Search Results - (Author, Cooperation:G. Krause)

2018-10-06

Nature Publishing Group (NPG)

2158-3188

Medicine

2018-08-22

National Academy of Sciences

0027-8424

1091-6490

Biology

Medicine

Natural Sciences in General

2016-01-19

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2014-08-15

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Anti-Bacterial Agents/metabolism ; Basic Helix-Loop-Helix Transcription Factors/*metabolism ; Bone Marrow Cells/cytology ; Cytokines/immunology/metabolism ; Feedback, Physiological ; Humans ; Ligands ; Macrophage Activation ; Mice ; Mycobacterium tuberculosis/growth & development/*immunology/metabolism ; Phenazines/metabolism ; Pigments, Biological/chemistry/*metabolism ; Pseudomonas Infections/metabolism ; Pseudomonas aeruginosa/*immunology/metabolism ; Pyocyanine/metabolism ; Receptors, Aryl Hydrocarbon/*metabolism ; Receptors, Pattern Recognition/*metabolism ; Virulence Factors/chemistry/metabolism

2016-03-05

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Acclimation to periodic high-light stress was studied in tree seedlings from a neotropical forest. Seedlings of several pioneer and late-succession species were cultivated under simulated tree-fall gap conditions; they were placed under frames covered with shade cloth with apertures of different widths that permitted defined periods of daily leaf exposure to direct sunlight. During direct sun exposure, all plants exhibited a marked reversible decline in potential photosystem II (PSII) efficiency, determined by means of the ratio of variable to maximum Chl a fluorescence (Fv/Fm). The decline in Fv/Fm under full sunlight was much stronger in late-succession than in pioneer species. For each gap size, all species exhibited a similar degree of de-epoxidation of violaxanthin in direct sunlight and similar pool sizes of xanthophyll cycle pigments. Pool sizes increased with increasing gap size. Pioneer plants possessed high levels of β-carotene that also increased with gap size, whereas α-carotene decreased. In contrast to late-succession plants, pioneer plants were capable of adjusting their Chl a/b ratio to a high value in wide gaps. The content of extractable UV-B-absorbing compounds was highest in the plants acclimated to large gaps and did not depend on the successional status of the plants. The results demonstrate a better performance of pioneer species under high-light conditions as compared with late-succession plants, manifested by reduced photoinhibition of PSII in pioneer species. This was not related to increased pool size and turnover of xanthophyll cycle pigments, nor to higher contents of UV-B-absorbing substances. High β-carotene levels and increased Chl a/b ratios, i.e. reduced size of the Chl a and b binding antennae, may contribute to photoprotection in pioneer species.

Electronic Resource

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Sun and shade leaves of several plant species from a neotropical forest were exposed to excessive light to evaluate the responses of photosystem I in comparison to those of photosystem II. Potential photosystem I activity was determined by means of the maximum P700 absorbance change around 810 nm (ΔA810max) in saturating far-red light. Leaf absorbance changes in dependence of increasing far-red light fluence rates were used to calculate a ‘saturation constant’, Ks, representing the far-red irradiance at which half of the maximal absorbance change (ΔA810max/2) was reached in the steady state. Photosystem II efficiency was assessed by measuring the ratio of variable to maximum chlorophyll fluorescence, Fv/Fm, in dark-adapted leaf samples. Strong illumination caused a high degree of photo-inhibition of photosystem II in all leaves, particularly in shade leaves. Exposure to 1800–2000 μmol photons m−2 s−1 for 75 min did not substantially affect the potential activity of photosystem I in all species tested, but caused a more than 40-fold increase of Ks in shade leaves, and a three-fold increase of Ks in sun leaves. The increase in Ks was reversible during recovery under low light, and the recovery process was much faster in sun than in shade leaves. The novel effect of high-light stress on the light saturation of P700 oxidation described here may represent a complex reversible mechanism within photosystem I that regulates light-energy dissipation and thus protects photosystem I from photo-oxidative damage. Moreover, we show that under high-light stress a high proportion of P700 accumulates in the oxidized state, P700+. Presumably, conversion of excitation energy to heat by this cation radical may efficiently contribute to photoprotection.

