Effect of endurance training and chronic isoproterenol treatment on skeletal muscle sensitivity to norepinephrine

The purpose of this study was to determine the influence of metabolic stresses, such as endurance training and chronic isoproterenol treatment, on skeletal muscle sensitivity to norepinephrine. Using an isolated perfused rat hindlimb preparation, dose-response curves for skeletal muscle oxygen consumption (VO2) and vascular resistance were obtained with control, endurance trained, and isoproterenol treated rats. No significant difference was found between control and experimental groups for non-stimulated VO2. In response to NE infusion, trained rats showed a significantly greater increase in VO2 compared to control rats while the response of the isoproterenol treated rats was of the same magnitude as the one for their respective control rats. At the highest dose of NE infused, the vasopressor response was significantly lower in trained rats compared to control rats. At none of the doses was there a significant difference in the vasopressor response between control and isoproterenol treated rats. These results suggest that repeated exposures to high levels of catecholamines, as produced during endurance training, leads to an increased sensitivity of skeletal muscle to the effect of norepinephrine.     

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.     

Canopy transpiration and water fluxes in the xylem of the trunk of Larix and Picea trees — a comparison of xylem flow,porometer and cuvette measurements

Summary Leaf gas exchange, transpiration, water potential and xylem water flow measurements were used in order to investigate the daily water balance of intact, naturally growing, adult Larix and Picea trees without major injury. The total daily water use of the tree was very similar when measured as xylem water flow at breast height or at the trunk top below the shade branches, or as canopy transpiration by a porometer or gas exchange chamber at different crown positions. The average canopy transpiration is about 12% lower than the transpiration of a single twig in the sun crown of Larix and Picea. Despite the similarity in daily total water flows there are larger differences in the actual daily course. Transpiration started 2 to 3 h earlier than the xylem water flow and decreased at noon before the maximum xylem water flow was reached, and stopped in the evening 2 to 3 h earlier than the water flow though the stem. The daily course of the xylem water flow was very similar at the trunk base and top below the lowest branches with shade needles. The difference in water efflux from the crown via transpiration and the water influx from the trunk is caused by the use of stored water. The specific capacitance of the crown wood was estimated to be 4.7 x 10^-8 and 6.3 x 10^-8 kg kg^-1 Pa^-1 and the total amount of available water storage was 17.8 and 8.7 kg, which is 24% and 14% of the total daily transpiration in Larix and Picea respectively. Very little water was used from the main tree trunk. With increasing transpiration and use of stored water from wood in the crown, the water potential in the foliage decreases. Plant water status recovers with the decrease of transpiration and the refilling of the water storage sites. The liquid flow conductance in the trunk was 0.45 x 10^-9 and 0.36 x 10^-9 mol m^-2s^-1 Pa^-1 in Larix and Picea respectively. The role of stomata and their control by environmental and internal plant factors is discussed.     

Performance ofin vitro propagatedAlnus glutinosa (L.) Gaertn. clones inoculated withFrankiae

Summary ThreeAlnus glutinosa (L.) Gaertn. clones, obtained byin vitro propagation techniques, were inoculated with four strains ofFrankia. The ability of these clones to nodulate and fix nitrogen was previously reported; this study deals with the performance of 12 different combinations of pairs of symbionts.Shoot fresh weight, shoot height and collar diameter were measured 60 and 82 days after inoculation. Shoot fresh weight seems to be more sensitive and reliable than the other parameters. Nitrogenase activity, measured by the acetylene reduction assay, was assayed 78 days after inoculation and was consistent with the biomass measurements.Better growth was observed when type N strains were used. Significant growth differences were observed between clones AG-2 and AG-8 on the one hand and clone AG-4 on the other. Thus, the use of genetically defined host plants and microsymbionts permitted the demonstration of significant performance variation even among cloned plants from the same provenance (AG-4 and AG-8).The duration of the experiment influenced the results with differences becoming less significant with time. This might be caused by an external limiting factor such as the pot size, competition for light,etc. But it could also be indicative of differences in nodulation speed among the treatments.     

Selective decontamination,induced colonization resistance and connected immunological changes in piglets

14-d-old conventional piglets were picked from normal piggery, washed with disinfectants, placed into isolators suitable for germfree work, fed a sterile diet and treated with peroral antibiotics (nalidixic acid, kanamycin, and nystatin). Beginning with day 5 or 7, Enterobacteriaceae were not found in feces. The absence of these bacteria was proved by inoculation of germfree newborn piglets with caecal content. In selectively decontaminated piglets, the white blood cell count in blood had fallen to 6 X 10(9)/L; this decrease was due to an extremely low number of granulocytes (to 0.8 X 10(9)/L). On day 35, IgG-positive cells almost disappeared from the spleen, whereas IgA cells were found in an unusually great amount. Corresponding changes in serum levels were established. The colonization resistance effect in Enterobacteriaceae-deprived piglets was confirmed; settling of introduced various E. coli strains did not occur or was delayed.     

