Schistosoma mansoni: reduced efficacy of chemotherapy in infected T-cell-deprived mice

The effect of host immunosuppression on the efficacy of schistosomicidal chemotherapy has been tested in T-cell-deprived CBA mice infected with Schistosoma mansoni. The drugs hycanthone, oxamniquine, and praziquantel were found to kill fewer adult S. mansoni worms in deprived mice than in comparably infected strain-, age-, and sex-matched, immunologically intact controls. Inconsistent results were obtained with niridazole, and amoscanate was as effective in deprived mice as in controls. The possibility that hycanthone, oxamniquine, praziquantel, and previously studied antimony act synergistically with immune effector mechanisms in killing adult schistosomes is discussed.     

Measurements of conformational changes during adhesion of lipid and protein (polylysine and S-layer) surfaces

The adhesion forces between various surfaces were measured using the "surface forces apparatus" technique. This technique allows for the thickness of surface layers and the adhesion force between them to be directly measured in controlled vapor or liquid environments. Three types of biological surfaces were prepared by depositing various lipid-protein monolayers (with thicknesses ranging from 1 to 4 nm) on the inert, molecularly smooth mica surface: (i) hydrophobic lipid monolayers; (ii) amphiphilic polyelectrolyte surfaces of adsorbed polylysine; and (iii) deposited bacterial S-layer proteins. The adhesion, swelling, and wetting properties of these surfaces was measured as a function of relative humidity and time. Initial adhesion is due mainly to the van der Waals forces arising from nonpolar (hydrophobic) contacts. Following adhesive contact, significant molecular rearrangements can occur which alter their hydrophobic-hydrophilic balance and increase their adhesion with time. Increased adhesion is generally enhanced by (i) increased relative humidity (or degree of hydration); (ii) increased contact time; and (iii) increased rates of separation. The results are likely to be applicable to the adhesion of many other biosurfaces, and show that the hydrophobicity of a lipid or protein surface is not an intrinsic property of that surface but depends on its environment (e.g., on whether it is in aqueous solution or exposed to the atmosphere), and on the relative humidity of the atmosphere. It also depends on whether the surface is in adhesive contact with another surface and-when considering dynamic (nonequilibrium) conditions-on the time and previous history of its interaction with that surface. (c) 1993 John Wiley & Sons, Inc.     

Triadimefon a Plant Multi-Protectant

Triadimefon belongs to a group of highly active fungicides whichinhibit sterol biosynthesis. This report demonstrates that triadimefonin addition to its established fungicidal properties, also protectsplants from injury due to drought, chilling and ozone. (Received November 6, 1984; Accepted March 6, 1985)     

Diacylglycerol lipase and kinase activities in rat brain microvessels

Diacylglycerols can accumulate transiently in intact cells as a consequence of the degradation of phosphatidylinositol by phospholipase C, but little information is available concerning their metabolic fate in the vascular endothelium. Diacylglycerol lipase and kinase activities were measured in rat brain microvessel preparations. Lipase activity, measured by the release of free fatty acids, was much greater at pH 4.5 than at pH 7. The acid lipase was predominantly particulate and likely originated in lysosomes, whereas the neutral lipase was mainly soluble. The fatty acid at the sn-1 position of the diacylglycerol substrate was hydrolyzed faster than that at the sn-2 position at both pH 4.5 and 7. The 2-monoacylglycerol accumulated at pH 4.5 but not at 7 due to the presence of a monoacylglycerol lipase activity with a neutral pH optimum. The formation of phosphatidic acid (kinase activity) was also measured in microvessels. When lipase and kinase activities were measured simultaneously, the formation of phosphatidic acid from a 1-palmitoyl-2-[1-14C]oleoyl-sn-glycerol substrate was 4-fold greater than the release of fatty acid (oleate) from the sn-2 position. Introduction of arachidonic acid to the sn-2 position of the diacylglycerol substrate increased kinase activity but reduced lipase activity. The release of fatty acids from the sn-2 position of phosphatidic acid could not be detected.     

