Exploring of protein - protein interactions at the solid - aqueous interface by means of contact angle measurements.

In this article we present the results of the studies on interactions between the VC1 domain of the Receptor for Advanced Glycation End Products (RAGE) and its ligand, the S100B protein, performed by contact angle measurements. Histidine-tagged (His6) VC1-RAGE domain was covalently bonded to Cu(II) or Ni(II) complexes with dipyrromethene (DPM) self-assembled on gold surface. The method based on the theory of van Oss was used for the purpose of determining the Lifshitz-van der Waals (γ(LW)) component as well as the electron acceptor-electron donor (the Lewis acid-base, γ(+)-γ(-)) parameters of the VC1-RAGE-S100B complex. Moreover, the surface free energies of the interactions between the VC1 domain attached to the surface and the ligand present in the aqueous phase were determined. The specificity of the VC1- RAGE interactions with the ligand studied was also proved.

Fullerene modified supported lipid membrane as sensitive element of sensor for odorants.

A supported lipid bilayer membrane (s-BLMs) formed on a freshly cleaved metallic surface by the Tien method was applied for the design of an electrochemical sensor for detection of neutral odorant molecules. The lipid bilayer was modified by saturation with fullerene C(60), which possesses electron mediator properties and facilitates a redox reaction occurring at the border of the lipid membrane and metal surface. I(2)/I(-) and ferrocenyl trimethyl bromide were used as electroactive marker ions. The smell compounds adsorb on the surface of the lipid layer and change its structure. As a consequence the ratio of marker ion penetration to the lipid membrane is altered. The magnitude of these changes depends on the amount and chemical structure of adsorbed molecules. The research presented was carried out by cyclic voltammetry. The magnitude of the electrochemical signal generated by smell compounds was correlated with other parameters describing their molecular properties such as: octanol/water partition coefficients and dipole moments.

Potentiometric detection of organic acids in liquid chromatography using polymeric liquid membrane electrodes incorporating macrocyclic hexaamines.

Potentiometric detection employing coated-wire electrodes was applied to the determination of organic acids in liquid chromatography (LC). Poly(vinyl chloride)-based liquid membranes, incorporating lipophilic macrocyclic hexaamines as neutral ionophores were used as electrode coatings. The selectivity and sensitivity of the macrocycle-based electrodes were found to be superior to an electrode based on a lipophilic anion exchanger (a quaternary ammonium salt). Sensitive detection was obtained for the di- and tricarboxylic acids tartaric, malonic, malic, citric, fumaric, succinic, pyruvic, 2-oxoglutaric and maleic acids after separation in reversed-phase LC. Detection limits (signal/4sigmanoise=3) of 6 pmol for malonic acid and 2 pmol for maleic acid were attained. The detection was explained using a molecular recognition model. The hexaamine-based potentiometric electrodes had a 1-s response time at 1 ml min(-1) flow-rates. They were stable for at least 4 months, with an intra-electrode variation of 3.2% (n=5).

Polymeric liquid membrane electrodes incorporated with macrocyclic hexaamines for screening adenine nucleotides.

Lipophilic macrocyclic hexaamines supported by a poly(vinyl chloride) PVC matrix were used for the construction of liquid membrane electrodes sensitive toward adenine nucleotide polyanions. The membrane potential strongly depended on the pH of the sample solution. This phenomenon occurs due to the ability of the ionophore to accept protons. Therefore, the optimum pH was determined based on potential pH profile. The potential measurements were carried out at pH 6.0 in the presence of 10(-2) M 2-[N-morpholino] ethanesulfonic acid (MES) buffer. The potential response of these electrodes toward ATP(-4) and/or HATP(-3) was close to the Nernstian slope. The selectivities against ADP(-3), AMP(-2), HPO(4)(-2), and monovalent inorganic anions were estimated using the matched potential method. Chloride ions slightly affected potential response of the electrodes toward ATP(-4)/HATP(-3). The influence of ionophore chemical structure on the selectivity and the sensitivity of these electrodes is briefly discussed.

Contribution of membrane surface charge in the interaction of lead and tin derivatives with model lipid membrane.

The objective of this study was to determine the interaction of modified bilayer lipid membranes (BLMs) with lead and tin organoderivatives. The relative depolarization, of the lipid membrane, caused by organo metals, was used to estimate their activity. Dodecyltrimethylammonium bromide (TMDA) and sodium dodecylsulfonate (AS-12) were used to modify BLMs. The trialkylderivatives of tin (IV) were found to be the most active towards the lipid membrane, whereas dialkyltin (IV) and trialkyllead (IV) derivatives were less active. Also, a correlation exists between depolarization activity and the lipophilicity of organo metal hydrolysis products. The surface charge of modified membranes had a secondary influence on depolarization efficiency of the tin and lead derivatives.

[Epidemiology, pathogenesis and prognosis of gastric carcinoma in the light of clinical and statistical follow-up after gastrectomy (author's transl)]. / Epidemiologie, Pathogenese und Prognose des Magenkarzinoms unter Berücksichtigung klinischer und statistischer Nachuntersuchungen nach Gastrektomie.

Epidemiological, pathnogenetic and prognostic aspects of gastric carcinoma after a gastrectomy a long time previously are presented. Apparently an increase in the 5-year survival rate can only be achieved by an improvement in early diagnostic measures. Early, and consequently for a successful operation timely, recognition of early stages of a malignant tumor will possibly be improved by immunological methods when radiology, endoscopy, histology and cytology can no longer contribute to a considerable improvement of the diagnostic status now attained. A life worth living is possible after total or subtotal gastrectomy because initial deficiency states such as malabsorption etc. can be compensated by adaptation phenomena.

[Balance studies after gastrectomy, with particular reference to the risk factors for coronary heart disease (author's transl)]. / Bilanzstudien nach Gastrektomie unter besonderer Berücksichtigung von Risikofaktoren der koronaren Herzerkrankung

Balance studies in 15 patients who had undergone gastrectomy between 1957 and 1966 at the Heidelberg Surgical Hospital confirmed the suggestions in the literature that gastrectomied patients showed a reduced incidence of ischemic myocardiac diseases because of their altered living habits in relation to their age group. Consequently a gastrectomy is associated with a protective effect against the development of coronary heart disease, with underweight and hypotension having a particularly positive effect. This observation is not contradictory to the opinion that increased frequency of severe arteriosclerosis is supposed to be demonstrable in ulcer patients, because total and subtotal gastrectomies were carried out because of carcinoma.

Alpha 1-acid glycoprotein in gastric cancer juice.

Gastric juice was neutralized (nGJ) in vivo by 80 ml of a phosphate buffer containing radiolabelled vitamin B12 as dilution indicator. Unprocessed nGJ was analyzed in the double gel diffusion technique for the presence of serum proteins using monospecific antisera. Alpha1-Acid glycoprotein (AGP) was found in a high incidence (36 out of 38 subjects) in nGJ of gastric cancer patients. AGP was also observed less frequently in nGJ of patients with Billroth II resections (6/15), metaplasia (11/52), gastric ulcer (3/24), chronic atrophic gastritis (2/26) and chronic gastritis (3/63). AGP was absent in the control group (0/21), in patients with surface gastritis (0/38) and in subjects with normal acid secretion (0/45). Immunochemical studies demonstrated no identity of AGP with human "gastrointestinal tumor associated antigens." In 7 out of 17 AGP positive samples immunochemical differences between gastric and serum AGP were observed.