Adrenergic modulation of immune cells: an update

Sympathoadrenergic pathways are crucial to the communication between the nervous system and the immune system. The present review addresses emerging issues in the adrenergic modulation of immune cells, including: the specific pattern of adrenoceptor expression on immune cells and their role and changes upon cell differentiation and activation; the production and utilization of noradrenaline and adrenaline by immune cells themselves; the dysregulation of adrenergic immune mechanisms in disease and their potential as novel therapeutic targets. A wide array of sympathoadrenergic therapeutics is currently used for non-immune indications, and could represent an attractive source of non-conventional immunomodulating agents.     

Cellular localization of bovine pancreatic trypsin inhibitor and related molecular forms in bovine lung

Summary In addition to bovine pancreatic trypsin inhibitor (BPTI), three BPTI-related molecular forms (isoinhibitors I, II and III) were isolated from bovine lung by affinity chromatography on immobilized trypsin and subsequently purified by Fast Protein Liquid Chromatography. These inhibitors are identical to the isoinhibitors previously isolated from bovine spleen. Their localization in bovine lung was studied by immunohistochemical techniques, using two different immunoglobulin preparations, selectively recognizing BPTI or the other molecular forms.BPTI-related immunoreactivity was found to be restricted to isolated cells, often identified as mast cells by Toluidine Blue staining. In contrast, isoinhibitor-related immunoreactivity, which also occurs in the mast cells, is present in a number of other cell types. These types include: (i) the smooth muscle cells of different calibre vessels, (ii) the ciliated cells of the bronchial epithelium and the related mucus, and (iii) many cells at alveolar level.Comparison of these data with previous results obtained for bovine spleen suggest multiple physiological roles for these inhibitors.     

Feedback inhibition of homoserine dehydrogenase and threonine deaminase in the genusBifidobacterium

Feedback inhibition of crude and purified extracts of homoserine dehydrogenase and threonine deaminase activities in the genusBifidobacterium was studied. Homoserine dehydrogenase was partially or completely inhibited byl-threonine, and a marked inhibitory effect byl-isoleucine on threonine deaminase was observed. In the speciesBifidobacterium cuniculi high levels ofl-valine reversed the inhibitory effect ofl-isoleucine. The -aminobutyric acid-resistant mutant Ru 326/106 of the speciesB. ruminale, overproducer ofl-isoleucine, had a derepressed homoserine dehydrogenase and a lesser feedback inhibition byl-threonine. Homoserine dehydrogenase appeared to be in bifids specifically NAD dependent. The regulatory mechanisms of aspartate family amino acid biosynthesis in bifidobacteria was discussed.     

High-performance liquid chromatographic separation of aprotinin-like inhibitors and their determination in very small amounts

A reversed-phase high-performance liquid chromatographic method for the determination and quantitative recovery of fully active aprotinin (the basic pancreatic trypsin inhibitor or Kunitz inhibitor) and aprotinin-like inhibitors in amounts down to 0.5 μg is reported. The method, which allows separation of aprotinin isoinhibitors characterized by small differences in the primary structure with respect to aprotinin itself, appears to be suitable for the quantitation and identification of aprotinin-like inhibitors in human biological fluids, in which they appear to be present at very low levels.     

Characteristics and Regulatory Properties of the H+-ATPase in a Plasma Membrane Fraction Purified from Arabidopsis thaliana

The aqueous two-phase partitioning technique was utilized to isolate a plasma membrane (PM) fraction from etiolated seedlings of Arabidopsis thaliana. The purification procedure adopted yielded a fraction highly enriched in PM as compared to inner membranes, with a recovery of about 30%, as judged from the activities of PM markers such as vanadate-sensitive ATPase, FC binding and UDP-glucose sterol glucosyltransferase. The purified PM fraction displayed vanadate-sensitive H⁺ pumping activity. Its purity was confirmed by the biochemical characteristics of its ATPase activity assayed in the absence of Ca²⁺: sensitivity to vanadate (IC₅₀ ca. 1 μM), Mg²⁺-dependence, insensitivity to molybdate, oligomycin and nitrate, pH optimum at 6.6. The PM H⁺-ATPase activity was stimulated by fusicoccin and by a controlled treatment of the PM with trypsin. In both cases stimulation was much stronger on the activity assayed at pH 7.5 than on the activity at pH 6.6. Moreover, neither fusicoccin nor the treatment with trypsin stimulated the portion of activity (30 to 40% at pH 7.5) which decayed upon preincubation of the PM in assay medium without ATP.     

Keratinophilic fungi isolated from the air at Pavia

The presence of keratinophilic fungi was revealed by sampling the air of Pavia (Italy) from March 1981 to February 1982. The species isolated were: Chrysosporium indicum, Geomyces pannorum var.pannorum, Microsporum gypseum, Myceliophtora vellerea and Trichophyton terrestre. Several filamentous fungi tolerating high levels of cycloheximide were also recovered.     

Fusicoccin Binding to its Plasma Membrane Receptor and the Activation of the Plasma Membrane H+-ATPase. II. Stimulation of the H+-ATPase in a Plasma Membrane Fraction Purified by Phase-partitioning

The effect of fusicoccin (FC) on the activity of the PM H⁺-ATPase was investigated in a plasma membrane (PM) fraction from radish seedlings purified by the phase-partitioning procedure. FC stimulated the PM H⁺-ATPase activity by up to 100 %; the effect was essentially on V_max with only a slight decrease of the apparent K_M of the enzyme for ATP. FC-induced stimulation of the PM H⁺-ATPase was evident within the first minute and maximal within five minutes of membrane treatment with the toxin indicating that transmission of the signal from the activated receptor to the PM H⁺-ATPase is very rapid. Both FC-induced stimulation of the PM H⁺-ATPase and FC binding to its receptor decreased dramatically upon incubation of the membranes in ATPase assay medium at 33 °C in the absence of FC, due to the lability of the free FC receptor. FC-induced stimulation of the PM H⁺-ATPase was strongly pH dependent: absolute increase of activity was maximal at pH 7, while percent stimulation increased with the increase of pH up to pH 7.5; FC binding was scarcely influenced by pH in the pH range investigated. Taken as a whole, these results indicate that FC binding is a condition necessary, but not sufficient, for FC-induced stimulation of the PM H⁺-ATPase.     

The epoxide hydrolase catalyzed hydrolysis of trans-3-bromo-1,2-epoxycyclohexane. A direct proof for a general base catalyzed mechanism of the enzymatic hydration

The hydrolysis of (±)-$\text{trans}$-3-bromo-1,2-epoxycyclohexane in the presence of rabbit liver microsomes was investigated, and found to yield, beside $\text{c}$-3-bromocyclohexane-$\text{r}$-1,$\text{t}$-2-diol, 2,3-epoxycyclohexanol. It was demonstrated that the latter compound was the only product of the enzymatic reaction, whereas the diol resulted from a non enzymatic hydration in the reaction medium. These data provide the first direct proof for a general base catalysis in the enzymatic epoxide hydration, previously hypothesized on the basis of several lines of indirect evidence, and disprove alternative mechanisms involving protonation of the oxirane oxygen.