Electronic Resource

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Irradiation of Spinach oleracea intact leaf tissue and of mesophyll protoplasts of Valerianella locusta at 20° C with strong light resulted in severe (40–80%) inhibition of photosynthesis, measured as photosystem II electron transport activity in isolated thylakoids or as fluorescence parameter FV/FM on intact leaf disks. No net degradation of the D1 protein of photosystem II was seen under these conditions. However, in the presence of streptomycin, an inhibitor of chloroplast protein synthesis, net D1 degradation (up to about 80%) did occur with a half-time of 4–6h, and photoinhibition was enhanced. Thylakoid ultrastructure remained stable during photoinhibition, even when substantial degradation of D1 took place in the presence of streptomycin. When leaf disks were irradiated at 2°C, streptomycin did not influence the degree of photoinhibition, and net Dl degradation did not occur. These results suggest that in excess (photoinhibitory) light at 20°C, turnover (coordinated degradation and synthesis) of D1 diminished the degree of photoinhibition. The observed photoinhibition is thought to be due to the accumulation of inactive photosystem II reaction centres still containing D1. In the presence of streptomycin, the Dl protein was degraded (probably in the previously inactivated centres), but restoration of active centres via D1 synthesis was blocked, leading to more severe photoinhibition. Low temperature (2°C), by restricting both degradation and resynthesis of D1, favoured the accumulation of inactive centres. Streptomycin and chloramphenicol (another inhibitor of chloroplast protein synthesis) were tested for side-effects on photosynthesis. Strong inhibitory effects of chloramphenicol, but much less severe effects of streptomycin were observed.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

The effects of five levels of acid whey, a Torula yeast product and low fat processed American cheese on the flavor of bread were evaluated by an experienced sensory panel. From these data, response surface contour plots were drawn, and a formula was indentified which resulted in a bread with characteristics that were liked by 50 individuals 65 years of age or older. This formula. increased the calcium, thiamin and riboflavin content by 1.2, 2.0 and 1.2 times, respectively, over that of the best-liked commercial bread.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Portion-controlled menu items were heat processed in infrared and convection ovens to compare the effects of the heating methods upon nutrient retention. Product yields for hamburger and potatoes were significantly greater (P 〈 0.05) after convective heating; for tomatoes, after infrared heating. Nutrients analyzed foi selected menu items included: thiamin, riboflavin, vitamin C, β-carotene, seven fatty acids, 18 amino acids, ammonia, phosphorus, iron and sodium. Several significant differences between the heat processed samples were revealed. The riboflavin and vitamin A contents in hamburger and tomatoes, respectively, were significantly greater after infrared heating. The total amino acid contents were significantly greater after infrared heating for the hamburger patties and cod fillets.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Roasts were heat processed by infrared and convection to compare the effects of these alternate heating methods upon nutrient retention. In addition to proximate analyses, nutrients analyzed included: thiamin, riboflavin, seven fatty acids, 18 amino acids, ammonia, sodium, phosphorus and iron. Convective heating of turkey breast and corned beef produced a higher product yield. Few significant differences between heat processed samples were revealed. After convection heating of corned beef, riboflavin was significantly higher (P 〈 0.05) than after infrared heating. Similarly, arachidonic acid (C20:4) was higher in turkey breasts. After infrared heating of pork, aspartic acid, threonine, serine were lower than after convective heating; ammonia was higher.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Thermal conductivity values of white bread were determined during heat processing to provide information for analytical modeling required during convective heat and mass transfer of the baking process. Selected physical properties of bread were determined: moisture, volume, bulk density and porosity. White bread was baked in a forced-air convection oven for 8, 16, 24 and 32 min. Thermal conductivity values ranged from 0.00072–0.00064 watts/cm-°C. Although a downward trend was observed and explained, no significant differences were revealed among thermal conductivity values. Thermal conductivity values were indirectly linearly dependent (p〉0.05) on volume and porosity; directly, to bulk density and moisture loss.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Comparsion of data for two similarly designed investigations of microwave and conventional cooking of meat indicated that differences among sensory scores and shear values were a function of treatment differences and not cooking method. However, there was a trend toward larger F-values to be associated with data for microwave cooking.

