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W Fischer

Publications and source records attributed to W Fischer.

At least 163 records · Page 9Linked to original sources
PubMed1991

One-step purification of bacterial lipid macroamphiphiles by hydrophobic interaction chromatography.

Bacterial lipid macroamphiphiles extracted with phenol/water can be purified in one step by hydrophobic interaction chromatography. Lipids and the major part of protein are separated from macroamphiphiles during phenol/water extraction. Coextracted nucleic acids, polysaccharides, and residual protein are effectively removed by column chromatography on octyl-Sepharose whereby macroamphiphiles are primarily adsorbed and later eluted with a buffered propanol gradient. The procedure is applicable to macroamphiphiles with various lipid structures as was demonstrated using the diacylglycerol-containing lipoglycan of Micrococcus luteus, the lipid A-containing lipopolysaccharide of Salmonella typhimurium, and the diglyceryl tetraether lipoglycans of Thermoplasma acidophilum and Thermoplasma volcanicum. On elution from octyl-Sepharose, separation into molecular species of different compositions was observed with the lipopolysaccharide of S. typhimurium and the lipoglycan of T. volcanicum. It was also shown that, after phenol/water extraction, membrane lipids are completely recoverable from the phenol layer, which makes it possible to isolate lipids along with macroamphiphiles from the same sample of bacteria.

Chromatography, Agarose↗
PubMed1991

Separation of the poly(glycerophosphate) lipoteichoic acids of Enterococcus faecalis Kiel 27738, Enterococcus hirae ATCC 9790 and Leuconostoc mesenteroides DSM 20343 into molecular species by affinity chromatography on concanavalin A.

This study shows for the first time microheterogeneity of 1,3-linked poly(glycerophosphate) lipoteichoic acids. The lipoteichoic acids investigated were those of Enterococcus faecalis Kiel 27738 (I), Enterococcus hirae (Streptococcus faecium) ATCC 9790 (II), and Leuconostoc mesenteroides DMS 20343 (III). Lipoteichoic acids II and III are partially substituted by mono-, di-, tri-, and tetra-alpha-D-glucopyranosyl residues with (1----2) interglycosidic linkages. Lipoteichoic acid I is substituted with alpha-kojibiosyl residues only. Lipoteichoic acids I and III additionally carry D-alanine ester. Lipoteichoic acids were separated on columns of concanavalin-A-Sepharose according to their increasing number of glycosyl substituents per chain. It was evident that all molecular species are usually glycosylated and that alanine ester and glycosyl residues occur on the same chains. The chain lengths of lipoteichoic acid I and II vary between 9-40 glycerophosphate residues, whereas those of lipoteichoic acid III appear to be uniform (33 +/- 2 residues). Molecular species differ in the extent of glycosylation but their content of alanyl residues is fairly constant. All lipoteichoic acids contain a small fraction (5-15%) different in composition from the bulk and most likely reflecting an early stage of biosynthesis. Two procedures for chain length determination of poly(glycerophosphate) lipoteichoic acids are described.

Chromatography, Affinity↗
PubMed1991

Loss of AChE- and NGFr-labeling precedes neuronal death of axotomized septal-diagonal band neurons: reversal by intraventricular NGF infusion.

The time course of cellular changes in the medial septum (MS) and vertical limb of the diagonal band area (VDB) after a complete unilateral fimbria-fornix (FF) transection has been studied using prelabeling of the septohippocampal neurons by bilateral hippocampal injections of the fluorescent retrograde tracer Fluoro-Gold (FG), in combination with acetylcholine esterase (AChE) histochemistry and nerve growth factor receptor (NGFr) immunocytochemistry. The results show that the long-term disappearance of AChE-positive and NGFr-positive cells represents a combination of down-regulation of the marker proteins, cell shrinkage, and an actual cell loss. By 4 weeks after lesion the loss of FG-prelabeled cells amounted to 50% in MS and 30% in VDB. A further 25-30% of the MS neurons survived (as indicated by the presence of FG label), but were undetectable by the AChE and NGFr markers. Down-regulation of the marker proteins and cell shrinkage preceded the cell loss by more than a week: while shrinkage and reduced numbers of AChE/NGFr positive cells was evident already by 4-7 days, an actual cell loss (i.e., loss of FG-prelabeled cells) became evident only at 4 weeks after lesion. Continuous intraventricular NGF infusion (0.15 micrograms/day) was capable of counteracting all three types of changes. Infusion over 2 weeks reversed both atrophy and loss of AChE/NGFr staining, whereas infusion over 4 weeks completely prevented the later occurring cell loss. In addition, the NGF infusions induced significant hypertrophy in the undamaged cholinergic neurons in both nucleus basalis and striatum. It is concluded that down-regulation of marker proteins, such as AChE and NGFr, and cellular atrophy precede cell death in the axotomized septohippocampal system and that about 1/3 of the axotomized septal cholinergic neurons may survive for a long time in a down-regulated atrophic state. Exogenous NGF can prevent both the atrophic and the degenerative processes.

