Cytotoxicity of ethyl methanesulfonate in mice spermatogonia.

Enumeration of different types of spermatogonia, following a single i.p. administration of different doses of ethyl methanesulfonate in mice, showed a survival of A1-A4 and in spermatogonia is markedly reduced due to cell killing while the remaining types of spermatogonia were affected marginally. The cell killing effect was dose-dependent, and replenishment of these cells was observed by the end of one cycle of the seminiferous epithelium comprising of 8.5 days.     

Thyroid hormone receptor-mediated regulation of the methionine adenosyltransferase 1 gene is associated with cell invasion in hepatoma cell lines

The thyroid hormone T₃ regulates differentiation, growth, and development. We demonstrated that methionine adenosyltransferase 1A (MAT1A) was positively regulated by T₃ identified by cDNA microarray previously. The expression of the MAT1A was upregulated by T₃ in hepatoma cell lines overexpressing thyroid hormone receptors (TRs). Additionally, these findings indicate that MAT1A may be regulated by CCAAT/enhancer binding protein (C/EBP). The critical role of the C/EBP binding sites was confirmed by the reporter or chromatin immuno-precipitation (ChIP) assay. In addition, C/EBP was upregulated in hepatoma cells after T₃ treatment and ectopic expression of MAT1A inhibited cell migration and invasion in J7 hepatoma cells. Conversely, knockdown of MAT1A expression increased cell migration. Together, these findings suggest that the expression of the MAT1A gene is mediated by C/EBP and is indirectly upregulated by T₃. Finally, TR was downregulated in a small subset of hepatocellular carcinoma cells concomitantly reduced the expression of C/EBPα and MAT1A.     

Arachidonic acid release by ionomycin and phorbol ester is similar in C127 epithelial cells expressing wild-type or mutated (ΔF508) cystic fibrosis transmembrane conductance regulator

The Ca²⁺ ionophore ionomycin induced cytosolic [Ca²⁺]_i elevation as well as strong activation of Cl⁻ efflux in mouse mammary epithelial cell lines expressing wild-type or mutated (deletion of phenylalaline 508) cystic fibrosis transmembrane conductance regulator (CFTR) or vector. Ionomycin-induced Cl⁻ efflux was abolished by the intracellular Ca²⁺ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid, whereas both activators and inhibitors of phospholipase A₂ had no effect, indicating the involvement of Ca²⁺-dependent Cl^- channels. Stimulation of arachidonic acid release by ionomycin and phorbol ester was not significantly different between wild-type or mutated cell lines, whereas vector-transfected cells exhibited a significant higher release, which was shown to be due to larger amount of immunoreactive cytosolic phospholipase A₂. These results indicate that phospholipase A₂ activity of C127 cells was not influenced by the presence of wild-type or mutated CFTR. Received 27 April 1999; received after revision 11 June 1999; accepted 23 July 1999     

Comparative potency of gibberellins in inducing parthenocarpic fruit growth inMalus sylvestris mill

Zusammenfassung Die biologische Wirksamkeit der Gibberelline A₁ bis A₁₀, A₁₃ und A₁₄ wurde bei der Einsetzung von Parthenokarpie inMalus sylvestris Mill. festgestellt. Die Gibberelline A₄ und A₇ waren sehr wirksam, A₁, A₂, A₃, A₉, A₁₀, A₁₃ und A₁₄ waren von mittelmässiger Wirksamkeit, während A₅, A₆ und A₈ waren unwirksam. Die mehr wirksamen Gibberelline besitzen, vom molekularen Standpunkt betrachtet, in der Stellung 7 keine OH-Gruppe.

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On leave from Osaka Prefecture University, Osaka, Japan.     

A2 adenosine receptors in human glomerular mesangial cells

A₂ adenosine receptors were characterized in human glomerular mesangial cells using [³H] 5-N-ethylcarboxamidoadenosine (NECA) as a tracer. There was a single group of receptor sites with a K_D of 184 nM, and a number of sites of 317 fmol/mg of cell protein. Adenosine agonists increased 5-nucleotidase activity via A₂ receptor stimulation. The specific A₂ agonist-NECA, at 0.1 and 1 m, was a potent inhibitor of DNA synthesis.     

