Stimulation of the methylcoenzyme M reduction by uridine-5'-diphospho-sugars in cell-free extracts of Methanobacterium thermoautotrophicum (strain delta H)

The hydrogen-dependent reduction of methylcoenzyme M catalyzed by coenzyme-depleted cell-free extracts of Methanobacterium thermoautotrophicum was stimulated by micromolar concentrations of a UDP-disaccharide present in the organism. The compound was isolated and identified as UDP-1-O-alpha-D-2-acetamido-2-deoxyglucopyranose (UDPGlcpNAc) glycosidically linked to 2-acetamido-2-deoxymannopyranosyluronic acid. Maximal stimulation was observed when both the UDP-disaccharide and mercaptoheptanoylthreonine phosphate were present in the reaction mixtures. The UDP derivative isolated was not specific in its action: other UDP-sugars tested in micromolar concentrations stimulated the methylcoenzyme M reduction to the same extent. The activated sugars presumably substitute for ATP, which is usually required in much higher concentrations to activate the methylcoenzyme M reductase system.     

Effects of staphylococcin 1580 on cells and membrane vesicles of Bacillus subtilis W23.

1. Uptake of L-glutamic acid is inhibited, and preaccumulated L-glutamic acid is released from Bacillus subtilis cells treated with staphylococcin 1580. Uptake of alpha-methylglycoside is enhanced at low bacteriocin concentrations and inhibited by excess bacteriocin. 2. Inhibition of amino acid uptake into membrane vesicles is somewhat less sensitive to staphylococcin 1580 than uptake into whole cells under similar conditions, when the bacteriocin concentration is expressed per weight unit of membrane protein. Inhibition of uptake into vesicles is independent of the electron donor system used, but varies with different substrates. 3. Influx of L-glutamic acid into vesicles under anaerobic conditions is severely hampered by staphylococcin 1580. The L-glutamic acid carrier functions are slightly affected only. 4. Staphylococcin 1580 abolished the membrane potential induced by respiration or by a potassium diffusion potential in the presence of valinomycin, as measured with the fluorescent dye 3,3'-dipropylthiadicarbocyanine. 5. The effects of staphylococcin 1580 on cells and membrane vesicles allowed the classification into three groups with different sensitivity to the staphylococcin concentration.     

The behavioural phenotype in velo-cardio-facial syndrome (VCFS): from infancy to adolescence

In this contribution the current status and recent findings of the behavioural phenotype in VCFS (22q11 deletion) are discussed with regard to motor development, cognition and neurodevelopment, and behaviour and temperament. Motor: hypotonia in infancy, gross-motor milestones are delayed, problems with coordination and balance from preschool age on, problems with tempo/speed during adolescence. Cognition and neurodevelopment: learning disabilities (82-100%), intellectual disability (45%), better verbal abilities than performal abilities, poor attention and concentration, visuo-perceptual-spatia problems, good (auditory) memory. An important subgroup of children (55%) has a non-verbal learning disability (NLD). Behaviour and social-emotional development AD(H)D, withdrawn and shy, person-dependent social problems in relationships with peers, anxious, risk for child psychiatric problems as well as for the development of psychiatric problems during adolescence and early adulthood. Information on the behavioural phenotype in VCFS (22q11 deletion) is of great importance to clinicians as an aid to syndrome diagnosis, but even more to parents because it offers immense direct practical value to the management of the behaviour of their child. Appropriate counseling and information on the long-term expectations, and better insight in the behaviour will lead to the development of realistic ways of coping with their child.     

