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Biomedical subjects

G Reuter

Publications and source records attributed to G Reuter.

241 records · Page 14Linked to original sources
PubMedDate not supplied

Time course of the endocochlear potential in the isolated cochlea of the guinea pig.

The temperature of Hanks' solution changed its potential (-0.48 mV/degrees C in Na(+)-Hanks' and -0.23 mV/degrees C in K(+)-Hanks' solution), but the pH had no clear effect on the potential. The time course of the endocochlear potential (EP) in the isolated cochlea of the guinea pig was measured under some different conditions. When the cochlea was moistened with Hanks' solution, negative EP increased gradually toward 0 mV at 124 min after death. When the cochlea was immersed in Hanks' solution, positive EP was obtained but it depended on the oxygen and the circulation of Hanks' solution. Moderate cooling (5 degrees C) of Hanks' solution had no significant effect on the EP of the isolated cochlea immersed in oxygen-saturated Hanks' solution circulated by oxygen bubbles. The space constant and the amplitude of the displacement responses were independent of the EP in the isolated cochlea. Thus, the positive EP might not show the physiological condition of the isolated cochlea.

Animals↗
PubMedDate not supplied

[Probiotics--possibilities and limitations of their application in food, animal feed, and in pharmaceutical preparations for men and animals].

Probiotics are cultures of special microorganisms, which have been used as feed additives since the seventies of the past century and already since the twenties in food specimen and in pharmaceuticals. The definition of "Probioticum" was formulated in 1974 simultaneously with the use of living cultures in feed for various animals in order to substitute the application of nutritive antibiotics or chemotherapeutics. In the meantime probiotics are applied not only as feed supplements or pharmaceuticals but increasingly in suitable food specimens such as dairy products, fruit juices, chocolates, and even meat products. Of course, heating of such products prior to consumption or application must be ruled out. The selection of a suitable strain of a microorganism can be regarded as the primary requirement for the use as a probiotic. These cultures must be able to pass the stomach-duodenum barrier in a viable state and to multiply at the site of destination in the intestine. Additionally, they must be capable of producing antagonistic metabolites against a dominating saprophytic microflora resulting in a competitive growth. These abilities are common among lactic acid bacteria, e.g. lactobacilli and bifidobacteria. Yet, intended autochthonous species do not possess very good technological features for the enrichment in food specimens, because their viability will decrease rapidly under unfavourable conditions as it is the case with mineral supplements in feed or with low acidity in fermented dairy products. Therefore, some other microorganisms like spore-forming species or yeast cultures were introduced as probiotic components. These possess some similar features which render them suitable for probiotic use. But their physiological and ecological traits do not qualify them as probiotics of first choice. The special efficacy of probiotics must be strictly verified in animal nutrition due to restrictive EC-regulations, in pharmacy due to legal restraints, and in food applications in accordance with food law regulations. Safety aspects are considered very restrictively in feed applications, in the food and pharmaceutical sector they should be in accordance with the intended purpose of "fulfilling health claims". In the presented review the different requirements for the application of probiotics in animal nutrition, in food, and in pharmaceuticals will be provided. The special effect of competitive exclusion of pathogenetic and toxinogenic microorganisms in fowl performance are mentioned and even the application of probiotics as marine aquacultures of fish and Crustaceae will be included. Furthermore, the safety aspects resulting from the tremendous amount of industrially produced cultures which are distributed into the environment will be discussed. In conclusion it may be pointed out that probiotics may serve to partially replace the presently reduced or even prohibited application of nutritive antibiotics or chemotherapeutics in animal nutrition and in fulfillment of health claims in man and animals. Economic and environmental aspects will reduce the overall application of probiotics world-wide. Restrictions of use and controls of efficacy and safety are essential and must be implemented periodically.

Animal Feed↗
PubMedDate not supplied

Functional and biosynthetic aspects of sialic acid diversity.

Sialic acids comprise a large family of N- and O-substituted neuraminic acid derivatives as components of glycoconjugates. N-Glycolylneuraminic acid is formed from N-acetylneuraminic acid by the action of the CMP-N-acetylneuraminic acid hydroxylase studied in various animals. O-Methylated sialic acids originate from the action of S-adenosylmethionine-8-O-methyltransferase studied in starfish. Sialic acids are O-acetylated at diverse positions by the action of acetyl-CoA-4-O- and -7-O-acetyltransferases found in various animals and, leading to the O-acetylation of sialic acid glycerol side chain, also in man. Some properties of these enzymes are described and biological implications discussed.

Acetyl-CoA C-Acetyltransferase↗