Effect of metformin on insulin receptor binding and glycaemic control in type II diabetes.

To investigate the effect of metformin on insulin receptor binding and diabetic control, eight obese type II diabetic patients were studied before treatment, after one and four weeks of taking metformin (500 mg thrice daily), and four weeks after withdrawal of the drug. After one and four weeks of treatment the number of erythrocyte insulin receptors had increased by 116% and 184% respectively. This was due almost entirely to an increase in the number of low affinity binding sites. The number of receptors was still raised four weeks after metformin had been withdrawn. Diabetic control as assessed by urinary glucose, glycosylated haemoglobin (HbA1), and glucose tolerance values was significantly improved during metformin treatment, while plasma insulin concentrations were not altered. These results indicate that metformin produces a rapid and protracted increase in low affinity insulin receptors in type II diabetes, associated with greater insulin sensitivity and improved diabetic control.     

Acclimation of different strains of the olive fly, Dacus oleae, to low temperatures

Male and female D. oleae have similar powers of acclimation when exposed to low temperatures. Their torpor thresholds depend upon the temperature to which they have been acclimatised. During slow cooling (i.e. less than 1°C per min) they are capable of some rapid acclimation which enables them to lower their torpor threshold by almost 1°C degree, as compared with when they are chilled quickly. After abrupt transfer from 25°C to a different temperature, acclimation takes some time to be accomplished. At 15°C and above it occurs within 10 days but at temperatures below this, progressive acclimation lowers the torpor thresholds to the very low levels typical of flies overwintering under natural conditions. During this long term acclimation torpor thresholds may change by almost 0.5°C per 1°C change of acclimation temperature.No differences were observed in the ability of either flies from northern and southern Greece, or normal and γ-irradiated laboratory reared flies to acclimate to winter conditions in the field. In all cases, torpor thresholds were progressively lowered in advance of the decline in weekly minimum temperatures.     

Bronchial Reactivity to Cigarette and Cigar Smoke

The change in specific airway conductance produced by smoking a cigarette under standard conditions was measured in 91 heavy smokers. Subsequently 19 of the most reactive subjects smoked two cigarettes with different filters and another containing cigar tobacco. The results indicated that reactivity to cigarette smoke was reduced significantly by increasing the retention efficiency of the filter and that reactivity to inhaled cigar-tobacco smoke was no less than that to cigarette smoke.     

Field of genes: the politics of science and identity in the Estonian genome project

This case study of the Estonian Genome Project (EGP) analyses the Estonian policy decision to construct a national human gene bank. Drawing upon qualitative data from newspaper articles and public policy documents, it focuses on how proponents use discourse to link the EGP to the broader political goal of securing Estonia's position within the Western/European scientific and cultural space. This dominant narrative is then situated within the analytical notion of the “brand state”, which raises potentially negative political consequences for this type of market‐driven genomic research. Considered against the increasing number of countries engaging in gene bank and/or gene database projects, this analysis of Estonia elucidates issues that cross national boundaries, while also illuminating factors specific to this small, post‐Soviet state as it enters the global biocybernetic economy.     

Growth and developmental stability of Drosophila melanogaster in low frequency magnetic fields

Magnetic fields (60 Hz) of 1.5 and 80 microT caused a significant reduction in the weight of Drosophila melanogaster. Moreover, fruit flies in an 80 microT field showed lower developmental stability than either those in a 0 or 1.5 microT field. Developmental instability was measured by fluctuating asymmetry and frequency of phenodeviants. More of the flies in the 80 microT field had fused abdominal segments, and they were more asymmetrical for wing vein R(4+5). The flies in the 1.5 microT field actually showed greater developmental stability than the control flies. Fewer of them had fused abdominal segments, and they were more symmetrical for wing vein R(4+5). Thus, at low field strengths, flies are more developmentally stable than control flies, even though they weigh less.