In situ detection of spontaneous superoxide anion and singlet oxygen production by mitochondria in rat liver and small intestine

In the present study, the endogenous formation of reactive oxygen species was localized in rat liver and small intestine. The 3,3′-diaminobenzidine (DAB)-Mn²⁺ technique in which cobalt ions were included in the incubation medium was applied to unfixed cryostat sections of intact tissues. Addition of manganese ions to the DAB-Co²⁺- containing medium greatly increased the amounts of final reaction product formed compared with incubations with only DAB and cobalt ions. In liver, a blue final reaction product was deposited, particularly in hepatocytes surrounding portal tracts. In the small intestine, the DAB--cobalt complex was mainly found at the basal side of enterocytes. Goblet cells remained unstained. Electron microscopical images revealed that an electron-dense reaction product was exclusively present at both inner and outer membranes and at the intermembrane space in mitochondria of liver parenchymal cells and duodenal enterocytes. It was shown that the spontaneous formation of final reaction product was enzymatic and dependent on the presence of oxygen in the medium. Sulphide decreased the reaction, which may indicate that cytochrome c oxidase was partially involved. Benzoquinone and histidine, which are scavengers of superoxide anions and singlet oxygen respectively, reduced the amount of final reaction product considerably. Furthermore, the formation of final reaction product was sensitive to specific inhibitors of NADH:coenzyme Q reductase and aldehydeoxidase, indicating that these enzymes were at least partly responsible for the generation of superoxide anions and singlet oxygen and for the formation of the DAB--cobalt complex. This revised version was published online in November 2006 with corrections to the Cover Date.     

7-methylpterin derivatives in extracts of methanogens characterized by a relatively low methanopterin content

Cofactor extracts of five hydrogenotrophic methanogenic bacteria which contain relatively low amounts of methanopterin were screened for the presence of 7-methylpterin derivatives. Extracts of Methanospirillum hungatei, Methanobrevibacter smithii and Methanoplanus endosymbiosus were found to contain 7-methylpterin and methanopterin. These compounds were absent in extracts of Methanogenium thermophilicum and Methanogenium tatii. An unidentified methanopterin-like compound was detected in extracts of these two species and of Msp. hungatei, while a 7-methylpterin-like compound was found in extracts of Mp. endosymbiosus. A possible physiological role of the latter two compounds is discussed.     

Association of methanogenic bacteria with rumen ciliates.

In 11 species of rumen ciliates belonging to nine genera of the family Ophryoscolecidae (order Entodiniomorphida) an ectosymbiosis with methanogenic bacteria was found. The bacteria could be identified as methanogens on the basis of the presence of specific fluorescent coenzymes (F350 and F420). This somatic interaction may reflect a metabolic interaction in which efficient interspecies hydrogen transfer benefits both partners.     

Methanogenesis involving a novel carrier of C1 compounds in Methanogenium tationis.

The pathway of CO2 reduction to methane in Methanogenium tationis and Methanogenium thermophilicum is similar to that observed in other methanogens. In M. tationis a novel pterin, tatiopterin, is present. This pterin appears to be a structural and functional analog of methanopterin and sarcinapterin. Folate could not substitute for tatiopterin.     

Interleukin-1 and related pro-inflammatory cytokines in the treatment of bacterial infections in neutropenic and non-neutropenic animals

Bacterial infections in the immunocompromized host cause considerable mortality, and even the recently developed antimicrobial strategies often fail to cure these infections, especially in granulocytopenic patients. Cytokines and hematopoietic growth factors have been shown to stimulate host defense mechanismsin vitro andin vivo. We discuss the possible role of the pro-inflammatory cytokines interleukin-1, tumor necrosis factor-, interleukin-6 and interleukin-8 as modulators of host resistance to bacterial infections. Interleukin-1 has been shown effective in various animal models of potentially lethal bacterial infection, even during severe granulocytopenia. The protective mechanism of interleukin-1 may be mediated via downregulation of cytokine receptors and cytokine production, and via induction of acute phase proteins. Moreover, in subacute and chronic infections interleukin-1 interferes with microbial outgrowth, via mechanisms that have only been partially elucidated.Abbreviations G-CSF granulocyte colony-stimulating factor - M-CSF monocyte colony-stimulating factor - GM-CSF granulocyte-monocyte colony-stimulating factor - IFN- interferon-gamma - IL interleukin - LAK lymphokine-activated killer - LPS lipopolysaccharide - TNF tumor necrosis factor