Fatty acids and the inhibition of mitogen-induced lymphocyte transformation by leukemic serum

The effects of sera from 23 patients with acute lymphocytic leukemia on mitogen-induced transformation of normal human lymphocytes were examined. All sera (100%) at diagnosis and 70% of those obtained during the induction of remission demonstrated inhibition of mitogen-induced lymphocyte transformation as evidenced by decreased uptake of [3H]thymidine. The inhibition could not be overcome by an increase in the mitogen concentration. Eighteen sera demonstrating a mean inhibition of 44.2% had elevated levels of free fatty acids (FFA) compared with five sera showing no inhibition (p value = 0.001). Inhibition, within the range produced by leukemic sera, could be achieved by the purified methyl esters of linoleic and linolenic acid in this system. Flow cytometric analysis of mitogen-induced cycling of normal human lymphocytes suggested that deoxyribonucleic acid (DNA) replication was inhibited by leukemic sera containing elevated levels of FFA after the G1 phase of cell cycling. Similar inhibition could be achieved by the methyl ester of linolenic acid in this system. Gas chromatographic analysis revealed that sera demonstrating inhibition contained linolenic (C18:3) acid (p value = 0.015), and the majority showed one or more of the following: 1) a concentration of oleic (C18:1) acid greater than 2 standard deviations (SD) above the mean of the control leukemic sera (i.e., those not demonstrating inhibition); 2) an arachidonic (C20:4) to C18:1 ratio that is reduced to greater than 2 SD below the mean of the control group; or 3) the presence of an unexpected fatty acid fraction. The data raise the question of an influence of FFA and, specifically, an interplay of unsaturated fatty acids on immune function during the natural history of acute lymphocytic leukemia.     

Age-related Differences in Playfighting Strategies of Captive Male Red-necked Wallabies (Macropus rufogriseus banksianus)

Age-related differences in the playfighting strategy of captive male red-necked wallabies Macropus rufogriseus banksianus was examined. Our purpose was to determine whether wallabies adjusted their play in response to their partner's age and, if so, how. The way in which a wallaby played was dependent on the relative age of its partner, and this pattern tended to be the same regardless of whether it was the initiator or reactor of the interaction. If a wallaby's partner was younger than itself it adopted a defensive strategy in which it self-handicapped by standing flat-footed, Pawing rather than Sparring, and by not using its full strength. Its greater rate of Shaking suggests that this act may function as an appeasement signal in play. Furthermore, it was highly tolerant of the tactics used by its younger partner and took the more active role in prolonging interactions. If, on the other hand, its partner was older than itself, it adopted an offensive strategy involving vigorous Sparring, increased time in the High-stance posture and a greater percentage of bouts that were of high intensity. Indeed, it played with even more vigour than when it playfought with wallabies of the same age as itself. Differences in the play of same-aged partners were in the non-fighting components of play, while those of differently-aged partners were in the fighting components. Play between same-aged partners, however, tended to be more stable and more competitive than that between partners of differing age. These results are discussed with emphasis on the compromises made in order for play to occur and the potential benefits to each partner of play in mixed-age class encounters. We briefly consider the implications of self-handicapping in the categorization of macropodid fights as play or aggression.     

A comparative study of virulent and avirulent strains of Chromobacterium violaceum

A clinical isolate and a soil isolate of Chromobacterium violaceum were compared to determine differences in virulence-related characteristics. Purified lipopolysaccharide (endotoxin) from the virulent, clinical strain was more reactive than that from the avirulent soil strain as determined by the Limulus amebocyte lysate assay. There were no differences in hemolysin or cyanide production between the two strains. The virulent strain was more resistant to phagocytosis and intracellular killing by human polymorphonucleocytes. The clinical strain showed a superoxide dismutase activity 30% higher and a catalase activity fivefold higher than the activities of the soil-isolated strain. The clinical strain also was capable of producing approximately twice as much hydrogen peroxide during growth as compared with the soil isolate. This study suggests that virulence of C. violaceum may be, at least in part, associated with endotoxin, and some protection of the virulent, clinical strain from phagocytic attack is afforded by elevated levels of superoxide dismutase and catalase.     

The effect of the presence of glucose on the fermentation of mannose by the anaerobic fungus Neocallimastix frontalis strain RE1

Abstract The disappearance of mannose and the formation of formate, acetate, lactate, ethanol and succinate by Neocallimastix frontalis strain RE1 occurred slowly when mannose was the only substrate present. When an equal quantity of glucose was present, the fermentation of mannose increased. Incubations with ¹³C-labelled mannose and glucose confirmed that the presence of both substrates resulted in increased product formation from mannose and reduced product formation from glucose. The relative proportions of products formed from the two substrates varied, possibly in part due to differences in the rates of growth of the fungus. The strains of N. frontalis able to utilize mannose may have a competitive advantage in the rumen ecosystem.     

Removal of lead from solution by the non-viable biomass of the water fern Azolla filiculoides

Non-viable biomass of the aquatic fern, Azolla filiculoides, removed up to 93 mg lead/g biomass from solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 4.5. Lead removal decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. Lead removal remained at approximately 90% between 10 °C and 50 °C. Biomass concentration (4–8 mg/l) had little effect on lead removal. © Rapid Science Ltd. 1998     

Pinocytic uptake of divinyl ether-maleic anhydride (pyran copolymer) and its failure to stimulate pinocytosis

The effect of DIVEMA (pyran copolymer) and three DIVEMA derivatives on the pinocytic uptake of ¹²⁵I-labelled PVP and colloidal ¹⁹⁸Au by the rat visceral yolk sac and by rat peritoneal macrophages was studied in vitro. Contrary to expectations from some earlier data, there was no enhancement of pinocytosis and in some cases inhibition was seen. [¹⁴C]DIVEMA and ¹²⁵I-labelled DIVEMA were accumulated rapidly by rat peritoneal macrophages, the results indicating that this is by an adsorptive pinocytic mechanism.     

Factors affecting central inspiratory modulation of hypoglossal motoneuron activity in newborn pigs

In newborn pigs (4-6 days old), recordings of efferent whole hypoglossal and phrenic nerve discharges were obtained during hyperoxia (or normoxia) and during hypoxia, before and after bilateral vagotomy. With intact vagi, spontaneous hypoglossal inspiratory activity was not observed and was not elicited by either spontaneous changes of electroencephalogram (EEG) or hypoxic stimulation (15% O2 in N2). After bilateral vagotomy, some animals had episodes of spontaneous hypoglossal inspiratory activity; power spectral analysis of EEG demonstrated that this inspiratory activity appeared synchronously with shifts of major peaks in EEG spectra from the delta band (0.5-3.5 Hz) to the theta band (3.5-7.0 Hz). Hypoglossal inspiratory discharges were also elicited by hypoxic stimulation and usually had a decrementing discharge pattern; in some cases, this activity had an augmenting discharge pattern. Our results suggest that hypoglossal motoneurons are poorly modulated by central inspiratory drive, requiring additional facilitatory influences, i.e. corticobulbar, intra-bulbar, chemical drive, before such modulation is observed.