Studies on the Tissue Distribution of the Puromycin-Sensitive Enkephalin-Degrading Aminopeptidases

An antiserum generated to the soluble form of the rat brain puromycin-sensitive enkephalin-degrading aminopeptidase was used to determine the tissue distribution of the soluble and membrane-associated forms of this enzyme. All tissues examined contained significant levels of the soluble enzyme form, with this enzyme accounting for greater than 90% of the arylamidase activity in brain, heart, and skeletal muscle. Native gel electrophoresis coupled with activity staining as well as inhibition studies were used to confirm the presence of this enzyme in various tissues. Serum was found not to contain this particular aminopeptidase. In contrast to the results obtained with the soluble enzyme form, brain was the only tissue found to contain the membrane-associated enzyme form. Although all tissues contained membrane-associated aminopeptidase activity only the brain enzyme could be maintained in solution in the absence of detergent. In addition, the brain membrane-associated enzyme could be distinguished from the membrane-associated aminopeptidase activity in other tissues on the basis of its sensitivity to inhibition by puromycin.     

Glycogen concentrations and endurance capacity of rats with chronic heart failure

The endurance capacities of rats with myocardial infarctions (MI) and of rats having undergone sham operations (SHAM) were tested during a submaximal exercise regimen that consisted of swimming to exhaustion. During this test, a decrement in the endurance capacity of the MI rat was demonstrated as the SHAM rat swam 25% longer than the MI rat (65 +/- 4 vs. 52 +/- 4 min). Glycogen concentrations were measured in the liver and the white gastrocnemius, plantaris, and soleus muscles of SHAM and MI rats that were randomly divided into four subgroups, which consisted of resting control, swim to exhaustion, swim to exhaustion + 24 h recovery, and swim to exhaustion + 24 h recovery + a second swim to exhaustion. The results demonstrated that the glycogen concentrations found in the liver, white gastrocnemius, plantaris, and soleus muscles of the SHAM and MI rats belonging to the resting control groups were similar. After swimming to exhaustion the glycogen concentrations in these tissues were significantly reduced compared with those found in the resting control groups of rats, and after 24 h of recovery the glycogen concentrations in these tissues were again similar to those found in the resting control groups of rats. Since the magnitude of the glycogen depletion in the liver and the white gastrocnemius, plantaris, and soleus muscles was similar in the SHAM and MI rats and because the SHAM rats consistently swam for longer periods of time in each of the experimental groups, it would be logical to assume that the rates of glycogen utilization for the various tissues may have been greater in the MI rat during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protein synthetic activity and adenylate energy charge in Rhein-treated cultured human glioma cells.

The effect of Rhein (RH) on the protein synthetic activity and adenylate energy charge in human glioma cells cultured in vitro has been investigated. The results demonstrate that in RH-treated cells, the protein synthesis is strongly decreased, but no modifications in the qualitative pattern occur. The extent of inhibition is a function of the drug concentration as well as of the time of exposure. Such an inhibition must be ascribed mainly to a reduction of adenylate energy charge brought about by RH because of its effect on respiration and glycolysis. The correlation between the adenylate energy charge and cell viability, as well as the possibility of using rhein as a biochemical modulator to reduce or to reverse multidrug resistance, are also discussed.     

Plasmid DNA from methanogenic bacteria

In total, 73 strains of methanogen isolates from our laboratory and 6 from culture collections were examined for the presence of plasmid DNA. Five strains were found to contain detectable plasmids. Multiple plasmids were found in two isolates, while three strains contained only one plasmid each. A physical map of the plasmid pT3 was constructed by use of six different restriction endonucleases. All sites were aligned with a single BgII site, and the position of the restriction sites was determined by double or sequential digestion of the plasmid DNA.     

Phase variations inBifidobacterium animalis

Strains isolated from rabbit, chicken, and rat feces and from sewage and fermented milk products, all identified asBifidobacterium animalis, were found to show phase variations in colony appearance and in cellular morphology. The rate of transition in a switching system from opaque to transparent colonies and vice versa was determined. Differences in protein components and in penicillin-binding proteins (PBPs) of the cells from different colony types are shown.     

The role of air temperature in determining dormancy release and flowering ofCorylus avellana L.

Summary 7 years of airborne pollen monitoring in Perugia (central Italy) were used to determine the temperature requirements to break dormancy and to resume growth and bloom ofCorylus avellana L.,Corylus needs 1000 chill-units to complete its dormancy and this value, in the Perugian area, is met by the end of December or the first days of January. MoreoverCorylus trees require 220 growth degree hours before they are able to flower. If air temperature is high, this value can be achieved in only 10 days, but if the temperature remains too low, the heat accumulation can require up to 35 days. With these parameters it is possible to build a model to predict the date of the beginning ofCorylus avellana pollen season.     

Influence of cell cycle synchronization on digital image analysis of HL-60 granulopoiesis.

Retinoic acid (RA)-treated HL-60 cells subjected to density arrest (DA) and double thymidine block (TB) synchronization demonstrated image feature changes associated with cellular proliferation and differentiation. RA-treated TB cells demonstrated an increased level of morphologic differentiation (assessed by differential counts and quantitation of nuclear shape) and more rapid functional differentiation (assessed by superoxide production and expression of complement receptors) than RA-treated DA cells. By comparison to DA cells, TB cells had less variation in virtually all image features values. A Kruskal-Wallis test of image features ranked total optical density (TOD) of Feulgen-stained cells, nuclear area and shape factor as the top three features regardless of synchronization method. Statistically significant changes in image feature values of RA-treated cells were first noted on day 1. The computer-assisted ability to discriminate RA-treated cells on a given day after induction from paired controls by means of an unsupervised learning algorithm increased over a seven-day period for both DA and TB cells. However, in the dichotomous (RA-treated versus untreated) classification scheme employed, which did not account for continuous levels of morphologic differentiation, there was no advantage in the use of the TB over DA procedure.     

Influence of maize root mucilage on soil aggregate stability

This study was undertaken to determine the effects of root exudates on soil aggregate stability. Root mucilage was collected from two-month old maize plants (Zea mays L.) Mucilage and glucose solutions were added at a rate of 2.45 g C kg⁻¹ dry soil to silty clay and silt loam soils. Amended soils, placed in serum flasks, were incubated for 42 d with a drying-wetting cycle after 21 d. Evolved CO₂ was measured periodically as well as the water-stable aggregates and soluble sugar and polysaccharide content of the soil. In mucilage-amended soils CO₂ evolution started with a lag phase of 2–3 days, which was not observed in glucose-amended soils. There was then a sharp increase in evolved CO₂ up to day 7. During the second incubation period there were only small differences in evolved C between treatments. Incorporation of mucilage in both soils resulted in a spectacular and immediate increase in soil aggregate stability. Thereafter, the percent of water-stable aggregates quickly decreased parallel to microbial degradation. On completion of the incubation, aggregate stability in the silty clay soil was still significantly higher in the presence of mucilage than in the control. This work supports the assumption that freshly released mucilage is able to stick very rapidly to soil particles and may protect the newly formed aggregates against water destruction. On the silty clay, microbial activity contributes to a stabilization of these established organo-mineral bounds.     

Guaianolides and lignans from Centaurea solstitialis subs Schouwii

Aerial parts of Centaurea solstitialis subs schouwii afforded the guaianolides cynaropicrin and aguerin B and the lignans arctigenin and matairesinol. The structure of a third guaianolide previously found also in Centaurea behen was revised.