Polyreaktionen in orientierten systemen, 6.Mizellare assoziationen in 4-vinylpyridiniumsalzlösungen

Critical micell concentrations (cmc) of 4-vinylpyridinium or 4-ethylpyridinium salt solutions are determined from surface tension measurements and solubilisation of a dyestuff. Increase of the concentration of the gegenions decreases the cmc; at the same time, the composition of the polymerization product of the spontaneous polymerization in water also changes. Possible explanations for this are discussed.     

cis-Dichloro [bis(oligopeptidester)] platin (II)-Komplexe,Untersuchungen zum Nachweis der Antitumorwirkung mit bakteriologischen Testsystemen

cis-Dichloro[bis(oligopeptide ester)]platinum(II) Complexes: Investigation to Demonstrate Antitumor Activity with Bacteriological Test Systems The utility of the prophage induction test (E. coli K12 λ) as a screening method for the detection of antineoplastic platinum complexes is described.     

Die absolute Konfiguration des Pyrrolizidinalkaloids Seneciphyllin aus Adenostyles glabra

The Absolute Configuration of the Pyrrolizidine Alkaloid Seneciphyllin from Adenostyles glabra The pyrrolizidine alkaloid seneciphylline was identified in Crotalaria and Senecio species as well as in Adenostyles alliariae. Also it is described to be the major alkaloid in Adenostyles glabra. Its absolute configuration was determined by X-ray analysis. Accordingly seneciphylline is (?)-(13Z,1aR,6bR,10R)-10-Hydroxy-13-ethylidene-11-methylen-10-methyl-1a-2,3,6b-tetrahydro-5H-pyrrolizino[1a,6b,6a-b,c]-1,8-dioxacyclododecan-9,14-dione.     

Electrophysiological motor testing,MRI findings and clinical course in AIDS patients with dementia

Thirty-three HIV-positive patients with clinical signs of dementia according to the 1991 AAN criteria underwent psychometric, electrophysiological and radiological examination and were compared with a group of normal healthy subjects and a cohort of clinically asymptomatic HIV-1-positive individuals of comparable education and social environment. Compared with the other groups, test performance was severely impaired in the demented patients. Results of motor testing and MRI revealed that subcortical structures were not exclusively affected, but most severely and early, thus characterizing the clinical feature in HIV-1-associated dementia. In demented patients a rapid deterioration was observed, leading to death within about 12 months on average, which is a markedly shorter survival time than described in the literature for non-demented HIV-1-positive individuals.     

Use of electroporation in genetic analysis of enterococcal virulence

We present two methods for electroporation for the gram positive bacterium Enterococcus faecalis that can also be used as guidelines for work with other gram positive species. We demonstrate the use and the advantages of this technique for investigating genes, both chromosomal and plasmid-linked, encoding surface structures. Electroporation was used to deliver constructs created on shuttle vectors for insertional inactivation of a chromosomal gene involved in binding substance formation as well as for the expression of Aggregation Substance in strains with different chromosomal backgrounds. The influence of defects in lipoteichoic acid synthesis and the expression of Aggregation Substance on virulence was shown in a rabbit endocarditis model.     

Hepatic uptake of cadmium and its biliary release as affected by dithioerythritol and glutathione

Net cadmium uptake in the isolated perfused rat iiver was half-maximal at 5 μM, and the maximal rate of uptake was 22 nmoles/min per gram liver wet weight. Uptake was augmented when a permeable thiol, dithioerythritol, was infused, whereas it was restricted when glutathione as a nonpermeable thiol or also when bovine serum albumin were infused. The ratio of extra cadmium taken up versus dithioerythritol added was 1:2. Uptake of cadmium was insensitive to anoxia or to the infusion of cyanide. Biliary cadmium release in the perfused liver was not augmented by dithioerythritol but was rather suppressed, whereas bile flow or the release of added ³H-taurocholate were unaffected.     

Social hierarchy and adrenocortical stress reactivity in men

Baseline and stress induced salivary cortisol levels were investigated in 63 army recruits at the beginning and the end of six week boot camp training. At the beginning of the training, the recruits were randomly distributed to nine groups, and weekly measurements of the social hierarchy within each group were obtained. Independent of the social position, baseline levels increased over the first weeks of the training period. Under experimental psychological stress, salivary cortisol levels highly increased in socially dominant subjects (14.0 nmol/l), while only a modest elevation was observed in subordinate men (2.9 nmol/l). Similar differences in response patterns were observed under physical stress. At the end of the training, blunted cortisol responses were observed to both psychological and physical stress. The data suggest a close relationship between social status and pituitary-adrenal responsiveness to psychological stress in men.     

Relationship between tissue pO2 and chemoreceptor activity of the carotid body in vitro

Tissue pO₂ (pgO₂) and sinus nerve activity were recorded in the carotid body in vitro under hypoxic conditions produced either by interrupting the superfusion flow or by lowering the pO₂ of the medium (pmO₂). The pgO₂ gradient is the steeper the higher pmO₂ is. These findings point to a pO₂-dependent oxygen consumption. Under hypoxia produced by interrupting the superfusion flow, pgO₂ declines slowly down to final values and, concomitantly, the chemoreceptor discharge increases. Under hypoxia produced by lowering pmO₂, pgO₂ decreases rapidly down to values of about 3 torr, whereas the chemoreceptor discharge at first increases and then decreases, in spite of a maintained low pgO₂. The pO₂ threshold where the chemoreceptor starts firing under hypoxia, varies between 9 and 90 torr.     

Copolymers obtained by means of anionic ring-opening polymerization. Poly(2,2-dimethyltrimethylene carbonate-tapered-ϵ-caprolactone)

The anionic ring-opening polymerization of mixtures of 2,2-dimethyltrimethylene carbonate and ?-caprolactone in toluene as solvent, with sec-butyllithium or potassium dihydronaphthylide as initiator, results in the formation of polymers of the (A-X-B)_n type, where A represents a poly(2,2-dimethyltrimethylene carbonate) block, B represents a poly(?-caprolactone) block and X stands for a block of the two monomers with a composition gradient; n represents the number of portions by which the monomer mixture is added to the initiator or the living system. From the time-conversion curves it follows that the reactivity of the carbonate monomer is higher than that of the lactone. This difference in reactivity of the monomers is the reason for the special polymer architecture represented by (A-X-B)_n. The properties of these polymers depend upon the ratio of the monomers and the number n of additions. The polymers are characterized by spectroscopic, thermoanalytical, and thermomechanical measurements.