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Biomedical subjects

A Wiese

Publications and source records attributed to A Wiese.

45 records · Page 3Linked to original sources
PubMed1996

Planar asymmetric lipid bilayers of glycosphingolipid or lipopolysaccharide on one side and phospholipids on the other: membrane potential, porin function, and complement activation.

We have determined some physicochemical properties of the monosaccharide-type fraction (GSL-1) of glycosphingolipids, the major glycolipid components of the outer leaflet of the Gram-negative species Sphingomonas paucimobilis. These properties included the state of order of the hydrocarbon moiety, the effective molecular area, surface charge density, and intrinsic transmembrane potential profile of reconstituted planar asymmetric GSL-1/phospholipid bilayer membranes. We have, furthermore, investigated the insertion into and the function of porin channels in the reconstituted bilayers and the complement-activating capability of GSL-1 surfaces. All results were compared with respective data for deep rough mutant lipopolysaccharide of Salmonella minnesota R595. We found a remarkable agreement in most functional properties of the two glycolipids.

Biophysical Phenomena↗
PubMed1994

Influence of the lipid matrix on incorporation and function of LPS-free porin from Paracoccus denitrificans.

We have studied the role of lipopolysaccharide (LPS) for the insertion of LPS-free porin from Paracoccus denitrificans into planar lipid bilayers and its function therein. For this, we reconstituted the porin into different asymmetric planar lipid bilayers with or without LPS and into symmetric phospholipid bilayers. LPS-free porin added to the various bilayer systems was found to induce a step-wise increase in membrane conductance with different incorporation rates, depending on the presence of LPS in the bilayer leaflet opposite to porin addition. The incorporation rate into asymmetric LPS/phospholipid membranes from the phospholipid side was more than 10-fold higher than that observed for pure phospholipid membranes. The porin formed general diffusion pores without any salt specificity. The mean single-channel conductance did not depend on the presence of LPS and was about 4.2 nS for a subphase containing 1 M KCl in all systems tested. At certain applied transmembrane voltages, which depended on membrane composition and were approximately greater than 100 mV for the LPS/phospholipid system, single-channel closing in three steps was observed. Differences in the voltage dependence of porin-channel closing could be correlated with the surface charge of the bilayer. From the voltage-dependent gating behaviour proof for an oriented incorporation of the porin molecules, depending on the side of porin addition, and evidence for their orientation could be derived. Measurements at temperatures above and below the beta<==>alpha phase transition temperature of LPS gave evidence for the influence of membrane rigidity on the gating behaviour.

Carbohydrate Sequence↗
PubMed1993

Fingertip injuries management with semi-occlusive dressing.

We have developed a simple, cheap and efficient method of management of fingertip injury using a semi-occlusive dressing ("Opsite"--Smith and Nephew). The fingertip is covered with the "Opsite" once a week only. The dressing provides a temporary "skin", making the finger painless. This semi-occlusive "skin" allows the healing environment to reach an optimal milieu (e.g. pH, oxygen, tension, immunoagents) actively promoting granulation tissue formation and epithelialization. The result of 200 fingertip injuries treated with this method proves the development of a near normal pulp shape and useful epithelium within an average of 20 days.

Amputation, Traumatic↗
PubMed1993

Quality of life in patients with Addison's disease: effects of different cortisol replacement modes.

This study compares the impact of different modes of cortisol replacement therapy on the health perception and general well-being in patients with primary adrenocortical failure. 14 adults (8 female, 6 male) with Addison's disease on chronic cortisol replacement participated in the study. In a randomized double-blind cross-over design, all patients were treated with 3 modes of cortisol replacement for one week each (mode I: 20 mg hydrocortisone (HC) at 0700 h and 10 mg HC at 1900 h; mode II: 30 mg HC at 0700 h and placebo at 1900 h; mode III: placebo at 0700 h and 30 mg HC at 1900 h). Following the third week, the replacement modes were repeated in a different random order. For quality-of-life assessment the patients completed three different questionnaires (Addison-questionnaire, Basler Befindlichkeits-Skala, Beschwerde-Liste) and were interviewed about their general contentment at the last day of each treatment week. General well-being in terms of subjective contentment was best established during mode I (in 64% of patients) and less often stated with mode II (in 29%) and III (in 14%) (p < 0.05 mode I vs III). With the twice-daily replacement (mode I), sum scores of all questionnaires were changed towards improvement compared to both once-daily regimens (p < 0.05 vs mode II and III), but did not reach normal values of healthy subjects. Differences between mode II and III were insignificant. We conclude that quality of life in Addison patients is mainly influenced by the mode of cortisol replacement therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Addison Disease↗
PubMed1975

Effect of prednisolon on cell metabolism of candida.

In vitro effects of 2 water-soluble prednisolon-derivatives on 10 Candida albicans and 10 Candida tropicals species were investigated. Tests were performed during resting and proliferation phases. Changes of cell metabolism were measured by O2-consumption by the Warburg technique. With increasing corticosteroid concentrations (10-10000 gammaml) a dose dependent increase of cell respiration was found with and without addition of nutritive substrates. Even high concentrations of corticosteroid did not cause an antimetabolic effect. The tests did not yield different results for the two Candida species examined.

Agar↗
PubMedDate not supplied

The dual role of lipopolysaccharide as effector and target molecule.

Lipopolysaccharides (LPS) are major integral components of the outer membrane of Gram-negative bacteria being exclusively located in its outer leaflet facing the bacterial environment. Chemically they consist in different bacterial strains of a highly variable O-specific chain, a less variable core oligosaccharide, and a lipid component, termed lipid A, with low structural variability. LPS participate in the physiological membrane functions and are, therefore, essential for bacterial growth and viability. They contribute to the low membrane permeability and increase the resistance towards hydrophobic agents. They are also the primary target for the attack of antibacterial drugs and proteins such as components of the host's immune response. When set free LPS elicit, in higher organisms, a broad spectrum of biological activities. They play an important role in the manifestation of Gram-negative infection and are therefore termed endotoxins. Physico-chemical parameters such as the molecular conformation and the charges of the lipid A portion, which is responsible for endotoxin-typical biological activities and is therefore termed the 'endotoxic principle' of LPS, are correlated with the biological activity of chemically different LPS.

Anti-Bacterial Agents↗