Biomedical subjects

O Ludwig

Publications and source records attributed to O Ludwig.

At least 19 recordsLinked to original sources

PubMed1991

[Automobile driving studies to determine alcohol-induced driving insecurity after dark].

To further elucidate the question whether the criteria for assessing alcohol-induced unfitness to drive should be stricter for night-time than for day-time driving (cf. Schewe et al., 1977) 64 test persons performed automobile driving tests in daylight and in darkness while being sober and while under the influence of alcohol. The first set of tests was done in daylight. A test course of approx. 600 m involving six everyday driving maneuvers had to be covered, first in the sober state and then at blood alcohol concentrations (BAC) of 1.1 g % and 1.4 g %. The driving tests in the dark were performed on the same test course, first in the sober state and then at a BAC of 1.1 g%. In both test series the errors were counted and the driving times measured. Statistical evaluation of the test results was done parametrically (t-test for dependent random samples) and distribution-free (Wilcoxon's test for paired comparison). In the sober state 2.1 errors were made on average during the day and 3.2 errors, i.e. one error more, at night. At 1.1 g %, 4.3 errors occurred during the day but 8.0 errors at night (i.e. 3.7 errors more than during the day). The differences were statistically significant. With 8 errors during night-time driving at 1.1 g % the number of errors was still higher than the average number of 6.8 errors made during day-time driving at 1.4 g %. The average driving times required in the sober state were 241 s during the day and 256 s at night. At 1.1 g %, 243 s were needed during the day and 272 s at night, i.e. on average 17 s more than for day-time driving at 1.4 g % for which 255 s were needed. For an orienting comparison of driving performance it can be assumed that "performance" in the sense meant here is reciprocally proportional to the number of errors and reciprocally proportional to the time required, i.e. on the whole reciprocally proportional to the product from number of errors and time. The deterioration of performance can be illustrated best by assuming performance in the sober state during the day to be 100% and relating the other "performances" thereto.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

[Forensic value of analytic results from less than 5 (4) blood alcohol values of a blood sample].

1. If the material for blood-alcohol examinations is insufficient under the existing regulations (specification in the GUTACHTEN DES BUNDESGESUNDHEITSAMTES) it is possible to determine the mean value almost certainly, estimating the confidence-interval. This mean value can be taken as basis of the opinion with regard to safe driving. 2. The proposed statistical procedure is described and compared with other suggested calculations. 3. Testing the proposed procedure by means of 1,426 real data, the usefulness of the proposed calculation is shown.

Accidents, Traffic↗

PubMed1989

Porin of Paramecium mitochondria isolation, characterization and ion selectivity of the closed state.

Porin was isolated and purified from mitochondria of Paramecium tetraurelia. The protein showed a single band of apparent Mr 37,000 on sodium dodecyl sulfate polyacrylamide electrophoretograms. The reconstitution of the protein into artificial lipid bilayer membranes revealed it to be a porin giving pores with an average single-channel conductance of 0.26 nS in 0.1 M KCl. This conductance is about half of that of other eukaryotic porins studied to date. The pore formed by the mitochondrial porin of Paramecium was found to be voltage-dependent and switched to a defined substrate at membrane voltages larger than 20 mV. In the open state the pore exhibited the characteristics of a general diffusion pore because the mobility sequence of the ions inside the pore was similar to that in the bulk aqueous phase. The effective diameter was estimated to be about 1.3 nm. The properties of the low conductance state of the pore were studied in detail. In this state the pore favored the passage of cations, in contrast to the open state which favored anions slightly. The possible role of the low-conductance state in the regulation of transport processes across the outer mitochondrial membrane and in mitochondrial metabolism is discussed.

Animals↗

PubMed1988

Purification and characterization of the pore forming protein of yeast mitochondrial outer membrane.