Acetylcholinesterase↗
PubMed1991

Stimulation of monokine production by lipoteichoic acids.

Lipoteichoic acids (LTAs) isolated from bacterial species, including Staphylococcus aureus, Streptococcus pyogenes A, Enterococcus faecalis, Streptococcus pneumoniae, and Listeria monocytogenes, were tested for their ability to stimulate the production of interleukin-1 beta (IL-1 beta), IL-6, and tumor necrosis factor alpha in cultured human monocytes. LTAs from S. aureus and S. pneumoniae failed to induce monokine production when applied in the concentration range of 0.05 to 5.0 micrograms/ml. However, LTAs from several enterococcal species (0.5 to 5 micrograms/ml) induced the release of all three monokines at levels similar to those observed after lipopolysaccharide stimulation. The kinetics of IL-1 beta and tumor necrosis factor alpha release elicited by LTAs closely resembled those observed following lipopolysaccharide application. Cytokine production occurred in the presence of both fetal calf serum and autologous human serum. Hence, it was not dependent on complement activation and could not be suppressed by naturally occurring human antibodies. Deacylation caused the total loss of monocyte stimulatory capacity. Deacylated LTAs were unable to prevent monocyte activation by intact LTAs, so primary binding of these molecules probably does not involve a simple interaction of a membrane receptor with the hydrophilic portion of the molecule. The results identify some species of LTAs as inducers of monokine production in human monocytes.

Acylation↗
PubMed1991

Hemodialysis and blood coagulation: the effect of hemodialysis on coagulation factor XIII and thrombin-antithrombin III complex.

Blood membrane interaction during hemodialysis (HD) regularly leads to stimulation of leukocyte function and related release of granular enzymes. The present study aimed to investigate the possible influence of an HD-induced release of granulocyte elastase on blood coagulation. Therefore a highly sensitive substrate of polymorphonuclear elastase, the plasma coagulation factor XIII and its subunits A and S were determined in the course of HD. Consumption of both subunit A and S have been previously shown to be due to proteolysis by elastase, whereas a decrease in subunit A will be typical for thrombin activation. Furthermore, the thrombin-antithrombin III complex (TAT) acting as a predisposition parameter for thrombotic events was measured during HD treatment. Apart from a virtual fall in factor XIII total activity simulated by heparin, no significant HD-induced consumption of factor XIII could be observed. There was also no indication of an elastase- or thrombin-related change in subunit concentrations. Predialysis values of the TAT complex were generally elevated in HD patients, but only patients with acute renal failure showed a constant increase of TAT during HD. These findings suggest that HD patients are exposed to a latent activation of coagulation resulting in an elevated thrombogenetic risk mainly due to the underlying disease. An additional coagulatory stimulation by the HD procedure seems to be restricted to cases of acute renal failure.

Acute Kidney Injury↗
PubMed1991

NGF improves spatial memory in aged rodents as a function of age.

Aged rats were tested for place navigation in a circular water maze for spatial memory ability at 18 and 30 months of age; 45% of the 18-month-old rats displayed impaired place navigation performance relative to young control rats, while essentially all of the 30-month-old rats were impaired. The aged impaired rats were retested twice during NGF or vehicle infusion in the right lateral ventricle. In the 18-month-old group, NGF-infused rats showed improved retention of previously acquired place navigation performance and improved spatial acuity over the former platform site when the invisible platform was removed. NGF infusion also had a significant effect in the much more severely impaired 30-month-old rats: while the vehicle-infused aged rats showed a progressive decline in the performance between the first and second test weeks, the performance of the NGF-infused rats remained stable throughout the infusion period. The interpretation of these effects in the oldest animals, however, was confounded by a progressive decline in swim speed seen in the vehicle-infused animals. The 30-month-old vehicle-infused control rats showed a significant cell loss and cell shrinkage relative to the young control rats in the septal/diagonal band area, the striatum, and the nucleus basalis as assessed by NGF-receptor (NGFr) and ChAT double-label immunocytochemistry. A significant increase in the size but not in the number of cells was observed on the side of the NGF infusion in the 30-month-old NGF-infused rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

Investigation on the dosage/efficacy relationship of iron dextran in veal calves.

