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B Fricke

Publications and source records attributed to B Fricke.

50 records · Page 3Linked to original sources
PubMed1991

[Perceptibility of details in conventional and digital teleradiography--a comparative study].

By introduction of rare earth film-screen combinations instead of classical screens dose reduction has already been possible. By this study the extent of dose reduction without loss of clinical information was to be examined by comparing conventional radiographic rare earth film-screen combinations to digital radiography. Statistical analysis proves for conventional lateral cephalograms that soft tissue reference points can better be localized if small radiation doses are used. The localization of reference points in areas of less radiographic transparency is better when applying higher doses. These results were not found in images by digital radiographic technique. Reference points both of soft tissue and of more dense areas of the skull were equally to be localized independent from radiation dose by the linear sensibility characteristics of digital radiography. This enables reduction of radiation doses and therefore a contribution to radioprotection.

Cephalometry↗
PubMed1990

[Alternatives to steroid therapy in chronic uveitis].

In a search for alternative therapeutic methods other than corticosteroids and cytostatics, the effect of a dialyzable leukocyte extract (DLE), the antimetabolite 5-fluorouracil and the immunosuppressive agent cyclosporin A in corticosteroid-resistant idiopathic uveitis was studied. When DLE was administered to 26 patients who had uveitis forms with exogenous triggering (e.g., infection), as well as forms with an autoimmune background, there was a reduction in the number and duration of recurrences and a statistically proven prolongation of the inflammation-free intervals. This was particularly true in anterior and posterior uveitis and to a lesser extent in the intermediate form. No side effects were observed. 5-Fluorouracil, injected subconjunctivally, is indicated in intermediate uveitis with marked vitreous infiltration and beginning proliferation. Corneal erosion occurs relatively often. During treatment with cyclosporin A (low dose, 5 mg/kg of body weight per day), 14 of 17 patients (9 with intermediate uveitis, 6 with retinal vasculitis, 1 with sympathetic ophthalmia, 1 with panuveitis) showed improved results; in 2 cases the findings remained stationary and only 1 case had low-grade deterioration. If one takes into consideration the fact that in this patient any therapy would have failed, the results are convincing. This is particularly true of retinal vasculitis. There is no effect in cases of central hemorrhagic chorioretinopathy. So far, there have been no serious side effects.

Adrenal Cortex Hormones↗
PubMed1989

[The effect of long-term dialysable leukocyte extract therapy on the recurrence behavior of idiopathic uveitis].

26 patients with idiopathic uveitis (anterior uveitis 11, intermediate uveitis 8, posterior uveitis 7) were treated with Dialysable Leukocyte Extract (DLE) for a long period. In comparison with the period before DLE in anterior and posterior uveitis the numbers of relapses decrease, the inflammation-free intervals become longer. These prolongations are significant. In cases with intermediate uveitis such a significance is not available. But in all types of uveitis DLE therapy shortens the duration of inflammatory episodes. These effects lead to a highly significant decrease of the portion of the period during and after DLE therapy in which inflammatory signs occur in comparison with the period before DLE therapy. The latter result becomes evident for all types of uveitis.

Adolescent↗
PubMed1989

Characterization of a periplasmic insulin-cleaving metalloproteinase from Acinetobacter calcoaceticus.

In Acinetobacter calcoaceticus, a Gram-negative bacterial species, a soluble insulin-degrading proteinase, located in the periplasm as well as in the cytosol, could be established. The periplasmic and cytosolic enzymes agree in their inhibition pattern, pH-optimum and molecular weight. The insulin-degrading enzyme of Acinetobacter calcoaceticus resembles the corresponding proteinases of Escherichia coli. It is a metalloproteinase with a pH-optimum in the neutral range and can be reactivated by divalent ions after EDTA-inhibition, but it is not entirely identical with any of the described proteinases of Escherichia coli in its inhibitory behaviour.

Acinetobacter↗
PubMed1987

[Proteases in different membrane fractions of Acinetobacter calcoaceticus].

