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C Montecucco, E Papini, G Schiavo
A group of bacterial protein toxins interfere with vesicular trafficking inside cells. Clostridial neurotoxins affect mainly the highly regulated fusion of neurotransmitter- and hormone-containing vesicles with the plasma membrane. They cleave the three SNARE proteins: VAMP, SNAP-25 and syntaxin, and this selective proteolysis results in a blockade of exocytosis. The Helicobacter pylori cytotoxin is implicated in the pathogenesis of gastroduodenal ulcers. It causes a progressive and extensive vacuolation of cells followed by necrosis, after a cytotoxin-induced alteration of membrane trafficking by late endosomes...
December 15, 1996: Experientia
D A Lightner, D L Holmes, A F McDonagh
High-field 13C-NMR of 13C-enriched compounds in dilute aqueous d6-Me2-SO solutions provides a simple, accurate method for measuring pK(a)s of sparingly soluble carboxylic acids. Using this method, we found the pK(a)s of mesobilirubin-XIII alpha to be 4.2 and 4.9, much lower values than reported recently for bilirubin, and of mesobiliverdin-XIII alpha to be 3.9 and 5.3.
June 15, 1996: Experientia
A R Dluzewski, C R Garcia
We have examined the effects of seven protein kinase inhibitors (staurosporine, genistein, methyl 2,5-dihydroxycinnamate, tyrphostins B44 and B46, lavendustin A and R03) on the erythrocytic cycle of the malaria parasite, Plasmodium falciparum. One (staurosporine) strongly inhibits serine/threonine kinases, but the remainder all exhibit a strong preference for tyrosine kinases. We have been able to discriminate between effects on invasion and on intraerythrocytic development. All reagents impeded development of intraerythrocytic parasites, though at widely differing concentrations, from the sub-micromolar to the millimolar...
June 15, 1996: Experientia
H Baker, B DeAngelis, O Frank, M Khalil, S H Hutner, E R Baker
Using a prokaryote (Escherichia coli) and a metazoa-resembling eukaryote (Ochromonas danica), we surveyed antioxidants which might overcome redox stress imposed by menadione sodium bisulphite (MD) and buthionine sulphoximine (BSO). BSO oxidant stress was evident only in O. danica; MD oxidant stress was evident in both organisms. Glutathione, its precursors, e.g. cysteine, homocysteine, and 2-oxo-4-thiazolidine carboxylic acid, and red blood cells, emerged as prime antioxidants for relieving BSO and MD oxidant stress...
June 15, 1996: Experientia
A A Shaheen, A Abd El-Fattah, M Z Gad
The level of malondialdehyde (MDA), an index of lipid peroxidation, and the antioxidants superoxide dismutase (SOD) and glutathione (GSH), as well as the activity of Na+, K(+)-ATPase, were assessed in whole rat brain after immobilization, anemic hypoxia (NaNO2) and 72 h starvation. The effect of these stressors on plasma glucose and corticosterone levels was also observed. Hypoxia and starvation stimulated the lipid peroxide formation in brain as indicated by an increase in the level of MDA, being higher after starvation than hypoxia...
April 15, 1996: Experientia
I W Althaus, K M Franks, K B Langley, F J Kézdy, T Peterson, S E Buxser, D E Decker, L A Dolak, R G Ulrich, F Reusser
Few inhibitors of the RNase H function associated with the HIV-1 reverse transcriptase have been discovered to date. We observed that three novenamines, U-34445, U-35122, and U-35401, are specific inhibitors of the HIV-1 RT RNase H function. All three compounds are strong amphiphiles and contain one ionizable group. Hence, a priori, in aqueous solutions the inhibitors might exist in at least four different physical states, namely protonated monomers, ionized monomers, protonated micelles, and ionized micelles...
April 15, 1996: Experientia
M Asensi, A Garcia-España, F V Pallardó, J Vina, J M Estrela
The ability of nonprotein thiols to modulate rates of protein synthesis was investigated in isolated rat hepatocytes. Addition of cysteine stimulates protein labelling by [14C]Leucine. Glutathione depletion, induced by in vivo administration of L-buthionine sulfoximine and diethylmaleate, did not alter the effect of cysteine, although it decreased the rate of protein synthesis by 32%. The effect of cysteine on protein synthesis does not seem to be related to a perturbation of the redox state of the NAD+/NADH system or to changes in the rate of gluconeogenic pathway...
