Nitrogenase activity in a transfilter culture of rhizobia with a non-leguminous plant callus culture: Transfer of fixed15N2 from bacteria toPortulaca callus

Summary A transfilter culture of the non-leguminous plantPortulaca grandiflora var. JR andRhizobium sp. cowpea 32H1 was established. Using¹⁵N₂-analysis we demonstrated that¹⁵N-containing substances produced by the bacteria passed through the membrane and¹⁵N was enriched in the plant cells.Acknowledgment. The authors wish to express their gratitude to Prof. H. Marschner and Dr G. Hentschel for the determination of the nitrogen-content of our samples by the Dumasmethod and for advice on the optic emission method. Drs J. Burton, Milwaukee, Wisc., and Tjepkema, Oregon State University, are thanked for generous gifts ofRhizobium sp. cowpea 32H1. This work was supported by the DFG.     

Quantitative studies on the influence of the temperature applied in freeze-substitution on P,N, and dry mass losses in fixed tissues

Résumé Les auteurs ont constaté que la température a une influence sur la diminution du contenu en azote et en phosphore et sur celle de la masse déséchée après l'usage de méthanol au cours de la congelation-dissolution (freeze-substitution) des tissus. Ces diminutions sont moins marquées à la temperature de – 79°C. Après l'usage d'acétone, les diminutions atteignent leur minimum.     

Production of butyrylcholinesterase by Caco-2 cells: lack of relationship with triglyceride production

Elevated levels of butyrylcholinesterase activity occur under a number of hypertriglyceridemic conditions, including diabetes and obesity. This study examines whether butyrylcholinesterase activity has a direct effect on triglyceride production, using Caco-2 cells, a human intestinal adenocarcinoma cell line. Caco-2 cells were incubated with 500 μM oleate to stimulate triglyceride production, and butyrylcholinesterase activity was measured in the cellular homogenate. Butyrylcholinesterase activity was approximately 3 × 10^-3 mmol/min per milligram protein. Although triglyceride production increased by almost five-fold after 18 h of stimulation with oleate, butyrylcholinesterase activity was not increased. Furthermore, inhibition of butyrylcholinesterase activity using 1 mM tetraisopropylpyrophosphoramide did not significantly affect triglyceride production or secretion. Human insulin (100 μU/ml) increased the production of butyrylcholinesterase without increasing triglyceride production. This demonstrates that stimulation of fatty acid production and butyrylcholinesterase activity occur by independent mechanisms and suggests that their correlation in hyperlipidemic conditions is not due to a direct relationship in production in situ. Received 23 April 2001; received after revision 25 May 2001; accepted 20 June 2001     

Metabolism in Porifera. VII. Conversion of [7,7-3H2]-fucosterol into calysterol by the spongeCalyx niceaensis

Summary The spongeCalyx niceaensis metabolizes administered [7,7-³H₂]-fucosterol to produce labelled calysterol, the principal sterol component of the sponge, possessing the unique feature of a cyclopropene ring bridging C_23,24.     

The total synthesis of delphinine: Resolution of the racemic relay compound into optical antipodes by an asymmetric reaction

Zusammenfassung Das totalsynthetische Razematdl 1a gab bei Reaktion mitl-Camphorsulfonylchlorid das Sulfonamid 2 und die optisch-aktive Base 1b. Die Identität dieser totalsynthetischen, optisch aktiven Base 1b mit dem entsprechenden Abbauprodukt von Delfinin wurde bewiesen.     

Metabolism in porifera. VII. Conversion of [7,7-3H2]-fucosterol into calysterol by the sponge Calyx niceaensis

The sponge Calyx niceaensis metabolizes administered [7,7--(3)H2]-fucosterol to produce labelled calysterol, the principal sterol component of the sponge, possessing the unique feature of a cyclopropene ring bridging C23,24.     

Central glucoprivation: Some physiological effects induced by the intraventricular administration of 2-deoxy-d-glucose

Riassunto Il 2-desossi-d-glucosio somministrato nel ventricolo laterale del cervello del ratto provoca iperglicemia, inibizione della secrezione di insulina, iperfagia ed ipotermia a dosi che sono inefficaci per via sistemica.

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MissesF. Ferrari, S. Bianchi andL. Scapellato provided skilful technical assistance. This investigation was supported by Grant No. 70.01788.04115.2380 of the Consiglio Nazionale delle Richerche, Italy.     

