the table where the parameters of both cell types are listed. The validity of the regression analysis applied here is discussed from the point of the possibility it offers for carrying on the data processing quickly and without applying complex calculating means. The results are also considered regarding the current interest of our research group.     

Physiological properties of microbial population as a basis for graphical solution of multi-stage continuous cultivations

A proposal for a graphical solution of the design of a multi-stage continuous culture system is presented. The holding times in individual stages are derived from the reciprocal values of the growth rate and of the product formation rate and plotted against the cell and product concentrations. Characteristic changes of physiologically significant paramaters are then projected on these production curves. Dedicated to Academican Ivan Málek on the occasion of his 60th birthday     

Untersuchung der eiweißspindeln des kakteen-X-Virus mit fluoreszierenden Antikörpern

A?koliv na zá kladě mnoha pokus? se p? edpokládalo, ?e tzv. bÍlkovinná v?etena v buňkách tzn. buně?né inkluse X-viru kaktus? (Ca XV), jsou slo?ena z ?etních prodlou?ených ?ásti Ca XV, p?esto to dosud nebylo proká zá no. Proto jsme se pokusili pomocÍ fluoreskujÍcÍch protilátek doká ?at, ?e bilkovinná v?etena jsou skute?ně agregáty virových ?ástic. V těto práci jsme pouzili tzv. nep?Ímé metody. Nejprve jsme p? sobili na buňky obsahujÍci tato v?etena homologiokým antisé rem proti Ca XV, zÍskanym imunizacÍ králÍk? a teprve potom jsme buňky vlo?ili do roztoku fluoreskujicÍch protilátek proti králicimu γglobulinu. BÍlkovinná v?etena svitila potom ve fluorescen?nÍm mikroskopu silně ?lutozeleně (bylopou?ito fluoresceinisothiocyaná tu). Tato fluorescence ná m uká zala, ?e nastala pozitivnÍ reakce a ?e bÍlkovianá v?etena jsou slo?ena z virových ?ástic. ?etné kontrolnÍ pokusy potvrdily ná? základnÍ pokus.     

Increased sensitivity of the respiratory system of plants grown in gibberellic acid toward fluoride

V souvislosti s d?ívěj?imi údaji (Lu?tinec a Krektjle 1959, Lu?tinec, Krekule a PokornÁ 1960) o silném inhibi?ním ú?inku fluoridu na dychání rostlin pěstovaných v roztoku kyseliny giberelové byl pomocí specificky zna?ené glukosy a respira?ních inhibitor? zji?tován vztah krátko- i dlouhodobého p?sobení kyseliny giberelové k poměru mezi podíly glykolytického a pentosofosfátového odbourání v respiraci list? p?enice. V souhlase s výsledky Fanga a spol. (1960) byIo zji?těno, ?e kyselina giberelová v koncentracích 2 a? 80 mg/l neovlivńuje během několikahodinového p?sobení na roz?ezané listy p?enice poměr radioaktivit¹⁴CO₂ uvolněného z glukosy-6-¹⁴C a -1-¹⁴C (C₆/C₁) ani nemění v koncentraci 10 mg/l stupeń inhibice dýchání fluoridem, monojodacetátem a malonátem a spot?ebu kyslíku. Výdej¹⁴CO₂ z glukosy-l-¹⁴C a -6-¹⁴C kyselina giberelová sni?uje v lineární závislosti na pou?itých koncentracích. U rostlin pěstovaných v roztoku kyseliny giberelové (10–20 mg/l) se rychleji sni?uje poměr C₆C₁ i absolutní hodnoty radioaktivity během několika dní od vyklí?ení, ne? u rostlin pěstovaných ve vodě. To svěd?í o rychlej?ím zvět?ování podílu pentosového cyklu v respiraci pokusných rostlin. Fluorid brzdí p?i stejném nebo men?ím obsahu ve tkáni dýchání list? rostlin pěstovaných v roztoku kyseliny giberelové silněji ne? dýchání rostlin pěstovaných ve vodě, zatimco ûcinek monojodacetátu a malonátu je u stejně starých rostlin (4 dny) obou variant stejný. O mo?ných p?í?inách tohoto jevu bylo diskutováno.