February 15, 1996: Experientia
M L Wise, K Soderstrom, T F Murray, W H Gerwick
A polyenoic fatty-acid isomerase (PFI) from a red marine alga was used to convert anandamide (5Z,8Z,11Z,14Z-eicosatetraenoyl-N-ethan olamide) to the 5Z,7E,9E,14Z-eicosatetraenoyl-N-ethanol amide isomer. This novel eicosanoid, termed conjugated triene anandamide (CTA), was assessed for its ability to bind to the cannabinoid receptor in rat brain membrane preparations. CTA is a high affinity cannabimimetic substance whose novel structure provides new insight into structure-activity relationships of cannabinoid receptor ligands...
January 16, 1996: Experientia
A A Noegel, J E Luna
New avenues of cytoskeleton research in Dictyostelium discoideum have opened up with the cloning of the alpha- and beta-tubulin genes and the characterization of kinesins and cytoplasmic dynein. Much research, however, continues to focus on the actin cytoskeleton and its dynamics during chemotaxis, morphogenesis, and other motile processes. New actin-associated proteins are being identified and characterized by biochemical means and through isolation of mutants lacking individual components. This work is shedding light on the roles of specific actin assemblies in various biological processes...
December 18, 1995: Experientia
A Kuspa, T Dingermann, W Nellen
Over the past ten years, powerful molecular genetic techniques have been developed to analyze gene function in Dictyostelium. DNA-mediated transformation using a variety of selections and vectors has allowed the introduction of wild-type or modified genes that are under various forms of transcriptional control. Homologous recombination is efficient and can be used to modify the genome in precise ways. In addition, it is now possible to clone genes based on their mutant phenotype alone, either by insertional mutagenesis, or by screening antisense expression cDNA libraries...
December 18, 1995: Experientia
M N Tkachenko, V F Sagach
The results of experiments with isolated strips of rat portal vein, and of 'sandwich' experiments involving strips of the portal vein or aorta, revealed the involvement of endothelin in the development of myogenic reactions of the vascular smooth muscle, observed on distension of the vascular wall. Released by the endothelial cells, endothelin is capable of stimulating the contraction of these muscles.
September 29, 1995: Experientia
J Vittek
The primary objective of this review was to assess the size and consistency of Royal Jelly (RJ) effect on serum lipids in experimental animals and humans. The data from animal studies were pooled, where possible, and statistically evaluated by Student's t-test. Meta-analysis was used for the evaluation of human trials. It was found that RJ significantly decreased serum and liver total lipids and cholesterol levels in rats and rabbits and also retarded the formation of atheromas in the aorta of rabbits fed a hyperlipemic diet...
September 29, 1995: Experientia
M V Novotny, T M Xie, S Harvey, D Wiesler, B Jemiolo, M Carmack
Two male mouse pheromones, 3,4-dehydro-exo-brevicomin (DHB) and 2-sec-butyldihydrothiazole (SBT), are chiral molecules which were previously tested in their respective bioassays as racemic mixtures. The focus of this study has been to determine the absolute configuration of their natural forms and its relation to stereospecific biological action. DHB was established as the R,R-enantiomer possessing biological activity. Due to an extremely easy racemization of SBT under very mild conditions, enantioselectivity of its transmission and its action at the receptor site appear to be of secondary importance...
July 14, 1995: Experientia
S J Won, Y C Chuang, W T Huang, H S Liu, M T Lin
The effects of dopaminergic receptor inhibitors such as thiothixine (D1/D2), fluphenazine (D1/D2), trifluoperazine (D1/D2), pimozide (D2), flupenthixol (D1/D2), (+/-)-SKF 83566 (D1), and spiperone (D2) on splenic natural killer (NK) cell cytotoxic activities were assessed in vitro using mouse spleen lymphocytes or enriched NK cells. Both the activities of the splenic NK cell cytotoxicity and the effector-target cell conjugation were suppressed by thiothixine, fluphenazine, and trifluoperazine at concentrations from 2...