Flow of a solution into a tube filled with solvent: Static concentration and flow concentration of the solute

Résumé On étudie une solution introduite dans un tuyau rempli de solvent et on distingue entre la concentration statiquee et la concentration d'écoulementc du soluté. On présente un groupe d'équations s'appliquant à trois simples cas expérimentaux, qui donnent les relations dee et dec avec le volume de solution introduite et le volume d'écoulement total.     

Acceleration of the speed of neuronal growth by a new neurotropic substance: N-isopropyl-amino-2-pyrimidine]

16 hrs. after per os administration of 14C N-isopropyl-amino-2-pyrimidine (IAP) in the Rat, radioactivity of the sciatic nerve is significantly higher than in plasma and other organs. In vitro IAP (base, orthophosphate or dichloracetate) accelerates neurite outgrowth of explained spinal ganglion after 48 hrs. of incubation in nutritive medium. Results suggest that IAP incorporated in nerve cell acts on cellular mechanisms controlling nerve growth.     

Inhibition of cortisol metabolism in vitro by 2-methylnaphthoquinone (menadione): A possible interpretation of the potentiation of cortisol activity in vivo

Résumé Le degré de réduction du noyeau A du cortisole par les microsomes du foie du rat et par le NADPH est inhibé du 50% par le méthyle-2-naphtoquinone (ménadione). L'inhibition est partiellement allégée par l'addition de NADPH ce qui indique que la ménadione gêne la disponibilité du NADPH. En effet, il s'est trouvé que la ménadione active la diminution de NADPH par les microsomes du foie. Il est possible que l'augmentation précédemment signalée de l'activité pharmacologique du cortisole par la ménadione est apparentée à l'inhibition du métabolisme du cortisole.     

Effect of platinum derivatives on the inducible and repressible liver microsomal enzyme systems in the rat: inhibition of zoxazolamine-hydroxylase and induction of dimethyl-nitrosamine demethylase isoenzymes by cis-dichlorodiamine platinum (cis-PtCl2(NH3)2) and ammonium hexachloroplatinum (PtC16(NH4)2)]

Two platinum derivatives, cis-PtCl2(NH3)2 and PtCl6(NH4)2 have been studied for their effects on the Rat on cytochrome P450 in hepatic parenchyma on zoxazolamine-hydroxylase, a typical inducible system and on the two isoenzymes of dimethyl-nitrosamine demethylase, typical repressible systems. The inhibitory effect of PtCl6(NH4)2 on zoxazolamine-hydroxylase activity, previously shown by the authors, has been confirmed. The cis-PtCl2(NH3)2 also significantly inhibits zoxazolamine-hydroxylase activity. On the other hand, both of the platinum derivatives decrease cytochrome P450 level and enhance the dimethyl-nitrosamine metabolism. These various effects and their relationship are discussed.     

Parameters influencing inactivation-dissociation/reactivation-association phenomena induced by variations of ionic strength of L (+)lactate: cytochrome c oxidoreductase (cytochrome b2) extract of the yeast Hansenula anomala

H-flavocytochrome b2, a tetramer enzyme, is inactivated, at low ionic strength and can be reactivated, increasing the ionic strength of the medium. The inactivation-reactivation process was structurally manifested by a dissociation-association phenomenon between subunits. It was clearly shown that the inactivation-dissociation process appeared independent of enzyme concentration whereas the reactivation-association phenomenon was enzyme concentration dependent. However, proteins protect H-flavocytochrome b2 from inactivation-dissociation, only when electrostatic interactions are possible between the two proteins: Horse heart cytochrome c was a good protector whereas serum albumin had no protector effect.     

Cellular microbiology of intracellular <Emphasis Type="Italic">Salmonella enterica</Emphasis>: functions of the type III secretion system encoded by <Emphasis Type="Italic">Salmonella</Emphasis> pathogenicity island 2

The facultative intracellular pathogen Salmonella enterica resides in a special membrane compartment of the host cell and modifies its host to achieve intracellular survival and proliferation. The type III secretion system encoded by Salmonella pathogenicity island 2 (SPI2) has a central role in the interference of intracellular Salmonella with host cell functions. SPI2 function affects antimicrobial defense mechanisms of the host, intracellular transport processes, integrity and function of the cytoskeleton and host cell death. These modifications are mediated by translocation of a large number of effector proteins by the SPI2 system. In this review, we summarize recent work on the cellular phenotypes related to SPI2 function and contribution of SPI2 effector proteins to these manipulations. These studies reveal a complex set of pathogenic interferences between intracellular Salmonella and its host cells.Received 11 June 2004; received after revision 8 July 2004; accepted 12 July 2004