The efficacy of a single dose of 800 mg resp. 1600 mg iron in the form of an intramuscularly administrable iron (III)-dextran complex (Anaemex, CAS 9004-66-4) has been tested. On 3 groups of 13 calves each, 0 ml (comparing group), 4 ml resp. 8 ml iron dextran 20% have been applied. All calves received iron-containing food during the test period of 10 weeks. At the beginning of the therapy, 5 weeks and 8 weeks after application, the parameters: weight, hemoglobin, erythrocytes, hematocrit, mean corpuscular hemoglobin (MCH), MCH concentration, mean corpuscular volume, plasma protein, fibrinogen, leukocytes and serum iron were measured. After 10 weeks the dead weight has been determined and the spleen of some calves tested histologically. The study shows that, by the administration of 1600 mg iron as a depot injection, a better growth results with the same quality of veal. The red-coloring of the veal was not significantly different from that of the comparing group. The histological findings show especially that the iron depots of the spleen were empty in all three groups and thereby in this collective no connection exists between the color of the veal and the tested dosage of iron dextran 20%. It is considered meaningful and economic to renounce in future the iron-containing food and in its place to apply intramuscular a single dose of 1600-2400 mg iron per calf. The results are compared with a study on full term infants, which has shown that a intramuscular single dose of 150 mg of iron as iron dextran at birth affords a nutritional advantage in iron status for up to 15 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[The projection of the locus coeruleus and the mesencephalic raphe nuclei to the hippocampal region of the rat: a study with horseradish peroxidase].

In this paper we have investigated in 20 Wistar rats the projection of the locus coeruleus (LC) and of the two mesencephalic raphe nuclei Ncl. raphe centralis superior (NCS) and Ncl. raphe dorsalis (NRD) to the hippocampus by using the HRP-technique. 1. The noradrenergic projection of the LC courses mainly ipsilaterally. On the contralateral side their are in the LC only a few labelled cells (about 10% of the labelled neurons on the ipsilateral side). On the ipsilateral side their is to observe an increasing of labelled cells in the rostro-caudal direction. Mainly in the caudo-dorsal region of the LC their are about 50% of the HRP-containing cells. The labelled cells belong to the medium-sized multipolar type, seldom they are fusiforme or ovoid. 2. In the NCS labelled cells are distributed throughout the whole nucleus but they are frequently to observe in the medium and caudal part near the midline. They belong to the multipolar and fusiforme cell type; labelled ovoid cells are rare. 3. The NRD contains labelled cells especially in the median and caudal part. The rostral part shows only a few HRP-containing cells. The labelled cells are mainly concentrated in the ventromedial NRD between the Fasciculi longitudinales mediales. The HRP-containing neurons are of multipolar, seldom of fusiforme or ovoid shape. In general, the number of labelled cells is higher in the LC than in the two raphe nuclei. After injection of HRP in the caudal part of the hippocampus or in the ventral hippocampus the number of labelled cells in the studied nuclei is lower than after injection into the rostral and medial part of the hippocampus. The results demonstrate that as well the noradrenergic as the serotonergic nuclei have an important connection with the hippocampus. The sources of this projection demonstrate a neurotopistic order. The functional importance of these connections is discussed.

Animals↗
PubMed1991

[Plasma and urine kinetics of amitriptyline oxide and its metabolites. Comparison of intravenous infusion and oral administration in volunteers].

The study objective was to obtain detailed information on the plasma and urine kinetics of amitriptylinoxide (CAS 4317-14-0) and its metabolites. For this reason, 60 mg of amitriptylinoxide was administered to 12 subjects, both by intravenous infusion and by oral dosage, in a study performed according to a randomized two-way cross-over design. In plasma, we succeeded in analyzing the metabolites amitriptyline and nortriptyline in addition to the parent substance amitriptyloxide. The tests for the parent substance amitriptylinoxide revealed maximum plasma levels of 721 and 686 ng/ml at 1.96 h (i.v. infusion) and 0.82 h (oral formulation), respectively. Mean values of 2331 (infusion) and 1714 h.ng/ml (oral formulation) were determined for the area under the curve from time 0 to infinity AUC (0-infinity). We also produced a comprehensive evaluation of amitriptyline, however, this was not possible for the metabolite nortriptyline. In urine, we succeeded in a reliable quantification of 4 metabolites, namely cis-OH-amitriptylinoxide, trans-OH-amitriptylinoxide, amitriptyline and OH-nortriptyline, in addition to the parent substance amitriptylinoxide. In individual samples, nortriptyline, cis-OH-amitriptyline and trans-OH-amitriptyline were additionally identified. In the course of the study, there were no reports or observations of any adverse reactions in addition to the side effects known for amitriptylinoxide from literature. There were no clinically relevant differences in tolerability observed between these two preparations.

Administration, Oral↗