One of the major outer membrane proteins of yeast mitochondria was isolated and purified. It migrated as a single band with an apparent molecular weight of 30 kDa on a SDS-electrophoretogram. When reconstituted in lipid bilayer membranes the protein formed pores with a single channel conductance of 0.45 nS in 0.1 M KCl. The pores had the characteristics of general diffusion pores with an estimated diameter of 1.7 nm. The pore of mitochondrial outer membranes of yeast shared some similarities with the pores formed by mitochondrial and bacterial porins. The pores switched to substates at voltages higher than 20 mV. The possible role of this voltage-dependence in the metabolism of mitochondria is discussed.

Intracellular Membranes↗

PubMed1987

Porin pores of mitochondrial outer membranes from high and low eukaryotic cells: biochemical and biophysical characterization.

The mitochondrial porins from mammalian tissues and from low eukaryotic cells were purified with a high yield, and their biochemical and functional properties were investigated. When analyzed by SDS gel electrophoresis, all mammalian porins show a very similar apparent molecular mass (35-35.5 kDa). In contrast yeast and Paramecium porins have a molecular mass of 30 and 37 kDa, respectively. The peptide maps of mammalian porins are very similar although small differences are apparent between porins of different tissues of the same organism and also between those of the same tissue of different organisms. The peptide patterns of porins from yeast and Paramecium are completely different from those of mammalian porins. Antibodies raised against the rat liver porin cross-react with all the other mammalian porins but not with that of yeast. The incorporation of porins into artificial lipid bilayer membranes showed that they are able to form pores with approximately the same specific activity. The single-channel conductance is for all porins, except for that of Paramecium, about 4 nS in 1 M KCl, corresponding to an effective pore diameter of 1.7 nm. They are voltage-dependent and switch to substates at transmembrane potentials higher than 10 mV. The number of gating charges varies, however, for pores from different tissues, indicating a different sensitivity to the potential as a result of a possible different function.

Adenosine Triphosphate↗

PubMed1986

Pore formation by the mitochondrial porin of rat brain in lipid bilayer membranes.

The porin of the outer membrane of rat-brain mitochondria was isolated and purified. The protein showed a single band of apparent Mr 35,500 on dodecyl sulfate-containing polyacrylamide gels. The incorporation of rat-brain porin into artificial lipid bilayer membranes showed that it is able to form pores with an average single-channel conductance of 400 pS in 0.1 M KCI. The pores were found to be voltage-dependent and switched to substrates at higher transmembrane potentials. The voltage-dependence of the rat brain pore was considerably smaller than that of the other known eukaryotic porins. The possible role of the rat-brain porin in the regulation of transport process across the outer mitochondrial membrane is discussed.

Animals↗

PubMed1986

Capsaicin fails to produce disturbances of autonomic heat and cold defence in an avian species (Anas platyrhynchos).

Capsaicin was intravenously administered to adult domestic ducks of 1.8-2.6 kg body weight, with a cumulative dose of 1.0 g/kg body weight given in 4-6 single infusions at intervals of 2-3 days. There were no acute, nociceptive or hypothermic effects, as typically seen in mammals. Before and after capsaicin treatment respiratory evaporative heat loss (REHL, w X kg-1), breathing frequency (BF, min-1) and metabolic heat production (M, w X kg-1) were determined in a warm environment (35-38 degrees C) as a function of core temperature, measured in the esophagus (Tes), which was altered by graded heat extraction with a colonic thermode. Capsaicin treatment reduced the rate at which REHL increased with increasing BF, however, this was compensated by a steeper increase of BF with rising Tes so that the relationship between Tes and REHL remained unchanged. The Tes threshold for activation of M was increased by 0.3 degrees C and the slope reduced by 27% after capsaicin, but identical maximum M values were attained before and after capsaicin at identical degrees of hypothermia. Skin temperature measurements revealed no influence of capsaicin on the threshold Tes values for skin vasoconstriction. It is concluded that capsaicin fails to exert effects in birds on those afferents and central neurons which are involved in thermo- and nociception, in contrast to mammals in which these perceptive functions become severely impaired.

Animals↗

PubMed1978