Detection of toxic metabolites in the hemolymph ofBeauveria bassiana infectedSpodoptera exigua larvae

Highly active metabolites have been detected in the hemolymph of the lepidopteranSpodoptera exigua infected with the mycopathogen,Beauveria bassiana. A combination of phenyl sepharose and CM ion exchange chromatography was utilized to extract the active metabolites from infected hemolymph samples. The active in vivo metabolites, having a molecular mass greater than 10 KDa, were thermolabile and were inactivated by proteinase K. These metabolites were characterized by their ability to disrupt metamorphosis, killing treated larvae at the wandering or pupal stage. Additionally, injection ofS. exigua larvae with active samples caused a reduction in the number of filopodial-producing hemocytes. The biological activities and biochemical properties suggest that novel compounds are produced duringB. bassiana mycosis.     

‘Action substances’ of peripheral nerve re-visited

Fifty years ago, four action substances were described as being liberated from peripheral nerve in the course of activity. An attempt has been made to update this information. Confirmatory evidence is available that acetylcholine and thiamine do play a role in the course of activity. However, the question of the relationship in time between their release and the electrical events, and the possible effect on specific ionic gating mechanisms, remains unclarified. The liberation of potassium has been found to be a transmembrane K efflux, and the question of the existence of another substance similar to thiamine has not been pursued.a member of the Editorial Board of EXPERIENTIA from 1974 to 1982     

Pineal ‘synaptic’ ribbon numbers and melatonin synthesis of rat are resistant to guanethidine sympathectomy

Chemical sympathectomy is widely used to study the impact of the noradrenergic system on neuronal and neuroendocrine circuits. We tested the effects of intraperitoneal injections of guanethidine, an adrenergic neuron blocking agent, on selected functional parameters of the rat pineal gland which are known to be under sympathetic influence. The reliability of the method was demonstrated by the clear enophthalmus developed by experimental animals. However, neither the numbers of synaptic ribbons nor melatonin synthesis differed between treated and control rats, both parameters exhibiting the nocturnal increase seen in intact animals. These results are in striking contrast to those obtained upon chemical sympathectomy with 6-hydroxydopamine or surgical superior cervical ganglionectomy. We conclude that guanethidine is not capable of sufficiently removing noradrenergic influence from the rat pineal gland, and that this substance is thus inferior to other experimental methods of sympathectomy.     

Presence of hsp65 in bacterial extracts (OM-89): A possible mediator of orally-induced tolerance?

Heat shock proteins (HSP) have been implicated in rodent models of autoimmunity, particularly arthritis, and there is suggestive though inconclusive evidence that they may also play a role in human autoimmune disease. The simplest hypothesis is based on molecular mimicry due to the amino-acid sequence homology between mammalian and microbial HSP. Recently OM-89, an extract of several strains ofEscherichia coli, has shown some efficacy in the treatment of rheumatoid arthritis (RA) when taken orally. Using species-specific antibodies, we show here that OM-89 contains the 65 kDa HSP (hsp65), while hsp65 was not detected in another bacterial extract containing other microorganisms, includingStaphylococcus aureus (OM-85). We suggest that if the human homologue of hsp65 is a relevant target antigen in the human disease, the efficacy of the preparation could be due to induction of oral tolerance or to switching the Th1 response towards Th2. Alternatively, even if the human hsp65 is not a target molecule in RA joints, OM-89 may evoke bystander suppression of joint inflammation via induction of TGF-secreting effector cells. These hypotheses should be tested in further studies.     

Occurrence of 3-epi-22-deoxy-20-hydroxyecdysone and its phosphoric ester in diapause eggs of the silkworm,Bombyx mori

Ecdysteroids in diapause eggs of the silkworm,Bombyx mori, were analyzed using high-performance liquid chromatography (HPLC) combined with radioimmunoassay (RIA). A relatively large amount of an unidentified free ecdysteroid and its phosphoric ester (conjugated form) were detected. These two compounds were isolated by a combination of column chromatography on silicic acid, thin-layer chromatography (TLC), and HPLC using a reverse-phase (RP) column. The purified compounds were identified as 3-epi-22-deoxy-20-hydroxyecdysone (22d20E) and 3-epi-22-deoxy-20-hydroxyecdysone 2-phosphate (22d20E2P) by means of mass spectrometry and nuclear magnetic resonance spectroscopy. to our knowledge, this is the first report of 22d20E and 22d20E2P.     

Thrombospondin co-localises with TGFβ and IGF-I in the extracellular matrix of human osteoblast-like cells and is modulated by 17β estradiol