Die Dünnschichtchromatographie von Gibberellinen

Summary Thin-layer chromatography on silica gel is described as a new method for the separation and identification of the gibberellins A₁, A₃, A₄, A₅, A₇, A₈, and A₉.     

Caffeine as a psychomotor stimulant: mechanism of action

The popularity of caffeine as a psychoactive drug is due to its stimulant properties, which depend on its ability to reduce adenosine transmission in the brain. Adenosine A₁ and A_2A receptors are expressed in the basal ganglia, a group of structures involved in various aspects of motor control. Caffeine acts as an antagonist to both types of receptors. Increasing evidence indicates that the psychomotor stimulant effect of caffeine is generated by affecting a particular group of projection neurons located in the striatum, the main receiving area of the basal ganglia. These cells express high levels of adenosine A_2A receptors, which are involved in various intracellular processes, including the expression of immediate early genes and regulation of the dopamine- and cyclic AMP-regulated 32-kDa phosphoprotein DARPP-32. The present review focuses on the effects of caffeine on striatal signal transduction and on their involvement in caffeine-mediated motor stimulation.Received 8 July 2003; received after revision 7 September 2003; accepted 6 October 2003     

Préparation des acides desoxyribonucléiques de foie de rat par filtration sur Ultrogel A 2

Summary Rat liver DNA was prepared by 2 successive filtrations on Ultrogel A 2 (LKB, Sweden). The method gives a high yield (2.33 mg/g of fresh liver) of pure (A₂₆₀/A₂₃₀=2.44, A₂₆₀/A₂₈₀=1.88) HMW-DNA (s=26.2 S).     

Sopra un caso particolare della superficie F 4 (3) di M. Noether

Summary The Noetherian surfaceF ₄ ⁽³⁾ , which is represented on a plane by a linear ³ system ofC ₉(A ₁ ³ A ₂ ³ A ₃ ³ A ₄ ³ A ₅ ³ A ₆ ³ A ₇ ³ A ₈ ³ A ₉ ² A ₁₀), possesses generally only one linear pencil of elliptic cubics. IfA _i (i=1, 2, , 9) are the basis points of aHalphen pencil ofC ₉,A ₁₀ is infinitely near toA ₉, and in this caseF ₄ ⁽³⁾ is a not trivial example of such a surface with two pencils of elliptic cubics.     

Die Hämagglutination des Influenzavirus A2-Hongkong

Summary A₂-Hongkong influenza virus does not agglutinate the erythrocytes of the cow, the calf, the horse, the pony and the spiny mouse at room temperature, while the A₂-Asia influenza virus causes agglutination. At a temperature of 4 °C A₂-Hongkong was able to agglutinate the erythrocytes of all species examined except those of the spiny mouse. Whether the A₂-Hongkong virus does or does not agglutinate the erythrocytes of the chicken, the donkey, the goat, the spiny mouse and the horse at room temperature could depend on the speed of elution.     

Cytogenetic analysis of bone marrow cells and spermatogonia of male mice after in vivo treatment with arsenic

Summary Male Swiss Albino mice were injected i.p. with an As₂O₃ solution (0; 4; 8 and 12 mg As/kg) and sacrificed 12, 24, 36 and 48 h after injection. Neither chromatid nor chromosome aberrations were observed in bone marrow cells and spermatogonia.Acknowledgments. We thank Mr L. De Langhe for skillfull technical help. We acknowledge this work was supported by a grant of the Ministery of Public Health.     

