Influence of α-interferon therapy on blood lymphoid cells

Summary The influence of natural -interferon (-IFN) therapy (3×10⁶ units i.m. daily) on blood lymphoid cells was studied in 20 patients with gynecological neoplasias (7 patients with condylomata accuminata and 13 patients with ovarian carcinoma). There was a statistically significant increase in the intracellular levels of 2'–5'oligoadenylate synthese 1 day after the first injection of IFN and with few exceptions this activity remained increased during 3 months of treatment. In most of the patients, the capacity of blood lymphoid cells to produce IgA, IgG, and IgM following stimulation with pokeweed mitogen was decreased 1 day after the first injection of IFN and with few exceptions it remained low during 6 months of IFN therapy. In most patients there was a decrease in the capacity of lymphoid cells to act as stimulator or responder cells in a mixed lymphocyte culture during IFN therapy. The -IFN therapy had no major influence on the response of lymphoid cells to mitogens. We conclude, that neither this nor our previous studies on the influence of IFN therapy on immunological functions have given support to the hypothesis that the antitumor action of IFN is mediated by the immune system.     

Molecular characterization of the diurnal/circadian expression of the chlorophyll a/b-binding proteins in leaves of tomato and other dicotyledonous and monocotyledonous plant species

Diurnal oscillations of steady-state mRNA levels encoding the chlorophyll a/b-binding proteins were monitored inLycopersicon esculentum, Glycine max, Phaseolus vulgaris, P. aureus, P. coccineus, Pisum sativum, Sinapis alba, Hordeum vulgare, Triticum aestivum andZea mays. In these plant speciescab mRNA accumulation increases and decreases periodically indicating i) that the expression of the genes for chlorophyll a/b-binding proteins (cab genes) is controlled by a circadian rhythm, and ii) that the rhythm is widely distributed among monocotyledonous and dicotyledonous plant species. A detailed characterization of the pattern ofcab mRNA expression in tomato leaves shows that the amplitude of the oscillation is dependent on i) the developmental stage of the leaves, ii) the circadian phase and duration of light and iii) the circadian phase and duration of darkness. In addition to the chlorophyll a/b-binding proteins, genes coding for other cellular functions were examined for cyclic variations of their mRNA levels. The analysis includes genes involved in i) carbon metabolism (e.g. phosphoenolpyruvate carboxylase, pyruvate orthophosphate dikinase, alpha amylase, fructose-1,6-bisphosphate aldolase, triosephosphate isomerase), ii) photosynthesis (large and small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, Q_B-binding protein, reaction-center protein of photosystem I) and iii) other physiological or morphological reactions (e.g. ubiquitin, actin). However, no periodic fluctuation pattern was detected for the mRNA levels of these genes in tomato and maize leaves.     

Regional histochemical aspects of xanthine oxidase activity in ischemic and reperfused small intestine of the rat

The study describes regional changes of xanthine oxidase and succinate dehydrogenase activities as shown by the ischemic and reperfused small intestine of the rat. The results are obtained with enzyme histochemical methods, including densitometrical verifications, and are substantiated with biochemical enzyme determinations. The decrease of xanthine oxidase activity was best visible in the anoxic duodenum and jejunum, where the findings of histochemical enzyme determinations agreed with those achieved biochemically. The activities of succinate dehydrogenase as measured densitometrically may serve as a further control, considering also the typical intracellular distribution of the reaction products.     

Dietary zinc deficiency has no effect on auditory brainstem responses in the rat

Zinc has been shown to effect--in vitro--a number of processes associated with neurotransmission. We have tested whether the rate of impulse conduction--in vivo--as measured from the latencies of auditory brainstem responses (ABR), is influenced by dietary zinc deficiency in the rat. Dietary zinc deficiency for up to 26 wk had no effect on the wave I-IV interval compared to zinc-adequate fed animals. The results are discussed in relation to the observed constancy of brain overall and extracellular fluid zinc concentrations under conditions of dietary zinc deficiency.     

Non-invasive image analysis evaluation of growth during plant micropropagation

Microcomputerized video image analysis was adapted for rapid, objective, and non-intrusive quantification of shoot growth and development for plants growing in vitro. Custom-developed staging arrangements were essential to insure accurate viewing and representation of the plants in each of three standard culture vessels. Shoot length measurements from digitized culture images were strongly correlated with length measured manually ex vitro. Image analysis weighted density measurements of proliferating microcultures (even with irregular growth habits) provided a reliable indicator of shoot culture fresh weight. Non-destructive time course evaluations of growth rate and quality were demonstrated.Abbreviations FW fresh weight - WD weighted density     

Interaction of rat glutathione S-transferases 7-7 and 8-8 with gamma-glutamyl- or glycyl-modified glutathione analogues.