Lysosomal enzyme activities in polymorphonuclear leukocytes,macrophages, serum,and spleen of conventional,germ-free,and antigen-free minnesota miniature swine

The activities of lysozyme, myeloperoxidase, and elastase were lower in PMNs and AMs from GF and AF Minnesota miniature piglets than in the leukocytes from their CONV counterparts. In the spleen and serum of gnotobiotic piglets only the levels of lysozyme were slightly reduced. Substantially depressed activities of these LEs were found also in PMNs from precolostral piglets in comparison with PMNs from their CONV mother. The bisassociation of GF piglets with Enterococcus liquefaciens and Escherichia coli caused an increase of LE activities in their AMs, spleens, and sera. Fewer LEs were released after phygocytic stimulation with zymosan from PMNs of GF, AF, and precolostral piglets than from PMNs of CONV animals of the same age. These data suggest that the antigenic-microbial stimulation is important for the development of normal lysosomal enzyme activities in PMNs and AMs from gnotobiotic animals.     

Antigenic properties of T cell antigen-specific receptors isolated from the surface of rabbit and mouse spleen and lymph node cells

The presence ofa allotypic determinants was tested in fractions obtained by gel filtration of antigen-specific receptors isolated by immunoadsorption from lymphoid cells of antigen-stimulateda3-3 rabbits. This technique, as well as the inhibition of the reaction of isolated receptors with anti-T cell receptor antisera (anti R) by anti-a3 antibodies failed to demonstrate the presence of a allotypie determinants. The inhibitory effect of antigen-specific receptors isolated from the lymphoid cells of stimulated A/J mice on the cytotoxic effect of anti-Ia antibodies on mouse spleen cells in the presence of rabbit complement was tested. All preparations inhibited the cytotoxic reaction with the average effectivity of 60%. In order to confirm the presence of Ia determinants on the rabbit and mouse T cell receptor molecules it was shown that the reactions of three anti-R antisera with 12 different receptor preparations were inhibited by anti-la antibodies. SDS-PAGE analyses of¹²⁵I-labelled mouse specific receptors and the precipitate obtained by anti-R antisera showed that T cell receptors were present in fractions with molar mass 100 and 85 kg/mol. The molar mass of the former fraction after reduction and alkylation was 45 kg/mol.     

Bacteriocin production inAgrobacterium tumefaciens

Agrobacterium tumefaciens C58 forms “plaques” during layer cultivation. The “plaques” were shown not to be caused by the presence of a temperate bacteriophage or by random contamination. The “plaques” and their central microcolonies were used to repeatedly isolate cultures producing an antibiotic substance against the original strainA. tumefaciens C58, other nopaline strains, some octopine strains ofA. tumefaciens and some strains of the related genusRhizobium. The substance is thus a bacteriocin; in analogy to agrocins 84 and D286 it was named agrocin C58. The agrocin is not inactivated by trypsin. Its production by strain C58 was found only on cultivation on solid but not liquid media. The producing isolate ofA. tumefaciens C58 (strain C58i2) contains neither plasmid pTiC58 nor the plasmid analogous to pAgK84 which controls the production of agrocin 84 inA. radiobacter K84.     

Interaction of high mobility group proteins HMG 1 and HMG 2 with nucleosomes studied by gel electrophoresis

The binding of isolated high mobility group proteins HMG (1+2) with nucleosomes was studied using gel electrophoresis. The interaction of HMG (1+2) with mononucleosomes could be detected as a new discrete electrophoretic band with a decreased mobility only after cross-linking of HMG (1+2)-nucleosome complex by formaldehyde. Approximately two molecules of the large HMG proteins were bound per nucleosomal particle of a DNA length of 185 base pairs, lacking histones H1 and H5. Using the same techniques, no binding was observed with core particles of a DNA length of 145 base pairs.     

The carbohydrates of secretory granules and the glycocalyx in developing mucoid cells

Summary Complex carbohydrates in secretory granules and at the apical cell surface of mouse gastric mucoid cells were studied during embryogenesis and in the early postnatal period by various cytochemical methods; the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) and tannic acid-uranyl acetate (TA-UA) procedures made neutral mucosubstances (NMS) visible, whereas the hexose residues of glycoconjugates were identified using WGA-, RCA II- and ConA-ferritin. The glycocalyx was stained with ruthenium red (RR). During differentiation of the embryonic mucoid cells the number of secretory granules increased in parallel to the increase in their carbohydrate component. NMS-stainable parts in secretory granules also had binding sites for the conjugates RCA II- and WGA-ferritin, but the binding of ConA could not be identified. The increasing quantity of NMS in secretory granules was correlated with the increased amount of PA-TCH-SP and TA-UA positive substances in the apical glycocalyx only in 14- and 18-day-old embryos. The observed uniform affinity for RR and lectin conjugates in all analysed developmental stages remains to be explained.