PubMed Health⌕ Search

Biomedical subjects

H Irschik

Publications and source records attributed to H Irschik.

28 records · Page 2Linked to original sources
PubMed1985

Iron removal by desferrioxamine in patients on chronic hemodialysis--kinetic study and long-term results.

Serum ferritin levels, cumulative number of administered blood transfusions, number of monthly transfused blood units and total months on hemodialysis (HD) treatment differed significantly in 7 patients on hemodialysis with clinical, biochemical and histological evidence of hemosiderosis, when compared to 37 controls (p less than 0.001 for all parameters). As a new treatment method desferrioxamine (DFO) therapy was introduced for iron detoxification in these hemosiderotic chronically hemodialyzed patients. Hence, to maximize the biological half-time, 30 mg/kg body weight DFO were given after the end of HD in the iron-loaded patients. Iron removal during the subsequent HD and the increase of iron excretion by the stool after DFO was measured by atomic absorption spectroscopy. Iron removal by the artificial kidney was calculated by investigating the function (QDi + QF)CDo over the duration of HD treatment, which equals the total amount of iron removal during HD. Using numerical integration of measured data this removal was found to be 21.8 +/- 6.9 mg whereas cumulative iron loss via the feces was found to be 36.5 +/- 14.6 mg. Therefore, total iron elimination was calculated to be on average 50-60 mg after administration of a single dose of DFO. Furthermore, long-term treatment of 5 patients resulted in a significant decrease of serum ferritin levels from 2,309 +/- 295 to 715 +/- 177 ng WHO/ml (p less than 0.001) after a period of 36 +/- 5 months. We conclude, that DFO in a dosage of 30 mg/kg body weight given at the end of HD is able to remove more than 500 mg iron/month if it is administered following each HD. Long-term results indicate negative iron balance without significant change of transfusion frequency if not more than 2 U of blood (500 mg iron) are administered within 1 month. This treatment schedule might be superior compared to the previously used methods of administration where DFO was given at the beginning or throughout HD.

Adolescent↗
PubMed1983

The myxalamids, new antibiotics from Myxococcus xanthus (Myxobacterales). I. Production, physico-chemical and biological properties, and mechanism of action.

From the cell mass and culture supernatant of Myxococcus xanthus strain Mx X12 an antibiotic activity against yeasts, molds and some Gram-positive bacteria could be extracted. It consisted of 4 biologically active compounds which were named myxalamid A, B, C and D. The main component, myxalamid B, was shown to block in beef heart submitochondrial particles the respiratory chain at the site of complex I, i.e. NADH: ubiquinone oxidoreductase. The myxalamids are new antibiotics.

Animals↗
PubMed1983

The myxopyronins, new inhibitors of bacterial RNA synthesis from Myxococcus fulvus (Myxobacterales).

From the culture supernatant of the myxobacterium, Myxococcus fulvus strain Mx f50, an antibiotic activity was isolated which blocked growth of many Gram-positive and several Gram-negative bacteria, but not of yeasts and fungi. The activity consisted of two closely related compounds, myxopyronins A and B. The myxopyronins appear to be new antibiotics, and seem to specifically inhibit bacterial RNA polymerase.

Animals↗
PubMed1983

The myxovalargins, new peptide antibiotics from Myxococcus fulvus (Myxobacterales). I. Cultivation, isolation, and some chemical and biological properties.

Antibiotic activity was isolated from the culture supernatant of the myxobacterium Myxococcus fulvus strain Mx f65. It was active against Gram-positive bacteria (MIC 0.3 approximately 5 micrograms/ml), at higher concentrations also against Gram-negative ones (MIC 6 approximately 100 micrograms/ml), and not at all against yeasts and molds. The activity could be resolved into 4 closely related peptides, the myxovalargins. One of them, myxovalargin A, was by far the most plentiful. The compounds appear to be new antibiotics and seem to interfere with protein synthesis.