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1365-2036

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background : KC 11458, a motilin agonist without antibiotic properties, accelerates gastric emptying in animals and healthy humans.Aim : To evaluate the acute effects of KC 11458 on gastric emptying in diabetic gastroparesis.Methods : Twenty-nine patients (6 type 1 and 23 type 2) with gastroparesis underwent assessments of: (i) gastric emptying of a solid/liquid meal using scintigraphy, (ii) glycaemic control (blood glucose at 0, 30, 60, 90 and 120 min during the gastric emptying measurement) and (iii) upper gastrointestinal and ‘meal-related’ symptoms (questionnaire), at baseline and after treatment with KC 11458 in a dose of 8 mg t.d.s., or placebo for 8 days.Results : KC 11458 had no statistically significant or clinically relevant effect on gastric emptying of either the solid intragastric retention at 100 min (T100) (P = 0.87) or liquid 50% emptying time (T50) (P = 0.17) components of the meal. KC 11458 slightly worsened (P = 0.04) upper gastrointestinal symptoms when compared with placebo. The magnitude of the change in solid gastric emptying correlated with the change in the blood glucose concentration (r = 0.49; P 〈 0.05).Conclusions : KC 11458, in a dose of 8 mg t.d.s. for 8 days, does not accelerate gastric emptying in patients with diabetic gastroparesis. The absence of efficacy may relate to an effect of hyperglycaemia.

Electronic Resource

0014-5793

Heteronuclear NMR ; Protein conformation ; Redox protein ; Thioredoxin

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Physics

Electronic Resource

0039-6028

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

0375-9601

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

1399-3054

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The relationship between susceptibility to photoinhibition, zeaxanthin formation and chlorophyll fluorescence quenching at suboptimal temperatures was studied in chilling-sensitive maize and in non-acclimated and cold-acclimated Oxyria digyna, a chilling-tolerant plant of arctic and alpine habitats. In maize, zeaxanthin formation was strongly suppressed by chilling. Zeaxanthin formed during preillumination at 20°C did not protect maize leaves from photoinhibition during a subsequent high-light, low-temperature treatment, as judged from the ratios of variable to maximal fluorescence, Fv/Fm. However, such preillumination significantly increased non-photochemical quenching (qN) at low temperatures, mainly due to an enhancement of the fast-relaxing qN component (i.e., of energy-dependent quenching. qE). In O. digyna, cold-acclimation resulted in an increased zeaxanthin formation in the temperature range of 2.5–20°C. Cold-acclimation substantially decreased the susceptibility towards photoinhibition at 4°C, but qN remained nearly unchanged between 2 and 38°C, as compared to control plants. Effects of cold acclimation on photosynthesis, photochemical quenching and quantum efficiency of photosystem II were small and indicated a slight amelioration only of the function of the photosynthetic apparatus at suboptimal temperatures (2–20°Ct. I) is concluded, that the xanthophyll cycle is strongly influenced by cold acclimation, while effects on the photosynthetic carbon assimilation only play a minor role in O. digyna.

Electronic Resource

1399-3054

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The role of high light stress in a natural environment was studied on spinach plants (Spinacia oleracea L. cv. Wolter) grown in the field during the winter season. Fluorescence induction (at 293 K and 77 K) of leaves was used to characterize the stress effects. Night frost with minimum temperatures between – 1.5°C and –7.5°C (i.e. above the‘frost killing point’at ca. –11.5°C) led to impaired photosynthesis. This was seen as increased initial fluorescence (Fo), decreased ratio of variable to maximum fluorescence (FV/FM) and lowered rates of O2 evolution. The freezing injury was reversible within several frostless days. Exposure to high light (about 900 mol m–2 s–1) at chilling temperatures in the field caused photoinhibition, manifested as decreased variable fluorescence (FV) and FV/FM ratio without changes in FO. The photoinhibitory fluorescence quenching was not stronger after frost than after frostless nights; synergism between light stress and preceding freezing stress was not observed. Fluorescence induction signals at 77 K showed that FV of photosystems I and II decreased to the same extent, indicating increased thermal deactivation of excited chlorophyll. Photoinhibition was fully reversible at +4°C within 1 h in low light, but only partially in moderate light. Preceding night frosts did not affect the recovery. The photoinhibition observed here is regarded as a protective system of thermal dissipation of excess light energy.

Electronic Resource