April 15, 1995: Experientia
N Liu, T Tomita, J G Scott
A cytochrome P450, termed P450lpr, is the major P450 responsible for pyrethroid resistance in the Learn-PyR (LPR) strain of house fly. Recently, the putative gene (CYP6D1) coding for P450lpr has been sequenced from the LPR and aabys strains of house fly. Allele-specific polymerase chain reaction (ASPCR) was used for linkage group analysis with backcross progeny from the wild type LPR strain and a multiple marker strain (aabys). We found that CYP6D1 is linked to chromosome 1. The possible role of regulatory or modifying genes responsible for elevated P450lpr expression is discussed in relation to the chromosomal linkage of CYP6D1...
February 15, 1995: Experientia
M Batiste-Alentorn, N Xamena, A Creus, R Marcos
To provide further background data on the wing spot somatic mutation and recombination assay, 10 selected carcinogens (acetamide, acrylamide, benzo(a)pyrene, cyclophosphamide, diethylstilbestrol, 4-nitroquinoline N-oxide, propyleneimine, safrole, thiourea, and o-toluidine) were tested in this assay. 72-h-old third-instar larvae, trans-heterozygous for 2 recessive wing cell markers: multiple wing hairs (mwh) and flare3 (flr3) were fed with 3 concentrations of each carcinogen during the rest of their development until pupation, and the genotoxic effects were measured as significant increases in the appearance of visible mutant hair clones on the adult wing blade...
January 15, 1995: Experientia
Y Oshima, K Namao, A Kamijou, S Matsuoka, M Nakano, K Terao, Y Ohizumi
The methanol extract of the Oriental medicinal plant Vitis coignetiae (Vitaceae) showed hepatoprotective activity in the in vitro assay method using primary cultured rat hepatocytes. Activity-guided fractionation of the extract afforded epsilon-viniferin as an active principle. The protective effect of epsilon-viniferin against mice carbon tetrachloride-induced hepatic injury in mice was shown by serum enzyme assay as well as by pathological examination. In addition to epsilon-viniferin, plant oligostilbenes, ampelopsins A, C, F and the mixture of vitisin A and cis-vitisin A were also present in the extract...
January 15, 1995: Experientia
A I Spielman, X N Zeng, J J Leyden, G Preti
The characteristic odor which arises in the human axillary region consists of volatile C6-C11 acids with the most abundant being (E)-3-methyl-2-hexenoic acid (E-3M2H). This acid, as well as several other components of the characteristic axillary odor, can be liberated from the odorless, aqueous soluble components of apocrine secretion by either saponification or bacteriolysis. It is therefore likely that a major characteristic odor is being carried to the skin surface bound to a water soluble precursor where it is liberated by axillary bacteria...
January 15, 1995: Experientia
B Iyengar
The pineal, serotoninergic and pigmented neurons are associated with light-dependent sleep/arousal, serving as a biological clock with a circadian rhythm. This rhythm is maintained by melatonin which serves to recognise the 'dark' phase. The neural network that responds to seasonal variations in day/night length has not been identified. The present study demonstrates that melanocytes in human skin respond to changes in the duration of UV exposure, and can serve as a biological calendar. These responses are mediated by two indoleamines, serotonin and melatonin...
August 15, 1994: Experientia
S F De Cabo, M J Hazen, M L Molero, J Fernández-Piqueras
The cytotoxic effect caused by the hypomethylating agent S-adenosyl-L- homocysteine (SAH) was compared with that of two drugs commonly used to induce DNA hypomethylation, 5-azacytidine and 5-aza-2'-deoxycytidine. Two in vitro cytotoxicity tests, the tetrazolium MTT assay and the intracellular lactate dehydrogenase (LDH) activity test, suggest that SAH induces hypomethylation without causing any cytotoxic effect. We propose the use of SAH as a non-cytotoxic agent which may be more suitable for inducing experimental DNA hypomethylation...
July 15, 1994: Experientia
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