Anti-Bacterial Agents↗
PubMed1982

The myxovirescins, a family of antibiotics from Myxococcus virescens (Myxobacterales).

The myxobacterium, Myxococcus virescens strain Mx v48 produced a family of at least 12 closely related antibiotics, the myxovirescins. At a concentration of 1 to 5 micrograms/ml, the main component, myxovirescin A, was bactericidal for many Gram-negative bacteria, in particular enterobacteria, and at 20 to 50 micrograms/ml it also inhibited some pseudomonads and Gram-positive bacteria. The antibiotics seem to interfere with cell wall synthesis. The molecular formula of myxovirescin A was C35H61NO8. It is a new antibiotic.

Anti-Bacterial Agents↗
PubMed1978

Intracellular location of flexirubins in Flexibacter elegans (Cytophagales).

The inner and outer membranes of 2 strains of Gram-negative Flexibacter elegans, Fx e1 and Fx 3/4, could be separated on sucrose density gradients after the cells had been converted into spheroplasts, and the spheroplasts had been lysed in presence of EDTA and the detergent Brij 58. The light fraction (rho = 1.14 g . cm-3) contained the components of the respiratory chain in high concentrations, but only low amounts of the lipopolysaccharide component, 2-keto-3-deoxyoctonic acid, and was thus mainly material from the inner membrane. The heavy fraction (rho = 1.175 g . cm-3) contained only traces of respiratory chain enzymes, but the majority of the 2-keto-3-deoxyoctonic acid, and was thus mainly material from the outer membrane. The flexirubin pigments were found almost quantitatively in the latter fraction. Strain Fx 3/4 produced carotenoids in addition to flexirubins; in this case the flexirubins were located in the outer, and the carotenoids in the inner membrane.

Bacteroidetes↗
PubMed1976

The effect of transfer from low to high light intensity on electron transport in Rhodospirillum rubrum membranes.

The effects of transfer from low to high light intensity on membrane bound electrontransport reactions of Rhodospirillum rubrum were investigated. The experiments were performed with cultures which did not form bacteriochlorophyll (Bchl) for about two cell mass doublings during the initial phase of adaptation to high light intensity. Lack of Bchl synthesis causes a decrease of Bchl contents of cells and membranes. Also, the cellular amounts of photosynthetically active intracytoplasmic membranes decrease. In crude membrane fractions containing both cytoplasmic and intracytoplasmic membranes the initial activities of NADH oxidizing reactions increase only slightly (about 1.2 times) per protein, but the initial activities of succinate oxidizing reactions decrease (multiplied by a factor of 0.7). On a Bchl basis activities of NADH oxidizing reactions increase 3.4 times while activities of succinate dependent reactions increase 1.9 times. With isolated intracytoplasmic membranes activities of NADH as well as succinate dependent reactions increase to a comparable extent on a Bchl basis (about 1.8 times) and stay nearly constant on a protein basis. Cyochrome c oxidase responds like succinate dependent reactions. The data indicate that in cells growing under the conditions applied NADH oxidizing electrontransport systems are incorporated into both, cytoplasmic and intracytoplasmic membranes, while incorporation of succinate oxidizing systems is confined to intracytoplasmic membranes only. Activities of photophosphorylation and succinate dependent NAD+ reduction in the light increase per Bchl about 1.8 times. On a Bchl basis increases of the fast light induced "on" reactions at 422 nm and increases of soluble cytochrome c2 levels are comparable to increases of photophosphorylations and succinate dependent activities. But increases of slow light "off" reactions at 428 nm and of beta-type cytochrome levels become three times greater then increases of cytochrome c2 reactions and levels. These results infer that although electrontransport reactions of intracytoplasmic membranes change correlated to each other, Bchl, cytochrome c2 and beta-type cytochromes cellular levels are independent of each other. Furthermore, the data indicate that cytochrome c2 rather than beta-type cytochrome is involved with steps rate limiting for photophosphorylation.

Bacteriochlorophylls↗