The glycerophosphoinositols: cellular metabolism and biological functions

The glycerophosphoinositols are cellular products of phospholipase A₂ and lysolipase activities on the membrane phosphoinositides. Their intracellular concentrations can vary upon oncogenic transformation, cell differentiation and hormonal stimulation. Specific glycerophosphodiester phosphodiesterases are involved in their catabolism, which, as with their formation, is under hormonal regulation. With their mechanisms of action including modulation of adenylyl cyclase, intracellular calcium levels, and Rho-GTPases, the glycerophosphoinositols have diverse effects in multiple cell types: induction of cell proliferation in thyroid cells; modulation of actin cytoskeleton organisation in fibroblasts; and reduction of the invasive potential of tumour cell lines. More recent investigations include their effects in inflammatory and immune responses. Indeed, the glycerophosphoinositols enhance cytokine-dependent chemotaxis in T-lymphocytes induced by SDF-1α-receptor activation, indicating roles for these compounds as modulators of T-cell signalling and T-cell responses.     

Zur Kenntnis von Levorin A und Candicidin

Summary A sample of Russian provenance of the antifungal antibiotic levorin A, containing 30,000 microbiological units of activity/mg, was shown to consist of several components. Three components, designated levorin A₁, A₂ and A₃, were isolated and shown to be distinguishable by their partition coefficients in the system chloroform-methanol-borate buffer pH 8.4 (2:2:1). An enriched sample of the antifungal antibiotic candicidin, prepared from a commercial preparation of American provenance, showed a very similar pattern of distribution as levorin A did in 600 transfers. Levorin A₂, the main component of the levorin A sample, was not distinguishable within the error limits of the applied tests, from the main component of the enriched candicidin sample.

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64. Mitteilung der Reihe «Stoffwechselprodukte von Mikroorganismen». 63. Mitteilung: Experientia, im Druck (1968).     

Versuche zum enzymatischen Abbau der «gebundenen» gibberelline vonPharbitis purpurea

Summary Seeds and fruit walls ofPharbitis purpurea contain in addition to the free gibberellins A₈, A₃, A₅, more polar gibberellin-like substances, so-called bound gibberellins tentatively namedPharbitis and. After purification by thin layer chromatography, these 2 substances were treated with both Ficin and Emulsin in buffered solutions of pH 6.2. After treatment with Emulsin, the free gibberellins A₈ and A₅, after treatment with Ficin the gibberellins A₃ and A₅, were detectable in thin layer chromatograms.     

Über ein gebundenes Gibberellin ausPhaseolus coccineus L.

Summary In addition to gibberellins A₁, A₅, A₆ and A₈ previously isolated fromPhaseolus coccineus L., the occurrence of gibberellin A₃ and of 5 new gibberellin-like substances «Phaseolus -» was demonstrated. «Phaseolus» was proved to be a gibberellin bound to carbohydrates and ninhydrin-positive compounds.

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Gibberelline, II. Mitteilung. — I. Mitt. sieheG. Sembdner, R. Gross undK. Schreiber, Exper.18, 584 (1962).     

Noise and ‘pedagogic efficiency’ in school activities

Summary A group of 8 pupils born in 1962 and a group of 8 future teachers between 25 and 40 years of age, were submitted in 1975 to two types of tests in the presence of environment noises at various levels (45 to 75 dB_A), in order to assess the influence of this nuisance on the pedagogic efficiency. The results show a nocivity threshold for the pupils at around 55 dB_A and for the teachers at around 65 dB_A. Furthermore, backward pupils suffer more in this context from the interference of noise than the advanced ones.     

Cholinesterases are down-expressed in human colorectal carcinoma

The aberrations of cholinesterase (ChE) genes and the variation of ChE activity in cancerous tissues prompted us to investigate the expression of ChEs in colorectal carcinoma. The study of 55 paired specimens of healthy (HG) and cancerous gut (CG) showed that acetylcholinesterase (AChE) activity fell by 32% and butyrylcholinesterase (BuChE) activity by 58% in CG. Abundant AChE-H, fewer AChE-T, and even fewer AChE-R and BuChE mRNAs were observed in HG, and their content was greatly diminished in CG. The high level of the AChE-H mRNA explains the abundance of AChE-H subunits in HG, which as glycosylphosphatidylinositol (GPI)-anchored amphiphilic AChE dimers (G₂^A) and monomers (G₁^A) account for 69% of AChE activity. The identification of AChE-T and BuChE mRNAs justifies the occurrence in gut of A₁₂, G₄^H and PRiMA-containing G₄^A AChE forms, besides G₄^H, G₄^A and G₁^H BuChE. The down-regulation of ChEs might contribute to gut carcinogenesis by increasing acetylcholine availability and overstimulating muscarinic receptors. Received 19 May 2006; received after revision 5 June 2006; accepted 5 July 2006     