Analogues of GSH in which either the gamma-glutamyl or the glycyl moiety is modified were synthesized and tested as both substrates for and inhibitors of glutathione S-transferases (GSTs) 7-7 and 8-8. Acceptor substrates for GST 7-7 were 1-chloro-2,4-dinitrobenzene (CDNB) and ethacrynic acid (ETA) and for GST 8-8 CDNB, ETA and 4-hydroxynon-trans-2-enal (HNE). The relative ability of each combination of enzyme and GSH analogue to catalyse the conjugation of all acceptor substrates was similar with the exception of the combination of GST 7-7 and gamma-L-Glu-L-Cys-L-Asp, which used CDNB but not ETA as acceptor substrate. In general, GST 7-7 was better than GST 8-8 in utilizing these analogues as substrates, and glycyl analogues were better than gamma-glutamyl analogues as both substrates and inhibitors. These results are compared with those obtained earlier with GSH analogues and GST isoenzymes 1-1, 2-2, 3-3 and 4-4 [Adang, Brussee, Meyer, Coles, Ketterer, van der Gen & Mulder (1988) Biochem. J. 255, 721-724] and the implications with respect to the nature of their active sites are discussed.     

Immature rat epididymal epithelial cells grown in static primary monolayer culture on permeable supports

Summary N-acetylglucosaminidase (NAG), acid phosphatase (ACP) and alkaline phosphatase (AKP) were localised histochemically in fixed cells from the 37-day-old rat epididymis grown in static monolayer culture for 2–8 days. ACP and NAG were cytosolic enzymes found in perinuclear positions, whereas staining of AKP was consistent with a membranous position. These enzymes were also examined in frozen tissue sections of the epididymis, from rats of the equivalent age, where NAG had intense activity in both supra- and infra-nuclear cytoplasm and ACP was more active apically. For the first time AKP was localised along basolateral membranes of the epithelium and in the lumen of the mid-caput region. The monolayer in culture was of principal cells only and they maintained their polarity and ultrastructural characteristics, but the height of the cells was reduced compared to that obtained in situ.     

Corrosion casts as a method for investigation of the insect tracheal system

Summary The tracheal systems of five insect species (two species of ants, worker bee, housefly and the cabbage butterfly) have been studied by scanning electron microscopy of corrosion casts. This technique, which is commonly used for the investigation of vertebrate vasculature, is adapted to demonstrate the ultrastructure of the insect respiratory organ. The problem of filling a blind ending system was solved by injecting the resin Mercox into the evacuated tracheae through a thoracal spiracle. After polymerization of the resin, the tissue was digested enzymatically and chemically. The three-dimensional structure of the tracheal system was investigated by scanning electron microscopy. The technique used here displays for the first time the complex morphology of the entire tracheal system in fine detail, especially the structure of spiracles, airsacs, tracheae and tracheoles. Smooth-walled terminal tracheoles show up in flight muscles. The finest tracheoles that could be identified have diameters of approximately 70 nm. This approaches the finest tracheoles portrayed by transmission electron micrographs.     

Mutant proteins of human interleukin 2. Renaturation yield, proliferative activity and receptor binding

Muteins, i.e. proteins altered by mutation of their genes, of interleukin 2 (Il2) were generated by oligonucleotide-directed mutagenesis in vitro. All acidic and basic residues conserved between man and mouse were exchanged as well as four lipophilic residues contained within four hydrophobic segments of the protein. The muteins were produced in Escherichia coli and submitted to a renaturation and purification protocol, before bioactivity and receptor binding of each of them was determined. All muteins besides two (K44/T125 and Q110/T125) could be renatured and purified. One mutein (K94/T125) exhibited a more than tenfold-improved renaturation yield. One amino exchange (Asp-20 to Asn) resulted in an about 20-fold reduction in proliferative activity and high-affinity receptor binding. The binding to the low-affinity Il2-binding protein (Tac antigen) was unimpaired. A second exchange (Arg-38 to Gln) had no effect on proliferative activity. The binding to both the high- and the low-affinity receptor, however, was reduced about 20-fold. Preliminary trials on the stability of these muteins by guanidinium hydrochloride denaturation studies detected no differences between wild-type interleukin 2 and muteins. It is suggested that Asp-20 forms part of the binding site for the large receptor subunit whereas Arg-38 is involved in the contact site to the small subunit.