Biomedical subjects

E Stenberg

Publications and source records attributed to E Stenberg.

5 recordsLinked to original sources

PubMed1997

Chitooligosaccharides stimulate Atlantic salmon, Salmo salar L., head kidney leukocytes to enhanced superoxide anion production in vitro.

Chitosans and chitooligosaccharides stimulated Atlantic salmon, Salmo salar L., head kidney leukocytes in vitro to produce elevated levels of superoxide anion. Both soluble and insoluble chitooligosaccharides were stimulatory 2 and 7 days after addition. Protein-chitooligosaccharide conjugates were also stimulatory in vitro both at 2 and 7 days after addition. Deacetylation seemed to be of little importance for the stimulatory capacity. High concentrations of the 80% deacetylated chitosan/chitooligosaccharides were toxic to the leukocytes as judged by reduced reduction of nitroblue tetrazolium and morphology.

Acetylation↗

PubMed1993

Introducing a biosensor based technology for real-time biospecific interaction analysis.

This report describes a system for real-time biospecific interaction analysis, using biosensor technology based on the optical phenomenon surface plasmon resonance. The biospecific interface is a sensor chip consisting of a thin gold film deposited on a glass support and covered with a hydrogel matrix. One component of the interaction being studied is attached covalently to the hydrogel, and other interactants are passed over the chip in solution. The interaction is followed in real time in terms of changes in the mass concentration of biomolecules at the sensor surface. Surface concentrations down to 10 pg/mm2 can be measured. The technique does not require molecular labels such as isotopes or spectroscopic markers, and purification of interacting components can often be avoided. Repeated analyses can be performed on the same sensor chip. With this system, the same general procedure can be used for a wide range of different applications, including concentration determination, kinetic measurements and multi-site binding studies. The sensitivity of the technique can be adjusted by choice of reagents and experimental procedure: determination of specific proteins in serum down to 20 ng/ml and macromolecular association constants from 10(7) M-1 up to 4 x 10(11) M-1 are documentated examples. No other single analytical system has the same versatility and general applicability to biospecific interaction analysis. The system is developed and marketed by Pharmacia Biosensor AB, Sweden.

Biosensing Techniques↗

PubMed1984

Amino acid and lactate catabolism in trimethylamine oxide respiration of Alteromonas putrefaciens NCMB 1735.

The nonfermentative Alteromonas putrefaciens NCMB 1735 grew anaerobically in defined media with trimethylamine oxide as external electron acceptor. All amino acids tested, except taurine and those with a cyclic or aromatic side chain, were utilized during trimethylamine oxide-dependent anaerobic growth. Lactate, serine, and cysteine (which are easily converted to pyruvate) and glutamate and aspartate (which are easily converted to tricarboxylic acid cycle intermediates) were metabolized at the fastest rate. Growth with lactate as growth-limiting substrate gave rise to the formation of 40 mol% acetate, whereas serine and cysteine were nearly completely oxidized to CO2. Molar growth yields with the latter substrates were the same and were 50% higher than with lactate. This showed that more ATP was formed when acetyl coenzyme A entered the tricarboxylic acid cycle than when it was converted via acetyl phosphate to acetate. Also, growth with formate as substrate indicated that the reduction of trimethylamine oxide to trimethylamine was coupled with energy conservation by a respiratory mechanism.

Adenosine Triphosphate↗

PubMed1984

Trimethylamine oxide respiration of Alteromonas putrefaciens NCMB 1735: Na+-stimulated anaerobic transport in cells and membrane vesicles.

Alteromonas putrefaciens NCMB 1735 required the presence of NaCl for anaerobic growth with serine, cysteine, and formate as substrate and trimethylamine oxide ( TMAO ) as external electron acceptor. When lactate was substrate, the organism grew equally well in the absence of NaCl. Anaerobic uptake of glutamate, aspartate, serine, cysteine, and lactate in resting cells was strongly stimulated with NaCl, and cytoplasmic membrane vesicles energized by electron transfer from formate to TMAO displayed active Na+-dependent uptake of serine. The data suggested that participation in transport processes was the only vital function of Na+ in A. putrefaciens. Formate- and TMAO -dependent anaerobic serine uptake in vesicles was sensitive to the protonophore carbonyl cyanide m-chlorophenyl-hydrazone and the ionophores valinomycin and gramicidin. Transport-active vesicles contained cytochromes of b and c type, and both serine uptake and TMAO reduction with formate were inhibited with the electron transfer inhibitor 2-heptyl-4-hydroxyquinoline N-oxide. Thus, reduction of TMAO to trimethylamine in A. putrefaciens appeared to be coupled with a chemiosmotic mechanism of energy conversion.

Amino Acids↗

PubMed1982

Trimethylamine oxide respiration in Proteus sp. strain NTHC153: electron transfer-dependent phosphorylation and L-serine transport.

Cells of Proteus sp. strains NTHC153 grown anaerobically with glucose and trimethylamine oxide (TMAO) were converted to spheroplasts by the penicillin method. The spheroplasts were lysed by osmotic shock, and the membrane vesicles were purified by sucrose gradient centrifugation. Vesicles energized electron transfer from formate to TMAO displayed active anaerobic transport of serine. An anaerobic cell-free extract of Proteus sp. disrupted in a French pressure cell reduced TMAO with formate and NADH with the concomitant formation of organic phosphate. The net P/2e- ratios determined were 0.1 and 0.3, respectively. The NADH- and TMAO-dependent phosphorylation was sensitive to uncouplers of oxidative phosphorylation (protonophores), and the formate- and TMAO-dependent serine transport was sensitive to ionophores and protonophores. We conclude that TMAO reduction in Proteus sp. fulfills the essential features of anaerobic respiration.

Adenosine Triphosphate↗