Thrombospondin (TSP) is a multifunctional glycoprotein which is synthesised by several cell types including osteoblasts, and incorporated into the extracellular matrix (ECM) of these cells. The function and regulation of TSP in bone is not clear. In this study, using a long term culture model of human osteoblast-like cells, we examined the distribution of TSP in the ECM and its modulation by added estradiol. In this model the osteoblast-like cells form a regular multilayer which continues to increase in depth up to 50 days post confluence. In the ECM of these cultures and in 19-week fetal bone, the bone markers osteocalcin and alkaline phosphatase were diffusely distributed in the matrix. In contrast, labelling for TSP was concentrated, confined to the banded collagen and its immediately adjacent ECM. This pattern of labelling resembled that of the growth factors transforming growth factor-I (TGF), and insulin-like growth factor-I (IGF-I), with which TSP label co-localised. Labelling intensities were comparable between fetal bone and the in vitro material for TSP, TGF and IGF-I. TSP label was present by 10 days post confluence, reached a maximum by 20 days, and declined slowly thereafter, a time course which was similar to that of IGF-I. Incubation of osteoblast-like cell cultures with 17 estradiol resulted in an increase in multilayer depth and a maximal 3-fold increase in TSP labeling at 30 days as well as approximately 2-fold increases for TGF and IGF-I. The dose-response relationship for these responses to estradiol treatment was biphasic with maximal increases at 10^–10 M–10^–11 M of added estradiol. Treatment with 17 estradiol produced labelling intensities that were not significantly different from controls. Studies with other cell types have suggested that TSP may be involved in modulation of growth factor activity. The similarities between TSP, TGF and IGF-I, in terms of their distribution and regulation by 17 estradiol treatment, may indicate a role for TSP in modulating bone cell proliferation and function through interaction with local growth factors.     

Sex pheromone of the pine sawflyDiprion pini (Hymenoptera: Diprionidae): Chemical identification,synthesis and biological activity

The main component of the sex pheromone secretion of femaleDiprion pini L. (Hymenoptera: Diprionidae) from insects collected both in Finland and in France has been identified as athreo-3,7-dimethyl-2-tridecanol (8 ng per female) stereoisomer by GC-MS and synthesis. The secretion also contains lower and higher homologues in small amounts (1–4% of the main component). Combined gas chromatographic-electroantennographic detection showed activity in both natural and esterified extracts (acetates and propionates); the esters of the main component gave the largest responses. The acetates and propionates of the eight stereoisomers of 3,7-dimethyl-2-tridecanol were synthesized from enantiomerically highly enriched (>99% ee) building blocks. The stereochemistry of the main component was established to be (2S,3R,7R)-3,7-dimethyl-2-tridecanol by GC analysis of the natural material. It was purified by liquid chromatography prior to the GC analysis of both its pentafluorobenzoates and its isopropylcarbamates on a non-chiral polar column (ECD) and a chiral column (NPD), respectively. Field tests demonstrated that both the acetate and propionate of the main component (100 g of each applied on cotton roll dispensers) were active in attracting males, with or without the presence of several of the minor compounds. Experiments with smaller amounts of the acetate and the propionate (1 g in France and 50 g in Finland) demonstrated that the propionate was more active than the acetate, and that it also caught more males than a blend of the two compounds.     

Fourth World Conference on Women: the Namibian perspective

This consideration of some of the issues raised at the Fourth World Conference on Women (WCW) from a Namibian perspective begins by mentioning the pernicious nature of domestic violence and briefly summarizing some of the main points raised at a 1994 symposium on domestic violence. The discussion continues by noting that Namibia's report for the WCW reaffirms that it is crucial for women to be involved in the decision-making process at all levels. Next, the paper notes that traditional male attributes of strength are losing their importance in a world that values mental alertness, intuition, and traditional female qualities of love and service. This has led to a call for a transformation of society supported by the education of women and their economic empowerment. The essay ends by defining an empowered person as possessing a belief in the ability of human intervention to change the world, a sense of self-worth, a sense of the self as a viable agent of change, and a notion of what constitutes a better life.     

Atmospheric carbon dioxide concentrations before 2.2 billion years ago

The composition of the Earth's early atmosphere is a subject of continuing debate. In particular, it has been suggested that elevated concentrations of atmospheric carbon dioxide would have been necessary to maintain normal surface temperatures in the face of lower solar luminosity in early Earth history. Fossil weathering profiles, known as palaeosols, have provided semi-quantitative constraints on atmospheric oxygen partial pressure (pO2) before 2.2 Gyr ago. Here we use the same well studied palaeosols to constrain atmospheric pCO2 between 2.75 and 2.2 Gyr ago. The observation that iron lost from the tops of these profiles was reprecipitated lower down as iron silicate minerals, rather than as iron carbonate, indicates that atmospheric pCO2 must have been less than 10(-1.4) atm--about 100 times today's level of 360 p.p.m., and at least five times lower than that required in one-dimensional climate models to compensate for lower solar luminosity at 2.75 Gyr. Our results suggest that either the Earth's early climate was much more sensitive to increases in pCO2 than has been thought, or that one or more greenhouse gases other than CO2 contributed significantly to the atmosphere's radiative balance during the late Archaean and early Proterozoic eons.     

用于VLSI的新型介质膜界面陷阱的特征

采用雪崩热电子注入技术和高频Ｃ－Ｖ准静态Ｃ－Ｖ特性测试,研究了新型快速热氮化的ＳｉＯｘＮｙ介质膜界面陷阱的特征,侧重于研究界面陷阱的特性与分布。结果表明：这种ＳｉＯｘＮｙ薄膜禁带中央界面陷阱密度随氮化时间的分布变化呈现”回转效应“,且存在着不同类型、密度悬殊很大的电子陷阱、指出雪崩热电子注入过程中在Ｓｉ／ＳｉＯｘＮｙ界面上产生两种性质不同的快界面态陷阱;给出了这两种界面态陷阱密度在禁带中能量的分布