Distinct protease activities were found in membrane fractions from Acinetobacter calcoaceticus grown on acetate-NH4+ medium until early stationary phase. Mechanical or enzymatic cell disintegration followed by membrane fractionation through sucrose gradient revealed higher activities in the outer membrane than in the cytoplasmic membrane. Using azocasein and synthetic p-nitroanilides as substrates we found very low proteinase activities in intracytoplasmic membrane fractions. However, these fractions contained a significant aminopeptidase activity which was absent from cell envelope membranes. Peptidolytic activities in intracytoplasmic membranes of gram-negative bacteria have not been described before.

Acinetobacter↗
PubMed1987

Leucine aminopeptidase in intracytoplasmic membranes of Acinetobacter calcoaceticus.

Cells of Acinetobacter calcoaceticus strain 69-V contain an aminopeptidase that cleaves L-leucine amide, leucylglycine or leucine hydrazide with high efficiency. Leucine 4-nitroanilide and hydrazide are hydrolyzed to less than 0.1% and 1%, resp. of leucine amide. Grown on acetate-NH4+ medium the activity of the enzyme in the cytoplasm is increased 5-fold compared with cells grown on a casamino acid medium or on yeast extract. In these cases the specific activity of the unpurified enzyme is about 5 nkat/mg for the cytoplasmic and membrane-bound enzyme species as well. Up to 30% of the aminopeptidase activity were found mainly in intracytoplasmic membranes, less in cytoplasmic membranes and only traces in outer membranes, presumably as contaminations. It is solubilized by detergents but not by high salt concentrations. An addition of antipain or Z-Ala2-Phe-CH3 before cell rupture did not change the distribution of the enzyme. A mixture of EDTA and 1.10-phenanthroline diminished the membrane-bound enzyme from 11.4% to 4.3% and leupeptin or E-64 increased it to 20%. The enzyme is regarded as leucine aminopeptidase (LAP) bound to intracytoplasmic membranes.

Acinetobacter↗
PubMed1986

Ultracytochemical localization of aldehyde dehydrogenase in Acinetobacter calcoaceticus.

A membrane-bound aldehyde dehydrogenase is induced in Acinetobacter calcoaceticus grown on aliphatic hydrocarbons as sole carbon source. This enzyme is NADP-dependent and is able to oxidize medium- and long-chain aliphatic aldehydes to their corresponding fatty acids. Electron micrographs of sectioned alkane-adapted bacteria showed hydrocarbon inclusions in the cytoplasmic matrix. The cytochemical phenazine methosulphate-tetranitro tetrazolium blue capture reaction allowed to localize the activity of the aldehyde dehydrogenase near the surface of these inclusions. At the same location we also found a NADPH tetrazolium-reducing activity.

Acinetobacter↗
PubMed1986

[Cell envelope-bound proteinase activities of Acinetobacter calcoaceticus].

Acinetobacter calcoaceticus contains proteolytic activity after growth on various culture media. The enzyme activity could be found in the cytosolic fraction as well as in the cell envelopes (also containing the intracytoplasmic membranes). The highest proteolytic activity could be detected during the transition from the logarithmic growth phase to the stationary phase and in the early stationary phase, respectively. In the culture medium proteolytic activity was only evident in the later stationary phase. This activity was very instable and was liberated apparently by autolysis of the cells. The concentration of the nitrogen source (NH4+) in the medium (i.g. with acetate as carbon source) influences the proteinase activities of the cells. When nitrogen is limited, the proteolytic activity increases strongly in the stationary phase. The pH-profile of the azocaseinolytic activities of the cytosol was nearly the same as that of the cell envelopes (pH-optima are between 7 and 9). A partial inhibition of the proteolytic activities in the cytosol as well as in the cell envelopes could be attained by serine proteinase inhibitors. Inhibitors of thiol- and metalloproteinases showed no effects.

Acetates↗
PubMed1982

[Optimization of culture conditions for Acinetobacter calcoaceticus grown on n-alkanes in a laboratory fermenter].

The growth conditions for the cultivation of Acinetobacter calcoaceticus in a commercial laboratory fermenter have been optimized. This was done taking former results of shake cultures as a basis. At the end of the logarithmic phase up to 10 g/l dry weight were obtained. The following culture conditions have been used: The medium contained 10 ml/l n-alkane and 6 g/l NH4Cl. The pH was adjusted to 6.5 and pO2 employed to 70% saturation. A 12 times higher amount of dry weight was observed compared with shake culture technique.

Acinetobacter↗