The effect of pentagastrin on the A1-cells of the pancreatic islets in guinea-pigs

Zusammenfassung Meerschweinchen wurden für 5 Tage mit Pentagastrin injiziert und die Kerngrössen in den Pankreas-Inseln mit Karyometrie bestimmt. Die Kerne der A₁-Zellen nahmen in den behandelten Tieren am Anfang ab und schienen kleiner als in den Kontrollen. In den A₂-und B-Zellen wurden keine Veränderungen nach Pentagastrin notiert. Die Resultate stützen die Auffassung, dass Gastrin in den A₁-Zellen produziert wird.

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The work was supported by grants from the Swedish Medical Research Council No. B70-2297-03. The pentagastrin (Peptavlon) was kindly supplied by Imperial Chemical Industries (ICI).     

Characterization of the 5-HT1A receptor of the honeybee (Apis mellifera) and involvement of serotonin in phototactic behavior

Serotonin plays a key role in modulating various physiological and behavioral processes in both protostomes and deuterostomes. The vast majority of serotonin receptors belong to the superfamily of G-protein-coupled receptors. We report the cloning of a cDNA from the honeybee (Am5-ht1A) sharing high similarity with members of the 5-HT₁ receptor class. Activation of Am5-HT_1A by serotonin inhibited the production of cAMP in a dose-dependent manner (EC₅₀ = 16.9 nM). Am5-HT_1A was highly expressed in brain regions known to be involved in visual information processing. Using in vivo pharmacology, we could demonstrate that Am5-HT_1A receptor ligands had a strong impact on the phototactic behavior of individual bees. The data presented here mark the first comprehensive study—from gene to behavior—of a 5-HT_1A receptor in the honeybee, paving the way for the eventual elucidation of additional roles of this receptor subtype in the physiology and behavior of this social insect.     

4-Hydroxynonenal-modified amyloid-beta peptide inhibits the proteasome: possible importance in Alzheimer's disease

The amyloid β-peptide (Aβ) is a 4-kDa species derived from the amyloid precursor protein, which accumulates in the brains of patients with Alzheimer’s disease. Although we lack full understanding of the etiology and pathogenesis of selective neuron death, considerable data do imply roles for both the toxic Aβ and increased oxidative stress. Another significant observation is the accumulation of abnormal, ubiquitin-conjugated proteins in affected neurons, suggesting dysfunction of the proteasome proteolytic system in these cells. Recent reports have indicated that Aβ can bind and inhibit the proteasome, the major cytoslic protease for degrading damaged and ubiquitin-conjugated proteins. Earlier results from our laboratory showed that moderately oxidized proteins are preferentially recognized and degraded by the proteasome; however, severely oxidized proteins cannot be easily degraded and, instead, inhibit the proteasome. We hypothesized that oxidatively modified Aβ might have a stronger (or weaker) inhibitory effect on the proteasome than does native Aβ. We therefore also investigated the proteasome inhibitory action of Aβ _1–40 (a peptide comprising the first 40 residues of Aβ) modified by the intracellular oxidant hydrogen peroxide, and by the lipid peroxidation product 4-hydroxynonenal (HNE). H₂O₂ modification of Aβ _1–40 generates a progressively poorer inhibitor of the purified human 20S proteasome. In contrast, HNE modification of Aβ _1–40 generates a progressively more selective and efficient inhibitor of the degradation of fluorogenic peptides and oxidized protein substrates by human 20S proteasome. This interaction may contribute to certain pathological manifestations of Alzheimer’s disease Received 26 September 2000; accepted 26 September 2000